HORSE HEALTH
ISSUE NO. 1 | Spring 2020
Spotlight
FEATURED
Spring Spruce Up for Your Horse and Farm Before you race off for fun in the sun, take a bit of time to dust off your farm and to make sure you’re setting your horse up for a healthy season. Spring brings more and more daylight hours, which means you get the opportunity to spend more and more time in the saddle. But first, spend some of that time evaluating your farm and taking measures to make sure your horse is ready to spring into, well, spring. Start by checking in with your veterinarian. If you own a performance horse, you’re accustomed to having your veterinarian do regular performance and soundness checks, but don’t overlook basic healthcare needs. The same applies to recreational riders. All horses should be seen by a veterinarian at least annually for a physical and dental exam, vaccinations and deworming evaluation. During this exam, your veterinarian can give you guidance on items that can help your horse ward off illness. Veterinarians can also suggest a few easy ways to make sure your farm promotes good horse health. Rest assured, the ideas don’t call for a brand new barn or a line of new fence (but if you’re looking for an excuse to upgrade, don’t let this stop you!). They’re simple solutions you can implement with a little planning and a bit of elbow grease.
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HORSE HEALTH SPOTLIGHT | Spring 2020
IMMUNOLOGY Vaccines could be equated to the worker bees of preventing infectious disease. Which means your veterinarian acts as the queen bee by designing a vaccination program that’s tailor-made for your horse and farm. Your veterinarian considers the American Association of Equine Practitioners’ (AAEP) core and risk-based vaccination guidelines along with your horse’s age, medical conditions and lifestyle. These individual factors affect which risk-based vaccinations your horse needs–or doesn’t need.
For your horse If you own more than one horse, it’s important that all horses be included in your vaccination program. Just a single unprotected horse can serve as a reservoir of infection to others. Devastating diseases such as West Nile Virus (WNV) and Eastern/Western encephalomyelitis (EEE/WEE) are not discerning–any horse exposed to infected mosquitoes is susceptible. Keep in mind, senior horses may experience declining immune function due to age–this is known as immunosenescence. As a result, vaccination strategies for senior horses may require further customization. Horses being transported or shipped and those in competitions are particularly susceptible to infectious disease because they
come into contact with many horses and environments and often are immunocompromised (immune system cannot respond appropriately) due to stress.
Immediately isolate horses with nasal discharge, cough, fever or diarrhea from other horses and have them examined by a veterinarian.
For your farm
STRESS REDUCTION
An understanding of the principles of biosecurity go a long way in preventing disease in your horse. Here are a few biosecurity measures you can implement today:
Horses who travel, train and compete are under a lot of stress, regardless of whether they show outward signs. While stress is a part of life for all living creatures, there are ways to help minimize stress and, thus, reduce its potential negative effects on the horse’s immune system. Sue McDonnell, M.S., Ph.D., founder and head of the equine behavior program at the University of Pennsylvania’s New Bolton Center, offers these practical tips for reducing stress for the traveling horse.
Segregate different populations to manage introduction of disease. For example, keeping horses that travel frequently in another part of the farm is smart because they have different risk factors, are more susceptible to infectious disease and present a risk to resident horses that rarely travel. Quarantine new horses for a minimum of two weeks before introducing them to the resident herd. ractice good hygiene, such as regularly cleaning and P disinfecting tack, equipment and stalls, and washing your hands after handling each horse.
For your horse Take care to ensure your horse trickle feeds– eats small amounts frequently. Wet the hay and offer water at least every couple of hours. Empty bellies for most horses are stressful both psychologically and physically. If at all possible, take a stable travel companion, even a mini or pony mascot.
Minimize nose-to-nose contact and avoid use of communal equipment and water sources.
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For your (temporary) farm If your horse uses a toy or treat at home, take the same toy or treats with you, both for use in the transport vehicle and in the end-destination stable. Also take the home feed tub, hay net, and water bucket. Go a step further, bringing water from home in a container that doesn't impart a chemical odor or flavor. Anything you use at home that is easily portable will reduce the effects of a new environment and may serve as what is known as a safety signal. When you return home, be sure to disinfect any items you took with you to help prevent introduction of disease.
PARASITES Before you head to the feed store to grab a tube of dewormer, talk to your veterinarian. Just like with vaccines, there is no one-size-fits-all deworming program. For example, your weanling in the pasture faces different parasitic risks than your 10-year-old performance horse in the stall. What’s more, your farm is unique, which means your horses and their parasite burdens are unique and may benefit from management solutions that go beyond chemical parasite control strategies.
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AAEP Parasite Control Guidelines (revised February 2016)
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HORSE HEALTH SPOTLIGHT | Spring 2020
For your horse The goal of parasite control is not to eradicate all parasites from a particular horse. Instead, the goal is to control fecal egg shedding and limit parasite infections so your horse remains healthy with no evidence of clinical disease. Because approximately 20 percent of horses shed 80 percent of the eggs on a farm, fecal egg counts (FEC) should be conducted by your veterinarian to identify which horses are actually shedding the parasite eggs. Horses should then be ranked according to their level of shedding as “low,” “moderate,” or “high,” as designated in the AAEP Parasite Control Guidelines.1 Most experts agree animals should be treated differently based on their shedding history. The same individual horse may require more treatments, but this method helps eliminate using dewormers on horses that don’t need treatment.
For your farm The majority of parasites are found in your horse’s environment, which is why FECs play only a partial role in determining deworming needs. Ideally, your veterinarian will visit
your farm once a year, collect and perform a fecal evaluation and assess other non-chemical opportunities. Then your veterinarian can customize a plan for reducing parasite loads on pasture and breaking the transmission cycle. A comprehensive plan could include non-chemical control strategies for reducing parasite egg and larvae buildup. There are multiple options, and your veterinarian can help you decide which ones are realistic for your farm.
NON-CHEMICAL STRATEGIES TO CONSIDER: 1. Cross-graze pastures with other ruminant species, preferably sheep 2. Don’t overstock pastures or allow pastures to become overgrazed 3. Keep pastures mowed 4. Remove manure from pastures and paddocks at least twice weekly 5. During hot, dry weather, harrow or rake pastures to disperse manure piles and expose larvae to sun. Rest the pasture a minimum of four weeks after harrowing
By monitoring your horse’s body score and sharing the results with your veterinarian, you can make sure your horse is getting the right nutrition without contributing to digestive problems.
For your farm Where and how you feed impacts horses almost as much as what you feed. Check all outdoor bins and feeders to make sure winter weather didn’t expose sharp nails or create damage that could harm your horse. Feed hay and grain in raised containers and not directly on the ground to prevent mold and parasite exposure. If you have multiple horses that must be fed as a group, use individual feeders spread far apart, put out extra feeders and make provisions for low-ranking horses to ensure they have the opportunity to eat adequately. The only way to ensure that each horse meets its nutritional requirements is to feed separately. Of course, there’s no magic trick that can completely stop horses from becoming sick, but all these precautions will help you keep your horse in top shape. As you go through spring, partner with your veterinarian to provide your horse thorough preventive care and a sound environment. This dynamic combination will set you up for a season of healthy riding.
6. Harvest a hay crop off pastures 7. Clean water sources regularly to prevent fecal contamination 8. Compost manure. Properly composted manure will kill strongyle larvae and many ascarid eggs
NUTRITION Nutrition is a hot topic among all horse owners. Everyone wants to find that “special recipe” that will help their horse thrive and look fantastic. Luckily, feeding a horse doesn’t have to be complicated, but the ration should meet basic nutritional needs.
For your horse If winter weather resulted in less riding time, your horse may have put on a few pounds. The best way to help you establish whether your horse is overweight, underweight or maintaining the proper weight for its size and frame is through Body Condition Scoring. The target for most horses is a body score of 5, where ribs aren’t visible but are easy to feel. Each condition score above 5 represents 45 to 50 pounds, so a body condition score of 7 is about 100 pounds overweight.
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DISEASE 101
Equine Influenza Virus (EIV) Equine influenza virus (EIV)–or equine flu–is one of the most common and contagious infectious upper respiratory diseases in the horse. It spreads rapidly with clinical signs appearing within 24 to 72 hours following exposure. A coughing horse can propel equine influenza virus more than 50 yards and shed virus for 7 to 10 days following infection.
