By Erica Tolar, DVM, DACVO
Canine influenza, or the dog flu, has made another appearance in 2017. There are two strains of canine influenza, H3N8 and H3N2. The H3N2 strain is making its way through multiple states after originating at a dog show in Georgia this spring. This is the same strain that caused the 2015 outbreak in Chicago. The H3N2 strain was previously only reported in Asia. The canine influenza, H3N2, is not 100% identical to the Asian virus and is thought to have originated from the direct transfer of avian influenza to dogs in live bird markets.
The influenza virus has two clinical presentations, a mild form and a severe form. Dogs with the mild form have symptoms that can be similar to kennel cough; soft moist cough, lethargy, fever, and reduced appetite. Symptoms can persist for 10 to 30 days. They can also have ocular and nasal discharge. The severe form is more concerning as they can develop high fevers and severe pneumonia. The fatality rate associated with pneumonia is less than 10% and most dogs recover in 2 to 3 weeks.
Canine influenza is very contagious and thankfully not very hardy in the environment for very long. The virus can be transmitted between dogs by people though. This can happen on clothing, shoes, hands and other items. Good hygiene is necessary to prevent inadvertently spreading the disease. The virus is easily killed with a 1:30 dilution of bleach. Transmission requires direct contact with an infected and contagious dog’s fresh saliva or oro-nasal secretions. Unfortunately dogs are often contagious before they are showing any clinical signs. There are no reports of people being affected by the canine flu, however there are reports of cats getting sick that live in households with affected dogs.
The million-dollar question everyone has is should I vaccinate? There is a vaccine available with the H3N2 and H3N8 strains of influenza. The vaccine doesn’t completely protect against or eliminate the virus but it reduces the clinical signs and ability to transmit the virus to other dogs. If your dog is in a high risk situation (dog shows, boarding, dog parks, or in an area with a known outbreak) I would recommend vaccinating for canine influenza.
The vaccination series for influenza is a two shot series. The second booster is given 2-4 weeks after the initial vaccine. You should wait 3-4 weeks after the second booster before taking your dog into a high-risk situation.
Treatment of dogs with influenza is supportive care. In some cases this may require intravenous fluids, cough suppressants and possibly anti-virals. Dogs with pneumonia require hospitalization and aggressive antibiotics to combat any secondary infection.
Dogs with canine influenza should be isolated for at least 21 days even if their symptoms resolve well before that 21-day period. The canine influenza virus was demonstrated to shed for a prolonged period of time. Affected dogs that are only isolated for 14 days still have the potential to spread the virus and continue an outbreak.
Canine influenza can be a life threatening disease and with more outbreaks cropping up across the country I strongly recommend vaccinating your dog. Since this is a new virus to the United States
most dogs don’t have any immunity. Vaccination will at least be a start in protecting them from getting sick. If you are located in an area of an outbreak I would recommend using caution when taking your dog to high risk places. It is even worth a call to your vet to see if any dogs with influenza have been through the clinic before you bring your dog in. If your dog begins to have symptoms please reach out to your primary care veterinarian right away for advice.
AVMA, May 2017, Canine Influenza: Pet Owner’s Guide. Retrieved from https://www.avma.org/public/PetCare/Pages/CanineInfluenza.aspx
AVMA, April 2016, Canine Influenza FAQ Questions, Answers, and Interim Guidelines. Retrieved from https://www.avma.org/KB/Resources/FAQs/Pages/Control-of-Canine-Influenza-in-Dogs.aspx
Prolonged intermittent virus shedding during an outbreak of canine influenza A H3N2 virus infection in dogs in three Chicago area shelters: 16 cases (March to May 2015), Newbury, S., et. Al., Journal of the American Veterinary Medical Association, May 2016, 248, 9, 1022-1026.