Merck Equine Partners in Practice Magazine: Spring 2020

ISSUE NO. 1 | Spring 2020

MAGAZINE

AN INFLUENZA STRAIN

BY ANY OTHER NAME IS JUST NOT THE SAME Tracking the ever-changing flu virus demonstrates that influenza vaccines must evolve with the strains

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GET THE WHOLE FLU STORY

RON'S CAMPFIRE

DISEASE DU JOUR

Cowboys, Wire Cuts and Chewed-up Broadleaves

Your New Drive-Time Habit

The Science of Significant Protection Explained

PARTNERS IN PRACTICE | Spring 2020

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Featured

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HA STALK

NA Figure 1. - Equine Influenza Surface Proteins.

Influenza strains are named based on the hemagglutinin (HA) and neuraminidase (NA) surface glycoproteins.

AN INFLUENZA STRAIN

BY ANY OTHER NAME IS JUST NOT THE SAME Tracking the ever-changing flu virus demonstrates that influenza vaccines must evolve with the strains

By Duane E. Chappell, DVM, Merck Animal Health Equine Veterinary Professional Services

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here’s much ado about flu of late and with good reason. The incidence of equine influenza virus (EIV) has been trending upward since 2008.1 Equine influenza was the most common infectious upper respiratory disease of the horse in 2019, with significant increases noted in February, March and June.1,2 Adding to the flu intrigue is the high number of cases occurring in vaccinated horses. Of the horses with known vaccination status, 61% of positive EIV cases occurred in horses vaccinated against EIV.

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Tracking an Evolving Target To find a plausible cause for the EIV vaccine failure that’s been ramping up since 2013, researchers at the

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Figure 2. - Key antigenic sites of the HA glycoprotein

University of California, Davis School of Veterinary Medicine compared the heterogeneity of circulating wildtype EIV strains in the United States with Ohio ‘03 (OIE recommended clade 1 influenza strain) to determine whether vaccine failure was due to the introduction of foreign EIV strains or the natural selection of EIV strains (antigenic drift).

Their conclusion: Foreign EIV strains have not been circulating in the United States. Only EIV Florida clade 1 strains have been circulating and have evolved separately from clade 2 strains.3 “EIV strains are mutating through selection—antigenic drift —in order to escape the immune system,” Kyuyoung Lee, DVM, MPVM, PhD Candidate and lead study author said.

Antigenic drift of U.S. EIV is the most plausible cause for the high rates of vaccine failure, underscoring the need to update vaccine strains.

Responding with Updated Vaccines Recent equine influenza outbreaks bring these findings into focus. Consider the 2013 outbreak in Southern Florida that occurred in a large number of well-vaccinated horses.

By analyzing samples submitted to the Equine Respiratory Biosurveillance Program—managed by Merck Animal Health in partnership with University of California, Davis School of Veterinary Medicine—researchers identified and isolated a new influenza strain, Florida ‘13, which is representative of current circulating U.S. field strains.

Sequencing work revealed Florida ‘13 differs from Ohio ‘03 (OIE recommended clade 1 isolate recommended for EIV vaccine production) by six amino acid changes, and all six of those mutations occur on the surface of the HA glycoprotein and are in or near regions associated with antibody binding or receptor binding sites4—making them critically significant.

See figures 1 and 2 to left.

In response to this information, Merck Animal Health added the Florida ‘13 influenza strain to the PRESTIGE® inactivated influenza-containing vaccines. Only PRESTIGE® flu-containing vaccines include the industry’s most current clade 1 strain of equine influenza. The Biosurveillance Program is ongoing and, through it, sequencing work at the time of publication shows that Florida ‘13 continues to be representative of current flu strains circulating in the U.S.

Get the Whole Flu Story“ The impact from the growing threat of equine influenza virus (EIV) is playing out in barns across the country.

If you’ve experienced an EIV outbreak, you know the effects can range from medical challenges to time away from performance and production to a hearty dose of stress­—for you and your clients.