THE VIRUS CAN SURVIVE
72 48
Hours on wet surfaces
Hours on dry surfaces
INDIRECT TRANSMISSON
RECOVERY TIME
I ndirect transmission can occur via hands, clothing, vehicles and trailers, stalls, and common use articles such as brushes, buckets and bits
quine flu requires significant E recovery time
HANDS
TRAILERS
STALLS
BUCKETS
• a t least three weeks, and up to six months, depending on severity
3 WEEKS to 6 MONTHS
WATCH FOR
These Signs Fever (102.5° to 106.5° F) Frequent dry cough Nasal discharge Lethargy Anorexia Possible secondary bacterial pneumonia
Talk to your veterinarian today to ensure your horse is receiving current influenza protection. For more information, visit www.merck-animal-health-equine.com. 2
Lee K, Pusterla N, Barnum S, Martinex-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.
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AAEP Risk-Based Vaccination Guidelines (www.aaep.org/guidelines).
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GET TO KNOW
The Terminology UNITED STATES Clade 1
CLADE
STRAIN
A group of organisms with a common ancestor • I n the case of equine influenza, clade is used to describe recently isolated viruses (or strains) of equine influenza that belong to the same family
Strains are identified by place and date of first isolation (e.g., Florida ‘13). Additional or more current strains may be added to a vaccine to provide additional or enhanced protection.
•C urrent equine flu strains belong to either the Florida clade 1 or clade 2 families • Clade 1 primarily circulates in the United States • Clade 2 predominantly circulates in Europe (important for horses traveling internationally)
H3N8 (A2): The subtype of equine influenza A virus (first identified in 1963) circulating in horses today
ANTIGENIC DRIFT
UNITED STATES Clade 1
EUROPE Clade 2
Mutations in the equine influenza virus that lead to new strains. The primary reason equine influenza vaccines are periodically updated.
IMPORTANCE OF
Updated Influenza Vaccines
Only PRESTIGE® vaccines feature the most current equine influenza protection available, including: Florida ‘13 Clade 1 & Richmond ‘07 Clade 2, in addition to KY ‘02.
Similar to human flu vaccines, equine influenza vaccines must be updated to protect against the strains currently threatening horses. Continued changes in circulating strains of equine influenza in the U.S. have resulted in numerous reports of influenza outbreaks over the past several years, even in well-vaccinated horses. The most likely cause for these outbreaks is vaccines that don’t account for changing influenza strains, according to a recent study.2
VACCINATION IS THE #1 WAY TO
Protect Your Horse •E quine flu season typically peaks from December to April, but can occur any time of year •
H orses at greatest risk should be revaccinated at 6-month intervals3 • Horses that travel and are in frequent contact with large numbers of horses •H orses at home exposed to traveling horses • Horses with compromised or immature immune systems
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
Vaccine Reactions Why do some horses react to vaccines and how can I be better prepared if my horse experiences a reaction?
HERE ARE THREE TYPES OF VAAEs
Vaccination is one of the safest and most cost-effective ways to help prevent your horse from contracting many infections and potentially life-threatening diseases. That’s why your horse’s veterinarian recommends an individualized program consisting of core and risk-based vaccines.
By far the most common type of VAAE. Usually occur within the first 24 hours after vaccination and resolve shortly thereafter.
Vaccines do their job by creating a cascade of events within your horse’s immune system to ward off disease. These events, on rare occasion, can lead to vaccine associated adverse events (VAAEs). For perspective, think about the last time you received a flu shot. Your arm was a little sore; maybe you felt lethargic or possibly even had a mild fever but, for the most part, it didn’t slow you down for long. Similarly, your horse may also experience a mild reaction after vaccination. In the same way, some people have allergies to certain medications. Similarly, vaccine reactions in horses may be based upon the unique immunological makeup of individual animals and their response to the vaccine. This is why it’s so difficult to identify individual horses who are predisposed to allergic reactions and why we know reactions are not generally due to a faulty or defective product. The best way to prepare for–and decrease the chances of–a VAAE is for your veterinarian to administer all vaccinations. He or she understands the appropriate vaccine handling and injection techniques and will be available on the rare occasion that a serious reaction does occur.
