You should seek the advice of your veterinarian if your pet is ill as only he or she can correctly advise on the diagnosis and recommend the treatment that is most appropriate for your pet.

A main differentiation to make is whether a cough is caused by respiratory disease or cardiac disease

A cough may be caused by respiratory or cardiac disease, and differentiating between the two is a main objective in making the diagnosis in coughing dogs. This can be  particularly difficult in older dogs when there may be chronic diseases of both systems present concurrently.

The following Table of the main features seen has been extensively modified after Atkins C et al Proceedings of the North American Veterinary Conference 2001 and may prove useful :

 

Sign	Respiratory Disease	Cardiac Disease	Comments
Cough	Made worse by exercise. Can be severe. Harsh, hacking dry cough seen in  main airway disease - trachea or bronchi. Honking - due to trachea collapse or foreign body obstruction Soft cough - lower airway disease eg bronchopneumonia or oedema	Worse when lying down (eg at night time) and during exercise. Usually a mild cough due to oedema.	In older dogs it's not uncommon to have chronic bronchitis present AND pulmonary oedema or compression of the main bronchi due to heart failure and cardiac enlargement.
Sputum	May bring up mucopurulent material	May cough up white or pink fluid	Often sputum that is coughed up is swallowed - so it may not be seen. Need to differentiate saliva from coughed up mucus
Dyspnoea	May or may not be present	Present when acute pulmonary oedema occurs, or in advanced heart failure	Acute pulmonary oedema occurs when chordae tendinae rupture
Lung sounds on auscultation	May be none, crackles or wheezing. Lack of normal sounds if lung collapsed or consolidated or if they are masked by the presence of intrathoracic fluid	May be none, crackles or wheezing
Heart murmur	May be present in old dogs with endocardiosis - even though it is not a contributory factor to the cough	Always present in cases with mitral valve regurgitation	Do not assume mitral regurgitation  is the cause of a cough. Look for other causes.
Heart Rate	Normal or slow	Increased usually
ECG examination	Normal cardiac rhythm. May have p-pulmonale or evidence of right ventricular enlargement	May be normal but usually tachycardia is present. May have left-sided enlargement or p-mitrale
Radiography	A variety of findings may be seen. Bronchial or interstitial pattern. Nodules in airways (eg Oslerus osleri) Airway collapse. Consolidation of lung, lung collapse. Radiodense masses (neoplasia). Foreign bodies may be detected.	Pulmonary oedema (alveolar pattern  and interstitial pattern -especially in the hilar region). Cardiac enlargement. Ventral displacement of intrathoracic trachea (due to enlarged left atrium). Increased vascular pattern (distended vessels) including vena cava.	If right-sided heart failure is present as well as left-sided failure : enlarged liver, ascites
Echocardiography	Normal cardiac size unless old dog with concurrent endocardiosis. Tricuspid regurgitation and pulmonary insufficiency - variable high velocity	Cardiac enlargement (left-sided) in mitral regurgitation. Distension of pulmonary veins.
Body weight	Normal or often obese.	Weight loss very common	Older animals may be thin due to a variety of concurrent factors/disorders
Haematology	Variable : inflammatory response especially if infection or allergy present	Usually normal.	Concurrent disease in older animals eg anaemia associated with renal failure.
Response to diuretics	Unreliable - usually unresponsive unless non-cardiogenic oedema or intrathoracic fluid present.	Responsive due to resolution of oedema, but not to atrial pressure on main bronchus

Updated January 2016