vetMaybe you’ve heard of the “dog flu” or canine influenza. It’s a real virus that’s highly contagious; it’s also preventable through vaccination. However, there’s a lot of misleading and incorrect information out there, so Long Animal Hospital and Emergency Center has put together a simple primer on canine influenza and vaccination.

What is Canine Influenza?

Canine influenza is a highly contagious respiratory disease caused by a virus. There are two known strains of the canine influenza virus (CIV): H3N8 and H3N2.

The H3N8 strain has been around for several years, but the H3N2 strain was just discovered in early 2015. It first affected around 1,000 dogs in the Chicago area; our Charlotte dogs may not have been exposed to it yet. 


Dog flu symptoms are similar to other canine respiratory illnesses and can include:

  • Coughing
  • Retching
  • Lethargy
  • Loss of appetite
  • Runny nose
  • Discharge from the eye
  • Fever

However, signs and symptoms vary greatly from dog to dog; some dogs only cough while others may show no signs at all – but they’re still contagious.

How is Canine Influenza Spread?

Canine influenza is highly contagious among dogs and possibly cats. There have been no known reports of CIV spreading to humans.

All it takes is one interaction with an infected dog or contaminated surface to spread the disease. It’s commonly passed along in the following ways:

  • Direct nose-to-nose contact
  • Friendly licks (dog kisses)
  • Through the air when an infected dog sneezes, coughs, or barks
  • Shared items (food and water bowls, leashes, toys, etc.)
  • Contaminated clothing, hands, or shoes of caregivers and human family members

The virus can live on contaminated surfaces for 48 hours; on hands, clothing, and shoes, it can remain for up to 24 hours.

Diagnosis and Treatment of CIV

Diagnosis of dog flu can be complicated, as signs are similar to those of many other canine respiratory illnesses. However, there are laboratory tests available to determine the presence of CIV.

Unfortunately, there’s no treatment for CIV. Once your dog is infected, they may be sick for up to 4 weeks, and they’re likely contagious during that time. Keep your pet away from other dogs and public places to avoid spreading the disease further.

For some dogs, the virus makes them more susceptible to secondary infections and other complications, including pneumonia. Unfortunately, some dogs die from complications of CIV.

Canine Influenza and Vaccination

One of the most common questions we get asked is whether dogs need the flu vaccine. Our answer? It depends. The recommendation for CIV vaccination hinges on a variety of factors, including lifestyle and overall health. Our veterinarians are happy to discuss this during your pet’s next preventive care exam.

There are three reasons vaccination may be appropriate for your dog:

  • Dogs can be infected days before any symptoms appear; some dogs can be contagious even with no signs of the disease.
  • The virus can live for up to 48 hours on contaminated surfaces.
  • People can unknowingly spread the disease because the virus can live on clothes, shoes, and hands for up to 24 hours.

Really, the only way to stop the disease from spreading is to prevent dogs from contracting it in the first place (i.e., vaccination).

If you have any questions or concerns about canine influenza and vaccination, please don’t hesitate to give us a call.