What is canine influenza?

Canine influenza is a respiratory virus that spreads rapidly between dogs through direct contact and airborne particles. When infected dogs cough or sneeze, the virus travels easily to other dogs in close quarters. Two main strains circulate in the United States: H3N8 and H3N2, both of which can cause illness in unvaccinated dogs regardless of age or breed.

Symptoms typically appear three to five days after exposure and include a persistent dry or productive cough, fever, nasal discharge, and lethargy. Most dogs recover in two to three weeks, though some develop secondary bacterial infections or pneumonia, particularly puppies and senior dogs. The virus does not cause illness in humans.

Because day care and boarding facilities bring multiple dogs together indoors, canine influenza spreads more readily in these settings. Many dog day care centers in Durham recommend or require vaccination against H3N8 and H3N2 to protect their boarding populations and reduce outbreak risk. Vaccination does not prevent infection entirely but significantly reduces severity and duration of illness. Facilities that enforce vaccination requirements often communicate this policy upfront, as it shapes which dogs can attend group play sessions.