The classic sign of CIRDC is a frequent, honking cough that comes on suddenly. This cough has also been described as gagging or retching, and it can involve froth that looks like vomit. Coughing generally worsens with activity or exercise, which can irritate the airways.
Even so, not all dogs with CIRDC will have a cough. Other common signs include sneezing and a runny nose or eyes.
In most cases of CIRDC, the illness is mild and dogs fully recover within 7 to 10 days. However, depending on the infecting organism(s) and the dog's ability to fight them, some dogs may develop more severe signs like lethargy, decreased appetite, fever, productive cough, and rapid or labored breathing, which can signal that bacteria have infected the lungs (bacterial pneumonia) and immediate veterinary attention is needed.
Dogs in which canine distemper virus is one of the infecting organisms may also have gastrointestinal signs (e.g., vomiting or diarrhea), hardened footpads, and, as the disease progresses, neurologic signs (e.g., head tilt or circling behavior). These dogs, as well as puppies and older dogs with other health problems, are at greater risk of severe disease, and even death.