You don’t want to waste time in an equine emergency! The American Association of Equine Practitioners (AAEP) offers these tips to keep you organized and calm in your horse’s time of need.
If you own horses long enough, sooner or later you are likely to confront a medical emergency. From lacerations to colic to foaling difficulties, there are many emergencies that a horse owner may encounter. You must know how to recognize serious problems and respond promptly, taking appropriate action while awaiting the arrival of your veterinarian.
Preparation is vital when confronted with a medical emergency. No matter the situation you may face, mentally rehearse the steps you will take to avoid letting panic take control. Follow these guidelines from the American Association of Equine Practitioners (AAEP) to help you prepare for an equine emergency:
Many accidents can be prevented by taking the time to evaluate your horse’s environment and removing potential hazards. Mentally rehearse your emergency action plan. In an emergency, time is critical. Don’t be concerned with overreacting or annoying your veterinarian. By acting quickly and promptly, you can minimize the consequences of an injury or illness.
For more information about emergency care, ask your equine veterinarian for the “Emergency Care” brochure, provided by the AAEP in partnership with Bayer Corporation, Animal Health. More information can also be obtained by visiting the AAEP’s horse health web site, www.myHorseMatters.com.
The American Association of Equine Practitioners, headquartered in Lexington, Kentucky, was founded in 1954 as a non-profit organization dedicated to the health and welfare of the horse.
Regenerative therapies, such as stem-cell therapy and platelet-rich plasma, can help speed up healing in equine tendon and ligament injuries and make the repairs stronger.
Stem-cell therapy is one of several treatments that fall under the umbrella of regenerative medicine, a fast-growing field that’s creating major buzz in veterinary and human medical circles. These treatments use the body’s own repair tools with the goal of better healing. In this article you’ll find what you need to know about two regenerative treatments being used in horses, stem-cell therapy and platelet-rich plasma. For guidance we turned to Alison Stewart, DVM, an equine surgeon and stem-cell researcher at the University of Illinois, and Jamie Textor, DVM, an equine surgeon who is researching PRP at the University of California at Davis.
These treatments are exciting, but they are very much works in progress. Researchers are searching for the most effective ways to use them, and there are many questions about how?and how well?they work in different situations. They require specialized facilities and know-how that may not be available in every private veterinary practice. But they’re becoming more widely used, and if they live up to their promise, that trend will continue.
Stem cells are cells that have the potential to develop into some or many of the different specialized cells that make up body tissues, such as muscle, bone, blood and nerves. There are different kinds of these chameleonlike cells:
The commercial stem-cell treatments available for horses ?today make use of adult mesenchymal stem cells, or MSCs, which can differentiate into bone, cartilage, fat and fibrous connective tissue. The cells are autologous?derived from the horse being treated. (Experimental treatments have also been done using donor, or allogenic, stem cells.)
“The commercial treatments are ?mainly being used for soft-tissue injuries??tendons and ligaments,” Dr. Stewart says. They are used less for joint problems generally, although some veterinarians think that they can be helpful for stifle injuries that involve a lot of soft-tissue damage.
Tendons and ligaments have different functions?tendons transfer the action of muscles to the skeleton, while ligaments lash bone to bone and keep joints from wobbling. But both are made up mostly of organized networks of dense, elastic connective tissue, rich in a tough protein called collagen. And they basically heal in the same way?that is, slowly and often poorly, with disorganized scar tissue in place of organized collagen fibers. This leaves your horse prone to reinjury.
MSC therapy may allow better repair, with more organized collagen and less scarring, Dr. Stewart says. Your horse will still need a lengthy layup and rehab period, though. The therapy seems to help most when it’s given in the first few weeks after an injury, during the time when healing is getting underway. It’s much less effective for longstanding or chronic conditions.
MSC Treatment. If you and your veterinarian decide to try stem-cell treatment for your horse’s injured tendon, the first step will be to collect MSCs. The cells are harvested from bone marrow or fat, depending on the treatment method used. This is done with your horse standing and sedated, with local anesthesia.
