Showing posts with label EQUUS Magazine. Show all posts
Showing posts with label EQUUS Magazine. Show all posts

Friday, September 28, 2018

Applied genetics

Dozens of genetic tests are now available that can offer insights into equine health, coat color and even performance potential. Here’s what they can and can’t tell you.

ABIGAIL JEFFERIES NOV 17, 2017

Turn on the radio or television and you can’t miss them: Advertisements for genetic testing are almost as common as commercials for laundry detergent and auto insurance. Just a decade or two ago, such ads were unheard of. Yet today, genetic testing services---for animals as well as people---are more numerous, more accurate, more affordable and more convenient than ever.

“What most folks don’t know about genetics is really how advanced it has become,” says Christa Lafayette, CEO of Etalon Inc. of Menlo Park, California. “Genetics is the new smartphone. Think back to when you first heard someone say, ‘There’s an app for that,’ and you had no concept as to what, exactly, an ‘app’ was. Now they are completely taken for granted and just common knowledge. That is where genetics is headed.”

The first genetic tests for horses became available in the 1990s, and for many years they were used only occasionally. Dozens of tests are now available. Most are being used in breeding decisions that will shape future generations of horses, but others offer insights into the health, beauty and potential of horses here today. As genetic tests become increasingly affordable and accessible, the role they will play in the horse world will only continue to grow.

Identifying inheritable diseases

Many inherited diseases result from single gene mutations that cause changes in how the body functions. The mutation is considered dominant if a foal needs to inherit only one copy of the defective gene to be affected by the disease. If the mutation is recessive, the foal needs to inherit two copies of the defective gene, one from each parent, to be affected. A horse with only one copy of the recessive gene is a carrier---he may be completely normal but is capable of producing a foal with the disease when mated to another carrier (see “Basics of Inheritance,” page 40). A mutation is considered incomplete dominant if a horse with one copy of the mu- tated gene is more mildly affected and a horse with two copies is more seriously affected.

Most tests for heritable diseases are breed specific, and some organizations require testing for particular genes prior to registering breeding stallions to limit the prevalence of certain conditions in the population.

Since 2015, for instance, the American Quarter Horse Association (AQHA) has required all registered breeding stallions to undergo a five-panel test for the following genetic diseases:

• glycogen branching enzyme deficiency (GBED), a fatal condition caused by the body’s inability to store glycogen, resulting in progressive weakness and organ failure

• hereditary equine regional dermal asthenia (HERDA), a connective-tissue disorder which causes fragile skin that tears easily and is so slow to heal and prone to infections that euthanasia is often the most humane option

• hyperkalemic periodic paralysis (HYPP), which is characterized by episodes of muscle weakness and tremors and, in severe cases, collapse and respiratory or cardiac failure

• malignant hyperthermia (MH), a condition in which extreme stress, exercise or anesthesia triggers muscle rigidity, fever, excessive sweating, shallow breathing and an irregular heart rate

• polysaccharide storage myopathy type 1 (PSSM1), which causes an abnormal accumulation of sugars in the muscles leading to cramping, tremors and characteristic dark urine as the kidneys flush the byproducts of muscle damage. Note: Although testing for PSSM1 is required for Quarter Horse breeding stallions, the disease has been found in more than 20 breeds, including several drafts and warm- bloods with European bloodlines as well as American stock horses.

In addition, a test can determine whether Quarter Horses carry the gene for androgen insensitivity syndrome, which causes males horses to have female physical attributes, but it is not required for registration of breeding animals.

Beginning January 1, 2018, the American Paint Horse Association will require all breeding stallions to undergo the genetic tests in the AQHA five-panel profile, plus one other, overo lethal white syndrome (OLWS), which produces foals who are born almost pure white and have undeveloped nerves in the intestinal tract, making it impossible to process food and pass feces. OLWS appears in Paint Horses as well as mustangs, Spotted Saddle Horses and any other breeds that can show a frame overo coat pattern.

While other registries may not require genetic testing for diseases right now, many other tests for breed-related conditions are available, including:

• congenital stationary night blindness (CSNB), which is limited or no nighttime vision caused by a gene linked to the leopard-spotted coat pattern. Leopard spots are best known as a breed-defining pattern in Appaloosas and Pony of the Americas but can also occur in other breeds such as the Knabstrupper, Noriker and some Spanish mustangs.

• junctional epidermolysis bullosa (JEB), which inhibits the production of proteins that help adhere the skin to the body, leading to blistering, sloughing of skin and fatal infections. JEB was first discovered in Belgians (Belgian-JEB); a form of the condition is also found in Saddlebreds (Saddlebred-JEB), although the genetic cause is different.

• severe combined immunodeficiency disease (SCID), which inhibits the body’s ability to produce white blood cells that play a vital role in immune functions, and lavender foal syndrome (LFS), which causes several neurological signs. Both of these are found in Arabians, along with cerebellar abiotrophy (CA), which causes the death of neurons in the cerebellum that affect balance and coordination, and is occasionally found in other breeds.

• ocular squamous cell carcinoma (SCC), a type of tumor that appears on the edges of the eyes and on the third eye- lid, in Haflingers

• warmblood fragile foal syndrome (WFFS), which causes fragile skin that tears easily and is slow to heal, lax joints that may prevent standing, and lesions within the mouth.

Knowing a horse’s genetic status can help an owner make more informed management decisions. If you know your horse is susceptible to ocular SCC, for example, you can make sure to protect him from sun exposure with a fly mask and take other precautions to try to prevent the condition or at least catch it early. Genetic testing is also becoming a common part of prepurchase exams.

While horse owners may find genetic tests useful, breeders are their primary users. By identifying stallions and mares with one copy of recessive genes associated with certain diseases, breeders can avoid mating carriers to other carriers to avoid producing affected foals.

But that doesn’t mean carriers can’t be bred at all---in many breeds, removing all carriers from the breeding pool would severely limit genetic diversity. “If we were to eliminate all horses that had one copy of one of the five-panel disorders, we would probably eliminate 30 to 40 percent of all American Quarter Horses, thus greatly reducing the gene pool,” says Arne de Kloet, director of Animal Genetics in Tallahassee, Florida.

By breeding carriers of undesirable genes only to noncarriers, breeders can avoid producing foals with recessive diseases while still preserving other desirable traits these horses may have. “Animal Genetics reports all SCID test results to the Arabian Horse Society,” says de Kloet. “Interestingly, the number of carriers we see is almost the same as it was 15 years ago, but the number of homozygous [horses with two copies of the mutation] positives we see is almost zero. This tells me people have been breeding smart. If I have a stallion that has one copy of SCID, I’ll never breed him to a mare that also has a copy of SCID, and we’ll never have a problem. This enables horses with many great qualities to remain in the breeding program.”

Currently, genetic testing is required only for Quarter Horse breeding stallions, but many breeders are opting to test prospective broodmares of the breed as well. “There is both breeder wisdom and market pressure pushing increased testing of mares,” says Cecilia Penedo, PhD, director of the Veterinary Genetics Laboratory of the University of California–Davis.

Even with the new information that genetic tests can provide, breeding decisions still require a balancing act. “Some mutations have been maintained for advantage,” says Kathryn Graves, PhD, director of the Animal Genetic Testing and Research Laboratory of the Gluck Center at the University of Kentucky. “The PSSM1 mutation may have given working draft horses superior abilities to pull or carry heavy loads. The mutation that has given us the beloved Appaloosa color pattern that can also be associated with night blindness, but do we want a world without Appaloosas? We have to be careful not to make our first response a rush to eliminate all mutations. The irony is that genetic testing is giving us new tools to undo the results of our own selective breeding.”

Colors, patterns and parentage

Genetic analysis isn’t all about health, though. Tests are also available that provide insight into your horse’s coat color, patterns and parentage ---traits that may seem obvious at first, but a peek at your horse’s DNA can reveal surprising or otherwise un-knowable information.

Testing can determine whether a horse carries one, two or no copies of the genes required for more than a dozen coat colors and patterns. These include

• base colors, which will be either black, red or bay.

• dilution factors, which are five testable genes that modify the color of the base coat. These are champagne, cream, dun, pearl and silver.

• patterns, which are genes that eliminate pigment and produce white hairs on the body, including dominant white, gray, tobiano, splashed white, overo, sabino, leopard complex and roan.

Tests for coat colors and patterns are relatively inexpensive, and they can be used by owners who simply want to know what color their horses are. Many coat colors can look very similar ---a palomino, for example, can be hard to distinguish from a silver-dappled bay---and if a horse’s parentage isn’t known, the only way to be certain is by a genetic test.

Mostly, however, genetic tests for coat colors and pattern are used by breeders who want to be able to predict what colors their mares and stallions can produce. This capability has both pros and cons, if too strong a focus on coat colors or patterns outweighs other desirable traits.

“There is a definite danger there,” Graves says. “We have seen this happen in some breeds already. For example, if a registry has strict color requirements and horses of any other color are excluded, the breed runs the risk of becoming inbred, which may bring consequences such as infertility or an increase in the prevalence of other undesirable genetic traits.”

These tests are more critical in the case of the frame overo pattern. Breeders need to identify horses who carry this mutation to avoid producing a foal with lethal white syndrome. One of the splashed white genes may also produce lethal white foals, but that connection has not been proven.

Finally, confirming parentage of a horse was one of the original uses of genetic testing and remains one of the most common. A number of breed organizations require that foals have their parentage confirmed before they can be registered. These tests require the submission of hair samples pulled from the foal as well as from both his sire and dam. If the sire is uncertain, then samples can be submitted from all possible sires.

By comparing inheritable traits in the DNA, these tests can confirm a foal’s parentage with efficacy greater than 99 percent; an incorrect sire can also be excluded with 100 percent certainty. “We compare the genetic profile of the sample of mane or tail hair submitted to our database profiles of the sire and dam,” Graves says. “We verify the parents and send those reports to the registries.” However, these tests do not reveal the breed of an individual horse.

Owners seeking to register their horses are the most common users of equine genetic testing. “The DNA test for parentage verification represents the largest number of samples tested,” Penedo says. “Most horse breed registries now require DNA testing for registration, which translates to hundreds of thousands of horses being tested yearly around the world.”

What lies ahead?

