Sunday, July 21, 2019

Fit and Fun for life

Margie Engle: Fit and Fun for Life

How a legendary grand prix rider extends her jumpers’ careers without dampening their enthusiasm for the sport.

My number-one priority is always the horse. I’m constantly seeking new ways to extend my mounts’ careers without making them mentally or physically sour. I avoid overdrilling them not just to prevent unnecessary stress on their legs but also because I want them to look forward to their work with the freshest, happiest attitudes possible. I accompany my husband, Steve Engle, DVM, to veterinary conferences to keep up to date on the latest science and strategies for strengthening and conditioning horses while also reducing their risk of injury as much as possible. I also pay attention to methods that trainers use in other disciplines. Here are some of the most important lessons I’ve learned:

1. Minimize the pounding. Over time, concussion may lead to injuries in horses’ feet, joints, tendons and ligaments. The bigger the jumps, the greater the concussion. So small jumps are best for schooling sessions.

2. Avoid excessive repetition. Just as repetitive motions can cause tendonitis in humans, they can lead to muscle fatigue in horses, which, in turn, causes physical structures to break down. This can be challenging in sports like jumping, where a certain amount of practice is necessary for both horses and riders to develop and refine their skills. If you don’t practice at all, you and your horse may not have the required strength and timing to perform to the best of your abilities without risking injuries. So it’s a fine line. Some practice is a must, but change things up before your horse gets sore or bored.

3. Target the entire body. Focusing too much on one body part eventually leads to compensation. For example, if you constantly ask your horse to land on one particular lead, his muscles on one side of his body may fatigue. To compensate, he’ll try to shift the load over to the other side of his body. This is how many lamenesses develop. The stronger your horse’s entire body is, the less risk he’ll have of getting injured. So choose exercises that work both sides of his body equally and also strengthen his stomach, back, neck, etc.

4. Use interval training and cross-training. Event riders are especially good at interval training. They know how to bring their horses’ heart rates up, maintain the intensity for several moments, then ease off to bring the rates back down again. Gradually increasing the number of these interval “sets” improves overall strength and fitness.

I also incorporate the gallop into my jumpers’ routine programs not just to improve their adjustability and get them comfortable at the gait but also to expand their lungs.

Dressage is excellent cross-training and a great way to improve rideability and responsiveness. All horses should be taught basic dressage. If you are able to progress to a more advanced level, the gradual incorporation of collection into your jumper’s routine will strengthen different muscles from the ones he is accustomed to using. When Olympic dressage rider Lisa Wilcox rides my horses, it’s like sending them to the gym: She makes them use their hind ends in brief repetitive sets, asking them to do the equine equivalent of human squats.

5. Work on different surfaces. Riding your horse on a variety of terrain—sand ring, grass ring, trails, hills and even firm surfaces—strengthens different structures in his body and gets him comfortable performing on diverse types of footing. It’s great for his mental health, too.

6. Repeat exercises in both directions whenever possible. Horses’ brains don’t work exactly like ours do. When you perform an exercise and then approach it from the reverse direction, for them it’s like seeing it for the first time. You’ll always get the most out of a lesson if you can do it both ways.

I design my schooling sessions with all of these principles in mind. Below are three of the exercises I use to keep my horses’ programs fresh and effective.

Exercise 1: Football Grid



Setup: Place four poles 3 to 3½ feet apart with a single, adjustable cavalletti support on one end of each pole, arranged so the cavalletti are angled in an alternating fashion. Start with the poles flat on the ground or at their lowest setting.

Step 1
I approach the poles in a collected trot. I normally begin this exercise at the sitting trot to have maximum control of the rhythm and pace, but I use a rising trot on Alter Ego, owned by Lea Allen, because he stays naturally animated in his hind end and is already familiar with the exercise.

Step 2
This is a good example of how the poles help to improve the connection between your leg and hand. By using too much hand and not enough leg, I’ve made it difficult for Alter to lengthen his stride. As a result, he steps into the exercise a little shallowly. His front hoof has landed close to the first pole rather than where I’d like it to be: halfway between the first and second poles.

