The cough is one of the most powerful reflexes in the body and serves as both a protective and early warning system for the pharynx and respiratory system. Disease of any part of the respiratory system (nasopharynx, larynx, trachea, bronchi, lungs, pulmonary vessels) or surrounding structures (esophagus, pleura or heart) can result in a cough but some of the more common causes in this region are;
Tick toxin paralyses the larynx and esophagus which can result in pooling of mucus, phlegm and vomitus in the oropharynx. Change in voice or a cough or vomit can precede the more classic hindlimb weakness so a good tick search for any new cough is advised.
Canine infectious respiratory complex encompasses a wide range of bacterial and viral infections. Affected dogs’ have a classic “goose honk” cough with a hack like expectoration at the end, sometimes accompanied by a small amount of clear, white or yellow tinged mucous. Unfortunately vaccination is not 100% protective.
Heartworm causes coughing by damage to the pulmonary vessels, lungs and eventual right sided congestive heart failure. The cough is often associated with rapid breathing and exercise intolerance. Milton Village Vet offers free heartworm tests year round for owners wanting to start yearly injections at the time of vaccination.
Congestive Heart Failure
Most dogs with this disease have left sided valvular heart disease and an audible murmur on chest auscultation. Recent studies have deemphasised the cardiac cough as a predictor of disease (ie murmur + cough does not always equal heart failure) with greater reliance on increases in sleeping respiratory rate, decreased exercise tolerance, ECG, radiographic and sonographic findings.
Small Airway Disease
Chronic bronchitis is more common in overweight middle to older aged dogs and apart from the cough these dogs can appear clinically normal. The cough is often long standing and frustratingly difficult to treat.
There are many, many more. The combination of a good history, physical exam, blood tests, x-rays and in unusual cases, sampling of actual cellular secretions via bronchoalveolar lavage helps us differentiate the various causes of a cough and allows appropriate and targeted treatment.