Treating parasites in 2017

by Veterinary Practice News Editors | May 2, 2017 4:35 pm

While part of the U.S. is under the misconception that harsh winters minimize parasite populations, experts say most of the country should brace for last year’s levels as well as continued growth in tick- and mosquito-borne diseases.

For that, practitioners can thank atypical weather.

Randy Lynn, DVM, MS, Dipl. ACVP, manager of technical services in the U.S. Companion Animal Business Unit at Merck Animal Health, is warning his colleagues to be particularly vigilant in the South, such as where he works, in North Carolina.

“We’ve had another unusually mild winter, as have many other parts of the nation,” Dr. Lynn said. “I expect that most of the country is going to see parasite loads that meet or exceed those we saw in 2016.”

In regions of the U.S. hit by extreme winter weather, such as New England and the upper Midwest, pet owners—and some veterinarians—must abandon the false notion that prolonged frosty winters mean fewer pests throughout the year.

“The mosquito vectors and reservoirs of infection, such as coyotes and dogs without proper prevention, continue to expand across the U.S., and with the warm, wet winter most of the U.S. has experienced, this likely won’t decrease in 2017,” said Tony Rumschlag, DVM, director of regional consulting veterinarians for Elanco Animal Health.

“Most ectoparasites can overwinter even in very cold areas,” said Elizabeth Hodgkins, DVM, JD, director of veterinary relations at Ceva Animal Health in Lenexa, Kan. “Further, those parasites that find themselves in protected microenvironments—warmer pockets that occur in all urban and suburban areas—do extremely well during winter.”

Over the past decade, the U.S. has seen dramatic growth in the prevalence of tick- and mosquito-borne diseases, and Dr. Hodgkins said she expects that trend to continue.

Compliance is the Issue

Misconceptions about parasite populations and milder weather pose big problems, but an even greater—and familiar—issue persists.

“The elephant in the room with parasite control is compliance[1],” Lynn said.

Despite promoting and selling monthly products at clinics year over year, countering client resistance to buying into parasite control continues to be an uphill battle, he said.

“The average compliance for the average dog and cat owner is somewhere between four and five doses a year,” Lynn said, adding that persistence is key.

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Constant reminders and prodding are essential in the battle against the particularly dangerous heartworm disease, said Chris Rehm, DVM, president of the American Heartworm Society.

“As always, veterinarians should be on the lookout for missed heartworm prevention doses,” Dr. Rehm said. “This means asking every client at every visit about every pet in their household—cats, too—even the ones fed outside.”

A generic “Are you good on your heartworm preventive?” is sorely insufficient in Rehm’s opinion. He recommended that practitioners be direct: “When was the last time you administered your parasite preventive, and what was the product you used?” Then follow with a review of the client’s purchase history, he said.

“If doses are missed—and usually there are several—veterinarians should test now and calculate and schedule a microfilariae and antigen test for heartworm about six to seven months from last missed dose,” Rehm said.

Rehm suggested setting up a client reminder system, reinforced by reviewing at-home reminder methods, such as, calendar stickers, annotating product packaging or signing clients up for monthly delivery from the clinic’s online pharmacy.

“Ensure that everyone in the practice who has any interaction with clients understands and supports your product choices for prevention of these parasites,” said Dr. Rumschlag. “A clear and specific recommendation for a specific product is most effective in helping the client to keep their pets safe from parasites.”

“Adopt an approach the whole team can get behind, and use it during every visit,” Rehm said.

The American Heartworm Society recommends year-round heartworm prevention in all parts of the country[2], but this year, external protection for fleas and ticks may not be such a seasonal requirement as before, Rehm said.

The Hard Truth

Pet owners need to hear sobering messaging, such as explaining that the pathology of heartworm disease is devastating and that it’s nearly 100 percent preventable with affordable and easy-to-use products, said Rhem.

“If heartworm were a human disease, I am convinced we would nearly eradicate it, because we have such good products to prevent it and to control the vector that transmits this deadly disease,” he said.

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Stronger, or just more parasite messaging, might be a welcome thing. According to Lynn, before Merck launched its most recent topicals, the company conducted market research that offered encouraging insight.

“Clients actually want to know more about parasites than what veterinarians may think,” Lynn said, urging practitioners to not hold back.

One way is to tell clients that inertia is a bad idea.

“Clients shouldn’t wait until they see their first flea, tick or mosquito to begin using parasite control,” Hodgkins said. “By the time they see these pests, it is safe to say their dog or cat has already become a host, which means they may already be in the home exposing pets and family members to the diseases they carry.”

It’s important to talk to pet owners about the importance of year-round protection—even for pets that go outside infrequently, she added.

“Most parasite vectors of disease have many means of coming indoors,” Hodgkins said. “They can fly inside or travel on clothing, packages or other animals. Some ticks and all fleas can overwinter in the home. In other words, they never leave the interior, so housebound pets are unprotected all year against these parasites.”

Appealing to the pet owner’s love for their animal can be highly effective, said Dryden.

“We must discuss how lifelong prevention is much better than reaction—putting out the flea fire,” he said. “Dogs and cats deserve better. There is no need for them to suffer from the affliction of a flea infestation.”

In the Arsenal

The availability and efficacy of products to battle parasites makes it hard to believe pets still are being unnecessarily exposed to such dangers, Dryden said.

“The new systemic flea control products—Nexgard, Bravecto and Simparica—are proving remarkably effective in combating fleas and managing flea allergy dermatitis,” he said. “Their rapid residual speed-of-kill is profound.”

Merck Animal Health offers its monthly heartworm preventive for roundworms and bookworms, Tri-Heart Plus chewable tablets for dogs, and monthly topical products, like Activyl Tick Plus, which contains Indoxacarb, a sodium channel blocker. According to the company, its Scalibor Protector Band provides up to six months of protection against ticks that carry Lyme disease, Rocky Mountain spotted fever, babesiosis, anaplasmosis and ehrlichiosis.

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Bravecto, made with fluralaner, is a 12-week treatment that has made a difference with clients, said Randy Lynn, DVM, MS, Dipl. ACVP, manager of technical services in the U.S. Companion Animal Business Unit at Merck, adding that its easy administration schedule drives those improvements.

Ceva Animal Health’s Vectra 3D repels and kills mosquitoes that may transmit heartworm, offering extra protection when administered with the heartworm preventive, Hodgkins said.

According to the company’s research, Vectra 3D repelled and killed more than 97 percent of mosquitoes that attempted to feed and blocked transmission of all microfilaria from dogs to mosquitoes, Hodgkins said.

The drug effectively blocked the transmission of heartworm via infective third-stage larvae (L3) to dogs, something a heartworm preventive alone cannot do, she said.

Dan Carey, DVM, a veterinarian with Bayer Animal Health, highlighted the company’s Advantus for dogs.

“It’s the first FDA-approved soft chew flea treatment available without a prescription,” Dr. Carey said. “We not only expect veterinarians to get a lot of in-clinic use out of Advantus, but we also expect dog owners to appreciate that they simply feed the savory chew to their dogs.”

The upsides of Advantus are that it’s safe to administer daily, it isn’t applied to a dog’s skin so there’s no messy residue, and it contains no animal proteins, so it may be suitable for dogs with animal protein allergies, Carey said.

Elanco Animal Health’s Interceptor Plus protects against heartworm disease and some common intestinal parasites (Ancylostoma caninum, Toxocara canis, Toxascaris leonine and Trichuris vulpis).

“Elanco has a broad portfolio of products to help owners prevent the problems associated with harmful parasites,” said Tony Rumschlag, DVM, director of regional consulting veterinarians. “For the broadest protection for the parasites of greatest concern in most parts of the country, Trifexis provides 3-in-1 parasite protection against fleas, heartworms and intestinal parasites.”

Originally published in the April 2017 issue of Veterinary Practice News. Did you enjoy this article? Then subscribe today![3] 

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