Step 3
This time through the exercise we have the opposite problem: I’ve used too much leg and not enough hand (see the slight loop in my rein). As a result, Alter extends too much and tries to jump the cavalletti.

Step 4
Finally, we get the connection just right! He’s stepping almost perfectly between the poles, flexing his hocks and knees exceptionally well and stretching his head and neck forward and down, making good use of his back and topline muscles. I can really feel the animation and suspension in his steps here.

Step 5
When Alter feels ready, we rotate the cavalletti to the next height (8 inches), and when that goes well, we move them up to 10 inches. You can tell by the nice curve in his topline that he’s engaging his neck, back and hindquarter muscles to raise his legs higher over the poles, creating a more suspended gait.

Step 6
Finally, we rotate the cavalletti to their highest height (12 inches). Note how much he’s flexing his joints and using his topline. This is a great low-impact way to strengthen his muscles.

This exercise reminds me of the tires that football players run through to improve their agility and coordination. It strengthens a horse’s topline, engages his hind end, increases the suspension in his gaits, teaches him to regulate his pace and gives him a better awareness of where his feet are. At the same time, it improves straightness as well as the rider’s leg-to-hand connection with the horse.

To set up the grid, you can use any equipment that enables you to raise a cavalletti on just one side. I have boxes that I can roll over to create different heights (6 inches, 8 inches, 10 inches and 12 inches). Jump standards would work, too, if yours have holes that go as low as about 6 inches. Place three or four poles about 3 to 3½ feet apart—up to 4 feet apart for bigger horses—with a block or standard next to each pole.

For the first few passes through the grid, set both ends of each pole on the ground so they’re just normal trot poles. Approach them in an active, collected sitting trot. (Sitting trot is ideal because it provides the most control over your horse’s rhythm and impulsion and gives you the best feel of what he is doing underneath you. But rising trot is fine, too, if you’re not comfortable sitting the trot yet.) Wrap your legs down around your horse’s sides so you can feel his hind end and back working. Think of pushing his hind legs forward while creating more suspension in his steps, asking him to march up to the poles.

Trot straight through the center of the poles, then change direction, make a loop and ride back through them the other way. Change direction again, this time turning the opposite way after the poles (if you made the previous loop to the left, make this one to the right), so you end up riding a sort-of figure-eight pattern over them. Focus on riding a very accurate track: straight in the approach, over the poles and afterward, then making nice bending turns. Use the ends of the ring to maximize your straightness in each approach to the exercise.

If your horse is nervous or tries to rush through the poles, bring him down to the walk, remove a pole or two (from the beginning and/or end of the series so the remaining poles are still 3 to 3½ feet apart) and walk over the remaining poles very slowly and deliberately. This will teach him to step in between the poles. When he’s doing that well, go back to trot and approach the poles in a very quiet, controlled manner. After several successful repetitions, add the other pole(s) back in.

Once he is comfortable with the ground poles, raise the alternating ends of each pole so that one end rests on the ground and the other end is raised by the block or standard, set at its lowest height. For example, raise the first pole on the right side, the second on the left, and so on. Approach the grid in the same way, in your sitting trot if possible. Stay connected with your legs and hands so your horse understands he’s still supposed to step over the rails and not jump them.

Repeat this a few times in both directions, praising him each time he does it correctly and taking plenty of walk breaks. Then, if he seems really comfortable with the exercise, raise the pole ends to the next height. Don’t go above 8 inches in your first session. If he has a good first experience and is feeling confident and coordinated, you can start your next session where you left off and gradually increase the height and/or add more poles, if you like. Also, if you feel secure in the saddle, try the exercise a few times without stirrups.

