Canine Influenza

*Photo by Will Marlow

1. What is canine influenza?

Canine influenza (CI), or dog flu, is a highly contagious respiratory infection caused by influenza A virus. The causative canine influenza virus (CIV) strains have been classified as H3N8 and H3N2.

2. Where does canine influenza occur?

Canine influenza has been documented in 30 different States. The March 2015 outbreak in Chicago and surrounding areas is the first documentation of the H3N2 strain.

3. What type of infection does CIV cause?

Canine influenza virus causes an acute respiratory infection in dogs. It is one of several viruses and bacteria that are associated with canine infectious respiratory disease (CIRD), or what’s commonly referred to as “kennel cough.” CIV infection can cause respiratory disease by itself or along with other canine respiratory pathogens.

4. What are the clinical signs of canine influenza?

CIV causes flu‐like illness consisting of cough, sneezing, and nasal discharge. Fortunately, most infected dogs recover within 2 weeks without any further health complications and 20% of infected dogs show no clinical signs at all. However, in some dogs the disease progresses to pneumonia from secondary bacterial infections. While the overall mortality rate for canine influenza is low, less than 10%, the secondary pneumonia can be life‐threatening. There is no evidence that age or breed play a role in which patients may develop pneumonia during canine influenza.

5. Who is susceptible to canine influenza?

Because canine influenza is due to a virus that is new to the canine population, dogs lack preexisting immunity to the virus. Dogs of any breed, age or health status are therefore susceptible to infection.

Outbreaks are more commonly seen in situations where groups of dogs are in close contact especially those that have a high turnover of dogs in and out of the facility, such as shelters, kennels, dog daycares, groomers, dog shows and boarding facilities. These types of facilities in areas where the virus has been isolated are particularly at risk. Dogs that mostly stay at home and walk around the neighborhood are at low risk.

There is no evidence that CIV can infect people, and there is no documentation that cats have become infected by exposure to dogs with canine influenza.

6. How is canine influenza transmitted?

Canine influenza is spread through the air and contaminated objects such as kennel surfaces, food and water bowls, collars and leashes and people moving between infected and uninfected dogs. The virus can remain viable (alive and able to infect) on surfaces for up to 48 hours, on clothing for 24 hours, and on hands for 12 hours. Fortunately, the virus is easily inactivated by washing hands, clothes and other items with soap and water.

Dogs are most contagious during the 2 to 4 day incubation period for the virus, when they are initially infected and start shedding the virus in their nasal secretions but are not yet showing signs of illness. Infected dogs continue to shed virus that may infect other dogs in their respiratory secretions for an additional 7 to 10 days.  Once the virus has run its course, the dog is no longer contagious. Therefore, we recommend that dogs with canine influenza be isolated from other dogs for two weeks. CIV does not cause a permanent infection.

7. How is canine influenza diagnosed?

Canine influenza cannot be diagnosed by clinical signs because all of the other respiratory pathogens cause similar signs of coughing, sneezing, and nasal discharge. There are special tests – either nasal swabs or blood tests depending on how long the signs have been present - that can determine if canine influenza is causing a patient’s clinical signs.

8. How is canine influenza treated?

Since canine influenza is a viral infection, treatment consists mainly of supportive care while the virus runs its course, much like for human influenza. A veterinarian can determine what type of supportive care is needed, including whether antibiotics should be given for secondary bacterial infections. Dogs with complications like pneumonia may require more intensive care.

9. Is there a vaccine for canine influenza?

There is a vaccine available for H3N8 strain of canine influenza. The canine influenza vaccine contains an inactivated virus, so there is no chance that the vaccine itself can cause respiratory infections.  It is unclear if this vaccine would protect against the new circulating strain (H3N2). There is some thought that the current vaccine could provide some level of cross-protection to reduce the severity of clinical signs of the new strain. Therefore it is our recommendation that owners consider vaccinating dogs at higher risk for infection. 

Currently at Prior Lake Pet Hospital, canine influenza vaccine is a “lifestyle” vaccine, in that it is intended for dogs at higher risk for exposure to CIV. The vaccine requires an initial injection, a booster in 4 weeks, then once yearly for ongoing protection. 

You may want to consider the vaccine if your dog participates in activities that expose them to facilities with large populations of dogs such as:

• Dog parks
• Boarding or training facilities
• Show events
• Travel to areas with reported cases
• Groomers
• Doggie daycare

In summary, the current strain of canine influenza has not yet been seen in the Prior Lake area and the vast majority of infected dogs have recovered without complications. A vaccine is available, but there is question about its ability to protect fully against the newly emerging strain. However, dogs at higher risk for transmission of the disease should consider the vaccine because the likelihood of potential adverse effects of the vaccine are very low. Please call us to discuss whether the vaccine is the right decision for your pet or if you have any questions or concerns about this illness.

UPDATE:  On May 27, 2015, the MN Board of Animal Health reported confirmed cases of the H3N2 canine influenza virus in Minnesota. All cases were reported in dogs from a single boarding facility in Detroit Lakes and all infected dogs have recovered from the illness. There have been no new cases reported in Minnesota since April 25, 2015.

https://madmimi.com/p/c52546?fe=1&pact=30588689495

Resources:

http://www.cdc.gov/flu/canine/index.htm

http://sheltermedicine.vetmed.ufl.edu/shelter-services/tools-tips-fact-sheets/canine-influenza-3/

https://www.avma.org/KB/Resources/Reference/Pages/Canine-Influenza-Backgrounder.aspx