When presented with a dog in respiratory distress, the veterinarian will take a history and perform a physical examination. He probably will rather quickly recommend taking thoracic radiographs (chest X-rays), which may or may not identify the cause of the dog’s condition. Routine blood work (a complete blood count and serum biochemistry profile) and urinalysis are usually unremarkable and unaffected by emphysema. Performing an arterial blood gas analysis on a blood sample is likely to show an abnormally low level of circulating oxygen (hypoxia), which is one of the most consistent diagnostic findings in dogs with this disease. Fecal examinations should be done to rule in or out the presence of respiratory (or other) parasites that could cause or contribute to the dog’s respiratory difficulties.
The most definitive way to diagnose emphysema is by taking surgical biopsies of tissue in affected areas of the respiratory tract. This can be done via a thoracotomy or a thoracoscopy. A thoracotomy is a surgical procedure in which a large incision is made in the chest wall, between two ribs, allowing the veterinarian to open up the thoracic (chest) cavity and visualize the lungs, heart and trachea and take appropriate biopsies of any obviously abnormal tissue. Thoracoscopy involves making a much smaller incision in the chest wall and using a wand-like instrument with a camera on its tip to enter the thoracic cavity, take a look around and then take biopsy samples. In either case, the tissue samples will be submitted to a veterinary diagnostic laboratory for microscopic assessment through a process called histopathology.
Computed tomography (CT scan) and magnetic resonance imaging (MRI) may be more specific diagnostic tools than standard radiographs to detect lesions associated with emphysema. However, these are expensive procedures and are only available at highly specialized veterinary facilities and veterinary teaching hospitals, and their usefulness in diagnosing the cause of canine emphysema is not yet established.