Here’s everything you need to know about the highly contagious dog flu and how to protect your pet this season.
In January 2004, a pack of greyhounds at a Florida racetrack fell mysteriously ill. They all showed signs of some kind of respiratory distress: coughing, fever, and runny noses. The symptoms could easily be mistaken for “kennel cough,” a disease caused by the bacteria Bordetella bronchiseptica.
But, it soon became obvious that this particular group of dogs wasn’t suffering from a simple case of kennel cough. In total, 8 of the 24 infected dogs eventually died while researchers zeroed in on the culprit.
What they found wasn’t some new disease. It was the flu.
Veterinary scientists discovered that the dogs had been infected with an influenza A virus of equine origin — this flu came from horses.
The racetrack where the dogs fell ill also happened to host horse racing. This particular strain of influenza, H3N8, had apparently made the jump to a new host species.
The flu’s ability to do so isn’t uncommon. It’s known to exist in many different variations in many different species, including birds, pigs, and humans.
However, this incident was the first time that the flu was isolated in canines. Dogs were often considered “refractory,” or resistant, to influenza, but no longer.
That outbreak, the first known of its kind, eventually spread to racing greyhounds in nine different states between 2004 and 2006. Canine influenza has since spread throughout the United States, sporadically flaring up from year to year.
In 2018, the dog flu appears to have reared its head again: Over 100 cases have been reported in Michigan. Nearby Wisconsin has also reported recent cases, as have a handful of states on the East Coast, including Massachusetts, Virginia, and Connecticut.
It’s garnered headlines from nationally syndicated news media, saying that a mysterious, highly contagious disease is spreading, feeding into the fear of a new doggie epidemic.
“There’s a lot of hype and hysteria,” said John de Jong, DVM, president of the American Veterinary Medical Association (AVMA). “It’s not much worse than any previous time. The AVMA wants to make sure that pet owners realize there’s nothing to panic about at this time. We see outbreaks like this flare up from time to time.”
American Veterinary Medical Association
(AVMA). “It’s not much worse than any previous time. The AVMA wants to make sure that pet owners realize there’s nothing to panic about at this time. We see outbreaks like this flare up from time to time.”
You can further be assured that while, yes, canine influenza is highly contagious, it’s rarely fatal. It’s estimated to have a mortality rate of less than 10 percent, and only in young puppies, geriatric dogs, or those with suppressed immune systems.
Nevertheless, it’s a real disease and owners should be informed about it.
Current outbreaks are largely restricted to a handful of geographic regions in the United States.
The Cornell University College of Veterinary Medicine has even created a canine influenza surveillance map to track the presence of the disease.
The symptoms of canine influenza include coughing, fever, runny nose, lethargy, and lack of appetite, although individual symptoms may vary from dog to dog.
It’s spread through excretions and aerosolized particles from the respiratory tract, meaning coughs and sneezes will spread it, as will “nose-to-nose” contact between dogs.
Canine flu hasn’t been found to be seasonal the way that human influenza is, though the weather can play a role in spreading it.
“This seems to be more of a problem in the spring, when dogs are going to dog parks and people are traveling so dogs are going to kennel situations. Because it’s so very contagious,” Pamela Greenwald, DVM, a Michigan veterinarian and state representative for the Humane Society Veterinary Medical Association, told Healthline.
Greenwald noted that people traveling with their dogs throughout the summer can also spread dog flu to areas it otherwise wouldn’t spread.
“I think with most outbreaks, they do tend to start in urban and suburban environments because there’s a lot more contact,” she said.
In 2015, Chicago became the site of the worst outbreak of canine influenza seen since its discovery a decade earlier. More than 1,000 cases of the disease were reported at that time.
The outbreak also marked a new development for canine influenza. A new strain appeared.
Whereas the initial greyhound cases in 2004 were linked to H3N8, the strain that caused the Chicago outbreak was determined to be H3N2, an avian influenza A variety that had already been reported circulating among dog populations in South Korea.
Again, a strain of influenza, this time in birds, had made the jump to dogs.
One year later in 2016, H3N2 was discovered to have made another species jump and infected cats in an animal shelter in Indiana.
The spread of canine influenza to and from different species has raised the prospect of a potentially serious epidemic — should it become capable of infecting humans.
But, to be clear: There’s never been a case of a human becoming infected with canine influenza and there is no evidence that it can spread to humans. The Centers for Disease Control and Prevention consider canine influenza a “low threat to humans.”
However, that doesn’t mean that the idea isn’t worrisome.
“It’s so contagious that the concern about it is that just like the swine flu and avian flu, the influenza virus can very quickly mutate. At this point they haven’t seen any evidence of mutation, but how contagious can this be and how quickly can it spread?” said Greenwald.
According to current estimates from The Humane Society, there are roughly 90 million pet dogs living in the United States today, or about 1.5 dogs per household. The notion of man’s best friend, an animal held near and dear to so many people’s hearts, carrying a highly contagious disease is understandably troubling.
Worse, some researchers have pointed to dogs as a potential “mixing vessel” for influenza. The flu isn’t easily spread between all species — human to bird and vice versa, for example. But, some species, the so-called “mixing vessels,” can play host to a wide variety of forms of influenza.
This can result in influenza viruses swapping genetic information and creating novel forms of the virus with pandemic potential.
The deadly H1N1 “swine flu” influenza strain that caused a global pandemic 2009 resulting in the deaths of hundreds of thousands of people — a combination of avian, swine, and human flu virus — is believed to have resulted from the “mixing vessel” phenomenon.
For now, however, the idea of canine influenza spreading to humans is merely speculation.
Treatment options for dog flu are robust. There is in fact a canine influenza vaccine for either strain. There’s also a bivalent option available, meaning that it protects against both strains.
The flu vaccine for dogs is generally regarded as safe and effective, but it’s still quite new, and experts say it isn’t for every dog. The vaccine is regarded as a “lifestyle vaccine,” meaning that whether your dog needs it or not will depend on a few factors.
“If dogs aren’t leaving their home, they aren’t exposed to other dogs, I don’t know if it is necessarily required. But if they are going to go to the city or the groomer or if it’s required, I think it’s a good idea until we know what’s going on with this virus,” said Greenwald.
Some kennels are now requiring that dogs receive the vaccine before being housed there. Even if not required, the vaccine may be a good idea, simply because boarding facilities with many dogs in close proximity can be a place where influenza can spread.
And should your dog actually come down with a case of the flu, pay attention to their respiratory symptoms and have them diagnosed by a veterinarian. The disease is highly contagious so make sure to isolate the animal from other dogs and pets.
Caring for a dog with the flu is similar to caring for a human who’s been infected: Plenty of liquids and rest are in order.
In some cases, antibiotics are also used if there’s concern about possible bacterial infection.
In a majority of cases, dogs with the flu usually recover completely in two to three weeks.
“Dogs with basic supportive care recover from it just like a lot of people might recover from the common cold or a mild version of the flu that people might come down with during the winter time,” said de Jong.