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Canine Influenza Vaccine

Feeding dogs prone to pancreatitis or who can’t tolerate dietary fat.

News item written by Mary Straus, published in the Whole Dog Journal, August 2009.

A new vaccine for canine influenza virus (CIV) developed by Internet/Schering Plough was conditionally approved in May 2009 [Update: full approval granted 6/9/10]. Conditional licenses are granted before much is known about a vaccine’s effectiveness. This is a killed virus vaccine, so it cannot cause disease itself. The makers suggest that two vaccinations are given two to four weeks apart; it can then be given annually. (Whether it needs to be given annually is unclear, since most viral vaccines confer long-term immunity).

Canine influenza was first identified in 2004 in racing greyhounds in Florida. It has now been found in 30 states, though the number of cases is still small. The areas most affected are Florida, New York City’s northern suburbs, Philadelphia, Denver, and a recent outbreak in New Jersey. There is no evidence that it has spread to other countries. Most cases occur where dogs are housed closely together

CIV is a highly infectious respiratory disease that is considered one of many types of kennel cough. Each type of kennel cough is different, so vaccinations for other types will not protect against CIV. It is spread by contact with infected dogs, or with anything that has come in contact with those dogs. The virus can persist for up to a week in the environment, but is deactivated by common disinfectants, such as alcohol and bleach. It is most commonly found in high-traffic facilities, or kennels where many dogs are housed together.

The vaccine may only reduce the duration and severity of the disease rather than giving complete protection, similar to influenza vaccines in other species. It may also reduce shedding of the virus and so make it less contagious. Canine influenza is restricted to dogs and is not contagious to other species.

Virtually all dogs exposed to CIV will be infected, though the severity will vary considerably. Approximately 20 percent of infected dogs may show no signs at all. Symptoms can last up to a month, and may include a low-grade fever, nasal discharge, and a mild, productive cough. In 10 to 20 percent of cases, the virus can lead to high fever and pneumonia, usually caused by secondary bacterial infection. The fatality rate is currently between one and five percent of affected dogs. The virus is not responsive to antibiotics, though they can be helpful for secondary infections.

Should you vaccinate your dog? It depends on your dog's likelihood of exposure and overall health. Because the risk of CIV to most dogs is minimal at this time, few household dogs are likely to benefit from the vaccine. It may be helpful for kennels where large numbers of dogs are housed together, especially in areas where the disease is prevalent. Discuss the potential risks and benefits with your vet.

Update April 2015: An outbreak of canine influenza in the Chicago area is from a new strain of canine influenza, H3N2. We don't know how effective the vaccine will be against this new strain, but veterinarians are encouraging owners to vaccinate dogs in the area, as even partial immunity might be enough to save a dog's life. More info:

Update January 2018: Here's the best article I've yet seen on canine influenza, written by a vet tech:
Canine Influenza Vaccination: Does Your Dog Need It? (January 2018)

Also see Dog Flu in Calif. Has Not Spread Nationwide: Experts, which talks about how the virus spreads, including the following quotes:

"We don’t have the (dog flu) virus spreading across the country like the human flu, where everyone gets infected. The virus infects dogs in a city and tends to die out over a few months," said Colin Parrish, a professor in canine virology at Cornell.

AVMA spokesman Michael San Filippo said pet owners may want to talk to their vet, or stay away from dog parks or doggy day cares if concerned. "I do not feel like we are in the midst of a large outbreak that pet owners need to be concerned about," said San Filippo.

The following article talks about the bivalent vaccine that covers both H3N8 and H3N2 strains, approved in October 2016. Here's the press release:
Merck Animal Health Announces USDA Approval of Innovative Canine Flu Bivalent Vaccine

And here's a quote about needing revaccination annually:
"Dogs at risk for CIRDC (canine infectious respiratory disease complex) should be vaccinated at least yearly with both influenza strains, H3N8 and H3N2, in addition to the other causes of 'Canine Cough',” said Ronald Schultz, Ph.D., professor of pathobiological sciences at the University of Wisconsin School of Veterinary Medicine. “The occurrence of one strain or the other is unpredictable and so dogs should be protected against both. Because dogs do not maintain long duration of immunity against influenza, it is important to vaccinate them annually.”

I still do not understand why the duration of immunity should be short, but I trust Dr. Schultz, who has led the fight against overvaccination and proving that most viral vaccines last for many years, so if he says this one doesn't last, I believe him.

Canine influenza is considered a "lifestyle" vaccination and is recommended for the same dogs who should get a Bordetella (kennel cough) vaccine yearly, including those who go to boarding kennels, dog parks, doggie daycare, dog shows, or anywhere else where dogs congregate, particularly enclosed areas. Dogs most at risk are the very young and very old, and those whose immune systems are compromised due to illness or medication (such as corticosteroids (prednisone) and Apoquel that suppress the immune system).

More information:

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