Local injection site reactions
• Signs include: - Localized swelling of varying degree, injection-site tenderness, muscle soreness -D ecreased range of motion of the head and neck or limb less commonly • What you can do Walk or allow the horse to move freely for 20-30 minutes after vaccination, which can help decrease the likelihood of stiffness and local injection-site swelling. Mild systemic reactions Usually resolve within 24 to 48 hours without treatment. • Signs include: - Low grade fever (less than 102°F), lethargy, lack of appetite • What you can do Ask your veterinarian whether a non-steroidal antiinflammatory drug like flunixin meglumine or phenylbutazone and/or an antihistamine may make your horse more comfortable. Allergic systemic reactions Require veterinary attention. • Signs include: - S weating, elevated heart rate, respiratory distress, colic or hives - Anaphylaxis, extremely rare and most severe VAAE • What you can do Contact your veterinarian immediately, especially in the case of anaphylaxis, which is a medical emergency.
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Duane E. Chappell, DVM Owingsville, Kentucky USEquinePV@merck.com
Seeing a vaccine reaction in your horse can be scary and frustrating, but try to keep things in perspective. While reactions are an inherent risk of vaccination–and any medical procedure–the benefits of vaccination far outweigh the risks. Better understanding of what to expect following your horse’s vaccinations is an important part of caring for your horse. Armed with more information, you are better equipped to understand the outcomes and what to do should a VAAE occur, which makes you and your veterinarian a formidable team in the fight against disease.
Vaccinating reactive horses
Do you have a question you’d like answered by a Merck Animal Health veterinarian in a future issue? Message us on our Merck Animal Health Equine Facebook page.
About the author
If your horse has previously experienced an adverse event after vaccination, you must let your veterinarian know. Extreme caution is needed when vaccinating these horses. Your veterinarian can perform a critical disease risk assessment and risk vs. benefit assessment to design a more customized vaccination protocol.
Duane E. Chappell, DVM, received his doctor of veterinary medicine from Purdue University. He joined the Merck Animal Health equine veterinary professional services team in 2014. Dr. Chappell began practicing in the Midwest at mixed animal clinics. Throughout his career, Dr. Chappell has owned and managed solo and group mixed animal practices, and was a resident veterinarian at Richland Ranch Quarter Horse breeding farm. He also served as research monitor, participant and leader in trials involving R. equi, equine influenza, exercise cytokines and plasma antibodies while in practice. Dr. Chappell was most recently an assistant professor at Morehead State University in Kentucky.
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GET TO KNOW MERCK ANIMAL ASK A VETHEALTH EQUINE
Celebrating 12 Years of Helping Unwanted Horses Tens of thousands of horses are neglected or abandoned every year. To support the organizations that help these horses find the homes they deserve, Merck Animal Health Equine and the American Association of Equine Practitioners (AAEP) formed a nonprofit partnership called the Unwanted Horse Veterinary Relief Campaign (UHVRC). Established in 2008, the program provides qualifying equine rescue and retirement facilities with vaccines for horses in their care to help protect against: • • • • • •
West Nile Virus Eastern/Western encephalomyelitis Tetanus Rabies Influenza Herpesvirus
GET INVOLVED You may already be involved! Every Merck Animal Health Equine vaccine purchase goes toward supporting the UHVRC. To receive vaccines for an equine rescue center, visit UHVRC.org/GetInvolved, download the UHVRC application and follow the simple steps.
COMMITMENT BY THE NUMBERS
39,000+ 39,340 horses vaccinated to date… and counting
1 Million+ More than $1 million in Merck Animal Health vaccine donations
2,200+ More than 2,200 applications received to date
300+ Applications received from rescue and retirement facilities in 42 U.S. states
1,000 Nearly 1000 AAEP-member veterinarian supporters
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SUCCESS STORIES
Noel More than 200 pounds underweight and infested with intestinal parasites when she arrived at MSSPA in December 2015, Noel is among the horses at the facility to benefit from core and risk-based vaccines through the UHVRC in 2017.
Bedford Road Bedford Road, a 15-year-old Thoroughbred gelding and favorite of the Second Chance Ranch Equine Facilitated Learning program, is among 40 horses at the facility to receive core and riskbased vaccines through the UHVRC.