Does it matter where stem cells are collected and how they’re processed? “Some would say yes, but there has been no head-to-head comparison of the long-term effects,” Dr. Stewart says. The various stem-cell products are handled in much the same way when they come back from the lab:
After stem cells are havested and processed, they are injected directly into the injury site.
In most cases the veterinarian injects the stem-cell product directly into the injured tissue, using ultrasound to guide the injection into the lesion. The treatment also can be delivered into the blood supply around the site (regional limb perfusion), but this may not be as effective. “A study comparing the two methods found many more MSCs at the lesion when they were injected directly at the site than when ?injected using regional limb perfusion,” says Dr. Stewart.
The cost varies. “In most cases, from harvesting to reinjection, you’re looking at $1,200 to $2,000 to treat a tendon ?injury,” Dr. Stewart says.
Side effects are rare. As with any injection, there’s a small risk of transient inflammation or infection. But with autologous cells there should be no immunogenic reaction?that is, your horse’s immune system won’t target the cells as foreign and try to destroy them. “Even with cells from another horse, MSCs should be less immunogenic than adult cells,” Dr Stewart says. “But studies are still being done on this.”
Will It Help? Stem-cell success stories abound, but there’s not much peer-reviewed scientific research comparing outcomes with stem cells and traditional treatments. Researchers have done postmortem tissue studies that show good results in tendon and ligament injuries, ?including better alignment of fibers and less disorganized scar tissue?but benefits are hard to track in living horses because of individual differences in their injuries and care, Dr. Stewart says.
Four ultrasound sacans of an injured superficial digital tendon. You can see a large lesion in the scan at the time the bone-marrow aspiration takes place. There is some degradation a month later when the stem cells are implanted and then clear improvement two and four months post-implantation as the tendon regenerates.A recent follow-up study showed lower rates of injury after MSC treatment. Dr. Roger Smith, a professor of equine ?orthopedics at the Royal Veterinary College in Britain and developer of the VetCell technique, reviewed outcomes in 113 racing Thoroughbreds with core lesions in the superficial digital flexor tendons and found that treatment with marrow-derived MSCs cut reinjury rates by more than half. Horses who returned to training after stem-cell treatment and were followed up for three years had a reinjury rate of 27 percent, compared to 57 percent in conventionally treated horses. No comparable follow-up study has been done with fat-derived cells, Dr. Stewart says.
Stem cell therapy is evolving, and researchers are still trying to determine exactly what the cells do after they’re ?injected. “Early research evaluated MSCs for their potential to replace damaged tissue,” Dr. Stewart says. “More research now is directed at their ability to modulate inflammation and encourage healing.”
How long they hang around the injection site varies with the cell type and the tissue. “In tendon, bone-marrow-derived MSCs seem to be present up to two weeks, and then the numbers drop off. We don’t know if they’ve migrated somewhere else, died or divided so that the dye marking them no longer shows up,” Dr. Stewart says. “Embryoniclike stem cells seem to persist longer at the site of injection and travel farther, but they’re not yet commercially available.”
The cells don’t always behave as ?expected. Veterinarians at Cornell University tracked bone-marrow-derived MSCs injected into the fetlock or stifle joints of healthy and arthritic horses. They hoped the stem cells would migrate into damaged cartilage, where they might help repair it. Instead, the cells went to the synovial membrane, which surrounds the joint.
Platelet-rich plasma is blood plasma that has been enriched with platelets. PRP contains and releases several types of growth factors that stimulate soft-tissue healing.PRP is plasma (the straw-colored liquid portion of blood) with a high concentration of platelets, small cell fragments that circulate in the blood. Platelets are best known for their role in helping blood clot, but they also release high concentrations of growth factors that encourage healing. Injected into injured tissue, the premise is, PRP delivers a potent cocktail of these healing proteins to help stimulate tissue repair. This treatment has been used in dentistry for jaw repair and in human sports medicine. In horses, it’s being used primarily for tendon and ligament injuries, both alone and along with MSC therapy.
“We think acute lesions are most likely to benefit from PRP,” says Dr. Textor. “Chronic, degenerative tendon conditions are less likely to respond.” The ideal time for treatment isn’t known, she adds, “but three to four weeks after an injury is probably a good target.”