Like many other technologies, genetic testing is becoming faster, more affordable and thus more accessible. “The cost of sequencing a horse’s entire genome is coming down,” Graves says. “Today, this can be done for about $8,000 to $10,000. Soon, perhaps within 10 years, it will cost only about $1,000. At that point, the average horse owner will be able to sequence her horse’s entire genome.”

The challenge, says Graves, will be determining how best to use this information. “We still have a lot of work to do before we will know that,” she says. “We need to create maps of each breed of horse. This will enable us to look for desirable performance traits or for genetic anomalies in a horse that has chronic health problems.”

Could genetically engineered “super horses” appear in the future? Possibly, with a new technology called “gene editing,” which Penedo describes as using “molecular scissors” to insert, remove or replace DNA sequences in the laboratory. “I can envisage that it will be tried in horses, but given the costs it is unlikely to become common practice,” she says. One application of this technology that she does foresee, however, “would be to correct the DNA sequence in an early embryo from highly valuable parents that is affected with a genetic defect, as determined from pre-implantation embryo genetic testing. The expectation is that the defective gene could be replaced by a normal gene, and the ‘edited’ embryo could then be implanted.”

In the meantime, the number of specific tests available---both for diseases as well as other aspects of a horse’s health and physiology---will likely continue to grow as researchers learn more about equine genetics. “It is a constantly evolving field,” de Kloet says. “Just as with human genetics, it’s going to change and evolve in the number of tests available and with regard to how the testing is being done. We have software programs and the computer ability to go through and look at a billion nucleotides in only a couple of days.”

To help with further research, Etalon Diagnostics offers several tests to the public, for conditions such as lordosis (“swayback”), that are in the “discovery stage”---that is, although there is some evidence of genetic factors for these conditions, the results of these specific tests have not been fully validated by research studies. Etalon’s goal is to gain feedback from owners to help support the research.

“Our platform is collaborative, meaning that it relies in part on feedback from horse owners,” Lafayette says. “We look for associations between certain genetic mutations and performance or other health traits based on emerging research data. When we see a pattern that suggests a genetic link, we follow up with horse owners and track the input we receive from them. This leads to the discovery or confirmation of connections between genetic mutations and resulting traits faster than would be possible if we were to go the conventional research grant route.”

Lafayette admits, however, that this approach is still a work in progress: “Since this kind of horse- owner-driven research platform has never been attempted before, the learning curve is steep,” she says. “We have to continually adjust our methods, studies, and the way we approach and present the information.”

The demand for genetic testing is already large and is likely to continue to grow in the coming years as the technology develops and new tests become available. Already, says Lafayette, labs like hers are receiving all kinds of requests from people who want more information about their horses: “Big ones, little ones, wild ones and pocket ponies, all colors, all disciplines. People want to know everything from color and health to speed and gait. Folks are excited to talk and learn more about their horses, as are we.”

This article first appeared in the August 2017 issue of EQUUS (Volume #379)

SIDEBAR

Performance and personality testing

While genetic tests for diseases, colors and parentage can provide DNA “proof” of a condition, those looking for genes associated with performance-related traits yield less definitive information. How or whether these genes are expressed can be influenced by training, environment and other factors.

For instance, performance testing, aimed primarily at Thoroughbreds, looks at multiple genes to attempt to predict a horse’s speed, stamina and overall potential for success at the racetrack. One factor these tests analyze is the myostatin gene, which controls the amount of muscle mass developed. Other components of the tests may predict a foal’s height at maturity as well as whether he will do better on dirt versus turf tracks.

Gait testing identifies a mutation on the DMRT3 gene that influences a horse’s ability to perform lateral gaits. The mutation is recessive—horses with two copies of the gene are common in Icelandic Horses, Paso Finos, Tennessee Walking Horses and other gaited breeds. The effects of carrying only one copy of the mutation varies by breed, but those horses generally perform the lateral gaits with less speed and facility.


Having a particular “performance” gene isn’t a guarantee, however. After all, many a racing phenom has had full siblings who washed out at the track, and every so often a horse with a modest pedigree takes the show world by storm. DNA is only part of the equation.

Another test, described by its manufacturer as “curiosity vs. vigilance,” analyzes a mutation that affects dopamine0 receptors in the horse’s brain. Horses with two copies of the recessive gene are defined as more curious—that is, more inclined to take an interest in and approach new objects. Horses with only one or no copies of the gene are more vigilant, or less inclined to explore their surroundings.

“An oversimplified example of this might be that horses who test positive for ‘curiosity’ might outperform those who do not in, say, a trail competition,” says Christa Lafayette, CEO of Etalon Inc. of Menlo Park, California, who adds that the real utility of the test will only be known once owners begin interpreting the results. “It’s going to be interesting to see what owners say about it and whether or not they find a correlation between curiosity/vigilance and certain types of activity.”

This article first appeared in the August 2017 issue of EQUUS (Volume #379)

Answers about ancestry

For as much as equine genetic testing has expanded over the years, one type of test isn’t available yet. “We don’t yet have a test that can tell us what breed or mix of breeds is in an individual horse,” says Kathryn Graves, PhD, of the Gluck Center at the University of Kentucky. “We would be very popular if we could offer this test, because we get requests for it several times each week.”

The challenge is that many of our modern breeds descend from the same foundation stock, and researchers don’t yet have enough genetic profiles of individual horses of different breeds to be able to distinguish them. “While breed identification of purebred horses is more easily done, determination of breed contributions in crossbred horses is a far more complex problem,” says Cecilia Penedo, PhD, of the University of California–Davis. “Perhaps in the near future, this limitation may be overcome by careful selection of DNA markers for breed composition tests to become more informative and accurate.”

This article first appeared in the August 2017 issue of EQUUS (Volume #379)

BY ABIGAIL JEFFERIES

Friday, August 10, 2018

Bring Out Your Horse's Shine


CHRISTINE BARAKAT WITH MELINDA FRECKLETON, DVMOCT 1, 2017

While grooming trends vary among breeds and disciplines, a shiny horse is a head-turner in any arena. Some horses “bloom” more naturally than others, but there are some steps you can take to bring out the shine in any horse’s coat.

1. Don’t bathe him too often. The deepest shines come from the natural oils produced by your horse’s skin. Bathing too often strips this oil, so while your horse may technically be cleaner, his coat may be left looking dull. Skip the soap when you can, removing dirt with brushes and using only plain water to rinse your horse after a sweaty summer ride.

2. Lay on the elbow grease. Regular, vigorous hand grooming spreads oil throughout your horse’s coat, contributing to shine. Even after visible dirt has been removed, spend another 10 minutes brushing your horse to bring out a sheen. A soft brush works best for this final touch, or you can use a clean hand towel and wipe over your horse in the direction of coat growth using a slight bit of pressure.

3. Feed him right. Good basic nutrition is the foundation of a healthy coat, so ensure your horse is getting the correct amounts of quality feed. From that start you can consider adding a supplement intended to bring out the best in his coat. These supplements typically include some combination of biotin and omega-3 fatty acids.

4. Use a finishing spray. A light spritzing with a “shine” spray can put your horse’s glow over the top. There are many formulations of coat polish to choose from with different ingredients, actions and scents. Some of these sprays can make a horse’s coat slick, however, so be careful when applying it to hair you’ll need to braid later or on areas where tack will sit.

This article first appeared in the July 2017 issue of EQUUS (Volume #378)

Thursday, June 21, 2018

The challenge of EPM

Early detection and treatment are the keys to helping a horse recover from this neurological disease.

When your previously sure-footed horse starts to stumble regularly…. Or you notice his lip drooping and he’s dropping feed…. Or his gaits just seem to lack that usual smoothness under saddle….

Signs like these may be subtle, especially at first, but it is not good to overlook them. In fact, any persistent change in the way a horse uses his body---including his resting stance, his gaits, how he carries his tail, the pattern of his sweat, generalized weakness, a drooping ear or tilted head---could be a sign that he is developing a neurological disorder.

And one common neurological disease affecting American horses is equine protozoal myeloencephalitis (EPM). Horses may develop EPM after ingesting feed or water contaminated with Sarcocystis neurona, a one-celled organism called a protozoan, that is spread by opossums and carried by other animals. Less commonly, a different protozoan called Neospora hughesi may also cause EPM.

Most horses who encounter the organisms that cause EPM put up an immune response that fights off the infection. Sometimes, however---in less than 1 percent of exposed horses---the protozoa cross into the central nervous system and damage the brain and spinal cord. Several drug treatments are available that can curb the protozoal infection, but the damaged nerves will still require up to a year or more to heal, and some horses never recover completely. Relapses are common if the protozoal populations are able to rebound after treatment ends. A horse’s chances of a full recovery are better when treatment is started early, before the damage is too severe.

The most common signs of the disease are weakness and incoordination (ataxia), primarily in the hind limbs. Often, the effects are asymmetrical---one hind leg will be affected more than the other. As the disease progresses, the horse may develop muscle atrophy. In rarer cases, if the disease affects the brain, signs may include facial paralysis, seizures, difficulty swallowing, head tilt and behavioral changes.

Diagnostic difficulties

Determining whether a horse has EPM can be difficult. Because most who are exposed to the protozoa never develop the disease, the presence of antibodies alone is not enough for a diagnosis. A horse who is positive for antibodies to one of the protozoa could still have neurological signs due to some other cause.

That said, however, some of the newer testing methods---an indirect immunofluorescence antibody test (IFAT) and enzyme-linked immunosorbent assays (ELISAs)---can be used to determine the titer (the concentration of antibodies) in a blood sample. Although these types of test results are not a definitive diagnosis, many veterinarians consider a higher titer, along with neurological impairment, to be evidence of probable EPM.

The most definitive type of testing looks for antibodies to the protozoa in the cerebrospinal fluid (CSF), which surrounds the brain and spinal cord. Evidence that the organisms have penetrated the central nervous system is an even clearer indication that the horse’s neurological signs are attributable to EPM. Finding high titers of anti-bodies in both the blood and the CSF is the best indication of EPM that is currently available. However, even this evidence is not considered definitive proof that the EPM is the cause of any neurological signs. And because obtaining a sample of CSF is a more technically challenging and more in- vasive procedure, many veterinarians proceed on the assumption of EPM based on the blood tests and observation of signs alone.

