Canine Influenza: Is Dog Flu Something to Worry About?

You just picked up your dog from boarding after a lovely vacation. Everything seems fine – and then your canine companion starts coughing. He has some nasal discharge. He feels warm, and he doesn’t want to eat. You remember that you just saw on the news that canine flu was causing problems. Oh no! You panic. Has he contracted the flu during his stay at the boarding facility?

It’s certainly possible; boarding kennels and other places where high numbers of dogs congregate are the most common place for dogs to come into contact with one of the flu viruses.

Currently, two strains of flu have been identified in dogs within the United States: H3N2 and H3N8.

The initial outbreak in 2003-2004, identified as H3N8, was restricted to Greyhounds in Florida and had a high mortality rate (38 percent). There was then a lull in cases until 2015; then, in Chicago, another outbreak occurred and was later identified as a new strain of canine flu: H3N2.

The most recent flare-up starting in mid-2017 and into spring of 2018 included both strains, though H3N2 was more prevalent and found to be more virulent. As of now, canine influenza has been reported in 40 states.

Dog Flu Symptoms

Symptoms of flu include sneezing, coughing, runny nose, fever, lethargy, and loss of appetite. About 80 percent of the dogs who are infected with the virus will have only mild symptoms, with about 20 percent of infected dogs showing no symptoms whatsoever (these dogs, however, are still able to spread the virus). Most dogs recover in two to three weeks.

In severe cases, however, the flu can progress to pneumonia. Symptoms of pneumonia are high fever; thick, purulent nasal discharge; and difficulty breathing. In severe cases, the illness can be fatal.

Unfortunately, flu represents a diagnostic challenge. The clinical symptoms cannot be distinguished from those of other common canine respiratory diseases such as bordetella bronchiseptica, parainfluenza, respiratory coronavirus, and distemper virus.

Further, there are no point-of-care tests currently available to veterinarians. Unlike in human medicine, where a quick bedside test can be conducted to diagnose flu, testing for canine flu can be difficult. Careful specimen collection and handling is essential, and tests must be sent to outside laboratories. Due to the expense and difficulty of this, often canine influenza is not definitively diagnosed; instead, it’s treated like other canine respiratory diseases.

How to Treat Dog Flu

There isn’t a specific treatment for dog flu; rather, general supportive care is given, especially if your dog is only mildly affected.

If your dog has more severe symptoms or evidence of pneumonia, he may be treated in the hospital with antibiotics (in case of secondary bacterial infection), intravenous or subcutaneous fluids, oxygen therapy, and fever-lowering NSAIDs. Your dog may also be isolated in a low-stress environment to prevent further spread and to help minimize his anxiety.

Canine Influenza Transmission

Influenza is highly contagious and spreads rapidly in social situations. Transmission is via aerosolized droplets (coughing, sneezing) and direct contact. It can also be spread on contaminated objects such as food or water bowls, leashes, and kennels. The flu virus can live up to 48 hours on these surfaces, so proper disinfection is a critical part of prevention.

The most common places for a dog to catch the flu virus include dog parks, grooming facilities, kennels, and daycares.

Dog Flu Vaccines

Could you have prevented your dog from contracting the flu? There are vaccines available that protect against both strains. All of the canine influenza vaccines contain killed viruses.

As with the human influenza vaccine, it is important to remember that the flu vaccine doesn’t always prevent your dog from getting sick. In the event that he does contract the flu, the vaccine helps lessen the duration and severity of symptoms, including pneumonia and lung lesions. Dogs who were vaccinated against the flu but still transmitted the disease will shed the virus into their surroundings for a shorter period of time than unvaccinated dogs.

Side effects of the vaccine are uncommon and generally similar to other vaccine reactions: lethargy, low-grade fever, a lump at the site of injection, hives, and itching. In very rare cases, severe reactions can occur.

Pregnant dogs should not be vaccinated against the flu.

The influenza vaccination has been described by the American Veterinary Medical Association as a “lifestyle” vaccination, not a “core” vaccine (core vaccines are recommended for all dogs). A lifestyle vaccine is recommended for dogs who are at a higher risk due to their increased exposure to other dogs – such as dogs who attend daycare, boarding, or group classes, or frequent dog parks or dog shows. The first vaccine can be given as early as six weeks of age, and in all cases, it is critical that a booster is received two to four weeks later.

Don’t wait until a few days before boarding to get the vaccine. The dog should not be considered protected from disease until two weeks after his second vaccination. After the initial series, the flu shot is given annually.

If your dog is not in social situations or flu has not been reported in your state, the flu vaccine is not necessary. If you’re uncertain whether your dog should receive the vaccine, your veterinarian can help guide you.

Want more information on vaccination protocols for dogs? Find it here.

Conclusions

Overall, while canine influenza can be serious, in most cases the symptoms are mild and self-limiting. Even in severe cases, the mortality rate is low – but some dogs do die from the illness. Vaccination is very effective and should be pursued for dogs in highly social environments.

Catherine Ashe graduated the University of Tennessee College of Veterinary Medicine in 2008. After a small-animal intensive emergency internship, she has practiced ER medicine for nine years. She is now working as a relief veterinarian in Asheville, North Carolina, and loves the GP side of medicine. In her spare time, she spends time with her family, reads voraciously, and enjoys the mountain lifestyle.