In most horses, light exercise can help alleviate muscle soreness after vaccinations. Photo © Celia Strain/EQUUS

Q: What is the proper protocol for exercising your horse after he receives shots? Is it OK to work him or should he have the day off? When I had to have vaccinations because I was traveling out of the country, my arm was sore. Does this happen to horses, too?

A: Just as with people, horses may have a wide range of reactions after receiving vaccinations. The majority of equine vaccines are administered by intramuscular injections, or “shots into the muscle,” on the side of the neck.

For most horses, the

only reaction, if any, is a little local inflammation and soreness at the injection site, which lasts just a few days. Usually, light exercise the day of the vaccinations and the next will actually help make the sore muscles feel better. During these workouts you might notice a little stiffness, but most riders report that they cannot feel any difference. After the first day or two your horse can return to his normal exercise routine and level.

There are some exceptions to this rule: If your horse has significant swelling, a fever or severe stiffness after his vaccinations, talk to your veterinarian before resuming exercise.

Some equine vaccines are administered intranasally---via a fluid or mist shot up the

nose. These don’t cause muscle soreness, but they can make a horse run a fever or feel a little depressed, so a day or two of rest might still be a good idea.

Your best bet is to ask your veterinarian whether there is any reason for concern at the time she administers the vaccinations. She will have selected vaccines for their effectiveness and safety and will want to hear about any reactions your horse has had in the past.

Of course, you’ll want to use common sense: Don’t start anything new at the same time as the vaccinations, don’t increase your horse’s workload, don’t exercise him if the weather is excessively hot or cold, and schedule a break in his schedule if he has run a fever or had other significant reactions in the past.

Melinda Freckleton, DVM
Haymarket Veterinary Service
Haymarket, Virginia

When you receive injections, your doctor first wipes your skin with alcohol to prevent bacteria from entering the wound made by the hypodermic needle. When delivering an injection to your horse, your veterinarian skips this step.

Why? Because the density of your horse’s coat means that the application of alcohol to an injection site does little, if anything, to reduce the risk of infection. If your horse is filthy, your veterinarian may ask you to wash and dry the target area, but chances are she’ll just wipe the top of the medication bottle with alcohol and leave the horse alone.

Fortunately, infections at injection sites are not common in horses. Occasionally, a horse may develop a little localized swelling or even a small pus-filled abscess after receiving a shot. These typically heal with little treatment. In rare cases, a horse may develop a severe, life-threatening infection caused by clostridial0 bacteria. This is characterized by a large swelling that is hot and painful to the touch. This risk is the reason veterinarians prefer to administer injections to the side of the neck where any infections would be easier to drain and treat.

Veterinarians do, however, disinfect the skin before making an injection near a horse’s joints. The immune system cannot easily reach the fluids and tissues inside a joint, and any infections that take hold there can become catastrophic. Before injecting a joint, your veterinarian will scrub the skin with a topical disinfectant and may shave the coat to further reduce the chances of contamination.

Answer: This year has been record-breaking in terms of both West Nile virus (WNV) and Eastern Equine Encephalomyelitis (EEE). As of the end of August, the Animal and Plant Health Inspection Service (APHIS) was reporting 157 equine cases of WNV in 31 states¹ and 110 equine cases of EEE.² Nationwide, the number of WNV cases reported in all species (mosquitoes, sentinels, humans and horses) is the highest it has been since 2004.3 These life-threatening diseases are out there, and the best way to help protect your horse is to vaccinate.

Even if you haven’t stayed current with your vaccination schedule, it isn’t too late. But be sure to talk to your veterinarian about using a vaccine that is fast-acting.

In the case of WNV in particular, recombinant vaccines such as Merial’s RECOMBITEK® rWNV-EWT, have been proven to be very effective in providing protection, even after a single dose.⁴ In a study, onset of immunity occurred in just 26 days after the initial dose.⁴ This quick immune response is important if your horse hasn’t already been vaccinated.

