Veterinarians debate necessity of dog flu vaccines from Merck and Zoetis

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The outbreak of canine influenza earlier this year that sickened 1,000 dogs in the Chicago area spread fear among pet owners of an impending epidemic. And it created a business opportunity for animal health giants Merck ($MRK) and Zoetis ($ZTS), which answered the call by developing rival vaccines to fight the new strain of the virus, H3N2.

Now, veterinarians are wrestling with a big question about vaccinating dogs against H3N2: Is it necessary?

Ever since the outbreak of the new virus, cases of canine influenza have been reported in 25 states, according to data collected by Cornell University's veterinary school. But with the exception of Chicago, Atlanta and Cincinnati, most areas of the country have only seen a few cases, leading some veterinary experts to suggest that widespread vaccination isn't necessary. "We haven't had reports, so I'm not recommending the vaccination for my patients," said Virginia-based veterinarian Bruce Coston, a spokesman for the American Veterinary Medical Association, in an interview with The New York Times.

Problem is, when H3N2 does strike, it can be much more virulent than the previous strain of the virus that was prevalent in the U.S., H3N8. Within a week of getting the H3N2 virus, 80% of dogs become ill and all are contagious, according to the Times. That has some veterinarians worried as the busy holiday travel season approaches and families hit the road with their dogs. Still, many vets are making their recommendations based on how likely a dog is to be in the proximity of other dogs. "If your dog is in competitions for dog shows or gets groomed every week, I would consider the vaccine more strongly," Jerry Klein, chief veterinary officer for the American Kennel Club, told the Times.

In mid-November, both Merck and Zoetis won conditional licenses from the USDA for their vaccines to fight H3N2. Both products require two doses administered a few weeks apart. If dog owners want complete protection against both strains of canine flu, they have to get separate injections of the older H3N8 vaccine (sold by both companies). Neither Merck nor Zoetis is offering a combination vaccine as of yet. The price of the new vaccine will be set by veterinarians, but a Zoetis spokeswoman told the Times that it will likely cost $25 to $35 per injection.

Another complicating factor that veterinarians will need to consider in their advice to pet owners is that no canine influenza vaccine offers complete immunity against the disease. But because the new strain is quite severe, Zoetis is urging veterinarians and pet owners to consider that vaccination will lessen the symptoms in dogs that do become ill, and, more importantly, it will reduce the spread of the virus.

Eileen Ball, a veterinarian with Zoetis, told the Times she believes that with the new vaccine, "we can stop a severe virus from moving through the population."

- here's the New York Times story (sub. req.)