Canine Influenza (Dog Flu)
Dog flu is a contagious respiratory disease in dogs.
Dog flu is caused by the canine influenza virus, known as H3N8. It is a specific Type A influenza virus that causes disease in dogs but not humans. The H3N8 influenza virus was originally a horse influenza virus. The virus spread to dogs and has adapted to cause disease in dogs and be easily transmitted between dogs. There is now what is believed to be a dog-specific H3N8 virus.
The H3N8 influenza virus was identified in horses more than 40 years ago. It was not until 2004, however, that it was first reported in dogs. It was originally diagnosed in greyhounds, and has since spread throughout the dog population.
Dog flu is spread through airborne viruses from respiratory secretions, just like human flu is spread between people. The virus can be transmitted to a dog through direct contact with an infected dog, through contact with contaminated items, and by people who may be carrying the virus on their hands or clothing. The virus can remain alive and infective on surfaces for up to 48 hours, on clothing for 24 hours, and on hands for 12 hours.
Approximately 20-25% of dogs of exposed dogs will become infected, but show no signs of disease, even though they are able to spread the virus. In 80% of infected dogs who develop dog flu, the signs are mild and may include a persistent cough that does not respond to treatment, sneezing, runny nose and a fever. These signs may be very similar to those of "kennel cough." In the remainder of infected dogs, canine influenza can become very serious, with infected dogs developing pneumonia, with labored breathing and even bleeding into the lungs. Dogs will generally start to show signs of disease 2-4 days after they are exposed to the canine influenza virus.
A veterinarian will suspect dog flu if the dog is showing the above signs, but dog flu cannot be diagnosed solely on clinical signs. A specific antibody test is used to diagnose dog flu. It is performed on two blood samples, one taken at the time the dog is first suspected to have dog flu, and the second sample taken 10-14 days later. If the dog is seen very early in the course of the disease (within 72 hours of showing signs), the respiratory secretions can be tested for presence of the virus.
There is no specific treatment for canine influenza, but the dog is given supportive care. This may include fluids to prevent dehydration, good nutrition, and medications to relieve some of the symptoms. If the dog is more seriously ill, he may need supplemental oxygen. Antibiotics are often given to prevent or treat any secondary infection, especially if there is pneumonia or the nasal discharge is very thick or green in color.
Most dogs with mild signs recover fully. Death occurs mainly in dogs with the severe form of disease; the mortality rate is thought to be 1-5% or slightly higher.
Yes, an approved vaccine is available. It will not treat the disease, and may not entirely prevent it, but it may help decrease the severity of the disease if the dog acquires it. The vaccine will also decrease the amount of virus that is shed into the environment, so vaccinated dogs are less likely to transmit the virus to other dogs.
Any dog who is showing signs of a respiratory infection should be isolated from other dogs for at least 2 weeks. Any clothing, equipment, or surfaces that could be contaminated with respiratory secretions should be cleaned and disinfected. The virus is killed by routine disinfectants, such as a 10% bleach solution. People should wash their hands before and after having contact with a dog showing signs of a respiratory disease. To prevent dog flu and other infections do not allow your dog to share toys or dishes with other dogs grouped together.
To date, there is no evidence that the canine influenza virus can be transmitted from dogs to people. There is no reported case of human infection with the canine influenza virus. While this virus infects dogs and spreads between dogs, there is no evidence that this virus infects humans. There is also no evidence that influenza in horses can be spread to people.
Schedule an appointment with your veterinarian so your dog can be examined and tested, if indicated, and treated appropriately.