PRP has been tried as a way to spur wound healing in horses, but it doesn’t appear to help and may actually increase proud flesh formation, Dr. Textor says. It has also been tried as an equine joint treatment; but another blood-derived treatment, IRAP, is more often used there. (IRAP stands for interleukin-1 receptor antagonist protein, a substance that blocks a specific inflammatory agent involved in the erosion of cartilage.)
PRP Treatment. If you opt for this treatment, the PRP will be prepared in the clinic from your horse’s own blood.
A sample of blood is drawn and spun in a centrifuge to separate the plasma and platelets from the red blood cells and most of the white blood cells. The plasma is then concentrated so it contains higher-than-normal blood levels of platelets.
It’s ready for injection into the injury the same day, often in less than an hour.
The cost of a single treatment typically ranges from $400 to $1,000, depending on the veterinarian’s preparation method, Dr. Textor says.
As with stem-cell therapy and any other injection, there’s a small risk of infection or a brief flare of inflammation?but because PRP is derived from your horse’s own blood, the risks of an immunogenic reaction to the treatment are low.
Will It Help? PRP has several advantages?it’s easy to collect and prepare, the turnaround time (from harvest to reinjection) is short and the treatment is cheaper than stem-cell therapy. Those plusses are helping PRP gain acceptance in the horse world.
As with stem cells, though, there’s little published research on effectiveness. In a study of horses with experimentally created tendon lesions, Dutch researchers showed that a single PRP injection resulted in improved healing and increased tendon strength at six months. In a clinical study of racing Standardbreds with severe suspensory ligament lesions, Ohio State University researchers found that one PRP injection helped horses recover and return to racing. On the other hand, some studies in human medicine have cast doubt on PRP’s effectiveness in shoulder and Achilles tendon injuries.
The reasons for different outcomes may emerge with answers to some of the many questions about how the treatment works and how it should be given. For example:
“The main focus of my research is in trying to identify all the variables that go into PRP preparation and administration and figuring out what is the best way to do things so we can standardize our methods and be consistent as practitioners,” Textor says. “It may be that better results are achievable once we figure out how to maximize the benefit of PRP.”
Here’s one thing that seems certain: There will be new developments in this rapidly growing field.
Interest in human regenerative medicine is helping to fuel (and fund) a lot of the research into cell-based treatments for horses. People, like horses, heal slowly and often poorly after damage to tendons, ligaments, cartilage and bone?so the horse is an excellent research model for these treatments. That means research underway now may one day benefit you as well as your horse.
Reprinted from the February 2012 issue of Practical Horseman magazine.
If you compete in rated shows, here’s what you need to know to keep your horse healthy and maintain a level playing field.
If you’re like 99 percent of horse-show competitors, you don’t dope your horse. But you can’t help gulping when you hear those words?it’s like being called to the principal’s office in junior high. Did you or your trainer make a mistake? Are you in trouble?
The USEF regulations for drugs and medications can seem complicated, and changes this year may affect you. In this article Stephen Schumacher, DVM, chief administrator of the USEF Equine Drugs and Medications Program, explains the changes and tells you how to make sure you stay on the right side of the rules.
The goal of the USEF program is to protect horses from abuse and maintain a level playing field, so no competitor gains an unfair advantage through chemistry. And it’s working, Dr. Schumacher says. Of the 10,000 to 12,000 horses that the USEF tests annually (not a huge number, considering how often horses compete and the number of disciplines that the federation oversees), anywhere from 50 to 100 may test positive in a given year?1 percent or less.
“The low rate of positives doesn’t mean the program isn’t needed,” Dr. Schumacher says. “The numbers are low because the program is there?deterrence is its main effect. We would rather educate than adjudicate.”
Education starts with understanding what is and isn’t legal. It’s all spelled out in the USEF Rule Book.
Read All About It
General rules 401 through 413 outline the procedures for testing and enforcement and explain in general what is and isn’t permitted. These rules are carefully (and sometimes densely) worded but definitely worth the read. Anyone who signs an entry form at a USEF-recognized show needs to understand them because that person (usually the trainer, acting as the agent of the owner) has the primary responsibility for making sure the rules are followed. The separate “2012 Guidelines for Drugs and Medications,” available on the USEF website or in a pamphlet from the federation, provide a roadmap for staying out of trouble.
