When presented with a dog in respiratory distress, a veterinarian will take all necessary steps to ensure that the patient has a patent airway. Once that is accomplished, she will conduct a thorough physical examination and take a complete history from the owner. The initial data base typically includes routine blood work (a complete blood count [CBC] and serum biochemistry panel) and a urinalysis. The results of these preliminary tests may or may not be abnormal. Even if they are normal, pneumonia cannot be ruled out.
The next diagnostic step is to take thoracic radiographs (chest X-rays), from several different views. Chest films usually are diagnostic of the existence of pneumonia, but they cannot help identify the cause of the dog’s condition. Definitive diagnosis of the actual cause of the lung infection usually is made by collecting, examining and culturing blood samples. The results of advanced blood work should identify the specific microorganisms that are involved and provide guidance to the veterinarian in selecting the most appropriate antibacterial, antiviral, antifungal, antiparasitic or other treatment protocol.
Another common diagnostic tool is transtracheal lavage. This is a respiratory wash procedure that involves flushing the trachea with a sterile solution, drawing the fluid and dislodged airway cells back into a syringe and submitting the sample to a diagnostic laboratory for assessment and culture. Arterial blood gas analysis and pulse oximetry can be used to evaluate the levels of oxygen in the blood (this is called oxygenation). Bronchoscopy is a technique whereby the veterinarian inserts a wand-like instrument with a camera at its tip down the trachea and into the upper bronchi, enabling her to visualize the respiratory lining and remove any reachable foreign bodies that may be obstructing the upper airways. Tumors can also be seen and biopsied using this technique. Computed tomography (CT scan) is available in some specialized clinics but usually is unnecessary if good quality chest radiographs are taken.
Pneumonia is not extremely common in adult companion dogs. When it does occur, it often is discovered incidentally to some other condition or disease.