As we enter the fall and winter season, we all become aware of the risk for contracting influenza for ourselves and our family members. However, there is one family member that we don’t always consider as being at risk, our family dog.
In 2004, a new strain of influenza was found affecting racing greyhounds at race tracks in Florida. It was discovered that this strain of flu was a mutation from equine influenza and had jumped from the horses at the tracks to the dog population. This flu stain was given the name of H3N8. Initially it was contained to just the track population of greyhounds but in 2005 it started to be found in other dog populations in the Florida area. With this being a new viral strain to the dog population, no dogs had any natural immunity and the disease has spread across the United States at a rapid pace.
So we have a very high infection rate in exposed dogs and their symptoms of the disease can vary a great deal in the population. The disease is spread through the oral and nasal secretions of a sick dog being either directly shed onto an unexposed dog or the virus can persist for days on bowls, toys, and leashes. We feel that between 20-50% of the dogs infected will mount an immune response and have no or minimal symptoms of the disease. However, 50-80% of the exposed dogs will become sick and show symptoms. Runny nose, coughing, soreness, and fever are the most common symptoms. Of these sick dogs, a small percentage will develop pneumonia and national numbers suggest about a 5-8% mortality rate, especially if not treated aggressively. The pets will usually show symptoms in 2-5 days after exposure and symptoms can persist for 14-28 days.
The infection can be difficult to diagnosis because the symptoms initially are the same as several other less sever upper respiratory infections. A PCR test from a nasal or throat swab can be done to ID the virus but must be done in the first 3-4 days after symptoms develop and many times pets are not seen that quickly for this test to be effective. Flu titers can be done as well but you need two blood samples taken 2-3 weeks apart, so this test is not effective for rapid diagnosis. If your pet starts showing the symptoms of coughing, nasal discharge, soreness, and fever, they should be seen promptly by your veterinarian and testing and treatment can be initiated.
The good news is we now have a very effective vaccine for the canine influenza virus. The vaccine has a great track record for safety and effectiveness at preventing the serious pneumonia complications of canine flu infection. If a dog has never been vaccinated prior for the flu virus, the vaccine is given as an initial vaccine and then a booster 2-4 weeks later. Protective antibody levels can be maintained from that point with just one annual booster.
As we approach the time of year when we see an increase in dogs being boarded as their owners travel for the holidays, the need for getting our dogs vaccinated for influenza increases. If you have plans to board your pet in the near future, you should make sure they are current on their vaccinations to include Rabies, Distemper/Parvo/Para-influenza, Bordetella, Influenza, and a negative fecal test. Don’t let time slip away and find out at the last minute your pet is unprotected for their boarding appointment.
Matthew Thompson DVM