The rules allow different breeds and divisions to adopt different standards for permitted medications; endurance horses, for example, are subject to strict “no foreign substances” requirements. Here we’ll focus on the rules and guidelines that apply to hunter, jumper, eventing and dressage ?divisions. These rules don’t give you a list of every substance that is and isn’t allowed, although they do mention some specifics. New drugs are always being developed, and there will always be a few people willing to try new ways to gain an advantage.
To cover all cases, the rules classify substances based on their actions and uses. Permitted substances, which are not regulated by USEF, include vitamins, minerals, electrolytes, dewormers and most antibiotics (except procaine penicillin?penicillin is OK, but procaine is a local anesthetic that can linger in the horse’s system). They can be given to a horse at any time, including at a competition. Other drugs are sorted into two groups, restricted and forbidden.
These drugs can be used for therapeutic reasons?that is, to treat an injury or disease?but they’re subject to strict limits on the amount of the drug or its metabolites (breakdown products) that can be in blood or urine at the time of competition, as set out in Rule 410. They include the muscle relaxant methocarbamol (Robaxin), the corticosteroid dexamethasone (Azium) and seven nonsteroidal anti-inflammatory drugs: phenylbutazone, flunixin meglumine (Banamine), ketoprofen (Ketofen), meclofenamic acid (Arquel), naproxen (Equiproxen), diclofenac (Surpass, a topical) and firocoxib (Equioxx). Theobromine, a metabolite of caffeine and related substances, is also in this category; the limit is just enough to account for any the horse might get through diet.
You should know:
New this year:
These are drugs that can affect performance, give an unfair advantage, pose a danger to your horse or interfere with drug testing by masking the presence of other drugs. They include stimulants, ?depressants, painkillers and local anesthetics, and tranquilizers and psychotropic drugs, such as reserpine and fluphenazine. Prednisolone, bethamethasone, triamcinolone acetate (Vetalog, often used in joint injections) and other corticosteroids except dexamethasone are in this category. So are NSAIDs other than the seven listed in the restricted group. Although many of these drugs have legitimate therapeutic uses, they should not turn up in a horse-show drug test.
You should know:
New this year:
“We’ve run surveillance across the ?disciplines and never had an issue with anabolic steroids. But we’ve made them forbidden and provided withdrawal guidelines for the most commonly used ones to recognize their potential for ?unfair use and to be consistent with other groups,” he says. “We are actually the last horse-sport group to abolish their use in competition.”
Bending the Rules
The USEF rules are clear: If you give your horse something to calm him or make him less sore in competition, you’re in violation?even if the same something might be permitted for a legitimate therapeutic reason. But intent can be hard to judge, so it’s not always clear when someone steps over the line.
For example, you might see dexamethasone in horse-show medicine chests. Some competitors administer “dex” in the belief that it will calm a nervous horse, although the rules expressly forbid that use and there’s not much evidence that it works.
“Based on work done years ago, the level permitted under the rules would not be expected to sedate a horse,” Dr. Schumacher says. “Some people feel differently. I don’t think there’s any peer-reviewed scientific literature to support that, but there’s a racetrack mentality?people think it works so they use it.” The USEF Drugs and Medications committee will likely be reviewing the guidelines and recommendations for dex, he adds.
Magnesium is also used to quiet horses, something that Dr. Schumacher says is based on a misconception. ?”Hyperexcitability is a sign of hypomagnesia?magnesium deficiency?and giving therapeutic doses of magnesium corrects it. Based on that, some people conclude that giving any horse more magnesium will make him calmer even if he isn’t deficient, but there’s no evidence for that,” he says. Even if it were so, oral magnesium is not a concern because it’s unlikely that a horse could consume enough orally to be affected, he notes. But some competitors administer magnesium sulfate intravenously, which is dangerous. “Given this way, magnesium can affect cardiac rhythm and have a depressant effect, and it’s a horse-welfare issue,” he says.