Since the best way to help protect your horse is to vaccinate, do it as quickly as possible. Both WNV and EEE can be life-threatening, with 33 percent of the horses that show clinical of WNV ultimately dying or being euthanized⁵ and 90 percent of those that show clinical signs of EEE dying.⁶

Horse owners should also remain aware of potential threats to equine health present in their communities. Merial’s free Outbreak Alert program tracks reported cases of WNV, EEE, Western Equine Encephalomyelitis, Equine Herpesvirus, rabies, equine influenza and Potomac horse fever around the country. Those who have signed up for the service receive texts and/or email messages notifying them of confirmed disease threats in their areas. Owners who travel with their horses can enter multiple ZIP codes in the site’s search field to help them stay abreast of disease threats throughout the country. There are also veterinarian-exclusive features available, including printable materials veterinarians can share with their clients.

Now through the end of 2012, in the Exclusive Offers section of outbreak-alert.com, horse owners can download a coupon for up to $8 off when they have their veterinarians vaccinate their horses.

To learn more about WNV, EEE and other equine diseases and vaccination guidelines, or to sign up for Outbreak Alert, visit outbreak-alert.com.

About Recombitek rWNV-EWT
Recombitek rWNV-EWT vaccine is a combination vaccine labeled to aid in the prevention of disease and viremia due to West Nile virus and encephalitis caused by Eastern Equine Encephalomyelitis Virus (EEEV) and Western Equine Encephalomyelitis Virus (WEEV) and tetanus caused by the Clostridium tetani toxin.⁷

®RECOMBITEK is a registered trademark of Merial Limited. ©2012 Merial Limited, Duluth, GA. All rights reserved. EQUIBGN1236 (09/12)

¹Disease maps page. United States Geological Survey Web site. Available at: http://diseasemaps.usgs.gov/wnv_us_veterinary.html. Accessed August 29, 2012.
²Disease maps page. United States Geological Survey Web site. Available at: http://diseasempas.usgs.gov/eee_us_veterinary.html. Accessed August 29, 2012.
³Centers for Disease Control and Prevention. Press release. West Nile virus disease cases up this year. Available at: http://www.cdc.gov/media. Accessed August 14, 2012.
⁴Siger L, et al. Assessment of the efficacy of a single dose of a recombinant vaccine against West Nile virus in a response to natural challenge with West Nile virus-infected mosquitoes in horses. Amer Journ Vet Res. 2004;65(11):1459-1462.
⁵Guidelines for the vaccination of horses: West Nile virus. American Association of Equine Practitioners. Available at: http://www.aaep.org/wnv.htm. Accessed August 7, 2012.
⁶Eastern/Western equine encephalomyelitis. American Association of Equine Practitioners. Available at: http://www.aaep.org/eee_wee.htm. Accessed August 7, 2012.
⁷RECOMBITEK rWNV-EWT product label.

At Rancho Sierra Vista Equestrian Center in San Juan Capistrano, California, bad news came on the heels of the new year. “A little cough had been making the rounds of the barn, and we were on alert for that,” recalls trainer Cathy Hanson, who stables 30 horses at the 350-horse multidiscipline facility. “But in early January one horse developed neurological signs, and that prompted testing.”

The blood test came back positive for a form of equine herpesvirus-1 that can cause potentially fatal neurological disease in horses. “EHV is everywhere, and it’s super-contagious,” Cathy says. State animal health officials were called in, and on January 10 the facility was quarantined.

An outbreak of contagious disease is a nightmare at any barn, let alone a facility home to so many horses. This was the first such incident for Rancho Sierra Vista, but it was just one of several outbreaks that have put riders on edge around the United States in recent months. The list of disease-causing organisms that spread horse to horse includes viruses like EHV and equine influenza as well as bacteria like Streptococcus equi, which causes strangles. How can you protect your horse?

“We won’t be able to prevent all cases of these diseases,” says Josie Traub-Dargatz, DVM, MS, DACVIM, an equine disease expert at Colorado State University. But that doesn’t mean you’re helpless. In this article, Dr. Traub-Dargatz explains how you can ­assess—and reduce—the risks your horse faces. Those risks are greater if he lives at a big commercial boarding stable or is a regular on the show circuit than if he lives in your backyard and just makes a circuit of the pasture. But he faces some danger of infectious disease anytime he comes in contact with other horses.

