HORSE HEALTH
ISSUE NO. 2 | Fall 2020
Spotlight
FEATURED
Essential Fall Horse Care This season is prime time for some common equine diseases. Be prepared by working with your veterinarian to help prevent disease and catch any issues early. Fall colors and cooler days can make time in the saddle this season especially rewarding. However, this time of year also brings a host of disease considerations. With the lingering pandemic, you may be hesitant to invite a veterinarian onto your property for fear of exposure. Unfortunately, infectious diseases won’t wait. Mosquitos and parasites don’t care what’s going on in our human health headlines; they spread infection no matter what. Remember that veterinary care—regardless of whether it’s preventive or sick care—is an essential service. Rest assured that veterinarians are trained in strategies to control infection, including COVID-19, so your veterinarian will take measures to reduce your exposure when visiting your barn. Anytime your horse shows signs of sickness, don’t hesitate to contact your veterinarian. Waiting to treat diseases, such as equine protozoal myeloencephalitis (EPM), can have dire consequences for your horse. Delaying preventive care can also be devastating. All horses should be seen by a veterinarian at least annually for a physical and dental exam, vaccinations and a deworming evaluation.
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This is true for performance horses and recreational horses alike. (If your horse competes, keep in mind that performance and soundness checks aren’t a replacement for basic health exams.) During a regular exam, your veterinarian will give you guidance on the preventive treatments that are best for your horse’s situation. While there’s no magic trick to keep horses from becoming sick, preventive care and a watchful eye can help keep your horse healthy as winter approaches.
VACCINATIONS Enlist your veterinarian’s help to create a customized vaccination plan. In addition to the core vaccines recommended for every horse, every year, your veterinarian will help you determine which risk-based vaccines your horse needs based on your horse’s lifestyle and the diseases endemic to your area. (For a closer look at core and risk-based vaccines, see page 8.) Once a vaccine protocol has been decided on for your horse, be sure your horse’s vaccines are dispensed from and given by your veterinarian. This helps ensure proper technique to minimize vaccination reactions, plus pharmaceutical companies provide guarantees when their vaccines are given by a veterinarian.
Mosquito-borne diseases Mosquito populations tend to peak in the late summer and fall, which is why fall is often the time when veterinarians diagnose more cases of mosquito-borne diseases, including Eastern and Western equine encephalomyelitis (EEE/WEE) and West Nile virus (WNV). Last year in the United States, 184 horses were diagnosed with EEE and 90 with WNV.1,2 That means hundreds of owners had to watch their horses struggle and potentially lose their battle with these unforgiving diseases. This heartbreak can be prevented through a simple vaccination. Remember, EEE/WEE and WNV are considered core vaccines that every horse should receive, along with rabies and tetanus. A fall EEE/WEE and WNV vaccine booster may be warranted for horses residing in or traveling to areas where EEE/WEE and WNV are prevalent.