As of this writing, USEF had no prohibition on magnesium, although the substance is on the association’s radar. One problem is that magnesium is naturally present in horses and in all animals. “To regulate it, you first have to establish a threshold level that’s acceptable. It’s a different situation with drugs like NSAIDs that aren’t naturally present,” Dr. Schumacher says. Nevertheless, he adds, injected magnesium sulfate has been added to the FEI prohibited list this year, and administration will no longer be permitted at FEI show treatment areas.
If Your Horse Is Tested
How likely is your horse to be tested? The choice is pretty much random. “We test at 20 to 25 percent of competitions each year,” Dr. Schumacher says. “There is a focus on upper levels, where more is at stake and violations may be more likely to occur, but we test lower levels as well.” He selects the shows and then asks one of the veterinarians who works with the program to test perhaps one day out of four, at his or her convenience. The odds of being tested are greater for horses who display unusual behavior or place in the top five of their classes, but anyone can be selected. For example, in a dressage class, horses are picked randomly as they leave the ring before the placings are decided.
If your horse is tapped, be polite and take him promptly to the testing area. Arguing or stalling (by cooling out, bandaging and other delays) may be considered “noncooperation,” as much a violation as a positive test. Be helpful as the veterinarian draws blood and the technician working with the vet collects a urine sample.
The samples are handled according to standards set by the World Anti-Doping Agency. Both blood and urine are separated into A and B samples; the A samples are sent to the designated USEF lab for testing, and the B samples are held. If the A samples test clean, the B samples are discarded. But if the test is positive, the trainer (or whomever is responsible) has the right to have the B sample tested to confirm or disprove the result.
A positive test leads to an investigation and a decision on whether the rules were violated. The trainer usually has the choice of accepting an administrative penalty or responding at a hearing before a USEF committee, with or without legal representation. If the committee finds a violation occurred, it will weigh several factors?the type and (for drugs covered by Rule 410) the quantity of drug found, prior violations and how similar cases have been handled. Violators forfeit winnings and any points earned, and under USEF rules they face penalties that include fines ($750 to $5,000) and suspension (one to six months). The violation and the penalty are published, in itself a strong deterrent.
There are trends in violations, Dr. Schumacher says, like a recent spike in reserpine positives. “Medications pop up, but after a few positives, word gets around and the use tails off,” he says. Still, the most common violations ?involve NSAID levels over the limits set by the rules.
“These are ?speeding ticket’ violations, not as serious as, say, doping the horse with an antipsychotic medication,” Dr. Schumacher says. “In most cases we can identify the reason for the violation, and it’s a mistake. Maybe a groom dosed the horse, and the trainer was unaware and gave a second dose.”
To guard against such mistakes, he suggests, make sure your horse’s treatment program is secure, defined and documented:
Last fall, the American Association of Equine Practitioners published a set of guidelines for veterinarians treating nonracing performance horses, and they included several tips that may also help you stay out of trouble:
Maybe some competitors will always be ready to bend the rules (or ignore accepted ethics), even when doing so puts a horse’s health at risk. But statistics suggest these folks are a very small minority. Care and common sense will keep you out of their group.
Recognizing the signs of equine neurological disorders and starting ?treatment early will give your horse his best chance of recovery from these diseases.
Owners dread equine neurological disorders, such as equine herpesvirus type 1, equine protozoal myeloencephalitis or West Nile virus, and no wonder. Many of these problems are hard to diagnose and hard to treat, and they can damage a horse’s nervous system in ways that leave him unsafe to ride. But every neurologic case doesn’t end badly, and quick action?recognizing signs, getting a diagnosis and starting appropriate treatment?can give your horse the best chance.
If you think your horse might have a neurologic problem, it’s time to call your veterinarian. What exactly will your vet do, and what disorders might she find? In this article, we’ll walk you through a standard neurologic exam, tell you what else may be needed to make a definitive diagnosis and give you an overview of the most common problems.
