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March 16, 2016

Infrequently Asked Questions: Can I give my cat or dog the flu?

The world is full of questions we all want answers to but are either too embarrassed, time-crunched or intimidated to actually ask. In the spirit of that shared experience, we've embarked on a journey to answer all of the questions that burn in the minds of Philadelphians -- everything from universal curiosities (Why do disposable coffee cups still leak?) to Philly-specific musings (How does one clean the Liberty Bell?). 

You're resting up from the flu when Margaret the cat wanders to your chest to lounge for a few Z's. She stares, you stare back, and suddenly the eye-lock of love is broken by a coughing fit that lands a few wheezes right in poor Margaret's face.

Can Margaret catch your flu?

You're not alone in your wondering. We caught up with Deborah Silverstein, an associate professor at the University of Pennsylvania School of Veterinary Medicine, who has specialties in emergency care and respiratory health, for a clear answer on whether we should be worried about our cats -- or dogs -- when we're at our most contagious.

Is it dangerous for humans to be around their cat or dog when sick with the flu or common cold?

The easy answer is no, there’s not a lot of concern. But the more in-depth answer would suggest there have been reports of animals transmitting flu viruses to cats, and even ferrets. There’s less evidence for transmission to dogs, but the reports out there are not very numerous considering how many people get the flu every year, and the 100 million houses that have cats or dogs. The incidence of transmission is extremely low from humans to animals. 

Interestingly, though, there was a study 2010 when they looked at several hundred cats, took blood samples and measured for the virus affecting a lot of people around the time when the virus seemed to be more of an epidemic with the H3N2 virus, and they did find that a decent amount of cats had antibodies to the virus, which means they’d been exposed. That didn’t tell us ‘Do these cats have any clinical signs whatsoever or are they serving as a kind of carrier for the virus?' So let’s say your cat is sitting on your lap and you’re sneezing all over him, and then your cat jumps over to your child or spouse’s lap and they start petting the animal, they’re probably getting exposed to the virus from the cat having it all over them, and it seems dogs and cats can develop a little bit of an immune reaction to the virus but that they don’t necessarily get sick. 

There are a lot of reports here and there of ‘I had the flu and now my animal has respiratory signs,’ and probably the best thing to do in that situation is to take your animal to the vet and they can do testing for flu virus and try to figure it out. There’s a lot of different types, though. Some we know are very commonly attributed to causing infection in animals, whereas the ones humans probably get are not quite as commonly blamed for causing disease in animals, if that makes sense.

What if you have a dog?

If you have a dog, the dog flu is a very different type of influenza virus than the human flu virus. So both are influenza virus, both even Type-A influenza, but the subtype of that virus tends to be more species-specific. That said, there’s been, in recent years, mutations in those viruses’ DNA that’s caused them to infect other species. And that’s how dogs are first thought to have gotten the flu -- from horse strains that mutated and started infecting dogs. And the same thing with bird flu or the swine flu, or take a given subtype of this influenza virus and just a little bit of this DNA changes to be virulent for another species for which it wasn’t previously a problem. That’s the biggest concern for zoonosis, which means a virus can go from a pet to a human, or reverse zoonosis where a virus can go from a human to a pet. We always have to be on alert for the chance those viruses could mutate and cause a more severe and easy infection in our pets.

I think most people would recommend that if you’re sick, for the welfare of other people in your house but also your pets, you just practice the same good hygiene you would anytime. Washing your hands a lot, trying not to sneeze or cough on them, probably not a lot of kissing and hugging the way you normally would. But at the same time, if you’re home sick and feel horrible, I don’t know that you can’t have your furry friend on your lap to keep you company.

So is the idea that it depends more on the virus and strain, the disease itself, than whether it’s a cat or dog?

Yes, it is the strain. There’s definitely a higher number of reports of human influenza being transmitted to cats. And interestingly, there was a report from a zoo a few years back where a human was thought to have come infected with the H1N1 virus, the common one of recent years, often known as swine flu, that infected a whole colony of anteaters at the zoo. There are species other than humans that can be infected, it just tends to be less common.

Is it harder to transmit the flu among animals? 

Dog-to-dog is very easy, same as human-to-human is very easy. And same with cat-to-cat. There are reports from South Korea of dogs giving the canine influenza to cats. That’s not something that has commonly been reported. Usually, the dog flu we see in the U.S. is one of two strains: one that started in 2004 and another that started last year in 2015. These seem to be isolated to dogs and have not been reported to be transmitted to people or in the U.S. to cats or any other species. For now, we’re lucky with that, but it’s no guarantee of what the viruses have the potential to do. 

Anything to add?

The most important thing for people is to practice good hygiene in your house as well as other people. Don’t be scared, but try to avoid sneezing or coughing directly on your pets. There are some reports of animals getting human influenza virus, but it’s more likely that those animals are serving as a [carrier] for spread amongst people. But it is possible for the animal to get sick. So just watch for any signs of flu virus in your pets. 

And if you have dogs that will be in a setting with a lot of other dogs, like a boarding kennel or dog show, and you want to get them vaccinated for the dog flu, we do have vaccines available for both strains that minimize their chance of getting infected and decreases severity of the infection should they come in contact with the virus.

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