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Canine Influenza Disease and Vaccination - H3N8 Virus

Highly contagious for dogs housed together


Greyhound Nose / Janet Tobiassen Crosby DVM

Greyhound Nose

Janet Tobiassen Crosby DVM
The canine H3N8 virus, also called Canine Influenza Virus (CIV), is a relatively new influenza virus in dogs. Because this is a new disease, few dogs have been exposed to it and are considered susceptible. This virus is highly contagious for dogs in close contact or housed together (kennels, shelters), and can be deadly.
From the Iowa State University Canine Influenza Fact Sheet:
"Deaths typically occur in dogs with severe disease; the mortality rate is thought to be 1-5%, although some sources suggest that it may be as high as 8%. Secondary bacterial infections appear to contribute significantly to these deaths."

Originally discovered in 2004, the canine influenza virus is believed to have jumped from horses to dogs in Florida. This virus, H3N8, is a subtype of the influenza A virus, a highly contagious pathogen that can cause disease by itself or in conjunction with other respiratory pathogens.

Transmission: As with most infectious respiratory diseases, dogs housed in close quarters (kennels, shelters) and situations where there is lots of "dog traffic" (dog day care, grooming/training, vet clinics) are most at risk. There is no evidence to date that this virus infects humans.

Clinical signs: Similar to other influenza infections, this virus causes respiratory signs of sneezing, nasal discharge and coughing. Fever may occur, but not often.

Diagnosis: Because these signs are the same as many other respiratory infections including Kennel Cough, a special test is necessary to diagnose the H3N8 virus. This test is called a PCR test (polymerase chain reaction) and usually two samples are submitted over a 2 week period to positively identify infection.

H3N8 Treatment: Treatment for this disease is supportive; making sure that the dog maintains appetite, extreme coughing is controlled, and monitoring for fever or development of more serious complications, such as pneumonia.

Your veterinarian will determine if pneumonia is a risk and if antibiotics for secondary bacterial infection are warranted.

H3N8 Vaccine: The U.S. Department of Agriculture's Animal and Plant Health Inspection Service (APHIS) conditionally approved the first vaccine for the canine H3N8 virus on June 23, 2009. Full licensure for the Canine influenza vaccine Nobivac® was granted June 9, 2010. The canine influenza vaccine (CIV) is made by Intervet/Schering-Plough Animal Health from an inactivated (killed) virus.

Studies indicate that the vaccine can reduce the incidence and severity of lung lesions, as well as the duration of coughing and viral shedding. The product is administered by injection, and is recommended for use in healthy dogs at six weeks of age or older as an aid in the control of disease associated with canine influenza virus infection.
Read full APHIS press release on CIV vaccine

FAQ: Canine H3N8 Influenza Vaccine
Who is at risk? Learn the risk factors and vaccine specifics in this dog flu vaccine FAQ.

Is Your Dog At Risk?
At this time, vaccination is recommended for dogs who have a "lifestyle risk" - dogs that will be housed with other dogs and/or traveling in areas of Canine Influenza outbreak. Canine Influenza vaccination is not a core vaccination. Please speak to your veterinarian to determine if your dog may be at risk and if vaccination is recommended.

Related H3N8 Information:

Related: For the latest H1N1 news, please see the H1N1 and Animal News Archive

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