Canine distemper on the rise? New strains invading the U.S.? If you’ve had these questions lately, you can put your mind at ease.
“The problem you have is canine distemper is a fairly elastic virus,” says Edward J. Dubovi, Ph.D., a professor and the virology laboratory director at the Cornell Animal Health Diagnostic Center in Ithaca, N.Y. “CDV belongs to that virus group which makes numerous mistakes during the replication cycle. The result of this is that there are many different CDV viruses in the pool of virus collectively known as CDV.
“There certainly have been detected different strains or isolates of distemper virus as we continue to genetically assess the virus in the United States,” he says. But that doesn’t mean new strains are running rampant across the country. However, what have been considered traditionally European strains have been introduced as dogs and exotic animals enter the country, whether legally or illegally, he adds.
The real issue, though, is whether current vaccines given in the U.S. can “adequately protect animals that are properly immunized,” he says. According to the best of all current information, they do. The American Veterinary Medical Association reported in February: “There is no scientific evidence that the currently available vaccines won’t protect your pets.”
However, not all dogs that have been “vaccinated” are immunized, Dubovi says. Breeders who do their own vaccinating, for example, may think they’ve immunized puppies. “Sticking a needle in a dog doesn’t mean you’ve immunized it. Modified live vaccines have to be handled in a special way to maintain viability.” If you have a few vials, for example, vaccinate a litter, then do another litter a few weeks later, the vaccine may or may not have any effect.
One of the reasons dog owners are more aware of distemper is that surveillance programs are “phenomenally better than they were five years ago,” he says. “Some skunk dies in Michigan, and you know about it.”
Indeed canine distemper in wildlife is more widespread than in dogs.
Dubovi says that in just the last month or so there’s been a substantial outbreak in raccoons, skunks and foxes in the Northeast. “Those are the wildlife species that are highly susceptible. What we’re not seeing is dogs outside of shelter situations” turning up with distemper. “Even though there’s a lot out there in wildlife populations, we’re not seeing it spill over into dogs.”
Many news items about distemper in the U.S. focus on shelter outbreaks. When you put unvaccinated dogs into a shelter setting, “you’re going to have a problem,” he says.
Ronald Schultz, Ph.D., a professor in the University of Wisconsin School of Veterinary Medicine’s Department of Pathobiological Sciences, told the AVMA in February that over the last 10 years, 40 to 50 percent of the dogs entering large city shelters have been “antibody negative for CDV, meaning they’ve never been exposed to the virus either by vaccination or by exposure to an infected animal, and are thus susceptible.”
Dubovi believes another factor contributing to recent attention on distemper prevalence is the recession. If, for example, you found out how much distemper vaccine has been sold around the country, “in certain areas, you might see a downtick in the amount of vaccine being sold where people are choosing not to vaccinate for economic reasons,” Dubovi says.
In addition, he says, no evidence shows that immunized dogs exposed to distemper-infected wildlife are getting it. “Given wildlife outbreaks occurring, you would expect to start seeing somebody’s dog in their backyard having a run-in with a raccoon. “We’ll certainly be looking for it,” he says.
Unfortunately, no monitoring system exists to determine whether distemper in dogs is on the rise. “Many states choose to ignore companion animal health,” Dubovi says. Most state animal health agencies were set up to deal with production animal medicine for cows, pigs and other animals. “Each state deals with it in whichever way they choose. There are zero reporting requirements,” he says.
So, it’s “anybody’s guess” how many dogs get distemper each year in the U.S., he says.
Schultz and Dubovi, along with the AVMA and the American Animal Hospital Association, continue to recommend puppies have the full distemper series, with the last shot given between 14 and 16 weeks, regardless of where the puppies will live and their anticipated level of exposure to wildlife as adults. Schultz, a member of both the AAHA Canine Vaccine Task Force and the Veterinary Vaccine Guidelines Group of the World Small Animal Veterinary Association, advises that the distemper vaccine should not be given to puppies under 6 weeks of age and that after the series they should be tested to see if they have developed distemper antibodies.