Get the Facts First
Word of disease outbreak travels fast these days, via Facebook, Twitter, online forums, text messages, and email. “Social media can get information out extremely quickly,” Dr. Traub-Dargatz says, “but the accuracy of the information may be open to question.” To assess risk, you need to separate facts from rumors and exaggerations.

Some contagious equine diseases are reported to state animal health officials, and that makes it fairly easy to get reliable information about an outbreak. For example, in California, neurological cases caused by EHV-1 must be reported to the state Department of Food and Agriculture. During the San Juan Capistrano outbreak this allowed everyone to get frequent and accurate updates on the CDFA website, where outbreaks are categorized by county instead of by naming specific facilities. Reporting requirements for equine diseases vary state to state, so check with your state’s animal health officials to find out which diseases are reportable where you live.

Reporting requirements helped check a multistate outbreak in 2011, when more than 400 horses were exposed at a cutting-horse event in Utah and went home to barns in 19 states and Canada before the first case was recognized. State and federal officials worked closely to track the horses and get accurate, timely information to the public.

When the disease isn’t reportable to state animal health officials, getting information is much more complicated. For instance, California doesn’t require reporting for equine flu or common forms of EHV that cause respiratory disease in horses and abortion in pregnant mares. Where should you turn? Your veterinarian is the most likely source of reliable advice, but with no central clearinghouse for information it can be a challenge to get the facts.

The American Association of Equine Practitioners has formed a task force to develop a communications plan for disease outbreaks. (This is part of an effort by the American Horse Council to create a national equine health plan.) “The goal is to make sure owners and managers of events and horse facilities, industry associations, extension agents, horse councils and veterinary practitioners all have accurate information quickly, acknowledging that the source of that information may vary,” Dr. Traub-Dargatz says.

The task force will develop a draft plan and send it to the American Horse Council for industry input, so there’s an opportunity for horse owners and event organizers to get involved, she adds. “Think about what diseases you need to know about and what your concerns are. You can voice those concerns to breed or discipline associations or to your state horse council, which all communicate with the AHC.”

Because there is no cure or vaccine for EIA and a small percentage of infected horses can survive and become symptom-free carriers, we use Coggins tests to keep surveillance on the disease and combat its spread. Horses must be tested prior to interstate travel, change of ownership or entering an auction or sale, according to the U.S. Department of Agriculture. Some states even require horses being transported within the state be tested as well. The tests are very affordable—generally between $20 and $30 each—so most boarding stables are reasonable in expecting their clients to test annually. Even when it’s not legally required, veterinarians also generally recommend annual testing of horses, depending on their exposure risk.

EIA is transmitted from horse to horse through the blood, either by insect vectors (horseflies, deerflies, etc.) or—in very rare cases—by cross-contamination of shared needles. Your horse’s risk of exposure, therefore, depends on his proximity to infected horses and the population of potential vectors in your region. Certain environmental conditions, for example, may expose him to more blood-sucking insects. The farther these insects must fly from the disease host to your horse, the less likely he is to be infected. So pasturing him alongside a carrier is much riskier than having one several miles away.

Newly infected victims of EIA experience signs such as a high fever, severe depression and loss of appetite. Most die within weeks. If a horse has produced a negative Coggins test at some point in his life and has not shown these signs since, it’s extremely unlikely that he has contracted the disease.

Because EIA is a fatal disease, though, it’s perfectly reasonable to ask your barn owner when her retired horses were last tested. If they all had negative tests and have not shown any signs since then, their risk to your horse is negligible.

On the contrary, if you are taking your horse off the property and mingling with other, unfamiliar horses, he’s probably more of a risk to the resident horses. EIA is still highly unlikely, but this older population may be vulnerable to other viral diseases that traveling horses bring back to the property. (The barn owner, therefore, should still continue routine vaccinations.)

Your vigilance about equine diseases is a great example for the entire horse community. Thanks to good horse owners like you, we’ve nearly eradicated EIA from the United States!