Sorting Out the Signs
Signs of neurologic problems in horses run the gamut?seizures, abnormal behavior, abnormal gait, facial paralysis and more, says Debra Sellon, DVM, professor of equine medicine at the Washington State University College of Veterinary Medicine. “The most common neurologic problem equine veterinarians see in the United States is an abnormal gait,” Dr. Sellon says. “Affected horses are usually ataxic and weak, meaning that they walk with a staggering or drunken type of gait. They may drag their toes, stumble frequently or sway back and forth when they walk.”
Disruptions in a horse’s command and control system create these problems. For normal movement, nerve signals must flow from his brain along his spinal cord to the nerves that govern his muscles?and nerves must signal back to his brain, reporting where his limbs are. If the signals don’t get through, your horse may become uncoordinated or develop abnormal gaits.
Many neurologic disorders can disrupt the signals. In most parts of North America, Dr. Sellon says, the most common are equine protozoal myeloencephalitis and cervical vertebral malformation (“wobbler syndrome”). But there are plenty of others, including injuries, several viral diseases and degenerative conditions, such as equine degenerative myeloencephalopathy, which has been linked to vitamin E deficiencies in young horses.
“Veterinarians use a fairly standard ?approach to determine a diagnosis for horses with neurologic disease,” Dr. Sellon says. The process begins with gathering information on your horse’s history. When did he begin to stumble or show other signs? Has he fallen? Information on your horse’s age, breed and use is important ?because some neurologic problems are more common in certain groups of horses.
Step two is a thorough physical ?examination. This exam may reveal soreness or other non-neurologic causes for your horse’s signs, or it may turn up signs of an injury or a disease that produces neurologic problems. As she examines your horse, your vet compares the right and left sides of your horse’s body, looking for asymmetry and loss of muscle mass (atrophy) that may develop when muscles go unused, as happens in some neurologic conditions. She may check the range of motion in his neck by encouraging him to bend to each side, using a carrot or another treat as a lure. Limited range of motion may mean an injury or even fractured vertebrae in his neck (the cervical spine).
The third step is a detailed neurologic examination. “The goal is to determine, to the best extent possible, the site in the nervous system that is affected,” says Dr. Sellon. By finding out which functions are impaired, your veterinarian can figure out which nerves are involved. The process, called lesion localization, typically ?includes these steps:
General assessment: Your veterinarian observes your horse’s mental status and behavior. Is he alert or ?lethargic? Standing or down? Wandering aimlessly, circling or showing other odd behaviors or postures?
Basic reflexes: This part of the exam starts at the head with tests of the cranial nerves, which are involved in functions like hearing, vision, swallowing and facial sensation and muscle control. To test ?vision, for example, the vet quickly moves a hand toward your horse’s eye to trigger the menace reflex; your horse should blink and perhaps jerk away.
Along your horse’s neck and back on each side of his spine, your vet uses a ballpoint pen or similar object to touch your horse’s skin. A light but firm touch should trigger the panniculus reflex, the skin twitch you see when your horse is pestered by a fly. Lack of a reaction in any area suggests a problem with the nerves that supply that region. At the hind end, the vet checks muscle tone by lifting the tail; a limp tail may be a sign of a spinal cord problem. When his anus is gently stimulated, it should pucker and your horse should clamp his tail.
Maneuvers in hand: These tests show if your horse has control of his limbs and knows where his feet are. The vet watches as your horse is backed and turned in very tight circles in both directions to see how he places his feet. A normal horse keeps his rhythm and steps under his body, while a horse with a neurologic problem may interfere, take confused steps, swing a hind leg wide or pivot on one leg.
On a slope: Your vet may ask to see your horse led up and down a slope, to see if he stumbles, drags his toes or shows other gait abnormalities. Repeating this test with your horse’s head raised sometimes makes the signs more obvious.
Tail pull: This helps your vet assess your horse’s balance, strength and reaction time. As a handler leads your horse forward, your vet grasps his tail and pulls it firmly to the side. A normal horse will resist the pull; a horse with a neurologic problem may be tipped off balance. The test is repeated on the other side.
Foot placement: These tests help determine your horse’s awareness of his limb position. Your vet takes each foot in turn and places it over its opposite number?left front over right front, right front over left front, and the same behind. A normal horse will immediately put each foot back where it belongs; a horse with a neurologic problem may leave one or more feet out of place for a time.
