Should Your Dog Get a Flu Shot? the Real Facts About Canine Influenza

By Gina Spadafori | December 14, 2012

To give or not to give a flu shot to your dog?It's flu season, and with that come the nonstop reminders to get your flu shot and the nonstop warnings about what could happen if you don't. The U.S. Centers for Disease Control reports that up to a fifth of all Americans get the flu every year; more than 200,000 people will wind up hospitalized with complications, and approximately 50,000 will die.

Public-health authorities have done a good job of building awareness of the risks associated with the flu virus, and most at-risk people - as well as a significant number of those not at risk - get a flu shot every year. There is no doubt that this effort has saved many lives.

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But what about your dog? Does he need a flu shot? In 2004, a new disease, quickly dubbed "canine influenza," was discovered among Florida's racing Greyhounds, and it soon spread to the larger population of pet dogs. While there is a vaccine for this respiratory virus, parallels between human influenza and canine varieties - and the need to vaccinate at-risk pets - aren't as strong as the similar names might suggest. Unlike seasonal flu in humans, canine influenza isn't widely spread, and the vaccine doesn't change to meet the challenge of evolving flu strains. But that doesn't mean that this isn't a potentially serious health issue for your dog.

Dr. Kate Hurley of the Koret Shelter Medicine Program at the University of California, Davis, School of Veterinary Medicine spoke with Vetstreet about how canine influenza is spread, what puts dogs at risk and why she doesn't vaccinate her own dog.

Q. When the public first heard about canine influenza, it was pretty scary. Dogs were getting very sick and dying, and no one knew how far and fast this disease would spread. What has happened since?

A. Kate Hurley: "Two things, really: The disease has spread beyond Florida, and a vaccine has been developed. There's some good news there along with the bad. The disease is endemic in many places on the Eastern Seaboard, and we've also seen it erupt in other places, most notably Colorado and Texas. But it hasn't spread elsewhere at this point.

"For example, I see a fair amount of distemper in some California shelters, but I don't see canine influenza other than a rare case here and there. It's not clear why it hasn't become endemic, but we do suspect that's because unlike distemper, there's a small window for passing the virus. With distemper, dogs walk the earth shedding the virus, which they can spread for weeks or even months after recovery. With canine influenza, the period when the dog is shedding the virus - when other dogs could catch it - is short, and that's the good news.

"The vaccine is also good news, up to a point. It does not prevent the disease, but it does lessen the severity of the virus in dogs who contract canine influenza. And since even young, healthy dogs can get very, very sick and even die, lessening the severity is a very good thing."

Q. There's a lot of talk about needing to change the flu vaccine every year for people. Is the same thing true with canine flu? Why or why not?

A. "Human influenza has been around for many decades and has had a long time to mutate into various different strains. Every year, health officials perform surveillance to check for different strains than the one in the latest vaccine, and if there's a new one found, the vaccine is updated. Canine flu, by contrast, has only been around for about a decade. So far there has not been a lot of genetic variation, so we don't yet have the problem of all kinds of different strains circulating. We hope this means the current vaccines will remain effective for some time to come."

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Q. Is the flu "seasonal" in dogs as it is in people?

A. "Canine influenza is more about proximity than season. Dogs who get it are those who are exposed to high numbers of other dogs, such as in a kenneling environment [or] shelter or at a dog show. And unlike the normal flu, it's not even [dogs] with chronic illness or the elderly who are at highest risk: Vibrant, healthy dogs can get very sick. That's important to know because people will say, 'Well, my dog's healthy, so I don't have to worry about that.' But they do.

"Another reason why interactions with other dogs - kennels, shows, dog parks - is a problem is because there is some indication that Bordetella ('kennel cough') and other respiratory bacterial infections can damage the cells that protect the lungs, and that leaves them more vulnerable to canine influenza. And Bordetella, of course, is highly infectious in the same crowded, high-stress environments."

Q. How do I decide if I should vaccinate my dog? Is there a risk to the vaccine?

A. "The answer's not black or white. All vaccines have risk, even though that risk is generally very small. But not every dog is at high risk for canine flu, so in some cases, even a small cost and risk might not be worth the potential benefit.

"As an example, canine distemper is everywhere (raccoons carry it as well as dogs). Every dog should have this important vaccine. Canine influenza is a problem in some areas but rare in others. I don't vaccinate my own dog here in California for canine influenza, but if I lived in Colorado or another endemic area, I would. It's also about where your dog goes - for example, if you participate in dog shows or go to dog parks. Or if you foster rescue dogs, especially from a state where the disease is endemic, I would vaccinate to protect your own dog.

"You decide what risk you prefer, based on where you live and what you do. Ideally, your veterinarian will help you to figure it out. If canine influenza hits your area, your veterinarian should know, so be sure you discuss it every year."

Q. Should I avoid adopting a shelter dog? If I do take a chance on one, what should I look out for?

A. "I wouldn't say that, but I would say you need to be aware of what's normal and what's not after you adopt, and that doesn't just include canine influenza, which is still limited to certain parts of the country but not others. Before you adopt, be sure if you already have a dog that he or she is current on vaccines and other preventive health measures. That's important.

"It's not uncommon for dogs coming out of shelters to have a respiratory issue, and usually it's no big deal. A runny nose is nothing to worry about as long as the dog is bright and happy. You don't need to hit the panic button unless the dog is lethargic, isn't eating or seems to be laboring to breathe. If you see those symptoms, then yes, your dog needs to see a veterinarian.

"Even if your adopted dog seems healthy, it's not uncommon for a shelter dog to be shedding stuff - kennel cough, canine influenza or other contagious diseases. It's very important that for the first two weeks you protect other dogs by imposing a voluntary quarantine. Walkies for your new dog, yes; dog park, no. Don't take your new pet straight to the pet superstore to use all those coupons for a new collar and bowl. And most important, keep your new dog away from puppies. There will be time for all that visiting later, but keeping a potentially sick dog away from others is an important service to society."

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