Equine flu season Just like people experience a flu season, so do horses. Equine flu season has been clearly demonstrated as extending from December through April, according to ongoing data
(since 2008) from the Equine Respiratory Biosurveillance Program.3 This is typically before horses receive their spring EIV vaccinations and a few months after their fall vaccinations. Taking flu season into account, horses may benefit more from receiving an EIV booster in late November or early December rather than late summer or early fall. Even a one- to two-month adjustment in EIV vaccination timing could make a significant difference for your horse. What’s more, ongoing Biosurveillance Program data shows many horses are under-vaccinated, receiving just one EIV vaccination per year (or less). Some horses may also be receiving vaccines that don’t protect against current flu strains. Researchers at the University of California, Davis School of Veterinary Medicine, have shown that flu strains in the United States are changing. This is referred to as antigenic drift. The researchers found that horses involved in a 2013 influenza outbreak were infected with a new flu strain, named Florida ‘13 after the location and date of first isolation.3 They compared the Florida ‘13 strain with Ohio ‘03,4 the strain recommended
USDA APHIS 2019 Summary of Eastern Equine Encephalitis Cases in the United States. March 2020. USDA APHIS 2019 Summary of West Nile Virus Equine Cases in the United States. March 2020. Lee K, Pusterla N, Barnum S, Martinez-Lopez B. Is Current Vaccine Failure of Equine Influenza Virus Due to Evolution of Endemic Strains or Introduction of Foreign Strains? AAEP Proceedings. 2019 Vol 65. 4 Merck Animal Health Technical Bulletin, December 2019. 1 2 3
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by the World Organization for Animal Health (OIE) for EIV vaccination production. This work revealed Florida ‘13 differed significantly from Ohio ‘03. In response to these findings, Merck Animal Health added the Florida ‘13 influenza strain to the PRESTIGE® line of inactivated influenza-containing vaccines. To help prevent EIV in your at-risk horse this season, work with your veterinarian to schedule appropriately timed EIV vaccines that have evolved along with the virus. Also implement some straightforward biosecurity measures to reduce virus exposure. Take a look at the story on page 12 for some simple steps you can take at home and on the road. Even for horses who don’t leave the farm, the risk of influenza remains—particularly if there are other horses coming and going. Therefore, it’s important to adopt a farm-wide vaccination program.
PARASITE CONTROL Fall is prime parasite transmission time in much of the country. Because parasite transmission is not as high during the very hot or very cold times of the year, fall can be an ideal time to deworm your horse. Your veterinarian will help you determine the optimal program for your horse. With parasite resistance on the rise and no new deworming drug classes on the horizon, we must make sure we are deworming the right horse at the right time with the right product. A fecal egg count test may be recommended to determine the optimal timing and choice of dewormer.
Increased EPM risk Your horse’s risk of developing equine protozoal myeloencephalitis (EPM) is six times higher in the fall.5 Opossums that serve as hosts to the EPM-causing parasites, Sarcocystis neurona and Neospora hughesi, are more active when the weather begins to cool. Autumn is also a time when months of heavy exercise, transport and other stressful events for horses can take a toll, which can increase horses’ risk of EPM. Ideally you could prevent your horse from contracting EPM by ensuring they aren’t exposed to opossums. The horse ingests EPM-infective organisms found in opossum scat while eating or drinking contaminated feed or water. Maintaining a clean barn and property makes the farm less attractive to opossums, but keeping them away completely is difficult. That’s why knowing the sigs of EPM is important. Contact your veterinarian immediately if your horse exhibits any of these neurological signs:
• Gait abnormalities • Ataxia (incoordination) • Stumbling • Muscle atrophy • Weakness • Depression • Inability to chew or swallow • Head tilt or ear droop • Behavior change • Blindness • Seizures Early treatment for EPM is critical, but you must resist the urge to forego getting a proper diagnosis from your veterinarian. While many diseases cause symptoms similar to EPM, they won’t respond to EPM treatment. Therefore, when EPM is suspected, the crucial first step is for the veterinarian to perform a physical and neurologic examination. After homing in on EPM as a possibility, veterinarians then begin a more specific diagnostic process involving antibody testing to determine if there is evidence of a central nervous system infection. This testing is invaluable because you avoid wasting money and, most importantly, time on unneeded treatments. After diagnosing EPM, your veterinarian may recommend an FDA-approved treatment product like PROTAZIL® (1.56% diclazuril) Antiprotozoal Pellets. Horses treated with an anticoccidial drug like PROTAZIL® are 10 times more likely to improve than untreated horses.5 PROTAZIL® is the only FDA-approved product that comes in a convenient top-dress formula administered on the daily feed ration.
Take-Home Message Fall can be the best time of year to spend quality time with your horses—as long as pressing diseases don’t ruin the fun. Schedule a wellness exam with your veterinarian and keep the lines of communication open. By working together, you can help ward off infectious disease threats and keep your horse enjoying the changing season. IMPORTANT SAFETY INFORMATION
Use of PROTAZIL® (1.56% diclazuril) Antiprotozoal Pellets is contraindicated in horses with known hypersensitivity to diclazuril. The safe use of PROTAZIL® (1.56% diclazuril) Antiprotozoal Pellets in horses used for breeding purposes, during pregnancy, or in lactating mares has not been evaluated. The safety of PROTAZIL® (1.56% diclazuril) Antiprotozoal Pellets with concomitant therapies in horses has not been evaluated. For use in horses only. Do not use in horses intended for human consumption. Not for human use. Keep out of reach of children.
Reed SM, et al. Equine Protozoal Myeloencephalitis: An Updated Consensus Statement with a Focus on Parasite Biology, Diagnosis, Treatment and Prevention. J Vet Intern Med 2016;30:491–502.
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DISEASE 101
RABIES QUICK FACTS General Facts
Rare but terminal, rabies is contracted through the bite of an infected or “rabid” animal. It manifests through unpredictable clinical signs and results in fatal brain swelling. An unvaccinated horse will not survive infection, and its saliva poses a risk to humans and other animals. •
Fewer than 100 cases are reported in horses each year, but 100% of them are fatal6
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Horses are typically bitten on their face, muzzle or limbs after investigating the rabid animal
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The number of rabies cases is increasing due, in large part, to urbanization of areas where wildlife is infected
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Stalled horses are at risk as wildlife is drawn to feed rooms and barns
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Due to serious threat for human exposure, any suspected case of rabies should be handled as if it were positive until proven otherwise
100% fatal. Always preventable.
Most Commonly Infected Animals
Raccoons
Foxes
Skunks
Bats
Note: Any mammal can contract and spread rabies.
Talk to your veterinarian to ensure your horse is current on rabies protection. For more information on the PRESTIGE® EquiRab® rabies vaccine, visit PrestigeVaccines.com. Ma X, et al. Rabies Surveillance in the United States in 2017. J Am Vet Med Assoc 2018;253:1555–1568. AAEP Core Vaccination Guidelines (aaep.org).
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Treatment and Recovery If an unvaccinated horse is bitten by a rabid animal, contact your state animal health official Protocol varies from state to state, but often the bitten animal must be euthanized immediately or quarantined for 6 months. No treatment options are available to animals showing clinical signs. All confirmed equine rabies cases are fatal. Important! If a human comes in contact with a rabid animal’s saliva via bite or handling of an infected animal, seek medical treatment immediately.
Clinical Signs
Diagnosis
The signs of rabies infection can be nonspecific and confusing. Veterinarians often say it can “look like anything,” making diagnosis challenging and initial misdiagnosis common. However, at some point during the course of the disease, most rabid horses exhibit: •
Sensitivity to touch
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Fever
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Paralysis or impaired balance
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There is no definitive test to diagnose rabies in a live animal
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Diagnosis is made by examining the brain of the deceased animal
Prevention Prevention through vaccination is the best way to protect your horse against rabies. • Rabies is considered a core vaccination that every horse should receive every year7 •
Adult horses previously vaccinated against rabies should be revaccinated annually
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If a previously vaccinated horse is bitten by a rabid animal, please contact state animal health officials immediately
ADDITIONAL INFORMATION
Brought to you by:
www.equinediseasecc.org/disease-information www.AAEP.org/guidelines www.aphis.usda.gov
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ASKA A VET ASK VET
Custom Vaccine Protocols Does my horse really need so many vaccinations? Vaccination is one of the safest and most cost-effective ways to help prevent horses from contracting disease. The vaccinations your horse needs depend on your horse’s individual situation. When recommending a vaccination protocol, your veterinarian takes into account your horse’s age, environment, travel schedule, proximity to other horses and more. This information is critical to determining which diseases threaten your horse and, thus, which vaccines your horse needs. The American Association of Equine Practitioners (AAEP) vaccination guidelines do some of the work for you. They break vaccinations into two categories: 1. Vaccines recommended for every horse, regardless of geography and whether that horse leaves the farm or is around other horses. These include: • Eastern/Western/Venezuelan Equine Encephalomyelitis (EEE, WEE, VEE) • Rabies • Tetanus • West Nile Virus (WNV) 2. Vaccines horses may need based on their lifestyle. These include vaccinations for conditions such as: • Equine Influenza Virus (EIV) • Equine Herpesvirus (Rhinopneumonitis) • Potomac Horse Fever • And more Vaccinations recommended for every horse, also referred to as “core,” protect against diseases that are especially severe and could affect public health. Rather than the diseases being passed from horse to horse, they’re spread via mosquitoes, wildlife or pathogens in soil. These threats are found everywhere in the U.S., can be year-round concerns and can
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affect every horse regardless of age or health status. While you can take steps to reduce your horse’s exposure to these threats, vaccination is the most effective way to prevent the deadly diseases they cause. The second category of vaccinations is referred to as “risk-based.” They prevent diseases that may be a concern depending on your horse’s environment, lifestyle and life stage. Armed with information about your horse, your veterinarian will assess the threats and advise which risk-based vaccines your horse needs—and doesn’t need. Keep these variables in mind: Living situation. If your pasture shares a fence with your neighbor, viruses don’t know which horses belong to you versus your neighbor. The same is true if your horse lives in a boarding facility. Your horse’s proximity to other horses affects the vaccinations your veterinarian will recommend. Remember that if you own more than one horse, all your horses should be included in a customized vaccination program. Just one single unprotected horse can serve as a reservoir of infection to others. Travel status. Horses being transported or shipped and those competing are particularly susceptible to infectious disease, especially EIV, because they come into contact with many horses and environments and often are immunocompromised (immune system cannot respond appropriately) due to stress. Age. Foals and broodmares require appropriately timed vaccinations. Senior horses may experience declining immune function. As a result, vaccination strategies for senior horses may require further customization. Wanting to limit the number of vaccinations your horse receives is understandable. By working with your veterinarian to create a tailor-made vaccination protocol, you’ll ensure your horse receives the needed vaccinations—no more and no less.
Chrissie Schneider, DVM, MS, DABVP (Equine Practice) Columbus, Ohio
There’s more to vaccinations than simply giving a shot, which is why your veterinarian should administer vaccine injections. Veterinarians are trained in proper handling techniques, plus they plan the timing of the injection based on seasonal risk, area outbreaks and your horse’s health status. In the rare case your horse experiences a vaccine reaction, your veterinarian will be present to offer any needed care. Finally, most manufacturers offer guarantees when a veterinarian administers their vaccines.
About the author Dr. Chrissie Schneider joined Merck Animal Health in 2020 as a senior equine professional services veterinarian. After graduating with her Doctor of Veterinary Medicine from The Ohio State University in 2009, Dr. Schneider completed a rotating internship at Wisconsin Equine Clinic & Hospital in Oconomowoc, Wisconsin. She then returned to Ohio State for their Equine Field Service three-year combined American Board of Veterinary Practitioners (ABVP) residency and graduate studies program, earning a Certificate of Residency and Master of Science degree. She earned board certification in Equine Practice by the ABVP
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in 2013. Following her residency, Schneider spent nearly a year as a clinical instructor in Ohio State’s Equine Field Service. Before joining Merck Animal Health, Dr. Schneider worked for about six years as a veterinarian at Bella Vista Equine Veterinary Services in Blacklick, Ohio, where she focused her practice on preventive care, routine dentistry, emergency medicine and ophthalmic care on the farm.
