Canine Influenza: New H3N2 Vaccine for Dogs

Last spring, thousands of dogs in the Chicagoland area were innocently exposed to a newly arrived Canine Influenza Virus from South Korea, called H3N2. Daycare and boarding facilities were voluntarily closed for weeks to minimize viral spread. Dog owners avoided taking their pets to dog parks and grooming parlors. Many ill dogs presented to their veterinarian with a cough, runny nose, lethargy, depressed appetite and fever. Most ill pets required significant medical care for three to six weeks.

Canine influenza is a highly contagious virus and is spread from one dog to another dog via respiratory secretions. A single cough from an infected dog can spread the virus up to 20 feet onto clothing items, hands, and the environment. This disease has a relatively short incubation period of 2 to 5 days. Affected pets can be ill up to 6 weeks and are infectious to other dogs for up to 21 days. During this infectious period, we recommend isolating ill pets from well pets. Canine Influenza is not contagious to humans.

At the time of the 2015 Chicago Canine Influenza Outbreak, veterinarians did not have an effective vaccine for this new strain. Today, I am pleased to announce the presence of a new canine influenza vaccine for the H3N2 strain.

In most cases, I recommend this new H3N2 vaccine to dogs who are:

  1. Social – like to play with other dogs or go to dog parks.
  2. Going to grooming parlors, daycare or/and boarding facilities.
  3. Immunocompromised or visit a veterinary clinic often.
  4. Living in a multiple pet household or/and in an apartment building where shared spaces exist– like hallways, backyards and elevators.

Initially, this new vaccine is given in a series of two injections separated by 2-4 weeks. It can be given to any pet over 6 weeks of age. Protection against this virus is achieved 2 weeks after the second vaccine. After the initial series, it is repeated yearly. Since investigators do not know if a previous natural exposure leads to long term protection against this virus, I recommend waiting 6 to 12 months after your pet has completely recovered from canine influenza before getting the H3N2 vaccine.

In a recent study by Merck, presented at a VETgirl webinar on December 7, 2015, this new Canine Influenza vaccine dramatically reduced the severity of the disease in vaccinated dogs when challenged by the virus. In fact, 42 percent of the unvaccinated dogs ( the control group) when experimentally challenged by the virus were euthanized due to severe illness compared to none in the H3N2 vaccinated group.

For over a decade, the Canine Influenza strain H3N8 vaccine has been available. Unfortunately, there is no known cross protection with H3N8 strain vaccine to the new H3N2 strain viral disease. Personally, I have not seen this virus in Chicago since 2008 and I would strongly recommend talking to your veterinarian to see if they recommend the H3N8 vaccine for your dog. The H3N8 vaccine can be given simultaneously with the newer strain vaccine, preferably at a different location. At this date, there is not a single multi-strain canine influenza vaccine on the market, but we anticipate one in the near future.

If your pet shows flu-like symptoms, like coughing and runny nose, please visit your veterinarian. Not all coughing dogs have canine influenza, but if your pet does have it, you want to address it as soon as possible to increase your dog’s chance of a successful outcome and minimize its discomfort. Remember, be proactive with your pet’s health. If your pet falls into the high risk category for potentially acquiring canine influenza, contact your veterinarian and together decide if it’s appropriate to vaccinate your dog. Prevention is preferable, emotionally and financially, over treatment for this serious viral disease.

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