As your horse gets the hang of the exercise, you should feel his energy clearly flowing from your legs into a nice connection in your hands. Each time you go through the poles, try to find a happy balance between your legs and hands. If he slows down and drops behind your leg, ask yourself if you were using too much hand. If he gets flat and fast, ask yourself if you were using too much leg and too little hand. You never want to be rough with either your hands or legs, but instead want to maintain a light connection with both, allowing for and supporting a nice steady rhythm.

You will also feel more spring in his back as he lifts his legs over the poles. This is the elevation and suspension you want to feel—and it’s just the impulsion and “spring-loading” we want for jumping. Once you have a nice connection over the poles, it’s OK to do them at the rising trot. Be sure to continue asking for collection and suspension in each repetition of the exercise.

Remember not to overdrill. Once your horse seems to understand the exercise, repeat it just a few more times before going on to something else. Then incorporate it into your flatwork, doing some lengthening and shortening of the stride, lateral work, canter transitions, etc., elsewhere in the ring in between passes over the poles.

Exercise 2: Double Bounce



Setup: Build three verticals with ground rails on both sides of each, 9 to 10 feet apart from one another.

Step 1
The first time we go through the exercise, we remove the rail from the third vertical, leaving its two ground rails side by side in place. We approach this single bounce in a collected but animated canter. As Alter locks his focus on the first fence, I wait for him to...

Step 2
… jump up to me. I stay quiet in the saddle, keeping my eyes up and my hands softly following his mouth, letting him figure out the exercise.

Step 3
In this moment, Alter is setting himself up for the next jump: His front feet have already touched down and pushed off again while his hind legs are just about to land from the first jump. By engaging his hindquarters, he compresses his body into this tight round shape.

Step 4
As he jumps the second vertical confidently, already focusing on the next ground poles, I stay out of his way, letting the jumps do the work instead of my hands.

Step 5
Now we build the third vertical. I approach the grid in the same canter and stay quiet as he bounces through the exercise. He’s starting to engage his hind end to land and push off immediately. You can tell by his expression that he’s paying attention. The curve in his neck and back and the muscle ripples along his belly show that this exercise is “gymnasticizing” his entire body.

Step 6
Now we make the grid more visually interesting by raising a cup on one side of each vertical (two holes higher than the lower side), so the jumps are angled in an alternating fashion similar to the football-grid exercise. I canter Alter to it in the same way and then leave him alone to do
his job.

Like the last exercise, this one is great for improving straightness and rhythm while rocking your horse back onto his hind end and making him quicker with his front end. It helps to center his arc correctly over the tops of the fences. It also teaches him to learn from his own mistakes and back himself up from the jumps to avoid going “past the distance” or getting too close to the jump on takeoff. Meanwhile, you can focus on your own position and balance.

Only do this exercise with an experienced horse who is already familiar with bounce jumps.

Set up three small crossrails 9 to 10 feet apart. Alternatively, you can make each jump a single rail, raised at one end and resting on the ground on the other end as you did in Exercise 1. If you and your horse are more experienced, make the jumps small verticals, no higher than 2½ feet. If he has a naturally bigger stride, increase the distances between the jumps to as much as 11 feet. Place a ground rail on each side of every jump. This will help your horse’s depth perception and prevent him from going past the distances.

Approach the bounces in a collected canter, being sure that your horse is in front of your leg. In this exercise, it’s better to be a little tight to the jumps than too forward. When you arrive at the first jump, leave him alone to focus on his job. The more you can stay out of his way, the better. Hold your two-point position throughout the exercise, allowing him to jump up and close your hip angle over each obstacle.

If he gets quick over the bounces, think of being almost a little behind the motion with your body, using your weight—not your hands—to gently slow him down.

Jump the bounces in both directions. When that’s going well, you can gradually add another jump or two.

If you have a young horse and want to trot instead of canter into the exercise, put a placement pole 7 to 8 feet from the first jump to help him arrive at a comfortable takeoff spot. Then set a second placement pole 9 to 10 feet after the last jump. With this setup, jump through the exercise in only one direction so the trot pole is at the beginning, not the end.

Exercise 3: In-and-Out



Setup: Place a vertical and square oxer 21 feet apart with ground rails on both sides of each jump. Add two perpendicular rails on the ground in between the jumps to help keep the horse straight (10 to 11 feet apart from one another initially).

Step 1
We approach the in-and-out at a working canter in the vertical-to-oxer direction first. In the air over the vertical, I follow Alter’s mouth with my hands while focusing my eyes on the oxer.

Step 2
After we land from the vertical, I close my leg and continue to use a soft following hand to encourage him to keep cantering forward. I try to stay out of his way, allowing him to focus on the jumps, not on what I’m doing. As a result, he sets himself up to …

Step 3
… produce a nice round effort over the oxer. Next, we’ll canter the oxer to the vertical.

Step 4
The distance rides tighter this direction, but without any interference from me, Alter studies the problem and sets himself up properly to create an excellent jump out over the vertical, lifting his knees well and powering off his hind end.

This final exercise will continue to emphasize straightness while helping you focus even more on body control and reminding your horse to collect and rock back onto his hindquarters on takeoff.

Set up a small vertical 21 to 22 feet from a small square oxer. Place ground rails on either side of both jumps. Add another pair of ground rails in the middle of the exercise, perpendicular to the jumps, to create a straight chute for your horse to canter through. Some horses spook at these poles when they first see them, so set them 10 to 11 feet apart initially.

Approach this in-and-out at a working canter, starting in the vertical-to-oxer direction. This should ride comfortably at this distance, although you may need to add leg after the vertical to be sure the apex of your horse’s next jumping effort is directly over the center of the oxer.

When your horse has jumped the in-and-out well in that direction, approach it from the other direction. The distance might feel a little tighter this way, so after you close your leg to help him across the oxer, stay quiet in the tack, allowing him to figure out the exercise. Let the jumps back him off. Help him more with your body control than with your hands—by opening your hip angle and sitting a little taller with your upper body.

Continue alternating directions through the exercise a few times to feel how differently you need to ride the vertical-to-oxer versus the oxer-to-vertical. Meanwhile, if your horse is having trouble staying straight, gradually roll the perpendicular ground rails closer together until they are about 8 or 9 feet apart. If he has a major drifting problem, angle these rails into a mild “V” shape, bringing the ends of the poles slightly closer together (but no closer than 3 feet) in front of the takeoff of the second jump. At this point, only jump the in-and-out in this direction—or ask a ground person to reconfigure the “V” each time so that the narrower end is always pointing toward the second jump.

If you’re a more advanced rider and this exercise is going well, practice it without stirrups and/or tie a knot in your reins and put your hands on your hips or out to the sides like airplane wings over the jumps. This will help you improve your independence from your hands and focus on your position and balance in the air.

Remember, your horse’s welfare should always come first. Keep your schooling sessions fun and interesting without ever overdoing it—so you both can look forward to next time!

About Margie Engle

Margie Engle has been one of the winningest jumper riders in the U.S. for more than three decades. As a child, she cleaned dog and cat kennels in exchange for riding lessons until she was deemed big enough to muck stalls and groom horses. She didn’t own her own horse until her late 20s. In the meantime, she learned every aspect of horsemanship, working her way to the top of the sport. To date, Margie has won more than 200 grands prix classes, six World Cup qualifiers, more than 20 Nations Cups and a record 10 American Grandprix Association Rider of the Year titles. She competed in the 2000 Olympics, won team silver at the 1999 Pan American Games, team gold and individual bronze at the 2003 Pan Am Games and team silver at the 2006 World Equestrian Games. Last year, she and 13-year-old Oldenburg stallion Royce anchored the winning team at the Nations Cup in British Columbia before topping the field in the $130,000 ATCO Nations Finale Grand Prix. Proving her ability to extend the longevity of her mounts, Margie currently has two 18-year-olds competing in FEI-level classes: Bockmanns Lazio, who has already scored multiple top-10 placings this year, and Indigo, who placed third in the $205,000 NetJets Grand Prix CSI**** at the Winter Equestrian Festival this February with double-clear rounds. Margie and her husband of 23 years, veterinarian Steve Engle, are based at Gladewinds Farm in Wellington, Florida.

