Canine Influenza Comes to Montana

We’ve been getting some calls about dog flu.

The first outbreak of canine influenza in the US was at a Greyhound track in Florida in January 2004. Racing types being the travelers they are, it spread to other states and showed up in boarding kennels and shelters in several states the first year. These outbreaks were of the H3N8 Influenza A virus. This is very closely related to equine influenza virus and is thought to have mutated from it to a form that affects only dogs. There have been sporadic infections since that time. Then in April 2015 there was a big outbreak of canine influenza in Chicago, involving some 1,000 dogs. It was caused by a different strain — this one mutated from avian influenza and was first identified in dogs in Korea in 2007. It was Influenza A strain H3N2.

Both H3N8 and H3N2 strains of dog flu can cause two forms of disease. By far the most common is the mild form, with a cough, runny nose and a fever– essentially the same symptoms of kennel cough. The cough lingers, and can persist for a month. Then there is the severe form, with a high fever of 104 to 106 degrees F and signs of pneumonia. This is the form that can be life-threatening, but it’s rare. In the Chicago outbreak, it is reported that of approximately 1,000 infected dogs, 0.5% died from complications of the disease. Several thousand dogs across the US have been tested and confirmed positive for H3N2 influenza since then, in clusters of outbreaks that typically resolve in a few weeks or months. It is characterized as a high morbidity / low mortality infection, meaning that it infects many in a cluster but is fatal to few.   The virus has not been shown to infect humans, but it can be transmitted to cats. I haven’t found anything about the disease in cats beyond the fact that it’s possible.

Last week, a veterinarian in Helena tested a dog with a respiratory infection and it came back positive for the canine influenza virus H3N2. What does this mean, and how should we respond?

First off — don’t panic. This isn’t an epidemic; it’s one case. The virus is contagious, spread from dog to dog by direct contact and from people or objects touching the respiratory secretions of an infected dog and then not washing before coming in contact with a susceptible dog — just like any other upper respiratory infection. This is why you see us washing our hands all the time between patients. The virus doesn’t last long in the environment and is easily killed with common disinfectants. For folks in Helena, ask your veterinarian — should you avoid boarding kennels and day care for a few weeks, or even the dog park? I think I would be keeping my dogs pretty close to home, or on walks way out in the woods, while we see how this develops.

Then there is the subject of vaccination. Canine influenza virus remains a rare, sporadic disease. It is not endemic like parvovirus or canine distemper virus, which all dogs need to be vaccinated against as puppies and as adults. There is a vaccine for the H3N8 virus, though we have never offered it, as the risk of serious infection is so low. That vaccine would not protect a dog against this new strain, so now there is a new H3N2 vaccine that was just released, on “conditional approval” — meaning that safety and efficacy studies have not been completed. If we had a full – blown epidemic here, you bet I’d consider using the vaccine. But we don’t — and I’m not recommending it.

Bottom line — Avoid sick dogs, stray dogs, and unknown dogs, like you always would to protect your pets. Watch for symptoms — coughing, sneezing, runny nose, fever — and call your veterinarian if your dog is sick. Having a thermometer at home for your pets is always an excellent idea (normal being 99.5 – 102.5 degrees). If your dog gets the flu, the treatment is very similar to when you get the flu: Rest, plenty of fluids, and treatment with antibiotics when needed to control secondary bacterial infection. Remember that most dogs get the mild form. Make sure they’re protected with the core vaccines for the diseases that are prevalent here, and that we still see cases of every few months.

Feel free to call the clinic if you still have questions!

1 Comment

  1. Good stuff. Thank you for posting. Be careful, not fearful.

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