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TRENDING
Information Is Power Against Infectious Diseases By taking both a short- and long-term look at infectious diseases, you can give your horse the best protection. In the midst of the worldwide coronavirus outbreak in people, the minds of many horse owners naturally go to thinking about how equine infectious diseases could affect their horse. Thankfully, there are organizations that constantly track equine infectious diseases in order to better understand how to protect horses. One such organization is the Equine Disease Communication Center (EDCC), a non-profit group that issues real-time alerts on cases and quarantines of infectious diseases in North America ranging from strangles to equine herpesvirus to equine influenza and–yes–even equine coronavirus. The EDCC reports on cases that have been diagnostically confirmed by a state animal health official or an attending veterinarian. The group’s website equinediseasecc.org provides information about what horse owners should do in the first 30 minutes of a suspected outbreak. Of-the-moment information like this is essential during an outbreak, but it’s only part of the story. Long-term infectious disease monitoring allows organizations to analyze data that helps shape recommendations on vaccination, biosecurity and more.
TRACKING AN INCREASE IN FLU Equine influenza is one disease where immediate and extended information come together to create a thorough health picture. The EDCC broadcasts immediate flu cases and issues recaps of cases reported through the Equine Respiratory Biosurveillance Program, an ongoing initiative from Merck Animal Health in partnership with the University of California, Davis School of Veterinary Medicine. Through the Biosurveillance Program, veterinarians across the country voluntarily submit respiratory disease samples to the UC Davis lab for analysis.
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HORSE HEALTH SPOTLIGHT | Spring 2020
Using Equine Respiratory Biosurveillance Program data from 2008 to 2019, researchers completed a study confirming cases of equine influenza virus (EIV) are increasing.4 This points to evolving influenza viruses. In fact, Biosurveillance Program researchers identified and isolated a new influenza strain, Florida ‘13, which is representative of a current circulating strain responsible for a 2013 outbreak in a large number of well-vaccinated horses. In response to this finding, Merck Animal Health added the Florida ‘13 influenza strain in 2018 to the PRESTIGE® inactivated influenza-containing vaccines. The Florida ‘13 strain very closely aligns with the current circulating flu strain in the field and provides the protection not found in older flu strain vaccines.5 Check out pages 6 and 7 of this issue to learn more about equine influenza.
TAKE-HOME MESSAGE In the midst of all this infectious disease talk, focus on your horse and what you can do to decrease the risk of disease. Here are three key actions to take:
1
K eep vaccinations current. The first and most important step in preventing infectious diseases is working with your veterinarian to implement a vaccination program that’s right for your horse and that protects against the most current disease strains in circulation–like Florida ‘13 for EIV.
2
T ake biosecurity measures. For disease-preventing actions to take around your farm, take a look at the immunology section in our “Featured” story on page 2.
3
Get instant alerts. Stay up to date on infectious diseases by downloading the EDCC’s new smartphone app. Search “EDCC disease alerts” on Google Play and the Apple App Store.
Worried about coronavirus? Coronavirus in people is different from equine coronavirus, which is spread through feces. The Equine Disease Communication Center has reported just two cases of equine coronavirus from February 2018 through February 2019. There is no vaccine for equine coronavirus, so the best method of prevention is to maintain high sanitation standards and carefully dispose of manure.
Equine influenza cases are on the rise4 Monitoring trends like the increase of equine influenza virus (EIV) helps the equine industry better manage disease in horses by ensuring vaccinations and vaccine recommendations are current.
PERCENT OF EIV CASES BY YEAR
20
*
15
*
10 5 0 2008
2009
2010 2011
2012
2013 2014
2015
2016
2017
2018
2019
* EIV cases have been trending upward since 2008. The year 2013 marked the Florida outbreak, and cases spiked again in 2019, making EIV the most common infectious respiratory disease of the horse last year.
4
aala W, Barnett DC, James K, Chappell D, Craig B, Gaughan E, Bain F, Barnum SM, Pusterla N. Prevalence Factors Associate with Equine Influenza Virus Infection in Equids with Upper Respiratory Tract V Infection from 2008 to 2019. AAEP Proceedings. 2019 Vol 65.
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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.
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