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GET TO KNOW MERCK ANIMAL ASK A VETHEALTH EQUINE
Helping the Horses that Help American Heroes People who know horses also know that the power of the horse goes beyond athleticism. Connecting with a horse can elicit exhilaration, joy and peace all at once. Jeanne Springer and Billy Jack Barrett experienced this firsthand. Barrett managed the U.S. Air Force Academy (USAFA) Equestrian Center in Colorado Springs, Colorado for over 30 years, and Springer was on staff for 20 years. While working with the military members at the riding stables, Springer and Barrett realized the horses were helping injured veterans. So, they created the Remount Foundation to provide active-duty military, veterans, first responders and their families with equine-assisted therapeutic activities. With the horse playing such an important role in these warriors’ health, Merck Animal Health wanted to help the horses themselves stay healthy. In recent years, Merck Animal Health veterinarians and team members have visited the USAFA Equestrian Center to administer vaccinations and deworming agents to Remount Foundation therapy horses. The Merck Animal Health team was planning its 2020 visit when the COVID-19 pandemic hit. COVID-19 requirements forced the USAFA to restrict access to its facilities, including the Equestrian Center. The Remount Foundation stepped up. Working with the USAFA, the Remount Foundation was able to help some warriors and their therapy assistants to come on base so the warriors could spend time with the horses that help them get through their personal crises. During this time, the Remount Foundation also secured horses and facilities off the USAFA base for safe and secure contact between horses and those in need. The Foundation and USAFA Equestrian Center management also helped to arrange for three Merck Animal Health equine
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team members to visit the Academy this past spring to administer vaccinations and deworming agents to help protect the horses that give so much to American warriors. With steady resolve, the Remount Foundation continues its important service work in the midst of the ongoing pandemic.
REMOUNT FOUNDATION MISSION Provide active-duty military, veterans, first responders and their families with free equineassisted therapeutic activities within a healing, natural environment and a supportive community to empower them to heal physically, mentally and spiritually.
REMOUNT PROGRAM PARTICIPANTS • M ore than 4,500 warriors, veterans and their families have received help • 43% female, 57% male • Veterans from all eras including the Vietnam War • Many suffer from post-traumatic stress disorder (PTSD), including suicidal thoughts Learn more about the Remount Foundation at remountfoundation.org
MERCK TEAM IN ACTION
Even though we provided vaccinations and deworming, it seems team Merck got more from the Remount folks and horses than they got from us,” said Dr. Earl Gaughan, a Merck Animal Health Equine Professional Services Veterinarian who’s pictured here vaccinating a USAFA Equestrian Center and Remount Foundation miniature horse. He’s joined by other Remount volunteers.
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TRENDING
Biosecurity: Simple steps to reduce virus spread Horses don’t worry about social distancing or wearing masks, but you can apply some of today’s public health precautions to your horse. The measures are a basic form of biosecurity. While vaccination is the foundation of protection against infectious disease, a practical biosecurity program can broaden your horse’s level of protection. Biosecurity is especially important in controlling highly contagious diseases, like equine influenza virus (EIV), which ramps up in the fall. The measures also help prevent equine protozoal myeloencephalitis (EPM), a disease that increases along with increased opossum activity in the season’s cooler temperatures. (Learn more about both of these diseases in the cover story “Essential Fall Horse Care.”) Implementing a biosecurity program that helps limit the spread of disease between horses (and between diseasecarrying critters) can be as simple as following these steps: When you’re at home: • Include all horses in your vaccination program. A single unprotected horse in a herd can serve as a reservoir of infection to others. • Practice good hygiene and cleanliness, such as regularly washing your hands, cleaning out stalls and washing water sources. • Remove manure from pastures and paddocks at least twice a week. • Feed hay and grain in raised containers to prevent parasite exposure from manure contamination • Keep feed and grain stores secured to avoid enticing unwelcome visitors, such as opossums.
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• Isolate new horses and monitor them daily for fever and signs of infectious disease. • If horses have returned from traveling, separate and monitor them for at least two weeks. When you’re away from home: • Minimize nose-to-nose contact with other horses. • Don’t share items, including lead lines, halters, water buckets or tubes of oral medications. • Regularly clean your tack, equipment and stalls. • Monitor your horse’s temperature daily so you’ll know what’s “normal.” Deviations from normal might signify an infectious illness. Contact your veterinarian if you note a rise in temperature. • Practice good hand hygiene, washing your hands after handling each horse. (Hand sanitizers work well in the absence of soap and water as long as hands aren’t visibly dirty.)
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