This article was originally published in the April 2018 issue of Practical Horseman.

Sunday, July 7, 2019

What to do when your horse has a fever

What to do when your horse has a fever

When your horse’s temperature climbs, it may be best to simply let the process run its course. But sometimes you’ll want to get a veterinarian in right away. Here's what you need to know about fever.

You’ve been keeping tabs on your horse as you’ve gone about your barn chores, but something’s not quite right. Normally, he’s never far from his buddy, and he’d be ranging around his paddock looking for the best bites of grass. Today, however, he’s spent most of his time hanging in the shady corner by himself. He seems normal enough when you bring him in, but as you’re grooming, you get out the thermometer. That’s when you really start to wonder what’s up: His temperature is just topping 102 degrees Fahrenheit.


You know that’s a little high---you’ve been in the habit of checking your horse’s temperature once or twice a month, and it’s always been about 100 degrees---but what do a couple more degrees really mean?

“There are several reasons why horses can have an increased body temperature that would not be a fever,” says Rose Nolen-Walston, DVM, DACVIM, of the University of Pennsylvania. “So the first question to ask when you take a horse’s rectal temperature and it is high is, ‘Is this a fever or not?’”

A “normal” body temperature for individual horses can vary, from about 98 to 101 degrees Fahrenheit, with 100 being average. But it’s also normal for a horse’s body tempera-ture to fluctuate during the day. It may be somewhat higher in the evenings than in the mornings, for example, and it is likely to rise naturally on hotter days or after exercise. A mare’s temperature may rise and fall during different stages of estrus. All of these fluctuations are temporary.

“If you ride your horse and work him hard on a hot day, his temperature rises, but this is called hyperthermia rather than a fever,” says Nolen-Walston. “The main causes of hyperthermia include exercise, extreme heat and humidity, and anhidrosis [an inability to sweat].” Allowing him to rest and drink---and perhaps hosing him down with cool water---ought to bring his temperature down to normal within a half hour or so.

If, however, your horse’s temperature remains elevated with no obvious cause, then it’s time to investigate the reasons why. “Most of the time, if a resting horse has an increased rectal temperature it’s because he has a fever,” says Nolen-Walston.

Rise in body temperature is one of the first and most easily recognized signs of many illnesses, and it is part of the immune system’s defense against infection. “Fever is a response by the body---along with inflammatory processes---to try to combat pathogens by stimulating molecules to speed up healing processes,” says Katherine Wilson, DVM, DACVIM, of the Virginia–Maryland Regional College of Veterinary Medicine.

The best course of action when a horse has a fever can vary. How high his temperature is, and how long it lasts, can help you decide whether it’s best to let a fever run its course---or to call in a veterinarian right away. Here’s a look at how fevers work and how veterinarians suggest you handle them.

How Fever Works

Fever is related to the body’s internal temperature regulation system, which is controlled by the hypothalamus. A small structure at the base of the brain, the hypothalamus receives sensory input from sensors in the central nervous system that monitor the heat of
the blood as it circulates through the brain, as well as from nerves that detect temperatures near the surface of the skin. This gives the hypothalamus information about both internal and external temperatures.

“The hypothalamus determines the body’s temperature set point,” explains Nolen-Walston. That is, the hypothalamus determines the horse’s “normal” body temperature and acts to maintain a consistent internal temperature despite fluctuations in the external world. When the body’s internal temperature deviates too far from normal, the hypothalamus triggers a cascade of involuntary actions to “adjust the thermostat.”

