Symptoms of the canine flu in your furry friend include soft coughing that can last for weeks, or a fever of 104 - 106 degrees, which could lead to canine pneumonia and could be fatal. (azfamily.com)
The first sign of heartworm infestation may not manifest for a year after infection, and even then the soft cough that increases with exercise may be dismissed as unimportant by the owner. (canismajor.com)
With the mild form of influenza, dogs generally have a soft cough that persists for one to four weeks. (texvetpets.org)