When it comes to managing EIV, Merck Animal Health goes back to our roots of focusing on science and, most important, what’s best for the horse. That’s why we established the Equine Respiratory Biosurveillance Program. And that’s why we work tirelessly to stay up to date on the evolution of EIV. For the whole story on EIV sequencing and how we use it to provide horses the most up-to-date protection, take a look at our technical bulletin, “The Science of Significant Protection Explained.”

MERCK ANIMAL HEALTH

TECHNICAL BULLETIN

The Science of Significant Protection Explained Genetic Characterization of Recent Equine Influenza Outbreaks Influenza viruses are constantly undergoing genetic changes. Understanding these genetic changes –known as antigenic drift–through ongoing surveillance and sequencing of isolates is critical to evaluating and improving the efficacy of equine influenza vaccines.

Genome Sequencing Sequencing of the influenza virus is focused on the hemagglutinin (HA) and neuraminidase (NA) glycoproteins found on the surface of the virus. HA is the most important because it is the target for serum neutralizing antibodies generated by influenza vaccines. Through this process of comparing genetic sequences we can make informed decisions regarding: — How well an equine influenza vaccine might protect against a particular influenza virus — The genetic variations (mutations) that appear when viruses begin spreading more easily or causing more severe diseases — How closely equine influenza viruses are ‘related’ to one another (e.g., homology)

Homology Defined: The existence of shared ancestry between a pair of structures or genes.

Genome Sequencing Defined: The process that determines the order or sequence of the RNA nucleotides (e.g., A, C, G, U) in each of the genes present in the virus’s genome.

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Merck Animal Health

HORSE TIPS Timely Health Tips to Share with Horse Owners The incidence of vaccine-associated adverse events (VAAEs) is very low. Put your clients’ mind at ease —and reinforce the importance of veterinarianadministered vaccines—by sharing these tips.

What to Expect After Vaccinations Vaccine reactions vary in type and severity, with most reactions in horses resembling what a person might experience after a flu shot.

While severe reactions are rare, it's best for veterinarians to administer vaccines so they're available should a VAAE occur. Be aware of the three VAAE types: Local injection site reactions. By far the most common type of VAAE; usually occur within 24 hours of vaccination and resolve shortly thereafter: • Localized swelling of various degrees and tenderness at the injection site • Muscle soreness and decreased range of motion of the limb or head and neck are less common Mild systemic reactions. Usually resolve within 24 to 48 hours without treatment: • Low grade fever (less than 102°F), lethargy and lack of appetite Allergic systemic reactions. Require medical attention; call your veterinarian immediately if you see signs: • Can include sweating, elevated heart rate, respiratory distress, colic or hives

Data on file. Merck Animal Health.

— How equine influenza viruses are evolving Florida ‘13 was responsible for a significant disease outbreak in well-vaccinated horses. Sequencing and homology of recent outbreaks in 2018 and 2019 demonstrates Florida ‘13 is highly relevant to equine influenza circulating today in our U.S. horse population.1

• Anaphylaxis, the most severe and extremely rare VAAE

Delivering advanced influenza protection that matters to you and your clients.

Download Now Merck Animal Health and University of California, Davis School of Veterinary Medicine (Nicola Pusterla). Infectious Upper Respiratory Disease Surveillance Program. Ongoing research 2008-present.

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Vaala W, Barnett DC, James K, Chappell D, Craig B, Gaughan E, Bain F, Barnum SM, Pusterla N. Prevalence Factors Associated with Equine Influenza Virus Infection in Equids with Upper Respiratory Tract 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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Merck Animal Health Technical Bulletin, December 2019.

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Spring 2020 2019 | PARTNERS IN PRACTICE

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Ron's Campfire

RON’S CAMPFIRE

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here are no greater stories to be told than those of the practicing equine veterinarian. And if you’ve attended Vet Story Night at the American Association of Equine Practitioners (AAEP) annual conference the last few years, you’ve heard some of the best. That is exactly what inspired Ron’s Campfire. Storytelling comes in many forms—whether on stage with a microphone or at the tip of a pencil (or keyboard), equine veterinarians not only have scientifically gifted minds, they are also talented writers and storytellers. If you have a story or blog you’d like to share, we’d love to feature it in a future issue. Please email Ron McDaniel (ron.mcdaniel@merck.com) to learn more or submit contributions.

