By Pam Gleason, Photography By Gary Knoll
All horses have one thing in common: They are susceptible to injury. Horses that are athletes are at an even greater risk. Not only do they get cuts, bruises and hoof troubles, they can also be prone to a whole litany of sports injuries, from strained tendons and ligaments to sprained joints and broken bones. Keeping horses sound is a main goal of most training programs. Restoring them to soundness after an injury has traditionally been a long, and sometimes frustrating endeavor.
The likelihood of a hurt horse returning to work depends on what structures he has damaged and how badly. Another factor is how the horse handles his recovery. By their nature, horses with orthopedic injuries are not good patients. You can’t tell them to stay off their feet. If they were very fit at the time of their injury, they are likely to become restless and possibly self destructive when they are suddenly confined to a stall.
To complicate matters, athletic injuries in horses often do not heal very well. The most common injuries are to tendons and ligaments, and these body parts are notoriously slow to mend. They also tend to heal with scar tissue that is both less flexible and weaker than undamaged tissue. Because of this, horses with serious tendon and ligament injuries have traditionally not been able to return to their previous level of competition.
Over the centuries, there have been many ways that horse owners and their veterinarians have tried to encourage tendons and ligaments to heal successfully. Early on, veterinarians recognized that neither tendons (which attach bones to muscles) nor ligaments (which attach bones to bones) have very much blood flow, which is one reason why they heal so slowly. Early methods of increasing blood flow included putting blistering agents on the skin, or even pin firing the damaged tissue, which involved sticking it with a burning probe. These “counter-irritation” methods may have done some good, and they are occasionally still used, although they are decidedly old school. How old? Counter-irritation was once commonly used on people, too, and has its origin in the ancient medical theory that says that sickness and injury is the result of an imbalance in the body’s four “humors” (blood, black bile, yellow bile and phlegm.) Blistering and its cousins, bloodletting and induced vomiting, were supposed to help bring the humors back into balance.
Today, there are more modern ways to promote healing based on recent advances in science. The so-called "regenerative therapies" use small amounts of the horse’s own blood, fat and bone marrow to create custom-made, personalized medicines that can be injected into damaged tendons, ligaments and joints. These relatively new treatments provide the horse with concentrated amounts of his body’s own healing and anti-inflammatory chemicals delivered directly to the site of the injury. With their aid, along with a prescribed regimen of rest and progressive exercise, horses with injuries that once would have been career-ending have been able to return to the racetrack, the competition arena and the trail, with tendons and ligaments that truly are as good as new.
These therapies may sound out of the reach of the average horse owner, but they are not. Veterinary clinics here in Aiken use them on a regular basis. If your veterinarian does not have the technology inhouse, he or she can work with one of the larger clinics, or even with a company such as Comprehensive Blood Management that specializes in providing custom blood products to veterinary and human clinics. There are several different types of regenerative medicine that are available now, and veterinarians who use them say they have greatly improved the prognosis of horses with serious injuries.
Stem Cell Therapy
Stem cells are immature cells that have the ability to turn into any kind of cell in the body. True stem cells are found only in embryos and in navel cord blood, and they are not currently being used in any commercially available veterinary treatments. The type of stem cells used in veterinary medicine are called mesenchymal stem cells. These cells have the ability to become connective tissue (bones, ligaments, tendons and so on.) They can be isolated from the bone marrow and fat of adult horses. Stem cell therapy requires the veterinarian to harvest a small amount of bone marrow or fat from the injured horse. He then sends that tissue to a specialized laboratory for processing and culturing to increase the concentration of stem cells. The concentrated product is then shipped back to the veterinarian who injects it into the injured structure right at the site of the injury.
This injection doesn’t necessarily make a tendon or ligament heal faster, instead, it is said to help it to heal with healthy tissue instead of scar tissue. Exactly how it works is still being studied, but it is likely that the positive effects come from a combination of the stem cells turning into healthy tissue, along with natural growth factors, anti-inflammatory factors and other chemical signals that recruit cells to come to the site of the injury. The idea is that the injection, made from the horse’s own body, super-charges the horse’s ability to heal himself.