If the horse starts getting too cold, smooth muscles in the skin contract to raise the hairs on his body, trapping an insulating layer of warm air against the skin; muscle contraction also produces vasoconstriction, a narrowing of the blood vessels in the skin, to cut down on the heat escaping into the air. If he remains cold too long, he will begin shivering to generate heat. The hypothalamus might also stimulate the release of adrenaline and other hormones that increase metabolism, effectively causing tissues and organs throughout the horse’s body to “burn hotter,” and prompts behavior changes: The horse seeks shelter. Conversely, if the horse gets too hot, the hypothalamus initiates activities to reduce body temperature. The muscles supporting each hair will relax so his coat lies flat, and the blood vessels widen to facilitate radiation of heat away from the skin. If that’s not enough to cool him down, he will begin sweating.

The process that produces a fever begins when the immune system encounters a pathogen, such as a bacterium or virus. Among the first responders are lymphocytes, which initiate a cascade of biological events. To help neutralize the effects of the pathogens and eliminate them from the body, these cells release large number of cytokines, blood-borne protein messengers that affect the behaviors of other cells. Many of these cytokines have a pro-inflammatory effect---they stimulate all of the familiar signs of inflammation: localized heat, pain, swelling and redness. One type of cytokine, called a pyrogen, circulates in the blood and is detected by the hypothalamus, which responds by raising the body’s “set point” to a higher temperature. “Fever is one aspect of inflammation,” says Wilson. “We think of inflammation as redness, heat, pain and swelling---and fever is often a part of that.”

The raising of the body’s temperature set point is what distinguishes a true fever from other forms of overheating. “If there is something wrong in the body, like an infection, the body produces chemicals that change that temperature set point and make it higher for a while, and this is a fever,” says Nolen-Walston. “In other situations the body simply becomes hotter but the brain set point hasn’t changed.”

When the set point is raised, the hypothalamus stimulates the body to heat itself just as it would if it were in a cold environment. Vasoconstriction traps heat in the interior of the body, while the metabolic rate goes up. Eventually, the horse might start to shiver
to generate more internal heat, even on a warm day.

If a fever starts getting too high, the hypothalamus may abruptly switch to cooling mode: “The second stage of fever involves sweating and panting, and dilation of blood vessels at the skin surface to route more blood to the skin for cooling---making the skin feel hot,” says Wilson. “The horse is breathing hard to try to get rid of the extra heat via the respiratory system.”

How a rise in body temperature helps fight off infection isn’t entirely understood. “There is a lot of debate in human and veterinary medicine regarding the benefits of fever,” Wilson says. “It may improve healing by speeding up chemical reactions in the body and improving inflammatory reactions to foreign invaders.” The extra heat may also inhibit the activities of temperature-sensitive viruses and bacteria. “We think the higher temperature increases the horse’s metabolism and thus the ability to fight off infections,” says Nolen-Walston.

What we do know is that, as the infection wanes, the immune response eases, the levels of pyrogens in the bloodstream drop, and the body’s temperature set point will return to normal.

A Mild Fever

You might suspect something is wrong if your horse acts a bit dull and goes off his feed. But the only way to be certain that he has a fever is to take his temperature (see “How to Take a Horse’s Temperature,” page 29). You also need to know your horse’s normal temperature to interpret the results. A thermometer reading of 100 might be normal for most horses, but if your horse’s temperature is usually closer to 98, then 100 might be a mild fever.

A slightly elevated temperature---just two or three degrees higher than normal---that lasts only a day or two does no harm and is not usually a cause for concern. Your horse may simply be fighting off some mild infection you might never have noticed. If he was vaccinated recently, a slight fever might be just a side effect of building his immunity. If all you notice is a fever of less than two or three degrees and a slight dullness, you might just let your horse rest and check his temperature periodically for the next day or two. Because fever is an active part of the immune system’s function, you might actually prolong the illness if you give the horse medication to bring it down. Consider calling your veterinarian, however, if the fever persists for several days or if the horse begins showing other signs of illness.

“Most of the time we get called out for some other reason, rather than a fever. There are usually other important signs of disease that are noticed first, such as the horse has stopped eating or is breathing hard, rather than the fact that the horse has an elevated temperature,” says Wilson. “Some people, however, do take their horse’s temperature every day and may notice the fever before the horse is showing other signs of illness. I recommend doing this, because the horse’s temperature is good information to tell the veterinarian before he/she comes out to look at the horse.”

