Battling a newer strain of canine influenza

Friday, May 17, 2019

A new dog flu is making its way across the country.

The original canine influenza virus, identified since 2000, mutated from a horse strain and spread from infected dogs for about a week, meaning outbreaks were few and brief.

However, in 2015, a new strain of canine influenza emerged in Chicago. This strain lasts for up to a month and even dogs without clinical signs can spread it. Thus, more dogs have been infected for longer periods of time, leading to the spread of the virus across the country, where it has been identified in almost every major city.

The typical case of canine influenza looks identical to kennel cough.  Just like in human influenza, some dogs can develop a much worse condition due to the complication of bacterial pneumonia. This can also happen in traditional kennel cough. Since our dogs in America had never seen this Chicago virus before, they had not developed protection from previous exposures. And since it can be spread from dogs who are apparently healthy, controlling an outbreak is very difficult.

The virus is spread primarily through aerosol exposure — being around an infected dog who may have coughed or sneezed. A dog who gets within a few feet of an infected dog can be exposed. Signs — typically lethargy and a harsh cough — may develop in a week or less. The lethargy rapidly improves, but the cough can persist for weeks. In most cases, the disease is self-limiting and dogs recover without specific therapy. Unless it develops into a secondary bacterial infection, antibiotics have no effect on recovery.

Today, a vaccination exists to immunize dogs against both strains of canine influenza. The initial series requires two injections within four weeks. Protection is good, but similar to the human flu shot, it may only minimize the signs. After the initial series, dogs require an annual booster to maintain protection. This is a separate vaccination from the traditional kennel cough vaccine most veterinarians recommend. Like all vaccines, side effects are rare and typically mild, such as lethargy for a day or two.

If you have more questions about canine influenza, talk with your veterinarian.