Treatment and recovery

Three drugs currently have Food and Drug Administration approval for the treatment of EPM:
  • Ponazuril (trade name Marquis) is an oral paste delivered once daily for 28 days.
  • Diclazuril (trade name Protazil) is an alfalfa-based pellet that can be fed daily as a top dressing on a horse’s grain for 28 days.
  • Sulfadiazine and pyrimethamine (trade name ReBalance) is an oral suspension administered daily for as long as 270 days.
All of these drugs are antiprotozoal and cross the blood-brain barrier to either kill or inhibit the reproduction of the organisms within the central nervous system. The best choice for your horse depends on several factors, including which is easiest to admini-ster effectively.

Your veterinarian will advise you on special handling for the drugs. For example, some evidence suggests that administering DMSO (dimethylsulfoxide) in conjunction with ponazuril may help the drug to reach therapeutic levels faster. Also, especially in more severe cases, a veterinarian may opt to begin the treatment with a “loading dose” of ponazuril, with three to seven times the normal amount, to help the drug reach the central nervous system faster. In a few cases, longer treatment periods are needed.

Preventive measures

Currently, no vaccine is available to protect against EPM. For now, your best bet for preventing EPM lies in limiting your horse’s exposure to the protozoa. And, for the most part, that means taking steps to break the parasite’s life cycle and to prevent opossums from contaminating your horse’s feed and water:
  • Avoid attracting large numbers of scavengers. It is not necessary, or probably even possible, to keep all opossums away from your property. And that’s OK: Opossums eat prodigious numbers of pest species, including mice and ticks, which can also carry diseases. But you do want to keep their numbers to a minimum---and that means closing down the food sources on your farm that would attract opossums and encourage them to stick around.
  • Keep your feed in sealed containers and clean up spills immediately. Use sturdy garbage cans with tight-fitting lids. Pick up uneaten cat and dog food at the end of each day, and clean up fallen seed under bird feeders. If you have fruit trees, pick up fallen fruit. Killing or trapping opossums won’t help---if you’re still providing food sources, more will come.
  • Pick up animal carcasses. Opossums pick up S. neurona by scavenging carcasses of other infected animals---which can be many species, including skunks, raccoons, armadillos and cats. To reduce the risk that local opossums will get infected, remove any dead wildlife you may find on your property.
  • Keep hay and bedding clean. Make an effort to keep any roving opossums away from your horse’s feed and bedding. Store these materials in a secured shed or loft to keep out wild animals, and dispose of any you find that has been contaminated with animal feces. Use feeders to keep hay off of the ground; check them periodically for animal wastes and clean as needed.
  • Seal off the shelters. Clear up brush piles, which can provide shelter for wildlife, and close doors to sheds and other outbuildings, especially at night. Close off access to spaces underneath buildings, too---but first make sure you don’t already have animals in residence. You don’t want to trap them inside.
  • Limit your horse’s stress. Horses who travel frequently and undergo the stresses of training and competing in high-intensity sports are at greater risk of developing EPM, according to a 2000 study from Ohio State University. Your veterinarian can advise you on steps to avoid overtaxing your competition horse and to keep him generally healthy.
For more information, go to “On the Frontlines Against EPM” (EQUUS 451).

The life cycle of sarcocystis neurona

The opossum is the definitive host for Sarcocystis neurona, meaning that the protozoa can mature and reproduce within its body. 1. The opossum excretes the parasite eggs, called oocysts, in its feces. 2. The oocysts release a secondary stage, called sporocysts, which may contaminate feed or water and be consumed by other animals. 3. The horse may ingest sporocysts. Horses are considered aberrant hosts because, so far, no evidence has been found that the protozoa complete their life cycles in horses. 4. In some cases, the protozoa may cross into the horse’s central nervous system and damage the spinal cord and/or brain, causing equine protozoal myeloencephalitis (EPM). 5. Other animals—including raccoons, skunks, cats and armadillos—may ingest the sporocysts and become intermediate hosts. 6. Once inside the intestine of an intermediate host, the sporocysts hatch and go through other life stages. Even-tually, they invade the muscle tissue and form sarcocysts, which contain parasite spores. 7. When the intermediate host dies, its carcass may be scavenged by an opossum, which ingests the sarcocysts. The parasites mature in the opossum’s intestine, and the cycle begins again. Note: The life cycle of Neospora hughesi is less understood, but it appears that horses do not have to eat infected food or water to contract it: Mares who carry the organism can pass it to their offspring during gestation. This means that EPM may be a possibility even in areas where opossums are not found.

This article first appeared in the July 2017 issue of EQUUS and re-published here with permission.




Thursday, May 24, 2018

Summertime colic risks

Two types of colic can strike as a result of warm weather conditions, and knowing how they occur will help you to prevent them.

The risk of colic in winter is well known, but don’t let your guard down during the summer. Two types of colic can strike as a result of warm weather conditions, and knowing how they occur will help you to prevent them:

• Impaction colic. Dehydration from heavy sweating and/or reduced water intake, combined with dry hay or pasture in a drought situation, can lead to impaction colic. These impactions commonly occur at the pelvic flexure, the location where the large intestine doubles back on itself. A horse with simple impaction colic may seem only mildly uncomfortable, but if the blockage compromises blood supply to the intestine, pain can quickly intensify.

Veterinarians typically diagnose impaction colic with a rectal exam and by noting the absence of reflux (fluid backed up in the stomach) through a nasogastric tube. (If there is reflux, the problem is more serious, and the blockage is probably in the small intestine.) Treatment involves nasogastric fluids, laxatives and possibly intravenous fluids to rehydrate the horse and soften the mass, along with medication to control pain until it passes. In the rare cases when a blockage doesn’t clear on its own, the horse may require surgery.

Prevent summer impaction colic by ensuring your horse has plenty of fresh water at all times. If you’ve provided water but suspect your horse is drinking less than he usually does (most horses drink between five and 10 gallons a day) or if he shows any signs of dehydration, such as dark gums or skin that stays “tented” when pinched, call your veterinarian for advice.

• Gas colic. When grass recovers after a drought-breaking rain, the sugars it contains can ferment in an unprepared digestive tract, leading to gas colic. This is essentially Mother Nature causing the very same sudden dietary shift horse owners are cautioned to not make themselves. Gas colic can be intensely painful as the bubbles work their way through the digestive tract.

Your veterinarian will diagnose this type of colic based on rectal palpation, the absence of reflux when a nasogastric tube is passed and the horse’s response to analgesic medications; gas colics typically respond very quickly to a dose of flunixin meglumine or buscopan. Most gas colics resolve with time, but movement of a large gas bubble can cause an intestine to twist, cutting off the flow of blood. In these cases, medication does not relieve pain and surgery is needed to repair the twist and restore circulation.

To prevent gas colic in the summer, be cautious about how much you let your horse graze during times of pasture growth and regrowth. A grazing muzzle will allow him to enjoy turnout while limiting his grass intake.

 Re-published article with permission from EQUUS Magazine.


Monday, April 23, 2018

3 Things you (probably) didn't know about beet pulp

Although the popularity of this fibrous feedstuff continues to grow, misconceptions about it remain.


Chances are you’re pretty familiar with beet pulp. Most of us have scooped and soaked our fair share of this sugar-industry-byproduct-turned-equine-feed. The remains of sugar beets used in the manufacture of sugar, beet pulp is high in digestible fiber and a good source of “safe” structural carbohydrate-based calories, making it a popular horse feed throughout the country and around the world.

Straight from the bag, beet pulp is dried and shredded---almost resembling tobacco---or pressed into solid pellets. Soak either form in water for about a half-hour, and you’ll have a soft, soggy mash.

Yet as simple and easy as beet pulp is to feed, it has long been the subject of myths and misunderstandings in the horse world. Some of these misconceptions are harmless, but others could lead owners to needlessly rule out beet pulp as part of a horse’s diet or, conversely, rely on it too heavily and for the wrong reasons.

To make sure that doesn’t happen at your barn, we’ve compiled a list of three important facts about beet pulp. Read through them so you can make sure your horse gets the greatest benefit from this versatile feed.

Fact 1: Beet pulp provides a type of fiber that offers unique nutritional advantages.

“The main role of beet pulp in a horse’s diet is fiber, just as with hay,” says Pennsylvania State University equine nutritionist Burt Staniar, PhD.  “But the beet pulp fiber is not the same as the fiber in hay. It’s much more easily digested, so it’s processed faster. We don’t think of fiber as providing much energy---and in the human diet it doesn’t---but in horses it’s a significant source of energy. Because the fiber in beet pulp is digested quickly, the energy and the calories it provides are available to a horse much faster than those that would come from hay.”

This, says Staniar, makes beet pulp a useful source of energy for horses who need a boost for athletic efforts or to support other functions, such as lactation. “It’s going to have more benefit for [equine athletes or broodmares] than, say, an easy-keeper gelding who spends most of his day in the field,” he says. “And in cases where horses need more calories, adding beet pulp to a diet may be a better option than adding more hay because of the difference in fiber type.”

For the same reasons, beet pulp is often a good choice for older horses who have trouble chewing or digesting hay. “It can be very beneficial for older horses whose teeth or digestive tracts can’t handle other types of fiber,” says Coverdale. “In fact, many of the senior feeds that are formulated as ‘complete feed’---meaning they include fiber---are beet pulp based.”

Beet pulp fiber provides another advantage: promoting healthy gut flora. “A horse extracts energy from fiber via fermentation in the hind gut,” says Staniar. “That fermentation is done by bacteria, and different types of bacteria ferment at different rates.” A gut that is accustomed to only slow-digesting forage may be overpopulated with that type of bacteria, an imbalance that can lead to digestive upset.

“You want to support all those microbial populations,” says Staniar. “So when your horse has to make a transition in diet or location, he is going to be better able to adapt digestively. A little bit of beet pulp in every diet can help keep the population of fiber-digesting bacteria in the gut balanced so those changes won’t be as disruptive.”

Fact 2: Beet pulp contains very little sugar.

“Plain beet pulp is very, very low in sugar; it isn’t sweet at all,” says Coverdale. “If you pop some in your mouth expecting it to be, you’re going to be disappointed. It’s pretty boring and tasteless.”

In part, beet pulp’s unearned reputation as a high-sugar feed comes from its origins. “The name ‘sugar beet pulp’ is very misleading,” says Staniar. “Remember that this is a byproduct of the sugar industry. By the time it makes it to the feed store, all the sugar has been extracted. That’s what the sugar industry wants, and they just pass along the rest to us.”

In fact, molasses is often added to beet pulp to make it more palatable to horses. But even then, the amount of sugar isn’t enough to worry about unless your horse has a specific sensitivity to sugars. “There’s only about 3 percent molasses in those formulations,” says Wagner, “which doesn’t make a huge difference in terms of energy content, but it does make it tastier. If you have a horse with a history of insulin resistance or metabolic issues, you’ll want to eliminate the molasses because you’re cutting back on all sugars. And horses with hyperkalemic periodic paralysis [HYPP] need to avoid molasses for other reasons [see “For HYPP Horses, Hold the Molasses,” page 48]. But if your horse doesn’t have any of those issues, there’s not enough molasses in the sweetened beet pulp to trigger anything.”

If sugar or molasses in your horse’s diet is a concern, look for “plain” beet pulp, which most feed companies sell in addition to formulations with molasses added. Just check the label. But even if you can’t find unsweetened beet pulp, there’s still a fix: “If you soak, then squeeze beet pulp and drain off the water, you’ll remove most of the molasses,” says Staniar. “That’s an easy way to reduce the sugar content if you can’t find plain beet pulp.”

Fact 3: Beet pulp can help you stretch your hay supply.

Sometimes, despite your best efforts, you may find your hay supply running low, which is obviously a cause for concern. Without a source of roughage, a horse’s digestive system can’t function properly. That’s where beet pulp comes in: It can take the place of hay---at least partially---helping you stretch your supply until you can restock.

“In this area of the country, we go through a drought every so often, and people get very interested in alternative sources of fiber and roughage,” says Coverdale. “Beet pulp is a good option.” The conversion rate is straightforward ---for every pound of forage you take out of the diet, add in a pound of beet pulp. Start this when you know your hay supply might be getting low and you may be able to make it last long enough until you can refill the hay shed. There is a limit to how much substitution you can safely do, however.

“I wouldn’t recommend replacing all the hay in your horse’s diet with beet pulp,” says Coverdale. “Although the fiber content is similar, the vitamin and mineral content of beet pulp is very different than that of hay. When you rely on it too much, you can create some significant nutritional imbalances in a horse’s diet.”

Beet pulp, for instance is low in phosphorus compared to its calcium content. “The calcium/phosphorus ratio is about 10 to 1, which in small amounts isn’t a problem for a mature horse,” says Coverdale. “But in large amounts or in a growing horse or a lactating mare, that could cause issues with bone development.” To prevent such imbalances, she says, the general limit for feeding beet pulp is no more than 10 percent of a horse’s diet by weight, which works out to no more than two to three pounds a day for an average-size horse.”

Wagner cautions against trying to “eyeball” the correct amount of beet pulp to feed a horse. “You’ve got to remember it’s 10 percent by its dry, unsoaked weight,” she says. “You have to weigh the feed, not just consider scoop size. Beet pulp is light and fluffy. A pound of beet pulp is going to look like a lot more than a pound of alfalfa pellets, for instance.” Wagner adds that she keeps a fish scale in her feed room so she can hang a bucket to weigh out rations quickly and accurately.

Coverdale adds that the “scratch factor” of beet pulp may not be high enough to safely replace all the hay in a horse’s diet. “You need to take into account the physical attributes of long-stem roughage,” she says---“the fact that a horse has to chew it and that it provides bulk in the gut. We know this is all-important in ruminant digestion. We need more research into that in horses, but it stands to reason it would be.”

Of course, says Coverdale, there are always exceptions. “In many older horses, particularly those with dental problems, hay isn’t even an option any more,” she says. “In those cases, the rules go out the window and you do whatever you can. Beet pulp might be the only source of fiber an older horse can get. In those cases, I’d recommend a senior feed containing beet pulp that’s designed to be a ‘complete’ feed and replace hay. The nutritionists at those companies will have created a balanced diet, so you don’t need to worry about vitamin and mineral deficits. Trying to come up with your own formulation by mixing beet pulp with regular feeds can be very difficult and is unnecessary these days; the calculations have already been done for you with a commercial feed.”

If all this information has you thinking that you want to add beet pulp to your horse’s diet, check to make sure it isn’t there already. “Beet pulp is already in a ton of commercial grain mixes,” says Staniar. “It’s gotten increasingly popular as we’ve realized its nutritional benefits, and it shows up in all sort of places.”

Specialty feeds are particularly reliant on beet pulp. “Beet pulp is a major component of the high-fiber, low-sugar feeds that are so popular right now,” says Wagner. “It’s really the perfect ingredient for those---a good source of ‘cool’ energy. And if you look at senior feeds, you’ll see it’s a primary ingredient; that’s the reason those feeds soak up water so well. I think there are plenty of people out there who don’t realize they are already feeding beet pulp. And there are probably people thinking they’d never feed beet pulp, for whatever reason, but their horses are already thriving on it.”

 Re-published article with permission from EQUUS Magazine.


Thursday, March 15, 2018

Why your horse needs vitamin E

An equine diet based solely on hay may be lacking in this essential nutrient.


Hay is almost the perfect food for horses---most varieties offer the right balance of protein, fiber, nutrients and energy to keep the average horse healthy.

The key word there is “almost.” One nutrient that hay may not provide in sufficient quantity is vitamin E. This essential nutrient is present in fresh pasture but begins to degrade as soon as grass and legume plants are harvested. And the longer the hay is stored before it is consumed, the more of its vitamin E is lost.

So for horses whose forage comes primarily from hay, with little or no grazing, vitamin E deficiency is a possibility. And it’s even more likely for horses who are in training with limited turnout because exertion increases the need for this valuable antioxidant. Vitamin E requirements are also higher for aging horses, those who are ill and those with certain health issues.

Vitamin E helps keep a horse’s muscles, nerves and all his internal workings functioning smoothly. And if he’s not getting it naturally in a green pasture, then you’ll need to find a way to add it to his diet. Here’s a look at what vitamin E does and what you can do to make sure your horse gets enough---but not too much.

Vitamin E in nature


“Vitamin E” is a collective name for a group of eight naturally occurring compounds that all have distinctive antioxidant activity. There are four tocopherols and four tocotrienols. Each is designated with an alpha-, beta-, gamma- or delta-.

“The most biologically available form is alpha- tocopherol, and this is why we can measure this one in the blood,” says Tania Cubitt, PhD, an equine nutritionist with Performance Horse Nutrition, a consulting firm in Middleburg, Virginia.

Vitamin E is fat-soluble, which means it’s handled quite differently by the body compared to water-soluble vitamins, such as vitamin C, which are not stored and are eliminated in urine if too much is consumed. Fat-soluble vitamins can be stored in the liver and the body’s fatty tissues. This means the horse can keep a supply of the nutrient when it is abundant, and access it when it isn’t. And that’s exactly what he does in nature. Vitamin E is abundant in fresh, green grass, but the amounts diminish as grass matures and dies. Horses who spend the winter foraging on dried grasses will draw on their stored vitamin E; then they will replenish their supplies of the nutrient when the green plants start growing in the spring.

All of which means that a domesticated horse’s lifestyle can work against his receiving enough vitamin E. “The normal horse under natural conditions is able to cope with seasonal fluctuations,” says Cubitt. “We have thwarted this, however, by putting our horses in an artificial environment. About 30 to 80 percent of the vitamin E in hay can be dissipated during the drying for harvest and during storage. If horses are stuck in a stall and not on pasture, they are relying on us to supply most of their vitamin E. I have seen a lot of horses that are actually deficient in vitamin E because of the way they are managed. So today we see a lot of horses being supplemented with vitamin E.”

What Vitamin E does


Vitamin E plays a role in many functions throughout the body, but it is known primarily as a potent antioxidant, meaning it binds with and limits the damage caused by free radicals, which are atoms or molecules with an odd number of electrons. Because they have an unstable electrical charge, free radicals tend to “steal” electrons from other molecules to become stable. But when the original molecule loses its electron, it becomes unstable and in turn tries to steal another electron from somewhere else. All this activity not only damages the molecules that have their electrons stolen, it may inhibit their ability to do their jobs within the body. If there are too many free radicals present in the tissue, this chain reaction can run out of control and injure cell walls, DNA and other vital structures.

Free radicals are a natural byproduct of the utilization of fats, carbohydrates and proteins as fuel. They do have beneficial functions; they can help neutralize bacterial or viral threats, for example. But when the number of free radicals in the tissues climbs too high---such as in the muscles after a horse exercises---the body deploys antioxidants to bind with them, breaking the cascade.

In the case of vitamin E, action centers on the fats that form the structure of cell membranes, where the nutrient remains ready to bind with free radicals that might otherwise damage the cell walls. “It helps protect the cells,” says Carey Williams, PhD, an equine extension specialist with Rutgers, the State University of New Jersey. “The vitamin E incorporates itself into cell membranes and protects them from oxidative damage.”

A shortage of vitamin E might mean more oxidative damage occurs in cells throughout the body, including those in muscles, nerves and immune cells. In the case of a hardworking horse, outward signs of oxidative injury might be muscle soreness and a slower-than-expected recovery from exercise. And so, when a horse’s workload increases, his need for antioxidants, including vitamin E, also goes up.

“When you damage muscle, for any reason, you have some oxidative stress,” says Paul Siciliano, PhD, of North Carolina State University. “In the cell, when metabolism is taking place, some pro-oxidants are produced. You could equate it to a campfire out in the woods. The fire is producing heat energy and it might send up sparks in the process. As long as the sparks get put out, things are fine. But if one of them starts another fire and it grows, you could have a problem. Vitamin E attaches to the cell membranes and quenches those little fires and keeps things working properly.”

Oxidative damage is most likely to occur in tissues in the immune system, nerves and muscles, because they are more highly metabolic---that is, they “burn” energy faster. “Thus they produce a greater proportion of these pro-oxidants just as a cost of doing business,” Siciliano says. “There is higher likelihood to have a problem in those areas if horses are short on vitamin E.”

How much vitamin E does a horse need?