When faced with a horse with a mild fever but few if any other signs of illness, a veterinarian will first try to identify the cause. “A good history of the horse through the past day or days can be helpful. Was the horse coughing, or was there a change of diet or any evidence of diarrhea? Was there exposure to other horses that may have been sick? Did the horse have some kind of injury or serious wounds? All of these things might direct us to a diagnosis and the cause of the fever,” says Wilson.

“Then we usually try to determine which body system might have an infection, causing the fever. We listen to the lungs, check for diarrhea, look at the gums, etc.,” she adds. “Probably the biggest thing that helps us in diagnosis, however, is to run bloodwork on the horse. A complete blood count will help us know the degree of inflammation. Changes in white blood cell counts usually indicate an active infection, depending on which types of cells are elevated in number. This may help us know whether the infection is viral or bacterial.”

If the general examination yields some clues, the veterinarian can pursue more specific tests. “The ultimate way to diagnose an infectious disease is to test for that specific disease, usually by running some kind of bloodwork,” Wilson says. “The problem, however, is that there is no general screening test; you have to make an educated guess as to what it might be and then test for that particular disease.”

Often, however, the cause of a mild fever is elusive. “If we can identify a specific cause such as a virus or bacteria, we will try to target that disease process with the appropriate treatment,” says Wilson. “Unfortunately, even if we test for all the common things it might be, sometimes the tests all come back negative. The horse still has a fever, and we are scratching our heads as to why.”

If the horse seems generally well apart from an unexplained mild fever, the veterinarian might opt not to treat it. “Fever in itself is usually not a problem in horses,” says Nolen-Walston. “We almost never see brain damage from fever in horses. The important thing for horse owners to remember is that there is usually nothing particularly dangerous about the fever itself.”

The decision to treat the fever will depend on the horse’s general attitude. “Most of the time we treat a fever because the horse feels miserable and won’t eat or drink. Every horse is different regarding whether and when he might not feel good,” says Nolen-Walston. “If your horse’s temperature is 102 or 103 and he is happy---eating and drinking---there is no need to specifically treat the fever.”

A High Fever

A high fever---elevated by three or more degrees---is a more serious warning sign. In addition to dullness, you might see chills/shivering, sweating, increased respiration and pulse rate, fluctuations in skin temperature or reddening of the gums. An acute fever tends to spike high but come down quickly. A persistent high fever could indicate a serious illness. Either way, it’s a good idea to call your veterinarian.

“A few infections tend to cause very high fevers,” says Wilson. “Whenever I see a horse with a fever of 105 or higher, my first thoughts for possible causes would include strangles0, anaplasmosis0 and Potomac0 horse fever and some of the viruses, such as equine0 influenza. Often a viral infection will induce a higher fever than a bacterial infection, but this alone is not a good way to try to diagnose what is wrong with your horse.”

Another cause of high fevers is endotoxemia---a systemic inflammatory condition that develops when toxins released by certain bacteria as they die get into the bloodstream. “Horses are uniquely sensitive to endotoxins that are produced by a molecule that is part of the cell wall of gram-negative bacteria,” says Wilson. “There are a lot of these bacteria inside the horse’s intestine as normal inhabitants. They live and die there and go through their life cycle in the colon. When a horse has colitis0, some of the endotoxin from the bacteria’s dead cell walls may leak through the colon lining into the bloodstream. This causes a very dramatic cytokine response---and fever.” Endotoxemia can also occur if tissues of the lungs or uterus are inflamed.

