Your dog or cat has a cough. You call your veterinarian for an appointment. What should you expect?
That depends on:
- how ill your pet is.
- the nature of the cough.
- how many times he has had the same or similar cough in the past.
For a mild, unproductive cough with little or no fever, no nasal discharge and not much systemic effect (such as loss of appetite), a thorough physical examination is in order and a heartworm test if he’s been off heartworm preventive. If the findings on the examination are not severe we may begin symptomatic therapy without any further diagnostic tests.
Our approach is different, however, with a pet whose cough is severe, recurrent, or is accompanied by fever, loss of appetite and/or lethargy. These patients are much more likely to have pneumonia and multiple-organ dysfunction.
After an equally-thorough physical exam, the next step is a chest X-ray, probably with multiple views. A ventro-dorsal (VD) or dorso-ventral (DV) view gives us the best look at the heart, but also includes the lungs and ribs. These views have the X-ray beam go from front-to-back or back-to-front, respectively. If heart disease such as heart murmur and congestive heart failure (CHF) are suspected, these views provide the most information.
One or two lateral views may be obtained. Having the dog or cat lie on its left side directs the beam from right-to-left. In some cases lung cancer is most readily identified if both lateral views are seen.
Because systemic signs are present in this more-greatly-affected patient, Complete Blood Count (CBC) and chemistry profile, along with urinalysis are in order.
Important findings on a CBC might include anemia, which could indicate blood loss or chronicity in the illness, and elevated White Blood Cell count, which indicates an inflammatory process in the body.
The chemistry profile could reveal effects on the liver, kidneys and/or electrolytes.
Sufficient information might be obtained from the radiograph of the chest to give a tentative diagnosis and allow the clinician to institute treatment.
In some cases even more tests may be required. A common procedure for a chronically coughing patient is
trans-tracheal wash or bronchial lavage. In this process an anesthetized patient has a tiny tube passed down the trachea toward the lungs. Depending on the nature of the case and findings on the chest X-ray, the tube may be stopped where the trachea splits to left and right branches, or directed to continue deeper, into the bronchi. Then, with a “washing” action we extract fluid, cells, infection, whatever is present, upward through the tube.
The resulting specimen will be divided into two aliquots, one for bacterial culture and sensitivity and the other for cytology.
Culture and sensitivity might tell us what organisms are growing in the respiratory tract, and how best to kill them.
Cytology might reveal body cells reacting to infection or hypersensitivity. It could show cancer cells, parasites or even be normal.
Some cases might require even more involved diagnostics such as fungal titer, echocardiography, ultrasound, endoscopy, lung biopsy, magnetic resonance imaging (MRI), computed tomography (CT scan) or even radioactive techniques. Usually these more advanced techniques are performed at referral centers.
