Signs of canine influenza in dogs

Nearly all dogs exposed to the canine influenza virus become infected, with about 80% showing clinical signs of illness. Around 20% of infected dogs show no symptoms at all.

The most frequent symptom is a cough lasting 10 to 21 days. This cough can be soft and moist or dry, similar to the cough associated with canine infectious respiratory disease complex ("kennel cough”). Other symptoms include:

• Thick nasal discharge

• Fever (often 104-105oF)

• Lethargy

• Ocular discharge

• Reduced appetite

Complications such as secondary bacterial infections can occur in 10-20% of infected dogs, leading to more severe illness and pneumonia. The overall case fatality rate is considered low, at 1-5%.

The H3N8 virus has an incubation period of one to five days, with clinical signs usually appearing two to three days after initial exposure. Dogs infected with the H3N2 virus may begin showing respiratory symptoms between two and eight days after infection. Infections are most contagious during the incubation period.

Signs of canine influenza in cats

Cats infected with H3N2 may show signs of upper respiratory infection, including sneezing, nasal discharge, and congestion, as well as malaise, lip smacking, and excessive salivation or drooling.