A horse’s requirements for vitamin E have not been well established. “We have defined these requirements only because we know that horses consuming it at a certain level haven’t had any deficiency symptoms,” Siciliano says. Guidelines in the Nutrient Requirements of Horses from the National Research Council (NRC), last revised in 2007, recommend about 500 IU (international units) daily as a maintenance level for an 1,100-pound horse in light work.

“This isn’t a lot, so if a horse has access to pasture, that horse has plenty of vitamin E, since green pasture is the best source,” says Williams. “Just like your parents always told you to eat your vegetables---because they contain lots of vitamins ---our horses that are out on pasture will have those vitamin needs met.”

The NRC recommendations are higher for hardworking horses and for breeding mares and stallions. “Working horses might need up to 1,000 IU per day,” says Williams. “These figures are the minimums, however. There have been many studies, including some I have done, that have shown that more vitamin E is even better. Most of the studies I did looked at supplementing 5,000 IU per day for the average-size horse on a hay diet and not on pasture. These horses had lower levels of muscle enzymes in their blood, which means less muscle membrane permeability or leakage of material into circulation.”

Higher levels of vitamin E may also be recommended for horses with certain health issues. “The categories that the NRC does not touch on, but which we have anecdotal evidence and research looking at, are guidelines for disease-state horses---horses with allergies, tying up, metabolic0 syndrome, or those that are suffering from or recovering from illness,” says Cubitt. “In horses with allergies, we know that potent antioxidants are effective. One guideline that has been suggested is about 5,000 IU per day. Horses who tie up and have muscle problems can also benefit from 5,000 IU per day. Horses with metabolic syndrome, insulin0 resistance and laminitis should also receive that higher level. Horses recovering from surgery, illness or stress may need 1,500 to 5,000 IU per day, depending on the severity of the illness/stress.”

Given that vitamin E is stored in fat, it’s not surprising that severely underweight horses may also have deficiencies. “These horses have no fat, so they can’t store it, so we have to feed them more vitamin E than the normal requirement; they need about 1,500 to 2,000 IU per day,” Cubitt says.

But it is possible to give a horse too much vitamin E. “A person needs to be careful with high doses of vitamin E, because vitamin E and beta carotene [the building block for vitamin A] have the same absorption pathway,” says Williams. “We found that high levels of vitamin E can actually decrease the level of beta carotene in the body. In one study, 10,000 IU of vitamin E was fed daily, and there was some interference with uptake of vitamin A. You are inhibiting one vitamin by overfeeding another.”

Horses on pasture would probably be getting adequate amounts of vitamin A, because beta carotene is also abundant in green grass. “If they are in stalls being fed hay, however, receiving too much vitamin E could become a problem,” Cubitt says.

Your horse’s vitamin E status


Your horse’s turnout schedule and activity level can provide clues to whether he’s taking in enough vitamin E, but a blood test is the best way to determine with some certainty.

“If your veterinarian tests plasma or serum concentrations for alpha-tocopherol, greater than 2 micrograms per milliliter is considered adequate, 1.5 to 2 micrograms would be considered marginal and less than 1.5 would be considered deficient,” Cubitt says. “If we were able to examine horses in the wild and measure their blood levels seasonally, by the end of winter they might be marginal, but that level would soon increase once the spring grass starts growing.”

If your veterinarian suggests that you increase the amount of vitamin E in your horse’s diet, you have several options. Obviously increasing his access to fresh grass will help---assuming this won’t put him at risk of laminitis or obesity. Grass contains somewhere between 30 to 100 IU of vitamin E per kilogram of dry matter.

You may also want to see if you can get hay that has been cut earlier---grasses cut for hay while young and growing will have higher levels of vitamin E. Exactly how much of the vitamin hay loses, and how quickly, depends on several factors, including the conditions of harvest and the amount of sunlight it is exposed to when drying (sunlight denatures all vitamins). One study found that fresh alfalfa hay lost as much as 73 percent of its vitamin E after just 12 weeks in storage. In addition, some grains, such as corn, oats or barley, contain some naturally occurring vitamin E but only about 20 to 30 IU per kilogram of dry matter. Grains also lose some of their vitamin E over time in storage; dry, dark storage is best for all feedstuffs.

To avoid uncertainty and ensure that their horses receive what they need, many owners opt for supplements, balancer rations and commercial feeds formulated to provide the nutrients required by average horses or those at specific life stages or activity levels.

“Most commercial feed products are fortified with vitamins and minerals,” says Williams. “They usually provide about 100 to 150 IU of vitamin E per pound. So if a horse is eating two or three pounds of grain daily, this will be adequate if at maintenance or light work.” Vitamin E is included in a wide range of supplements, both as the primary ingredient and as an addition to products for joint health, digestive support and other formulas. However, if the goal is for a level of 5,000 IU per day, make sure you are feeding a sole concentrated source of vitamin E. Otherwise there is a risk of over- supplementing the other nutrients in the product to get to that level of E.

When it comes to keeping a horse healthy, often the best approach is the “natural” way---mimicking as closely as possible the way he would live in the wild---despite stalls, trailers and training schedules. When it comes to an essential nutrient like vitamin E, that means letting him graze as much pasture as possible during the warmer months. But when that’s not feasible, taking steps to make sure your horse gets enough of this essential nutrient will help to keep him healthy.

SIDEBAR


Synthetic and natural Vitamin E

Vitamin E can be provided to horses in both natural and synthetic forms.

“Synthetic vitamin E is what we see added to many horse feeds and supplements because it is less expensive,” says Tania Cubitt, PhD, an equine nutritionist with Performance Horse Nutrition, a consulting firm in Middleburg, Virginia. “When you see synthetic vitamin E listed on a label, it will be ‘dl-alpha-tocopherol,’ or some variation starting with a ‘dl.’ Natural vitamin E will be listed as d-alpha-tocopherol or the tocotrienols, without the ‘l.’”

There are differences in how the horse’s body absorbs the two forms. “Specific transport proteins in the liver seem to bind better to the natural form, allowing it to be transported to other tissues,” says Cubitt. “Synthetic forms are excreted faster than the natural form, and they don’t have as much time to get into the tissues where they are needed.” In other words, the horse has to consume more of the synthetic form to achieve the same levels in the bloodstream as the natural form.

However, the natural form costs more. “The natural products are expensive—usually about twice that of a synthetic product, or more,” says Carey Williams, PhD, of Rutgers. “Your choice depends on what you want to do: If you want to feed twice as much of the synthetic product at the cheaper price, you will be getting about the same effect. You can feed less of the natural product or a little more of the synthetic product. In terms of cost, it would end up very similar.”

Other effects are also likely to be about the same, according to Williams. “There’s been a huge debate regarding whether to use the natural or the synthetic products. There are a lot of people who swear by one or the other. I’ve done research with both types, but most of my research has been with the synthetic product, and we got antioxidant benefits.”

With either form, absorption can be improved by adding fat to a horse’s ration. The fats bind with the vitamin E and help to carry it across the intestinal wall and into the bloodstream. Researchers have also explored other methods to improve the absorption. Some products contain “micellized vitamin E,” which means it has been chemically changed to improve absorption. Another approach is called nanodispersion, which separates the vitamin E into tiny droplets that disperse across a wider range of intestinal wall. Both of these methods have been shown to aid absorption.

SIDEBAR


Diseases of vitamin E deficiency

Several neuromuscular disorders have been linked to vitamin E deficiency:

- Equine motor neuron disease (EMND) is caused by the degeneration of the motor neurons, which control the movement of the large muscles. “This affects the motor neurons and therefore the skeletal muscles,” says Paul Siciliano, PhD, of North Carolina State University. “In a horse with this problem, you’ll see great appetite—eating very well—but these horses waste away, losing muscle mass, and may die without intervention.

“I observed this problem firsthand in a group of blood donor horses maintained at a veterinary hospital,” Siciliano adds. “They were fed the leftover hay from the prior year. It was good hay, not moldy, but it had been stored a long time. Over time, the hay gradually loses the compound that has vitamin E activity. The horses became vitamin deficient and eventually developed motor neuron disease.”

EMND does not develop quickly. “When studies tried to replicate this in an experimental setting—to make horses deficient—it took nearly two years of feeding a low vitamin E diet before any signs occurred,” says Siciliano. “When people see a problem, they immediately wonder what they’ve done to cause this change, but the reality is that the problem occurred because they didn’t change anything—the horse stayed on a deficient diet for a long period of time.”

- Equine degenerative myeloencephalopathy (EDM) is caused by damage to the nerves in the spinal cord and parts of the brain. It typically develops in younger horses, those who are less than 2 years old, and it causes ataxia (incoordination) and loss of proprioception (the sense of where their body and limbs are located).

EDM seems to run in families, which suggests that the cause is genetic. However, the disease is also characterized by low levels of vitamin E, and supplementing with this nutrient helps horses improve. While low levels of vitamin E do not appear to be a direct cause of EDM, it’s possible that a vitamin deficiency could produce the signs in a horse who is also genetically predisposed to the disease.

- White muscle disease, a degeneration of the skeletal muscles, is caused by a deficiency of selenium, another potent antioxidant. But low levels of vitamin E also seem to play a role in the disease. “Selenium and vitamin E are both important for muscle function and work as antioxidants, but with slightly different jobs,” Siciliano says. Higher levels of one nutrient can help compensate for lower levels of the other, and signs of deficiency are more likely to occur in horses with low levels of both.

- Sporadic exertional rhabdomyolysis (“tying up”) is a severe, painful cramping of the large muscles that can occur during or just after exercise. “Exertional rhabdomyolysis has many causes, but one thought is that it can be caused by inadequate levels of vitamin E,” says Carey Williams, PhD, an equine extension specialist with Rutgers, the State University of New Jersey. “During research trials in my lab, we had a few horses that were marginal in terms of plasma vitamin E levels. They had more of a tendency to tie up during or after the exercise, or at least be very muscle sore with higher levels of creatine kinase [a muscle enzyme that is abnormally high in the blood when horses tie up]. Many people who have horses who suffer from tying up problems are feeding 5,000 IU of vitamin E, and that does seem to help.”

Why your horse needs vitamin E - Three Runs Plantation Equestrian Blog. Re-published article from EQUUS Magazine.


Monday, December 18, 2017

How to recognize radial nerve paralysis

Although it may look like a broken leg, radial nerve paralysis typically has a less dire diagnosis.