Vet Stories

Welcome

This installment of Ron’s Campfire features an original blog piece by Robert H. Koontz, DVM. Cowboys, Wire Cuts and Chewed-up Broadleaves I was working at a small American Quarter Horse breeding operation when the owner asked me to look at a wound on the left hind pastern of a 3-year-old filly.

We walked up to a large 10-foot-by-30-foot stall that did indeed hold a 3-year-old filly with a cut around her left hind pastern. That was about all I could ascertain as the filly paced the stall, occasionally kicking and snorting. It was probably the first time she’d been confined to a stall since being weaned from her mother.

The owner somehow got a lead rope hooked to the halter.

I walked up to a big filly that had earned her taut muscles by running with the herd. The owner muttered, “She ain’t been broke yet.” By the look of the too-small halter digging into her face, my suspicion was that she hadn’t been touched by human hands since her first halter lesson. My suspicions were confirmed when I walked up to pet her neck, and she immediately tried to strike me with her front hoof.

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As I moved along her neck, she tried to bite me. Finally, I got near the injured hind limb and she started kicking at me.

Somehow, I got her to stop kicking long enough to smear some antibiotic ointment on the wound. I prescribed some oral antibiotics then explained to the owner that we really needed to put the filly under general anesthesia to explore, clean and debride the wound. The owner agreed, saying, “Yea, we need to do that sometime.”

With that we were done for the day.

I was frequently back at the breeding farm attending to the broodmares.

Sometimes I would see the filly hobbling in the pasture. Each time I would reiterate to the owner that we needed to put the filly under general anesthesia and work on that wound. Each time he would promise to schedule an appointment to get it done. The call to schedule never came.

When I didn’t see the filly for a while, I asked the owner about the filly with the injured leg. He replied, “You don’t have to worry about her anymore. I gave her to a young cowboy.”

I did worry about her. Being given to a young cowboy didn’t sound like a good future for her. But in spring, things are busy in an equine practice, and I soon forgot about the filly.

Several months later I had an appointment to see a horse that had an old wound on the hind limb.

Reportedly, the wound had completely healed but the horse still moved a “little funny.” According to the computer, this horse was the same filly I’d seen at the breeding farm, only this time with a different owner.

The person holding the horse was indeed a young 25-year-old cowboy. He stood in worn boots with spurs, well-worn

Dr. Rob Koontz

jeans, a threadbare Western shirt and a dirty cowboy hat. The horse was indeed the same filly I had known; however, she was no longer filled with the anger I had experienced at the breeding farm.

She had transformed into a loving mare whose only desire seemed to be to please the cowboy at the end of her lead rope.

“What have you done to this horse!”

I exclaimed.

“Well,” mumbled the cowboy, “your antibiotic cream wasn’t working so I had to treat her my own way. I worked with her every day for a month until I could hold her hind leg up. It took another two weeks before she would allow me to pull this wire out of the cut,” he said, producing a fence wire from his pocket. “But what really saved her leg was an old trick my Dad taught me: broadleaves.”

The young man led me out to the yard and picked some weeds. He chewed up the leaves then gently picked up the mare’s leg. While the mare stood patiently, he spit out the chewed-up leaves and packed them into what was left of the wound. He proudly looked at me and simply said, “Broadleaves.”

The young man was proud of his father’s treatment. I remembered the filly’s kicking, striking and biting; I was much more impressed with the transformation of this horse from an angry filly to a kind and loving mare. “My father was wonderful with horses,” the cowboy mumbled longingly. “He could treat any ailment.”

If he wanted to give the credit to his father and some chewed-up broadleaves, it was fine with me. Some of my colleagues might point out that getting the piece of wire out of the wound was the key to treatment. In reality, it was the young cowboy who saved this mare’s life through love, patience and old-fashioned horsemanship.

Dr. Koontz is the chief executive officer of Conley & Koontz Equine Hospital in Columbia City, Ind. Read more stories from Dr. Koontz on his blog, Rob’s View from the Passenger Seat.

Spring 2020 | PARTNERS IN PRACTICE

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Merck Animal Health Business Tips

Did You Know?

THE EQUINE INDUSTRY IS REGAINING ITS HORSEPOWER

MAKE “DISEASE DU JOUR” YOUR NEW DRIVE-TIME HABIT

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he 2008 recession delivered a hard hit to the equine industry, causing lingering negative effects for years to come. Case in point, industry growth from 2015 through 2017 was described as "dismal"

by Animalytix CEO Chris Ragland.

The negative trend is now reversing.

The equine industry experienced 3.8 percent net growth year over year in 2019, according to data presented by Animalytix at its Annual Senior Executive Forum at Western Veterinary Conference in February. Ragland says this marks the third year in a row of positive growth.

And the good news continues. Overall, veterinary service is among the most profitable industries in the country as compared to net profit by sector for S&P 500 companies.

The equine industry is adding to that profitability.

So, take a moment to celebrate your hard work and the fact that a never-ending dedication to the horse always pays off in the end.

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ower up your windshield time— or any time—with a podcast made just for you. Merck Animal Health is partnering with EquiManagement to bring you the 2020 Disease Du Jour podcast series.

Disease Du Jour gives busy equine veterinarians like you a way to catch up on important disease developments, clinical techniques and research updates—anytime, anywhere.

There is so much happening in equine health, and Disease Du Jour is tackling the hottest topics. A few episodes to watch for include: • The latest on the Merck Animal Health Veterinary Wellbeing Study with Dr. Christine Royal • EPM: New Insights to Help Address Practical Challenges with Dr. Nicola Pusterla • Rhodococcus Equi in Foals with Dr. Noah Cohen • Updates on Equine Influenza Virus with Dr. Wendy Vaala A new episode of the Disease Du Jour podcast brought to you by Merck Animal Health launches every other Thursday throughout the entire year. You can find each podcast recording on EquiManagement.com or you can access Disease Du Jour episodes on iTunes, SoundCloud, Stitcher or your favorite podcast platform.

“We are thrilled to have Merck Animal Health join us in this veterinary industry educational endeavor. It is exciting to have a partner as focused on veterinary education as we are to help us bring these podcasts to our audience.”

– Kimberly S. Brown, Group Publisher, Equine Health Network

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Meet the Team

Q&A

MICHELLE SIMPSON TERRITORY MANAGER

Lexington, Kentucky michelle.simpson@merck.com

Tell us a little bit about your horse background.

My daughter, Sofia, has been riding since she was 5 years old.

She’s 14 now. We own a palomino pony named Sassy Cassie who’s your typical mare pony with lots of attitude! We spend a lot of time in the dressage ring and the jumping arena.

Outside of the equestrian world, what is your favorite hobby?

I enjoy spending time with my kids, Jackson and Sofia, and pretty much anything outdoors, like hiking, camping, mountain biking, boating and swimming. I also enjoy live music and the local music scene in and around Lexington.

How long have you been working for Merck Animal Health?

Nine months.

What is your favorite part of being an equine sales representative?

Meeting all of the dynamic people in the industry is the best part. I enjoy building relationships and offering solutions that keep their businesses moving forward.

If you were a horse, what type of horse would you be?

I wouldn’t be a Kentuckian if I didn’t say Thoroughbred.

Best horse advice you’ve ever received?

“It’ll be better tomorrow.” Patience is a virtue as a horse owner.

If there were one thing you would want customers to know about you, what would it be?

I truly care about the health and well-being of their patients.

My goal is to listen to the veterinarians to uncover their needs and expectations so I can offer them compassionate solutions that meet those expectations.

Spring 2020 | PARTNERS IN PRACTICE

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The Science of Healthier Animals 8

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PARTNERS IN PRACTICE | Spring 2020