Canine influenza, also called dog flu, is caused by an influenza A virus. In 2004, the first strain, H3N8 was reported in racing greyhounds in Florida. Shortly after the problem arose in Florida, other states, which permit greyhound racing, were faced with respiratory disease outbreaks. Eventually, the virus was reported in at least 40 states and Washington, D.C.
The second identified strain, H3N2, was originally reported in Korea, China and Thailand. It was not detected in the U.S. until the spring of 2015 when an outbreak in the Chicago area affected more than 1,000 dogs. In the past two years, thousands of dogs across the U.S. have been infected.
Dogs that are infected by the canine influenza virus can develop mild or severe disease or become asymptomatic carriers. Dogs with the mild form of the disease present with a cough, sneezing, discharge from the nose and eyes, a decreased appetite and lethargy. Dogs with the severe form of the disease initially develop the aforementioned symptoms, but eventually develop high fever and pneumonia. These dogs usually require hospitalization and supportive care including antibiotics, intravenous fluids and oxygen therapy. Fortunately, the majority (80%) of dogs will develop the mild form and recover within 2-3 weeks. Less than 10% of affected dogs will die from the influenza virus.
Although most dogs infected by the influenza virus will become ill, approximately 20-25% of dogs will show no symptoms of illness. These asymptomatic dogs are dangerous in that they are carriers and can transmit the virus to other dogs. Because of the highly contagious nature of the influenza virus, notify your dog’s veterinarian immediately if you notice coughing, nose or eye discharge, lethargy or a decrease in appetite.
If your dog is showing respiratory symptoms, do not visit dog parks, doggie daycare, groomers or boarding facilities. Be sure to notify the veterinary office of the nature of your dog’s symptoms when you call to schedule an appointment. The office staff will likely instruct you to wait outside until you and your dog are ready to be seen. Expect to be directly ushered into an examination room and avoid approaching or coming into contact with other dogs.
At your dog’s visit, the veterinarian will perform a physical exam, take your dog’s temperature, draw blood and possibly recommend chest x-rays and a nasal swab to test for the influenza virus. Based upon your dog’s symptoms, the veterinarian will discuss treatment options.
A bivalent vaccine is available which offers protection against both the H3N8 and H3N2 strains. The vaccine will reduce the risk of a dog contracting the virus and, although not guaranteed to completely prevent disease, it will minimize the severity and duration of illness.
In order to reduce the risk of your dog becoming infected with the influenza virus, necessary precautions must be taken. If your dog’s lifestyle includes play dates at a park or daycare, if your dog participates in agility or dog show competitions, or boards at a kennel, the bivalent vaccine is recommended. As an added safety measure, before allowing your dog to visit kennels or facilities in which many dogs are in close contact, ask whether the influenza vaccine is required and if screening procedures are in place. Do not wait until the last minute to have your dog vaccinated. The bivalent vaccine requires a series of 2 injections, 2-4 weeks apart. Your dog should receive the final booster at least 2 weeks prior to potential exposure to ensure appropriate immunity.
