Should You Stay Away From Your Pets if You Have the Flu?

Analysis by Dr. Karen Shaw Becker

reverse zoonosis

Story at-a-glance -

  • While not common, human-to-pet flu transmission, known as “reverse zoonosis,” can happen
  • The first cases in pets were revealed in 2009, when two U.S. cats died of severe respiratory disease. The infection turned out to be H1N1 influenza A, with the most likely source of infection being people in the household who had influenza-like illness or confirmed H1N1 flu
  • The first known case of a human transmitting H1N1 flu to her cat occurred in 2009, with additional human-to-animal cases reported in cats, dogs and ferrets since
  • There’s still much to be learned about human-to-pet flu transmissions, and the risk appears to be very low, but it is, indeed, possible to give your dog (or cat) the flu
  • Most healthy pet dogs will not get the flu; dogs most at risk are those living in crowded conditions, such as in some animal shelters

When flu season rolls around, you may start to wonder if you can pass the virus on to your pets, perhaps perpetuating a vicious cycle of flu transmission within your own household. While not common, human-to-pet flu transmission, known as “reverse zoonosis,” has happened.

Widespread human-to-animal transmission of H1N1 flu was detected in South Korea in 2009,1 with PLOS One researchers noting, “[T]he novel virus was able to travel across the globe and from humans to swine in less than two months.”2

The first known cases in pets were revealed in 2009, when two U.S. cats died of severe respiratory disease. The infection turned out to be H1N1 influenza A, with the most likely source of infection being people in the household who had influenza-like illness or confirmed H1N1 flu.3

By 2012, 13 cats and one dog had been identified with H1N1 flu infection that appeared to have come from their owners. Ferrets have also gotten the flu from their owners.

"It's reasonable to assume there are many more cases of this than we know about, and we want to learn more," Dr. Christiane Loehr, a professor in the Oregon State University (OSU) College of Veterinary Medicine, said in a news release. "Any time you have infection of a virus into a new species, it's a concern, a black box of uncertainty. We don't know for sure what the implications might be, but we do think this deserves more attention."4

Nearly 10 Percent of Dogs Carry Influenza A Antibodies

While it’s long been believed that humans can’t give the flu to their furry best friend, a test of more than 2,000 dogs and cats in the Midwest U.S. detected influenza A antibodies in 9 percent of the dog samples and more than 5 percent of samples from cats.5 According to researchers writing in the International Journal of Infectious Diseases:6

“Companion animal species living in very close proximity to humans and other domestic and wild animal species provide an exquisite environment for viral recombination, evolution and emergence. Every interspecies transmission event increases the probability of a high impact evolutionary event and contributes to a broadening diversity of influenza A subtypes and dynamics of viral transmission globally.”

There’s still much to be learned about human-to-pet flu transmissions, and the risk appears to be very low, but it is, indeed, possible to give your dog (or cat) the flu. The OSU researchers were cautious enough to suggest that if you have the flu, you may want to stay away not just from your other human family members but also from your pets.

Can You Get the Flu From Your Dog?

If your dog can get the flu from you, can you also get the flu from your dog? Dogs have long been considered to carry only one or two influenza A viruses that don’t typically pose a threat to humans.7 However, the existence of mutated flu viruses that could potentially jump to humans has been confirmed in Asian dogs.8

Researchers sequenced the genomes of 16 influenza viruses obtained from pet dogs in Southern China. The analysis revealed the flu viruses contained segments from three lineages known to exist in Chinese pig, which had resulted in the creation of three new canine influenza viruses.

Because of the known ease with which flu viruses are known to jump from pigs to people, it’s thought that canine influenza viruses that originate in pigs could pose a higher risk to humans than those that came from birds or other species, like horses.

Loehr also stated back in 2012, "All viruses can mutate, but the influenza virus raises special concern because it can change whole segments of its viral sequence fairly easily … In terms of hosts and mutations, who's to say that the cat couldn't be the new pig?”9 Likewise, who’s to say the dog couldn’t also be the new pig? To date, however, no cases of humans being infected with canine flu have been reported.

Advertisement
Save up to 39% on Select Flea & Tick PacksSave up to 39% on Select Flea & Tick Packs

How to Protect Your Dog From the Flu

It’s highly unlikely that your dog will end up getting the flu from you. In fact, most healthy family pets rarely get the flu. Dogs most at risk are those living in crowded conditions, such as some animal shelters, but if your dog will be spending time at a kennel or doggy daycare, he could be exposed.

Even in the latter case, however, I recommend avoiding canine flu vaccines because they don't prevent infection. The vaccine may reduce viral shedding once infection is present, and may lessen the severity of symptoms and their duration, but it does not keep your dog from acquiring canine influenza virus (CIV), and is adjuvanted, which means the potential for unwanted side effects is real.

Further, even if your dog does get the flu, he’ll likely recover quickly with no veterinary attention needed. Just as in humans, the best way to avoid the flu for your dog is to have an immune system in top working condition. You can support your dog’s immune health, and thereby help prevent the flu, by: