When a dog comes into a clinic with signs of an upper respiratory tract infection, the veterinarian will perform a thorough physical examination and take a complete history from the owner. Dogs that are young, immunocompromised, unvaccinated, elderly or closely in contact with a number of other dogs (adopted from shelters or pet shops, at a dog show or dog park, etc.) have an increased risk of developing upper respiratory tract infections. The physical examination of a dog with an URT infection usually is unremarkable, except that the veterinarian may easily be able to elicit a cough by palpating or pressing on the dog’s windpipe (trachea). 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 uncomplicated, URT infection, although they may disclose evidence of infection or inflammation. More advanced diagnostic tools include chest radiographs (X-rays) and sampling of upper airway fluids and 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 nostrils (nares; nasal openings).
Often, advanced testing is delayed pending assessment of how the dog responds to antibiotic therapy.