Cody Alcott, DVM, DACVIM grew up in Southern California, riding in rodeos and working with draft horses in pulling contests and other recreational driving activities, including camping with his family by covered wagon. “It was like a fancy RV, only with horses pulling it instead of a truck.” After graduating from Iowa State University College of Veterinary Medicine in 2004, he worked in an equine and small animal practice in Sacramento for several years. Since then, he has returned to Iowa State to teach equine medicine and pursue board certification in neurology. He still finds time to trail ride on the weekends.

In January, California authorities reported new cases of equine herpes virus myeloencephalopathy (EHM), the neuropathic for of equine herpes virus (EHV-1, commonly known as "rhino"). After the outbreak in mid-May 2011, H&R reported on biosecurity measures in the Emergency! section. Review those tips from contributing veterinarian Dr. Barb Crabbehere.

If there were an outbreak of an infectious equine disease in your locality, would you know how to keep your horses safe? Or what to do if they were exposed—or became ill?

We asked H&R’s contributing veterinarian, Dr. Barb Crabbe, for a step-by-step checklist to cover the various scenarios. Here’s what she told us.

Get Informed
First, don’t panic. Turn to a reliable source, such as your veterinarian, your local veterinary teaching hospital, or appropriate state/federal officials for accurate information that applies to your area.

Avoid Exposure
You needn’t automatically enact a stay-at-home policy unless your vet recommends it. But don’t take your horse anywhere there’s a known risk for the outbreak—such as a facility where horses are known to be sick.

Consult your vet about potential vaccination protocols (though there won’t always be one, depending on the disease).

Monitor/Isolate Exposed Horses
If your horse does inadvertently become exposed to a contagious disease, isolate him for at least two weeks (30 days is the ideal) in a stall or pen at least 30 to 40 feet away from other horses. Monitor his temperature every day, notifying your vet if it rises.

Contain Contagion
If your horse becomes ill, work with your vet to provide appropriate care while keeping the sick animal isolated from other horses. A separate barn is ideal, or else designate a quarantine area at the far end of your barn, away from other horses and the main traffic area.

Use duct tape on the barn floor so everyone knows where the quarantine area is. Wash your hands thoroughly before and after tending the sick horse, and keep hand sanitizer available for additional cleanings and for visitors to use. Follow disinfection techniques with all equipment that comes into contact with the sick animal (see “Disinfection” below). Always tend to sick or exposed horses last in your daily routine.

Establish a dedicated wheelbarrow and fork for cleaning the quarantined stalls; burn or otherwise safely dispose of the bedding. Designate one pair of rubber boots and rubber gloves, plus perhaps coveralls to use whenever you’re in the quarantine area; then remove them and leave them for use there only.

If need be, set up a shallow basin full of properly mixed disinfectant so other individuals can wash off their footwear before leaving the quarantine area.

Routine Biosecurity
As May’s equine herpes virus outbreak reminded us, a program of good, ongoing protective measures (popularly known as “biosecurity”) is your first, best line of defense against infectious diseases. Follow these recommendations:

At Home

• Work with your vet to set up a vaccination plan for all horses in your care.
• Be sure all horses entering your facility (or the one where your horse is boarded) are appropriately vaccinated and free of all communicable diseases; ideally, isolate all incoming horses for up to 30 days.
• Don’t share water or feed buckets, grooming equipment, or any piece of gear that may come into contact with a horse’s eyes, nose, or mouth.
• When cleaning or filling water containers, don’t allow the hose nozzle to touch the container.
• Remove all manure/waste products to a location away from the barn.
• Limit horses’ exposure to disease-spreading pests such as flies and mosquitoes.

When Traveling

• Monitor temperatures prior to traveling, and don’t ship a horse that’s had a fever within five days of a haul.
• Keep a disinfectant-filled spray bottle handy to disinfect stalls and stable areas before moving your horse into a show grounds or other new facility. (Spray liberally.)
• Don’t use common water buckets or feed areas at shows or event grounds.
• Don’t borrow/share halters, twitches, lip chains, or other items that may touch a horse’s eyes, nose, or mouth.

Disinfection
Items that can be disinfected when necessary include nylon halters, bits, lip chains, grooming equipment, stalls, buckets, shovels, pitchforks, and even shoes and car/truck tires.

Remove all excess dirt/debris from items to be disinfected, including stall floors and walls.

Wash the item or area first with laundry detergent or dish soap.

