Veterinarians across the country have recently reported cases of canine influenza, a highly contagious respiratory infection that spreads among our four-legged friends. The outbreaks, which picked up steam in southern states like Alabama, Georgia and Oklahoma at the end of 2022, are now spreading rapidly in the Northeast and beyond.
Most dogs that contract the infection will wind up with mild flu-like symptoms, like a cough, eye or nasal discharge, and fatigue, and they will recover in a couple of weeks. However, a small percentage may develop severe complications, including a high fever or pneumonia.
Dr. Rebecca Greenstein, a veterinarian based in Canada’s Ontario province and a veterinary medical adviser for pet care platform Rover, said she’s been seeing more and more dogs come into her practice with signs of respiratory infections. “We’re definitely seeing more cases, in clusters, of respiratory symptoms in otherwise healthy young dogs,” she said.
Though a canine influenza shot is available, most vets don’t routinely vaccinate against the dog flu since it hasn’t been much of an issue historically. But amid the recent rise in cases, many vets are encouraging pet parents to get their dogs vaccinated— especially if they board their dogs or take them to the dog park. “It’s now turning into enough of an issue that we’re reevaluating our vaccine protocols to heighten protection for our canine patients,” Greenstein said.
What Exactly Is Canine Influenza?
Canine influenza is a super-contagious respiratory infection that primarily spreads through large respiratory droplets, which dogs expel when they cough, bark and sneeze. (Sound familiar?) The virus can also spread through contaminated surfaces, like water bowls and places where dogs congregate (think groomers or doggy day care), Greenstein said. Dogs can also spread it by rubbing noses with one another.
Because canine influenza is considered an emerging disease and there’s little immunity in the doggy population, most pooches that are exposed will get infected. Up to a quarter of infected dogs will remain asymptomatic, and the rest — around 80% — will develop a mix of flu-like symptoms, including a cough, sneeze, nasal discharge, runny eyes, fever and malaise.
Symptoms will be mild in most dogs, Greenstein said, though a small number will develop pneumonia and may experience a severe cough, intense fatigue, upset stomach or difficulty breathing. Fewer than 10% of dogs that contract the flu will die because of it. Like humans, the types of dogs most at risk for serious outcomes include ones that are young, old or pregnant, and those that have underlying health conditions that weaken their immune systems.
It usually takes between two to four days for dogs to develop symptoms after they’ve been exposed to the virus. “During their incubation period, infected dogs may look clinically normal yet can spread the infection to other dogs,” Greenstein said.
While you’ll want to quarantine your dogs from other pups, you don’t need to social distance from your pet, as there’s no evidence that dogs can spread canine flu to their humans.
What’s Causing The Current Outbreaks?
Two influenza strains have caused outbreaks among dogs across the U.S. in recent years: H3N2 and H3N8, both of which originated in other animal species before they mutated and spread to canines. H3N8 jumped from horses to dogs around 2004, and H3N2 — which is what’s triggering the current surge in cases — likely hopped from birds to dogs, first causing outbreaks domestically in 2015 and 2016.
According to Edward Dubovi, a professor in the Department of Population Medicine and Diagnostic Sciences at Cornell University’s College of Veterinary Medicine, canine influenza initially made its way to the U.S. via dogs imported from Asia, where there was ongoing transmission.
Since then, canine flu outbreaks have occurred on a yearly basis. “We have this continual threat of the import of infected dogs into the United States,” Dubovi said.
Los Angeles was hit with a pretty bad outbreak in 2022, and this year the dog flu has spread in parts of the South and Northeast. When dogs travel — whether for vacation with owners or for adoption or show purposes — the flu spreads.
“This virus goes through the U.S. by movement of sick dogs,” Dubovi said. Some veterinarians believe the resurgence of dog flu can also be attributed to people traveling and commuting to offices again after two pandemic years (and, therefore, putting their dogs in day care and boarding facilities).
Here’s How To Prevent And Treat Dog Flu
The canine influenza shot targets both the H3N8 and H3N2 strains. According to Dubovi, it’s a standard, chilled vaccine that won’t stop infection but will help prevent hospitalization and death. We don’t know exactly how efficacious the shot is, but past research suggests that it does a great job of preventing severe disease and reducing viral shedding.
“You might see some mild respiratory signs in your dog, but it should not progress to severe pneumonia and probably will not progress to the point you have to take your dog to the vet,” Dubovi said.
We don’t have an antiviral for the dog flu, so if your dog tests positive, it’ll be treated like any other respiratory infection. Your vet will likely recommend rest and fluids and prescribe anti-inflammatory medications if a fever develops.
Your pooch might also be put on antibiotics to prevent secondary infections. Dogs that get severely sick and develop pneumonia may need an IV and supportive oxygen, according to Greenstein.
If you think your pup has the flu, talk to your vet. They’ll have a grasp on how prevalent canine influenza is in your area and can swab your dog to check for the flu and other respiratory infections. Most dogs will do just fine, but because things can go south in some pups, it’s worth getting them evaluated.
“If you’re unsure about your dog’s condition, it’s always better to be safe than sorry and ask your family vet,” Greenstein said.