Introduction
Upper respiratory tract (URT) infection in dogs is provisionally diagnosed based upon the clinical signs shown by the affected animal and by ruling out non-infectious causes of those signs. In some cases, additional tests may be conducted to rule out or confirm the cause of the disease.
Diagnosing Upper Respiratory Tract Infection in Dogs
When a dog comes into a clinic presenting signs of an upper respiratory tract infection, the veterinarian will perform a thorough physical examination and obtain a thorough history from the owner. Young dogs, immunocompromised dogs, dogs that are unvaccinated and those that recently were boarded or in close contact with a number of other dogs (adopted from shelters or pet shops, at a dog show or dog park, etc.) are all at an increased risk of having upper respiratory tract infections. The physical examination usually will be unremarkable, except that there often will be an easily-inducible cough when the veterinarian palpates or presses on the dog’s trachea (windpipe). There may also be a mild discharge coming from the nose or eyes of infected animals.
Most veterinarians will also perform an initial database of blood work (complete blood count and serum chemistry panel) and a urinalysis. The results of these tests are often unremarkable in cases of simple, or “classic,” URT infection, although they may disclose evidence of infection or inflammation. More advanced diagnostic tools include chest radiographs (x-rays) and possibly sampling of airway fluids/cells for culture by performing a transtracheal wash or a tracheobronchial lavage. A heartworm test should be done to rule out heartworm infection as a cause of chronic cough in areas where heartworm is prevalent. Fecal tests are used to identify lung fluke infestation, and canine nasal mites can be diagnosed based upon the dog’s symptoms and the actual appearance of mites around the nares (nasal openings).
Often, advanced testing is delayed pending assessment of how the dog responds to antibiotic therapy.