By the end of the exam your veterinarian should know whether your horse’s problem is neurologic and, if so, what areas of his nervous system are ?involved. She may not have enough information for a clear diagnosis yet because many neurologic disorders have variable signs. “Horses with EPM can show a wide variety of signs, ranging from ataxia and weakness, to individual nerve paralysis, to seizures, to problems with urination or defecation,” Dr. Sellon says. “The vast majority of wobblers present for examination with ataxia and weakness of all four limbs. That means a horse with EPM often looks different from a wobbler but sometimes looks just the same.”
Still, your veterinarian will have enough information to make a list of the diseases or disorders that are most likely the cause and then choose the most appropriate diagnostic tests to confirm or rule out the items on that list. Here’s what you can expect for three common conditions.
This disease is common in most parts of the United States, Dr. Sellon says, but diagnosing it can be problematic.
Cause: Microscopic protozoan parasites (Sarcocystis neurona) invade the horse’s central nervous system, damaging the spinal cord and/or brain. S. neurona is mainly carried by opossums, which shed sporocysts (dormant protozoa) in their feces. The horse ingests the sporocysts in contaminated feed or water. (Another protozoan, Neospora hughesi, has been reported in a small number of cases.)
Signs: Depending on the area of the central nervous system that’s affected, signs may include loss of coordination, loss of muscle mass, difficulty swallowing, abnormal gait or lameness, seizures or paralysis. Signs are often more pronounced on one side of the body, Dr. Sellon says.
Diagnosis: Blood and spinal fluid can be tested for antibodies against the EPM parasite, and a negative result rules out the disease. But a positive test doesn’t necessarily mean that your horse has EPM?just that he was exposed to the parasite at some time and mounted an immune response to fight it off. In some regions, 30 to 60 percent of horses have antibodies, but only a small fraction ever show signs of disease. Some new tests have been reported to give a clearer picture of antibody levels. But, Dr. Sellon says, a panel of experts has agreed that test results alone are not enough?it’s important to rule out other possible diseases as well.
Treatment: Drugs used to fight EPM include pyramethamine/sulfadiazine (or sulfamethoxazole) combination (paste, from compounding pharmacies) and ponazuril paste (Marquis, from Bayer). There’s also a pelleted medication, diclazuril (Protazil, from Intervet International), which can be top-dressed on feed if you’re sure your horse will consume the full dose. All the drugs are expensive, and treatment lasts weeks or months.
Be guided by your veterinarian in choosing what’s right for your horse, Dr. Sellon says. “The advertisements for some new diagnostic and treatment procedures may sound very exciting, but they may not have solid science backing them up.”
Outlook: Without treatment your horse will get worse. Medication can halt the progression of the disease, but his recovery depends on how badly nerve tissues have been damaged. If your horse is diagnosed and treated promptly, he may recover fully; but a severe or longstanding case may cause lasting neurologic deficits.
Prevention: So far no vaccine has proved effective against EPM, although research continues. You can take other steps to reduce your horse’s risk:
Wobbler syndrome usually appears in young, growing horses. It’s the most ?common noncontagious cause of neurologic problems.
Cause: The bones of the spine (vertebrae) have a central canal that lets the spinal cord pass through. A wobbler has a structural narrowing of the canal in vertebrae of the neck?a cervical vertebral malformation (CVM) that squeezes the spinal cord and damages nerve tissue. The pressure may be constant or occur only when the neck is flexed or extended. Rapid growth, a diet excessively high in nutrients and imbalances of various minerals have been blamed. The condition can ?affect any breed but is especially common in Thoroughbreds, and genetics may play a role. An injury to the spine may worsen the problem.
Signs: Your horse is incoordinated and weak behind and, often, in front as well. Usually both sides of your horse are affected equally. The signs may creep up gradually or appear suddenly, and the ?severity may vary from time to time.
Diagnosis: X-rays of the neck can help rule out a fracture, Dr. Sellon says, but confirming that your horse is a wobbler usually requires a myelogram. This is a set of specialized X-rays taken while your horse is anesthetized. A dye is ?injected into the space around his spinal cord, and the X-rays are taken with your horse’s neck in various positions to see if the bones impinge on the spinal cord.
Treatment: A wobbler may improve with rest, but the underlying condition doesn’t go away. In some cases a surgeon may be able to fuse the affected vertebrae to reduce pressure on the spinal cord.
Outlook: Most wobblers are not candidates for athletic careers. Successful surgery may improve the condition enough for your horse to be ridden, though.
Prevention: There’s no sure way to prevent CVM, but correct nutrition will help any young horse develop well.
Injuries to the skull or spine can produce severe neurologic problems.
Cause: These injuries typically ?occur when a horse falls or collides with a solid object. For example, a horse who pulls back in cross-ties, panics and flips over backward may strike his poll, sometimes with enough force to fracture his skull or the first few vertebrae of his neck. An event horse who doesn’t clear an obstacle and flips or plows headfirst into the ground may fracture vertebrae farther along the spine.
Signs: Head trauma may knock your horse unconscious, make him temporarily blind or disoriented or kill him instantly. But signs don’t always show up immediately?pressure from internal bleeding in the skull can build slowly, so you won’t know initially how serious the injury is. Signs of spinal injury depend on the location. Your horse may have difficulty rising, lack coordination and show other abnormalities.
Diagnosis: Your horse’s history and signs generally point to injury. X-rays can identify fractures in the skull and spine, but some sites are difficult to image.
Treatment: If a fracture leaves your horse paralyzed or severely incoordinated, not much can be done. Treatment for milder injuries focuses on reducing the inflammation and swelling that put pressure on nerve tissue. Your vet may put your horse on anti-inflammatory medications, perhaps intravenous DMSO, a cortico?steroid or a nonsteroidal anti-inflammatory such as phenylbutazone, depending on the case. Your horse will need a period of rest, followed by reevaluation.
Outlook: No two injuries are the same, so the outlook is different in each case. A horse with soft-tissue injuries ?obviously has a better outlook than a horse with a fractured spine.
Prevention: Accidents happen, but you can minimize your horse’s risks by being sure that he’s fit and ready for his sport and by avoiding situations in which he’ll fight head restraint. If you can’t tie him safely, don’t tie him.
Mosquitoes transmit viral diseases, such as West Nile Virus and Eastern and Western encephalomyelitis, through bites. | ? Joseph Berger/Bugwood.org
Several viral diseases can attack your horse’s central nervous system. Rabies, always fatal, may be the most devastating?but, fortunately, it can be prevented with vaccination and is fairly rare. These are more common.
West Nile Virus. West Nile is one of several mosquito-borne viruses that cause neurologic disease in horses. In the United States, the others are Eastern and Western encephalomyelitis. Another, Venezuelan encephalomyelitis, hasn’t occurred north of the Mexican border since the 1970s. Here are the basics:
EHV-1. Equine herpesvirus type 1 usually causes a flu-like illness or, in pregnant mares, abortion. But in some cases, the virus damages blood vessels in the brain and spinal cord, producing a deadly neurologic disease (equine herpesvirus myeloencephalopathy).
All these viral diseases are widespread in the United States, so take steps to protect your horse:
While Chance’s hind-end is still sunken, especially on the right side, he is looking much better than he did almost a year ago. In the last year, he has gained a significant amount of weight (and still needs to keep gaining) and muscle mass. This was achieved by upping his feed to 4 quarts and adding hay stretcher with each meal, along with Chance walking up and down small hills during the day.
The weather has been unrelenting over the last week. We got about 7 inches of snow and another 7+ inches 4 days later, with low temperatures and hail to boot! Poor Chance has been stall bound due to the slippery conditions. Some days it has even been too icy to hand walk him.
Regardless, Chance has been in good spirits and his back legs look great! He hasn’t stocked up and he is putting weight on the back right hind. I’m hoping that when he is able to go outside, his back right twist will have disappeared! Maybe wishful thinking, but I can still hope.
Wobblers, EPM, & Other Neurological Disorders Journal/Conference Below: