Since the canine influenza virus (CIV) H3N2 strain first emerged in Chicago in 2015, it has spread somewhat sporadically throughout the U.S. However, in late May, it turned up once again; the epicenter might have been two dog shows.
States with confirmed H3N2 currently are Florida, Georgia, Kentucky, Louisiana, Missouri, North Carolina, South Carolina, Tennessee and Texas. Guestimates are that 300 or more dogs have been infected with H3N2; approximately 30 to 40 have been confirmed via lab diagnostics, and several confirmed fatalities have been confirmed. Some states appear to have only a few sick dogs; others much more. H3N2 continues to occur in California, and many argue that H3N2 is endemic in the Chicago area.
Jerry Klein, DVM, chief veterinary officer at the America Kennel Club (AKC), believes the southeast outbreak began at dog shows in Perry, Ga., and DeLand, Fla.
Likely, no one will ever pinpoint how this happened, but it’s not surprising to Cynda Crawford, DVM, Ph.D., clinical assistant professor University of Florida College of Veterinary Medicine, Gainesville.
“H3N2 is in the environment and could have been brought into the shows in any number of ways,” said Dr. Crawford. “Because there’s no immunity to the virus, which is novel in the U.S., most dogs exposed get the virus.”
Dr. Klein is from Chicago, where H3N2 first hit, and he was at ground zero for the outbreak. He suggested what happened at the May dog shows is similar to what he experienced in 2015.
“At first, people assumed it was kennel cough, which is a nuisance but not awful,” he said. “But just as in Chicago, some dogs got significantly sicker. And we began to think about the dog flu pretty quickly.”
That fallout is occurring now. When the dog flu hits neighborhood boarding or grooming facilities, or local dog parks, the shedding dogs bring the virus home with them, maybe blocks or a few miles away. Because dogs at AKC shows often are states away, the bug spreads quickly.
Managing the Situation
The response within the dog show word has been swift. More than 200 dogs reportedly pulled out of the May 26-29 Blue Ridge Classic Dog Show near Asheville, N.C. The Kennel Club of Texarkana 50th Anniversary dog show, which was scheduled for June 17-18, has been cancelled.
“Many handlers I know are getting their dogs vaccinated and waiting the two to four weeks for the booster before working any show,” said Scott Tritsch, DVM, of Georgetown, Ky., adding that he’s currently dealing with a group of 39 presumably infected CIV dogs.
Among those in Dr. Tritsch’s care are nine 2-week old puppies.
“[They’re] still alive but not out of the woods quite yet,” he said.
Richard Hawkes, DVM, of Morehead City, N.C., noticed that two of his black Russian terriers began to cough and run fevers shortly after returning from the Perry dog show. Within just a few days, all 10 of his dogs were exhibiting similar symptoms. Diagnostic testing confirmed H3N2.
Those who show dogs see no reason to test all their dogs when it’s so likely they all have the same thing. It’s one reason why such a discrepancy exists between the number of dogs confirmed to have H3N2 via a diagnostic lab and those presumed to have H3N2. Why test them all?
Another explanation for the disparity is cost of testing. Encouraging the diagnostics is important. Clearly, veterinarians should know specifically what’s going on with a dog. Is it canine infectious respiratory disease complex (such as Bordetella or canine parainfluenza), CIV or even a co-infection? It’s important to medically understand and important to grasp what’s happening in a community. However, convincing clients of the value knowing this information can be challenging. Of course, treatment begins instantly—before the test results come back. Some clients can’t afford to pay for diagnostics and treatment.
“I get it,” Klein said. “When income is limited, I’d rather see the client spend dollars on treatment.”
Also, some exhibitors are afraid or embarrassed to admit their dog is infected. Irresponsibly, some might even travel to an event with sick dogs. Klein maintained that these are exceptions. In his experience, people are sharing information far and wide via social media; in fact, if anything, there may be some exaggeration, he said. Via Klein, the AKC has been transparent. From the start, he has collaborated with medical partners, including the American Veterinary Medical Association.
The Road Ahead
The H3N2 virus exhibits extremely high mobility and low mortality, and an estimated 3 to 5 percent of dogs infected die.
Dr. Hawkes lost one of his black Russian terriers—though he’s quick to point out that this particular dog had additional medical issues.
“It was pretty scary to see my 10 big dogs taken down in a matter of days,” Hawkes said.
A Nova Scotia duck tolling retriever that succumbed to H3N2 had a secondary Pseudomonas infection that wasn’t responsive to antibiotic therapy, said Tritsch, adding that the necropsy showed profound lung damage, necrotic and hemorrhagic pneumonia.
Even scarier is what Edward Dubovi, Ph.D., director, Virology Laboratory Animal Health Diagnostic Center, College of Veterinary Medicine, Cornell University, said: “We are sequencing all the time to determine if the H3N2 virus diverges into different clades (almost like substrains of flu). If that happens, it doesn’t mean that the vaccine won’t be effective, but it’s something to pay attention to.”
Dr. Dubovi said he is unsurprised by H3N2’s fast spread because it’s more contagious than H3N8, the strain first identified in Florida in 2008 after mutating from an equine flu.
The other problem with H3N2 is that for an influenza virus, it’s somewhat hardy and can live on fomites and be transported. Also, about 20 percent of infected dogs never exhibit clinical signs (but remain as infectious as the sick dogs).
That’s great for those individual dogs who are well enough to chase squirrels, but their owners have no way to know their dog is shedding virus.
The good news is that show dogs often don’t intermingle in the community; they likely stay at home or are on the road. However, that’s not always true. Anecdotally, it seems clear that at least some dogs now being diagnosed with H3N2 have never participated in a dog show or have associated with show dogs. In at least some communities the virus might have spread into the general population. No confirmed reports of the flu hitting a shelter or overwhelming a single community (as in Chicago) currently exist.
But a potential perfect storm could be brewing. Dog show season is ramping up, but so is travel season. When folks hit the road for vacation, many will board their dogs in spaces even more ripe for CIV transmission than a dog show, particularly when kennels offer dog playgroups.
According to Crawford, only two best methods of protection from CIV exist: dogs either must be completely antisocial or they must be vaccinated. If it were up to her, “You vaccinate all the show dogs, absolutely,” she said. “This is the primary tool; it doesn’t matter if you’re talking people, dogs, horse or pigs. Vaccination is the strategy.”
As an exhibitor, Hawkes said that vaccination is a worthy investment compared to the price of treating many dogs.
The AKC is doing all it possibly can inform handlers and exhibitors, and has created a handout with the latest information on CIV transmission, symptoms and hygiene to minimize risk, according to the organization. “The best protection is vaccination,” the AKC said in a statement.
But should the AKC mandate the vaccine for CIV (either for H3N2 specifically or the bivalent vaccine for H3N2 and H3N8)?
“Infectious nature is really high and the shedding period is very long,” said Tritsch. “Right now, we’re just hoping it’s not in the shelters. But this is a big deal not only for the dogs in the AKC shows and events, but also for the communities the dogs return to.”
Dubovi asks the million-dollar question that only a crystal ball can answer: Will the outbreak worsen or fizzle out on its own?
“I don’t know, but I do know dogs have died—even if it is a small percent,” he said.
Veterinarians are dammed if they do and dammed if they don’t. Recommend the vaccine and if nothing happens, clients may holler, “You’re only in it for the money!” If they do nothing and a dog gets the flu and requires treatment, clients may holler, “Why didn’t you say I should vaccinate?”
“The AKC needs to push now for all dogs to be vaccinated, and if your dog has been exposed—please don’t show for 30 days,” Hawkes said. “The problem is that people may not know if their dog was exposed.”
“It’s tough,” Klein said. “If we close for 30 days—as some have suggested—on day 31 the flu may appear. That really doesn’t seem to be the answer. Certainly, we endorse and encourage people to make their own choices based on all the information we provide openly. And absolutely discuss this with your own veterinarian. If there’s a human influenza virus in New York, and you get coveted tickets to a Knicks game or a Lady Gaga concert, do you still go? It’s a personal decision.”
Steve Dale, a regular contributor to Veterinary Practice News, is a certified animal behavior consultant and a regular speaker at animal welfare and veterinary conferences. Visit his website at stevedale.tv.