Usually, a horse with a high fever will show other obvious signs of illness that point toward a specific cause. “If there are swollen lymph0 nodes under the jaw or thick nasal discharge, this would make us suspect strangles. If the horse has a cough or abnormal lung sounds, we will suspect a virus or pneumonia. With Potomac horse fever, we would probably see diarrhea or signs of laminitis,” says Nolen-Walston. “If the horse has a colic in which the intestine is twisted, we may see endotoxemia and high fever along with severe colic pain. Horses with anaplasmosis may have a high fever with no other signs except maybe mild swelling
of the legs.”

With appropriate testing to confirm the diagnosis, a veterinarian will begin treatment for the disease as a whole, which will also ultimately address the fever as well.

Too High To Tolerate

Extremely high fevers---above 106 degrees---or any fever that goes on for too long can eventually take a physiological toll on a horse. The body uses calories and water to maintain the higher temperature, which over time can lead to weight loss and dehydration. Prolonged high temperatures may change the chemical structures of heat-sensitive enzymes, which can affect metabolic functions throughout the horse’s body. What’s more, too high a fever may make a horse’s immune response less effective.

That said, in practice, a veterinarian’s main concern is likely to be the effects a very high fever has on a horse’s willingness to eat and drink. “Rarely do temperatures get high enough for long enough time to actually damage tissues that are crucial for the animal to function,” says Wilson. “The biggest reason we end up treating fever most of the time is because a fever makes the horse feel bad. If the horse feels miserable he won’t eat or drink, and this can lead to secondary problems.”

For that reason, your veterinarian is likely to administer medications specifically to attempt to bring down a very high fever in addition to other treatments for the underlying disease. “The first thing we’d use to treat a fever is a nonsteroidal0 anti-inflammatory drug [NSAID] like flunixin meglumine [Banamine] or phenylbutazone [bute],” says Nolen-Walston. “These will often bring down a fever.”

These drugs do have to be administered with care, as directed, however. “The important thing for horse owners to know is that these drugs do not work any better if given at higher doses than recommended by the veterinarian, and they will actually be harmful,” says Nolen-Walston. She has treated horses who were hospitalized after their owners administered additional medication when the prescribed doses failed to curb the fever. “The owners told me they didn’t have any choice because the fever didn’t come down.
But if the fever doesn’t come down with the proper dose, giving more will be toxic,” she says. “I have seen horses die from too much Banamine
or bute.”

If your horse has been prescribed one of these medications, and his fever does not come down as expected, says Nolen-Walston, “consult your veterinarian to see what the highest safe level is. The important thing to remember is that these drugs are much more toxic when the horse is not eating or drinking. If the horse is feeling miserable and you are giving NSAIDs and he is not getting any better, don’t give these drugs for more than a day without having your veterinarian take a look and give you some more advice.”

If medications alone are not enough to reduce your horse’s fever, your veterinarian might suggest alternate methods of cooling him down. “Often we try to cool the body in some other way, by using fans or cold hosing, to help increase evaporation over the entire body,” says Nolen-Walston. “If the horse is really overheated, we can give cool intravenous fluids. You don’t have to cool the fluid very much, because even at room temperature it will be lower than body temperature.”

Cold hosing and fans can also be used to cool a horse at home, but remember that fever is only one symptom of a bigger issue that needs to be addressed. “If you are trying to bring down a horse’s temperature and cold water hosing isn’t doing the trick, call your veterinarian,” says Nolen-Walston. “Unless he/she tells you to do something else, most of the time you can wait for the veterinarian to arrive. It would be unusual that the horse would be in critical shape just from fever, but you could work at reducing the high temperature.”

As your horse recovers, it’s a good idea to keep tabs on his temperature at least once daily for another week or two. “There are certain specific diseases that cause fever for a day or so and then the temperature will drop back to normal,” says Nolen-Walston. “Then in three or four days the horse will have another fever. You can’t assume that just because the fever went down for one reading that you’re out of the woods.”

A mild fever may leave your horse feeling sluggish for a time, so it’s best to let him have some rest while he recovers. Most of the time though, a fever is just a sign that his immune system is keeping things under control, and your horse will be back to his old self in no time.

This article first appeared in EQUUS issue #448, January 2015.