No one would fault you for thinking the worst if you discovered your horse standing in his field, unwilling and unable to walk even a step. But before you panic, take a closer look and consider the possibility of radial nerve paralysis rather than a broken leg.

Radial nerve paralysis occurs when a kick or other blunt blow traumatizes the long radial nerve, which runs down the front of a horse's shoulder. It can also develop after a horse is anesthetized in a position that compresses the nerve for a lengthy period of time. Damage to the radial nerve leaves the horse unable to advance the leg, and horses will often stand with the shoulder of the affected leg "dropped" with that hoof knuckled over to rest on the toe.

If you find your horse standing in the field with a dangling leg, first, obviously, check for open wounds or other signs of fracture. Also observe the horse's demeanor. Radial nerve paralysis isn't particularly painful; if the horse appears agitated or in pain, call the veterinarian immediately. If all looks well, very, very carefully attempt to place the hoof of the "limp" leg flat on the ground. If the horse allows you to do so, you may be dealing with a case of radial nerve paralysis. Call the veterinarian and let her know what you're seeing.

The prognosis for radial nerve paralysis depends on the extent of the nerve damage. Mild cases may resolve in a matter of days with anti-inflammatory medications and DMSO. Your veterinarian is likely to wrap the affected leg as well as the opposite limb to ward off laminitis. Severe cases of paralysis, however, in which the nerve has been completely severed, can take months to heal or may never improve at all.



Friday, November 17, 2017

EQUUS Consultants: Proud Flesh

How to prevent proud flesh.

Question:

What is the best way to prevent proud flesh from forming in wounds below the knee? I've been told by some people not to use water on wounds below the knee, but others tell me it is the best thing. Also, my gelding has been licking a wound on my filly. Do you think that might promote proud flesh?

Answer:

Proud flesh is the excessive growth of granulation tissue within a wound that inhibits closure of the skin. In severe cases, proud flesh can protrude well beyond the original wound and become a target of parasites and infection.

Proud flesh is a common complication of wounds at or below the knee and hock, but most heal without incident if they are handled properly at the beginning. This means thoroughly cleaning the wound, taking care to remove irritants such as metal particles, rope fibers and dead tissue (especially bone, tendon or ligament). Beyond that, you can reduce the chances that proud flesh will develop by keeping the wound clean and protecting it from

  • rubbing, licking, biting and contact with pasture vegetation, sand or gravel;
  • disturbance caused by motion that opens and closes the gap in the skin;
  • flies and other creatures that will attempt to feed on or infect the site.Clean water will not cause or worsen proud flesh. In fact, hosing may be the best way to remove surface debris and reduce local wound swelling. Bandaging helps reduce adverse influences but does not speed the healing process or prevent the formation of proud flesh. The best way to prevent proud flesh is to ensure that all of the above criteria are met and if you do notice it forming, call your veterinarian right away to assess the situation before it gets a half-inch or more above the wound edges.If another horse is attracted to a wound as you describe, it usually indicates the presence of aromatic exudate produced in response to a foreign body, dead tissue or parasites. The licking itself is not a big problem, but the reason behind it most certainly is. In most cases, licking indicates the presence of the "summer sore" organism, Cutaneous Habronemiasis. Flies deposit these worm larvae in wounds on the head and lower extremities. They prevent healing, causing the wound to become round in shape and bulge slightly above the surrounding skin. I would suggest having your veterinarian take a look at your filly's wound and then keeping her in a stall or corral until it has healed.
  • Matthew Mackay-Smith, DVM, is the EQUUS Medical EditorThis article first appeared in EQUUS, issue 289.




Sunday, November 5, 2017

"Blowing Up" a Girthing Myth

Horses do not hold their breath to avoid girth tightening, but it is still important to take steps to ensure your tack is secure.

You were probably told, in your earliest riding lessons, that a savvy school horse might hold his breath to expand his chest and make it difficult to tighten the girth---and that's why it's important to recheck your cinch before mounting.

It's a good idea to check the security of your girth midway through a lesson or ride
While that advice is good, the reasoning behind it is not quite right. For one thing, a horse isn't likely to voluntarily hold his breath. But even if he did, the first 10 ribs, which lie directly under the saddle, are relatively immobile, which makes it nearly impossible for a horse to expand the diameter of his girth area through lung power alone.

That's not to say that some horses don't "puff up" while they are being saddled. But what is happening is that the horse is tensing his abdominal muscles, an action that expands the width of the chest slightly, allowing the cinch to loosen when he relaxes. The tension may come because the horse is anticipating an unpleasant experience or because the act of tightening the girth causes discomfort, but it's more likely just a natural response to the feeling of having something wrapped around his barrel.

The key to "deflating" a horse's belly is relaxation. First, double-check your tack fit to make sure you are not causing him discomfort when you saddle up. You might need to switch to a different type of girth, such as one lined with fleece.

When you go to tack up, first place the saddle on your horse's back and attach the cinch loosely, so it is secure but not tight, then finish grooming him or picking his hooves. Before you mount, tighten the girth a bit more and walk him around until he relaxes, then check it again. Remember that your weight will push the saddle down on his back, so you may need to tighten the cinch one final time after you mount.



Wednesday, November 1, 2017

Harnessing the Power of DMSO

Is DMSO a miracle drug or dangerous toxin? Here's everything you need to know about using the power of DMSO safely and effectively.

If you spend much time around horses, sooner or later you'll encounter dimethyl sulfoxide (DMSO). After all, this pungent, syrupy liquid is used to treat a variety of equine health problems ranging from orthopedic inflammation to neurological injury.

Yet DMSO's route to acceptance in equine veterinary care has been far more circuitous than that of most therapeutic substances. For starters, it was developed not in a pharmaceutical laboratory but from the industrial wastes of paper manufacturing. Initially, it was considered a potential miracle drug: "My first experiences with DMSO were in the 1960s," says Barney Fleming, DVM, of Custer, South Dakota. "At that time it was considered something magic and everyone wanted to stick their finger in it." But within a few years, the use of DMSO ceased entirely, in the wake of safety concerns. In the decades since, especially after it was approved for use in horses in 1970, DMSO has gradually gained renewed acceptance.

"DMSO is not just another medicine; we're looking at a whole new therapeutic principle," says Stanley W. Jacob, MD, of the Oregon Health and Science University medical school, who was the first in the United States to investigate the medical potential of DMSO. "A medicine treats a particular disease. A therapeutic principle is a new method for treating diseases in general."

In other words, DMSO doesn't just have specific effects on the body; its actions can also help other treatments work better. "DMSO is an economical therapy, and many people who have used it over the years swear by it and feel that it is a great help for many medical conditions," says Fleming.

However, DMSO is a powerful agent that must be used with care. "DMSO is a relatively safe product when properly applied, but it can be harmful if misused," says David McCarroll, DVM, DACVIM, of Interstate Equine Services in Goldsby, Oklahoma. "The best thing to do is use it under the direction of your veterinarian."

Solvent to solutions
DMSO's remarkable versatility as a therapeutic agent comes from its molecular structure, which allows it to interact with water in unusual ways. "DMSO is literally water's alter ego," said Jacob in a lecture to the American College for Advancement in Medicine in 1980. Because DMSO and water molecules are similar in shape, size and polarity, they share three important properties:


  • DMSO and water blend together extremely well, at all concentrations. "The DMSO-water bond is 1.3 times stronger than the water-water bond," said Jacob, in his 1980 lecture.
  • Water has two and DMSO has six hydrogen atoms that act like magnets to dissolve and "hold onto" large quantities of complex organic molecules without binding with them or changing their structures.
  • In the body, DMSO can pass through cell membranes as readily as water does without damaging the tissues, and it can replace water molecules within many bodily fluids. And, because DMSO so readily dissolves other molecules, it can also carry them through the cell membranes with it. "DMSO alters cell membrane permeability," says Jacob. "It moves through membranes and substitutes for water so that it pulls substances through cells that ordinarily would not move through them. This is its basic mechanism of action."


An indication of this action lies in that distinct taste DMSO causes in your mouth after it touches your skin: "When applied topically or by IV, DMSO goes into the blood quickly and is excreted through the lungs, giving the breath a garlic or burnt-almond smell," says McCarroll. "People need to be aware of this when they use it, so they won't be surprised."

These properties, along with a few others, account for the ways DMSO is currently used in veterinary medicine.

Anti-inflammatory action
In horses, DMSO is applied as a topical gel or administered in liquid form intravenously or through a nasogastric tube. It is classified as a nonsteroidal anti-inflammatory drug (NSAID) because it has antioxidant properties that can interrupt the inflammatory process. DMSO binds readily with hydroxide (OH) and other "free radicals," which are oxygen compounds that can damage or destroy healthy cells. Free radicals are often a byproduct of inflammation, and as they build up, they can stimulate more swelling and inflammation, which produces even more free radicals. Studies have shown that DMSO is a powerful free radical scavenger, and can slow or halt the destructive cascade of inflammatory damage to healthy tissue.

DMSO gel is sometimes applied topically to reduce swelling and inflammation associated with strained muscles and soft tissue injuries. Because the chemical is hygroscopic---meaning it attracts and binds to water molecules---it draws excess fluids out of tissues. "It makes a great sweat for swollen legs because it reduces edema," says Fleming, who frequently uses DMSO in his work with endurance horses. Liquid DMSO injections may also be used to treat bowed tendons and other injuries of dense tissues that are difficult to reach with other drugs.

In addition, DMSO is also often administered orally or intravenously in the early stages of laminitis to arrest inflammation in the soft tissues of the hooves. "The toxic effects that are taking place in the feet of the horse can be relieved considerably by administering a 10 percent solution of DMSO, adding it to the IV fluids," says Fleming. "It enhances the elimination of the toxins and reduces the damaging changes taking place in the foot."

Finally, DMSO is sometimes prescribed to treat brain or spinal inflammation associated with trauma, oxygen deprivation or diseases such as West Nile encephalitis or equine protozoal myeloencephalitis (EPM). "DMSO does two things; it reduces inflammation, and since it is hydrophilic it also draws moisture from the tissues, reducing edema and swelling in the meninges or spinal cord, or any other tissues," says Marlin C. Baker, DVM, of Alpha Equine Breeding Center in Granbury, Texas.

What more can DMSO do
DMSO also has wide-ranging applications that go beyond the control of inflammation:

Enhancement of drug action. When DMSO penetrates the skin and other membranes, it can readily carry many types of complex molecules with it---and that capability is often harnessed to help carry other drugs deeper into the targeted tissues. "For treating sore muscles, we just add DMSO to dexamethasone or prednisolone or any other drug we want to get inside the tissues as an anti-inflammatory," says Fleming. "When you rub those drugs over the skin they only work topically, but if you add DMSO to them, they go into the tissues and work better."

DMSO can also carry other drugs into tissues that are otherwise difficult to penetrate. For example, some skin infections, such as ringworm, rainrot or scratches can be hard to treat because the infective organisms can be deep under the skin or crusty scurf. DMSO can help other antifungal or antibacterial drugs reach their targets more effectively.

Not all drugs work well with DMSO, depending on their molecular weight, shape and electrochemistry. And DMSO will not carry bacteria or viruses across cell membranes because they are too large.

Pain relief. Research shows that DMSO slows or blocks conduction of impulses along nerve cells, which in effect reduces pain from musculoskeletal injuries, postoperative incisions and other sources. Relief is only temporary---lasting up to a few hours---because as the DMSO dissipates, normal function returns. However, DMSO is also often used in conjunction with other analgesic drugs to produce more long-lasting pain relief. "We also use it as an adjunctive therapy in intestinal surgeries and for analgesia postoperatively," says McCarroll. "Many surgeons use DMSO in postoperative colic cases to improve microcirculation around the bowel. This promotes better healing and also gives some pain relief."

Diuretic action. Because DMSO draws fluids from tissues, it may be administered intravenously in cases where it is necessary to increase the horse's urinary elimination, such as to flush toxins from the system faster. "We use it for cantharidin poisoning [blister beetle toxicity]," says Baker. "In this situation it is given intravenously, to lessen the effect of that toxin on the kidneys and GI tract."

Some veterinarians also routinely administer low levels of intravenous DMSO to horses who are tying up, experiencing massive cramping of the large muscles after exercise. "By giving it intravenously, with fluids, it also helps the horse urinate more," Baker says, which in turn both helps the horse flush out and excrete the waste products from the breakdown of muscle cells and increases blood circulation into the area.

DMSO may be used to draw fluids out of the lungs in cases of acute pulmonary edema. "It is beneficial in respiratory disease because it reduces inflammation and draws some of the fluid/edema out of the lungs," says Baker. "Along with DMSO, we use Banamine or some kind of corticosteroid (to also reduce swelling and inflammation) and sometimes it's hard to tell which one is doing the most good, but they seem to work well together to gain a better response."

Inhibition of microbial growth. DMSO is a bacteriostatic agent, which means it inhibits the reproduction of bacteria but doesn't necessarily kill them outright. Some veterinarians add it in low concentrations to flushes used to rinse out draining abscesses or other infected wounds. Baker uses DMSO when he flushes out guttural pouches: "It's not irritating when it's diluted enough, and it does help liquefy a lot of the heavy, purulent material that is often found in the guttural pouch."

Prudent precautions
Because DMSO carries molecules through the skin and into the body, it's important to make sure the skin is clean and free of any other chemicals that could be inadvertently carried into the bloodstream. Fly sprays, for example, are safe when used as directed on the skin, but they contain chemicals that could become toxic if they are absorbed into the body.

"[DMSO] should not be used in conjunction with any organophosphate or cholinesterase-inhibitor insecticides," says McCarroll. "If a person applies one of these types of fly repellents and uses DMSO, this can have an additive effect and cause toxicity. The insecticide or parasiticide would have been fine used alone, but when combined with DMSO it will potentiate or increase the effects of that drug and make it toxic to the animal."

Many liniments also contain ingredients that are toxic if taken internally. "You don't want to use [DMSO] with certain types of products, such as those that contain mercury salt," says McCarroll. "This would take the mercury into the horse and can cause a fatal mercury toxicity. Iodine is not as toxic to the horse, but could also cause a problem. Certain other drugs like alcohol, insulin, corticosteroids and atropine may be made more powerful if used concurrently with DMSO."

This ability of DMSO to ease absorption of other topical products is also an issue if a horse is to be drug-tested for competition. "There is a relatively new nonsteroidal anti-inflammatory drug called Surpass that is designed to be used topically," says McCarroll. "When used according to directions it will not cause a positive drug test. But if you combine it with DMSO the drug level will be too high within the body and will cause a positive test."

Because DMSO is a powerful diuretic as well as a vasodilator, it can be harmful when given to dehydrated horses and those in shock. "It can increase loss of fluid via the kidneys and further dehydrate the animal," says McCarroll. "It also dilates the peripheral blood vessels and can thus lower the animal's blood pressure. If the animal is in shock, this would make the condition worse."Repeated or overzealous topical use of DMSO can dry out the skin, leading to scurf and scaling, redness or rash. DMSO produces heat when applied with other solutions, such as water or saline, alcohol or acetone, which can have therapeutic benefits---but too high a concentration can actually burn the skin. "In these instances it will produce a significant amount of heat and can actually cause thermal injury if a person is not careful with it," says McCarroll.

Veterinarians often recommend mixing DMSO with Furacin ointment, which buffers it to reduce burning of the skin. Some horses may be more sensitive to this effect than others. "You also don't want to use it on any individual that has had a bad reaction to DMSO in the past," says McCarroll.

Intravenous administration of DMSO also carries the risk of side effects. If the concentration is too high or the solution is administered too quickly, muscle tremors, diarrhea, colic, seizures and/or other adverse reactions may occur. Large intravenous doses may also destroy red blood cells and inhibit clotting.




Wednesday, August 16, 2017

Feeding For Weight Gain

Feeding for Weight Gain


When your horse is too thin, whether it’s a short-term aberration or a chronic struggle, careful feeding can help to keep his weight up.


EQUUS
NOV 7, 2014


Overlooking subtle change is easier than it should be. When you care for your horse every day, you may not notice slight variations in his body condition. Then one morning it strikes you: Watching him turn toward you in the paddock, you can see a faint outline of every rib along his sides, and his haunches are looking a little less rounded, too. Clearly, your horse is losing weight. And suddenly the questions are flying through your mind: What’s wrong? Is he sick? Am I not feeding him right?

Take heart. Many thin horses are suffering from nothing more than “agroceroisis---a lack of groceries!” says equine nutritionist Sarah Ralston, VMD, PhD, DACVN, of Rutgers University in New Jersey. In other words, a horse loses weight simply because his caloric needs are not being met. Either he’s burning more energy than he’s consuming, or somehow he is not utilizing the feed that he does eat efficiently enough.

The next question, then, is Why? A number of underlying issues can cause weight loss in a horse, and to help him regain some pounds, you first need to understand and address what’s going wrong. Only then can you develop a plan to restore him to his proper weight.



Why horses lose weight


A number of factors, mental and physical, can cause a horse to lose weight, and in fact, his difficulties may stem from multiple problems. Of course, some horses seem naturally more prone to weight loss; a “hard keeper” may have a metabolism that requires more than the usual amount of calories for maintenance, or he may readily lose his appetite---and drop pounds---in response to even slight variations in management routine, weather or other factors. Likewise, a horse who is stressed by travel, intense training, herd squabbles or other disruptions may eat less and/or burn more energy and end up losing weight. But if your otherwise robust horse suddenly loses weight without apparent reason, ask your veterinarian to help you investigate the causes. Here are some of the possibilities:

• Illness. A number of diseases can lead to weight loss. Most will be accompanied by other obvious signs, such as diarrhea, colic, fever or lethargy---but in some cases signs of illness might be extremely subtle or nonexistent. “If your horse starts losing weight and his diet has not changed, get the veterinarian out ASAP,” says Ralston. “Check his liver and kidney function and screen for chronic infections.”

During the examination, your vet-erinarian may also suggest a fecal egg count and discuss your deworming schedule. A heavy parasite load can not only rob your horse of calories but also over time it may damage his intestinal tract to the point that it inhibits his ability to extract nutrients from his food.

Your veterinarian will also investigate possible sources of chronic pain, which can put a horse off of his feed. In fact, weight loss is one of the major signs of gastric ulcers, along with tooth grinding, a grumpy attitude and poor performance. Treating any underlying illnesses or injuries will likely be enough to get him gaining weight again.

In addition, the pain of arthritis can interfere with a horse’s feed intake by preventing him from walking to hay feeders or covering enough ground to graze sufficiently. Adding feed stations in strategic spots in larger pastures may make them easier to reach, and horses with pain in the neck or withers will graze more comfortably from a net or rack at shoulder height.

• Dental issues. Problems with a horse’s teeth can affect his ability to eat: Uneven wear can cause hooks, waves and other malformations that inhibit chewing, and cracked, broken or infected teeth can be painful enough to prevent a horse from chewing his food properly. In addition to weight loss, signs that a horse is experiencing dental problems might include dropping partially chewed feeds from the mouth, bad breath, fussiness with the bit and unchewed grains and bits of hay in the manure.

Routine dental exams---annually for most adult horses, or every six months for seniors or those who have had problems in the past---can catch and address any developing problems early, before they affect a horse’s over- all health and body weight. By the time he reaches his late 20s or 30s, a horse’s teeth may wear down completely so that he cannot properly chew coarse feeds or hay. At this point, he’ll need softer foods, such as soaked hay pellets, beet pulp or senior feed, to maintain his weight.

• Social problems. Horses who live in stable herds develop distinct social hierarchies, and those at the bottom of the pecking order---often the very young, the aging or the submissive---may be chased away from the hay feeder and other sources of food. One solution is to bring the low-ranking horse in to a small paddock or stall where he can eat undisturbed. Another option for horses in turnout is to distribute hay around to multiple feeders, or to use one that the horses can access from all sides without getting trapped against a fence, so that everyone gets access to a share.

Don’t forget that a horse’s social status can change over time, and the addition or subtraction of other members can rewrite the whole equation. Keep tabs on conditions in the field to make sure none of the horses are being bullied away from the food or water.

• Personality. We all know them---those busybodies who spend their time running back and forth between window and door, nickering to other horses and soliciting attention from every person. These social butterflies may have a hard time focusing on their meals. It might be best to move them to a quieter location, or offer them their larger meals at night when the barn is more peaceful, so that they can settle down and give their full attention to eating.

Then there’s the picky eater, who pushes his pellets around or picks out the choicest bits of hay and poops on the rest. If this is your horse, you may have to get creative, experimenting with different types of forage or changing its form. Some horses who pick through hay will readily eat pellets or cubes. And sometimes the horse who walks away from an overflowing manger will eat the same quantity if it’s divided up into six smaller meals per day. Slow feeders---hay nets or other devices with small openings that allow a horse to draw out only small amounts of hay at a time---can keep a horse interested in “grazing” longer, with less waste.

• Environmental conditions. Horses burn more calories to stay warm in cold weather, but extreme heat can also cause them to lose interest in food.

In the winter, steps to help a horse who is having trouble keeping on weight include adding blankets and bringing him into the barn when temperatures dip. Make sure pastured horses have access to shelter that will shield them from prevailing winds. Free-choice access to hay will also help a horse to generate internal heat around the clock. Slow feeders can keep the hay clean while helping the ration last longer.

On the hottest summer days, bringing horses into a cool, well-ventilated barn with fans can help them cope with the heat, and deep, shady shelters are essential in turnouts---to provide protection from the sun as well as from biting flies. Horses can expend huge amounts of energy stomping, shaking and running away from pests like horseflies. If biting flies are a problem in your area, protecting your horse with fly sheets, sprays, traps and other measures can help him to focus more on grazing.

Ample fresh water, of course, is essential year-round---loss of appetite is one of the effects of dehydration. Installing heaters or taking other steps to prevent water buckets from freezing in winter is crucial, and in the summer moving some of the outside sources into the shade can help to keep it more palatable. Soaking a horse’s feed can sometimes encourage him to eat more, but never provide more in one meal than he can eat before it either freezes in winter or goes rancid in the summer heat.


Getting started


Once you’ve identified and addressed the most probable reasons for your horse’s weight loss, it’s time to develop a strategy to put the pounds back on. If you’re faced with an extremely thin horse---one whose vertebrae, ribs, and other bones are prominent---call in veterinary help right away. Introducing starving horses to too much food too quickly can cause serious digestive consequences that may be fatal. However, if your horse is only moderately thin, you can probably handle managing his weight gain yourself---just be prepared to call your veterinarian if have any questions or run into difficulties.

First, it’s a good idea to establish a system for measuring your horse’s weight as accurately and objectively as you can. You have several options (see “Two Ways to ‘Weigh’ a Horse,” page 32). Whichever method you choose, record your measurements in a journal, starting with a baseline, to keep track of subtle changes over time. Photographs, taken in good light while your horse is standing on level ground, can be a good supplement to your records. Just don’t rely entirely on your eyes and memory---you may have difficulty recalling details if you need to explain anything to your veterinarian later.

Also establish a good baseline measurement, in pounds, of what your horse currently eats. If you don’t have one already, buy a food scale and weigh out your horse’s normal ration. Even flakes of hay can vary in weight, and if you’re measuring out feed by volume---in a coffee can, for instance---you may discover that you’re feeding substantially less than a manufacturer’s recommended portion, which is usually given by weight. But it’s important to know how much your horse eats up front so that you can begin increasing his feed in an orderly fashion.


If your horse has been inactive, consider implementing a moderate exercise program. It may seem counterintuitive to make a thin horse burn calories to gain weight, but the work will help him to build muscles, and exercise will increase his appetite.

As you develop your plan, keep one rule in mind: Go slowly. All changes to a horse’s diet need to be made gradually. Your horse didn’t become skinny overnight, and he can’t safely gain weight in a hurry, either. Abrupt changes in a horse’s diet can lead to colic, laminitis and other ills.



First, the forage


Before you go shopping for new products, the first step is to gradually increase a horse’s current feed, and of course, the cornerstone of the healthy equine diet is forage. In fact, the average pleasure horse in light to moderate work can maintain a healthy weight on forage alone.

To sustain a healthy weight, a horse needs to consume a daily ration of 2 to 3 percent of his body weight each day; of that, at least 1.5 to 2 percent needs to be some form of forage. That means two pounds of total feed for every 100 pounds that he weighs, or 20 pounds for a 1,000-pound horse just for maintenance---more will be needed for weight gain.

To help your horse gain weight, assuming he was getting restricted amounts of good-quality hay, Ralston suggests increasing his current forage ration until his total feed reaches at least 2.5 percent of his desired body weight. In other words, if your horse currently weighs 1,000 pounds, and you’d like him to be 1,100, then your target would be 2.5 percent of 1,100, or 27.5 pounds of hay.

The quality of the forage matters, too. If your hay and pasture are poor, then your horse is filling his gut with fiber but not getting adequate calories or nutrients. An extension agent can help you assess the nutritional value of your pasture and hay. Since few areas of the country allow for high-quality grazing year-round, most of us must supplement our horses’ diets at least part of the time with hay.

You want to choose the highest quality hay you can find for your thin horse. That means leafy, green hay with a minimum of brown stalks and mature seed heads. One quick test of the quality of hay is to squeeze a handful. Stiff stalks that hurt your palm are not a good choice when you need a higher calorie feed. If you want a more scientific analysis of your hay, you can send a sample off to a laboratory to have the nutritional value assessed.

Blending a flake or two of good-quality alfalfa in with a ration of grass hay is another way to add nutritional value to your forage. Alfalfa is higher in calories and protein than grass hays, which makes it an excellent choice to help to add weight to a thin horse. If your horse tends to be wasteful with his hay, he may eat more when offered alfalfa hay cubes or pellets.

Another fiber supplement is beet pulp, which contains about the same digestible energy as good quality hay. Most horses seem to like beet pulp, and it’s a good matrix for blending in supplements or other feed additives such as oils or rice bran. Introduce it slowly, one pound (dry weight) per feeding, up to 0.5 percent of your horse’s body weight. Although beet pulp is a good source of calories, it is not a complete protein source, and it’s relatively low in vitamins and most minerals, so it works best as an addition to, not a substitute for, your horse’s regular rations.



Fats, for calories


Forage may be the cornerstone of equine nutrition, but it’s not a calorie-dense food, and there’s a limit to how much a horse will eat in a day. If your horse has been consuming all of the forage he wants, and he still is not gaining weight after several weeks, it’s time to add some more calories to the ration.

The safest way to increase the energy in your horse’s ration is to bolster the fat content. While carbohydrates and proteins offer around four calories per gram, fats offer a whopping nine calories per gram. If introduced slowly, horses can adapt to higher fat intakes, and you can reduce the concerns associated with really high starch intakes such as wide fluctuation in blood glucose and insulin levels seen with high-grain concentrates.

You’ll find a number of supplements and feeds on the market formulated to help horses gain weight safely. Most contain high amounts of fat as well as amino acids, vitamins, minerals and other nutrients that help a horse build and maintain muscle. Some of these products can be pricey, however, especially if your hard-working hard-keeper needs to stay on them long-term to keep his weight up.

One of the simplest and cheapest ways to add fat to your horse’s diet is vegetable oil from the grocery store, which can be poured over his regular concentrate ration. Corn oil is palatable to most horses, but you can also use canola, peanut or any other vegetable oil your horse likes. Although you’ll hear debate about the ideal ratios of omega-3 to omega-6 fatty acids in all of these products, when you’re trying to put weight on a horse, all fats are good fats. Like with other dietary changes, oil needs to be introduced slowly, starting with a quarter cup per day, and adding another quarter cup every few days, up to a maximum of two cups for an average size horse---less for small horses and ponies. Too much too fast, and your horse will develop diarrhea and steatorrhea (fatty stools)---his manure will have an oily sheen from undigested oils passing through his system. Another problem with oils is they can go rancid, so be sure to store the bottle in a cool place and give it a sniff before feeding.

Rice bran is another source of fat that most horses love, and it’s also rich in vitamin E as well as fiber. The biggest concern with rice bran is that it is also high in phosphorus, which can inhibit the amount of calcium available in the horse’s body. If you’re feeding a natural rice bran, you might want to add a calcium supplement or another calcium-rich food, such as alfalfa. To be safe, consider purchasing a rice bran product formulated for horses that contains added calcium to balance the ratio of the two minerals.

As with oil, rice bran needs to be added to the diet slowly, starting with about a cup at a time, working up to one or two pounds daily. Follow feeding instructions on the label for serving sizes for any commercial products.



Finally, concentrates


Grains, sweet feeds and other starch- and sugar-based concentrates had long been the high-calorie foods of choice for thin horses, especially those in hard work. They are convenient to use, but the benefits come with a price: Feeds that are high in starch and sugar can pose some health risks if fed in large amounts. When a horse eats more starch in one meal than he can break down in his stomach and small intestine, the undigested molecules ferment in the hindgut, which increases the acidity and throws the microbial population out of balance---not only may the horse’s gut become less efficient at digesting fiber, the resulting changes can lead to colic and crippling acute laminitis. Although some horses seem to be more sensitive to starches than others, says Ralston, “You can induce laminitis in any horse with a sudden grain/starch overload.”

Commercial concentrates, which are formulated for complete, balanced nutrition, can be a valuable source of calories for a thin horse, but they must be used wisely. First, select a product that is formulated for your horse’s stage of life and activity level. Then, follow the instructions on the label to introduce the feed slowly and carefully to his diet.

Never feed more than 0.5 percent of a horse’s body weight of concentrates in a single meal, says Ralston. That’s five pounds for a 1,000-pound horse. If your hard-keeper or athlete needs more than that to gain weight, break his portion up into as many small meals as you can manage, spread throughout the day.

No matter what type of concentrates and added fats you incorporate into your horse’s diet, remember to make sure he always gets at least 1.5, preferably 2, percent of his body weight in forage each day. He needs it to keep his gut functioning at its best.

The basic concept behind fattening up a thin horse is fairly simple: Feed him more calories. But the devil is in the details. It may take some trial and error to find the right combination of forages, fats and concentrates to keep your horse healthy and strong. If you have trouble bringing your horse back to his ideal weight, don’t hesitate to consult with an equine nutritionist. Keeping weight on a perpetually thin horse can be tricky, but the effort will be worth it when you see him moving out across the pasture looking fit, strong and healthy.

This article first appeared in EQUUS issue #447, November 2014.