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Canine Influenza: Contagious Respiratory Disease in Dogs

Dogs that are kenneled for boarding, day care or grooming, are likely exposed to contagious diseases. This does not mean that these situations are a bad thing; after all, we do send our children to kindergarten. The benefits of these settings often outweigh the risks of exposure. Kennels can provide a safe place to stay while you are at work or traveling. Day care offers the benefits of socialization as well as mental and physical exertion that is integral in maintaining a healthy, happy, well behaved pet.

Every now and then there are outbreaks of disease, whether it be gastrointestinal or respiratory. These viral, bacterial, and parasitic diseases can cause mild to severe symptoms. Fortunately most of the time our pet’s immune system can effectively deal with the exposure, just as most individuals effectively respond to the common cold and flu. However, there may be conditions where a pet might not have an adequate immune response thereby allowing them to be more susceptible (very young or very old, concurrent illness, decreased immune function, inadequately vaccinated).  We have always recommended that these pets not be boarded or attend day care facilities.

Contagious respiratory disease is a syndrome caused by a variety of organisms. The bacteria Bordetella, the virus Parainfluenza and the virus Canine Influenza all cause a contagious respiratory illness of dogs that can vary in severity. In very rare instances, animals can die from the infection. The latest research indicates a 1-5% mortality rate; however, the veterinarians at River Cove Animal Hospital have never had a canine patient die from Bordetella, Parainfluenza or Canine Influenza.

Canine Influenza, often referred to as dog flu, is a relatively new pathogen. It was originally an equine influenza (Influenza A H3N8) before it jumped to canines.  It was first reported in racing greyhound kennels in Florida in 2004 (possibly associated with the feeding of raw horse meat).

Clinical signs of dog flu are similar to those in people: runny nose, cough and fever. Without laboratory diagnostics, canine flu is difficult to distinguish from other respiratory infections.  However, specific diagnosis does nothing to change the treatment of these animals, which is centered around supportive care. We often start the dog on antibiotics to prevent secondary bacterial infections like pneumonia. Cough suppressants can be used to reduce airway irritation and provide comfort from what can be a relentless cough.

The availability of the first Canine Influenza vaccine in 2009 raised questions among veterinarians across the country about the threat of dog flu and the value of immunizing pets against the virus. Interest in the vaccine originally appeared high among pet owners, probably because of a human flu pandemic occurring at the same time. Also playing a role might have been the manufacturer’s marketing of the vaccine.

It is important to know that if your dog does not come into contact with other dogs vaccination for canine influenza is not necessary, this is contrary to the general recommendation for people when it comes to the human flu vaccine. To quote Dr. Wolf, a veterinary specialist in Texas, “most dogs I know do not travel extensively in the company of hundreds of other dogs from all over the U.S. nor work eight hours a day in a closed environment with hundreds of other dogs from all over a local area…Few ride buses with other dogs, go to school or work in hospitals.”

Canine Influenza was first seen in local Vermont dogs in 2012 with an outbreak of upper respiratory disease.  Since this time we feel Canine Influenza has become endemic in our population. Therefore, it must be considered as one of the potential pathogens in canine infectious respiratory disease.

Does this change the way in which we treat dogs with upper respiratory infections? No it does not. What it does change is our counseling of our clients regarding ways to potentially prevent or diminish the signs from canine infectious respiratory disease. This includes a discussion of the risks versus benefits of vaccination, which is one form of prevention. The other way to prevent the disease is to minimize your dog’s exposure to other pets by avoiding areas where dogs congregate like dog parks, day care and boarding kennels.

Today, veterinary infectious disease and immunization experts generally recommend the Canine Influenza vaccine for dogs in states where the disease has been reported but only for dogs that come into regular contact with other dogs. In particular, this includes show dogs and racing dogs, but also pets that frequent dog parks or are kept in day care or boarding kennels.

The Canine Influenza vaccine does not necessarily prevent the disease. Vaccinated animals may still be infected with the virus and show clinical signs. The vaccine will hopefully reduce the severity of disease and it is thought to help reduce virus transmission to other pets.

The fact that the Influenza virus can change should also be considered when contemplating the vaccine. The Canine Influenza virus can mutate and no longer be recognized by the protective antibodies that a vaccine provides. The human flu vaccine is reformulated every year to try and create the best antibody response to the most current strain of virus. This is one factor in why vaccines against viruses capable of change (like the human flu virus) are never going to be 100% effective.

Recently a second strain of canine influenza virus was recognized in the Chicago area. This outbreak was attributed to a new strain of canine influenza, H3N2 (as opposed to the H3N8 strain that evolved from horses and was discussed above). This new H3N2 strain evolved from birds in Asia. Cats as well as dogs may be able to contract the new H3N2 virus. There is no evidence of transmission of either strain of canine influenza viruses from dogs to people. No cases of this new strain of canine influenza (H3N2) have been diagnosed in Vermont. Most of the cases are in the Mid-West. Currently we are not recommending vaccination for this new strain (H3N2).

Please remember it is most important to consider each individual’s risk of infection when thinking about an additional vaccine. Please discuss your dog’s life style with your veterinarian at River Cove Animal Hospital to see if the Influenza vaccine is right for you.

If the Canine Influenza vaccine is necessary for your dog two injections are needed 2 to 4 weeks apart and then a period of at least one week following the 2nd injection is required to achieve maximal immunity (3-5 weeks from the initial vaccination). Vaccinations are then repeated annually.