Immerse or thoroughly wet the item/area with an appropriate disinfectant. Products that are phenolic-based (Lysol) or quaternary ammonium-based (Roccal D) are most effective. (Although bleach is effective against most viruses and bacteria, it’s inactivated by organic material, making it less-than-ideal in a barn situation.)

Rinse the disinfectant off thoroughly with plain water.

As your pregnant mare awaits her bundle of joy, start planning well in ­advance—before she’s even bred in some instances—with this pre-foaling checklist to set the stage for the best outcome: a calm, comfortable mare; a healthy foal; a happy you.

Before She’s Bred
1. Insure your mare. In the unlikely event that you lose her during foaling, your ­emotional loss won’t be compounded by financial loss. Most equine mortality insurance policies offer major medical insurance at a relatively small additional premium—a great safety net if you incur foaling complications.
2. Make sure you have a practitioner who’s experienced and motivated to meet your needs. Determine now how closely she’ll work with you during breeding, pregnancy and foaling.
3. Educate yourself. The more you know about what to expect, the better. If you have an opportunity to see or help with actual foaling, take it!

Once She’s Pregnant
1. Plan to be there. Sometimes mares can handle foaling just fine without any help, but sometimes they can’t. If you’ve been monitoring your due-to-foal mare carefully enough to contact your vet at the first signs that birth is beginning, you increase your chances of having assistance on hand if needed. If you’re not sure you can be available, make arrangements for your mare to foal at a facility equipped to care for her.
2. Calculate your mare’s likely foaling date. The majority of my mares foal ­between 330–337 days from their breeding date, but I’ve had foals born as early as 320 days and as late as 390 days after breeding.
3. Immunize on schedule. Plan with your vet to vaccinate your mare four weeks before she’s due to foal and that all vaccines are specifically approved for use in pregnant mares. The antibodies these vaccines stimulate her to produce will pass to the foal in her colostrum.
4. Accustom your mare to udder handling to make nursing and (if necessary) milking easier. Clean your hands scrupulously before and after handling her udder.

Four to Six Weeks Ahead
1. Prepare the foaling stall and move your mare in at least four weeks before she’s due so she can relax and allow her immune system to build up antibodies to unfamiliar organisms in the stall. I bank the stall with two to three bales of straw but leave shavings in the middle. When she’s about to foal, I pull the straw in from the walls.
2. Set up a heat lamp if your climate is cold. Check that the lamp is free of dust and cobwebs (fire hazards), and ensure that the cord and plug are in good condition and out of reach of horses.
3. Arrange to have a helper. Even an experienced person shouldn’t foal a mare out alone. You need a second pair of hands.
4. Pin down hauling arrangements, just in case. Your mare may need attention at a full-scale surgical facility. Identify the facility; get 24/7 contact info and directions. Keep your truck and trailer hitched and ready to go. If you don’t have a rig, locate someone who can trailer you to the clinic at a ­moment’s notice.
5. Assemble everything you’ll need during the big event. I like to store this equipment in a “foaling cart” with drawers to keep things organized.

Final Few Days
1. Monitor your mare. Because foaling happens quickly once it begins, you need to observe her almost constantly. Consider installing a video camera in the stall or investing in a foal alert device.
2. Wrap your mare’s tail to make it easier to see underneath before foaling and to help keep tail hairs away from her vagina during the birth. Begin wrapping about a week before the due date.

By following this checklist, you’ll know you’ve done all you can to be prepared and avoid last-minute surprises when the big day—and bundle—arrives.

Deborah Borra’s Normandy Manor Farm is a Swedish Warmblood breeding facility in Western New York’s Genesee Valley.

Customize Your Horse"s Vaccination Plan | EQUUS Magazine

Your horse hesitates and steps awkwardly when he walks downhill. He’s dragging his toes, too, and a few times he has even stumbled while trotting in the ring. He doesn’t seem sore, and your trainer and farrier don’t see anything wrong with his feet—but you know he’s not right. Could he have one of several equine neurological disorders, like equine herpesvirus type 1 (EHV-1) equine protozoal myeloencephalitis (EPM) or West Nile virus?

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).

Neurologic Exam
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.