Stem cell therapy takes several weeks, since the raw material needs to be shipped to the lab and cultured for several weeks and then shipped back. It is also expensive, costing somewhere in the $2,500-$3,000 range.
Bone Marrow Aspirate
Before concentrated stem cells became available, veterinarians tried to improve healing through injections of raw bone marrow. Bone marrow can be drawn from the horse’s sternum, at the area of his girth, with a long needle. It can then be immediately injected into a damaged tendon. This technique came into use in the mid-90s and it is said to be helpful for horses with both chronic and acute tendon and ligament injuries.
The original theory behind bone marrow aspirate is that it works by delivering stem cells to the injury. More recent research has shown that the concentration of stem cells in the bone marrow is relatively low, and that any positive effects of this treatment may come from various growth factors and other chemicals present in marrow. The procedure is quick and relatively inexpensive, with a price of less than $400, making it the least expensive of all the biological therapies.
PRP, which stands for platelet rich plasma, is the latest entry into the equine regenerative therapy market. PRP has a history that goes back to the 1970s, but it didn't come into common use until the 1990s when the machines needed to make it became more convenient and affordable. It was most commonly used by dental surgeons who wanted a way to help their patients heal, and was first used on human tendons in 2006. It entered popular consciousness in 2009 after Hines Ward, the Pittsburgh Steelers' wide receiver, used it on a sprained knee before his team went on to win the Superbowl. Other athletes who have been known to use PRP include Tiger Woods, Rafael Nadal and Kobe Bryant.
Platelets are cells that circulate in the blood and bind together when they find an injury. They also contain at least nine different types of growth factor that are assumed to help speed healing. In the veterinary clinic, PRP is made by drawing a large syringe full of the horse's blood and putting it into a centrifuge that separates the platelets and the plasma from the red blood cells. Then the plasma is put through another machine that concentrates the platelets. PRP may also include some factors from white blood cells, such as Interleukin 8, a signaling protein that stimulates the creation of blood vessels and recruits other types of cells that combat infection and heal wounds. PRP can be made in a matter of 15 minutes or so, and then injected directly into the site of the injury. In horses, it is mostly used in tendons and ligaments, but it can also be used on other types of injuries, such as lacerations.
Although practitioners say it may not be entirely as effective as stem cell therapy, PRP has many advantages. First, it can be created and injected right away: you do not have to wait for it to be cultured and shipped to and from a distant laboratory. Second, it is significantly less expensive, costing an average of $800 to $900.
|Dr. Tom Stinner demonstrates the Magellan PRP |
machine at South Equine Service.
IRAP is generally used for damaged joints rather than for tendons and ligaments. It has potent anti-inflammatory properties, and is used for horses with arthritis, for horses that have recently undergone joint surgery, and for horses that have traumatic damage to their joints. IRAP injection can take the place of an injection of corticosteroids or hyaluronic acid. Its main advantage is that, where corticosteroids tend to have side effects, IRAP does not. Veterinarians also say that IRAP tends to last longer than traditional joint injections. A course of IRAP therapy is usually three injections given a week to 10 days apart. Extra serum can be saved for later injections: it is supposed to be used within a year. The cost to make the course of injections is in the neighborhood of $1,000 to $1,200.
Right for Your Horse?
"We do these therapies almost every day," says Dr. Jamie Carter of Southern Equine Service on Banks Mill Road. "The treatment we use most is IRAP."
"It isn’t just a high end treatment any more," adds Dr. Tom Stinner, who also practices at Southern Equine Service. "Part of it is that people are more educated about it and ask for it; part of it is that it isn't as expensive as it used to be. We also recommend it. Any horse that does enough that it might injure a tendon is a potential candidate."
Dr. Carter agrees. "I've done hunt horses, even trail horses. I've done it for people who love their horse, and he might have strained something or torn something, and they'll do it because they know it is right for him."
The clinic at Southern Equine Service is technologically up to date and has a room with machines for making PRP and IRAP injections. IRAP is so popular that there is even an entire freezer dedicated to storing injections for clients’ horses, about 100 at this writing. Dr. Carter says that in addition to IRAP for joints, he is also a proponent of bone marrow aspirate for tendons and ligaments, and has been using it since at least 1999. Dr. Stinner says that stem cell therapy has gotten less popular recently, mostly because PRP is so much more convenient and effective.
"A few years ago stem cells were supposed to be 'the thing,'" he says. "And they have been very helpful. But now, as far as the end result of having a sound horse that can return to his former level of activity, there isn’t that big of a gap separating stem cells from some of the other therapies."
Dr. Eric Johnson, who practices at Performance Equine Vets on route 78 is also a proponent of regenerative therapies.
"These are therapies designed to produce the best possible results when faced with fairly traumatic, sometimes career ending injuries," he says. "If we want to give a horse the best possible shot, we employ them."
He stresses however, that none of these therapies is magic. The horse still needs to be treated like an injured horse. It still needs stall rest followed by a progressive and controlled exercise program.
"How well it turns out depends on a case by case basis. A fair amount of having a good result is patient compliance. If everything is done as recommended by the veterinarian, we're pretty confident of a good result. We don't usually stop with just PRP or whatever we have used. We usually follow that up with shockwave therapy and a very restrictive exercise regime. If all of these procedures are followed, we get very, very good results in terms of animals returning to performance and their tendons healing well."
Drs. Carter and Stinner agree, saying that any biological treatment is just a part of a comprehensive rehabilitation program that might include traditional supportive therapy (wrapping, poulticing) as well as newer treatments such as shockwave therapy. Controlled, progressive exercise is also crucial to help the recovering structure heal correctly. Although the veterinarians say that there are some types of injuries that are unlikely to be cured by the regenerative therapies available today, these therapies seem to be helpful for many different conditions.
"Condition for condition, you have a better shot with these things than without them," says Dr. Stinner. "You may have no shot without them."
Dr. Carter adds that, with regenerative therapies, as with any other new technology, there is a tendency to think that the new treatment might be a panacea. It is important to remember that a new technology or a new machine is only as good as the person using it, and none of these technologies can take the place of good vet work.
"The number one thing I always tell everyone is that when you go to use any new therapies, be sure you are treating what is causing the lameness," says Dr. Carter. "The lameness needs to be localized, and you have to have a clear idea of what you are doing. It all boils back down to good veterinary medicine: palpating, blocking, x-raying, ultra sounding. Blocking is extremely important so that you are sure you are treating the right thing."
New Treatments, New Hopes
Although you could not yet say that regenerative therapies have provided the ultimate solution for orthopedic injuries in horses, they have at least brought their treatment into the 21st century. Research is still being done on other uses for IRAP, PRP and similar therapies, and there is still work to be done on making the treatments more effective. Although most practitioners probably recognize their potential, everyone doesn’t agree on how useful they are, and some studies have failed to show that they are particularly more effective than supportive therapy and controlled exercise alone. Elite human athletes use PRP and IRAP and swear by it, but it remains a controversial treatment in the U.S., and does not yet have solid backing in the scientific community, either for people or for horses.
In the future, biological treatments will probably be fine-tuned and adjusted. There will also probably be new treatments developed as researchers search for cures for major conditions such as arthritis and spinal cord injury. Advances in veterinary treatments tend to follow advances in human medicine, and even, sometimes, to precede them, simply because it can take so long to get something novel approved for human use.
"There are a lot of great new things coming, I'm sure," says Dr. Carter. Dr. Stinner agrees. "We are probably only scratching the surface."
This article is copyrighted and first appeared in The Aiken Horse. It is reprinted here by permission.