Quick answer: Dog flu (canine influenza) is a contagious respiratory infection that spreads where dogs gather, such as kennels, daycares, dog parks and busy salons. Common signs are coughing, sneezing, nasal discharge, fever, tiredness and reduced appetite. Most dogs recover in a few weeks, but some develop pneumonia. To lower the risk, limit close contact with unfamiliar dogs during outbreaks, ask your vet about vaccination, and choose one-on-one grooming instead ...