By Stephanie Oba, DVM
(First published in
The Rafu Shimpo on Jan. 26, 2012)


Flu season is obviously here. How many of your family and friends have various symptoms? Our dog companions are vulnerable to a newer strain of influenza virus, canine influenza. It’s seen a lot in kennels and with dogs who are socially friendly.

What is canine influenza?

First discovered in 2004, the canine Influenza virus is a novel influenza virus H3N8. Originally known to be a horse virus, it mutated and adapted to dogs. It spreads easily between canines, but as yet has not been known to infect humans. The first outbreak is believed to have occurred in racing greyhounds in 2004.

How is the virus transmitted?

It’s spread through aerosolized respiratory secretions. In other words, through coughing and sneezing, via contaminated objects, and people moving between infected and uninfected dogs.

This virus remains viable on surfaces up to 48 hours, on clothing for 24 hours, and hands for 12 hours. A typical incubation period is two to four days from exposure to onset of clinical signs.

Virus shedding usually occurs for up to 10 days of the onset. All dogs are susceptible since it’s a new pathogen. There is no natural immunity established yet.

What are the symptoms?

An abandoned but rescued three-year-old border collie mix, Chami, is perched at a kennel where the dog flu is commonly spread. (Courtesy of S. Oba)

The respiratory tract is attacked. You may notice coughing, sneezing, and nasal discharge. There is often a secondary bacterial infection that accompanies the viral infection. If this happens, you’ll see a yellow or green discharge.

Approximately 20 percent of infected dogs will show no signs of disease. These are the lucky ones. Yet, they’re still contagious.

Most dogs will exhibit the mild form of the disease, which is indistinguishable from other upper respiratory diseases, such as kennel cough.

An unlucky minority will suffer from severe pneumonia with a high fever, which can be fatal in a very small percentage of patients.

How is it diagnosed?

The most reliable diagnosis is to test for canine influenza antibodies in the blood. For a diagnosis, two blood samples are required. The first at the beginning of the disease, the second 10 to 14 days later.

A four-fold increase in the titer is diagnostic. If the dog has been ill for less than four days, a PCR test can be done to test for the virus. However, it is harder to collect this sample. A swab of the nasal or tracheal discharge is required. This usually requires sedating the dog.

You can’t get a diagnosis based on clinical signs alone. Many other respiratory infections have the exact same symptoms.

How is it treated?

As with all viral infections, treatment is usually supportive. Good nutrition, fluids and a clean environment are needed. Often a bacterial infection will accompany the viral infection that is treated with antibiotics.

In severely infected dogs, hospitalization with intravenous fluids and medication are required. The disease usually lasts two to three weeks.

Is there a dog flu vaccine?

Yes, a vaccine does exist. Although it doesn’t completely prevent the disease, it decreases clinical symptoms if the dog is exposed. It decreases the likelihood of getting the fatal pneumonia form of the influenza.

The vaccine also helps to decrease the amount of virus that gets shed into the environment as well. Hopefully, decreasing that amount will decrease the percentage of exposed dogs.

Call it a lifestyle vaccine. This means that not all dogs will need it. If your dog frequently visits areas where there are a lot of other dogs, you should talk to your veterinarian about getting the vaccine.

Some boarding facilities are starting to require the vaccine as well. Decontamination at these facilities can cause a two-week closure.

More than likely, house dogs will not require this vaccine.


Stephanie Oba is a contributing writer and physician for animals in  Alhambra. Opinions expressed in this column are not necessarily those of The Rafu Shimpo.

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