6.Corpulmonale 6. Cor pulmonale

Cor pulmonale is right heart disease secondary to pulmonary vascular or parenchymal disease. It is common in brachycephalic dogs with chronic airway obstruction due to stenosis of the nares, or collapse of the trachea or bronchi, or chronic bronchitis.


Aetiopathogenesis

Several causes have been described:


(1) Primary lung disease. In geriatric dogs the most common cause is chronic obstructive pulmonary disease (which includes bronchitis and emphysema).
(2) Pulmonary vascular obstruction due to heartworm, thromboembolism, or compression by neoplastic or other masses.
(3) Obesity restricting chest wall movement resulting in poor inspiration and hypoxaemia (Pickwickian-syndrome).
(4) Thoracic deformity such as pectus excavatum.


Pathophysiology

Pulmonary arterial hypertension leads to right-sided cardiac enlargement, with myocardial hypertrophy progressing to right ventricular failure.


Clinical findings

Onset may be acute or chronic. Severe cases may present with air hunger and abdominal breathing, cyanosis or sudden death; milder cases with anorexia, weakness, depression, wheezing, dyspnoea, panting, coughing, signs of right-sided congestive heart failure.

It is a diagnostic challenge to differentiate between a chronic cough caused by atrial compression or a mainstem bronchus, and a cough caused by chronic obstructive pulmonary disease, particularly in geriatric patients as both conditions frequently occur together. Nevertheless correct diagis essential if treatment is to prove successful.

Auscultation may reveal abnormal lung sounds depending upon the amount of fluid secretion. Heart sounds may be normal, or there may be a split second sound, and sometimes there is a murmur caused by tricuspid insufficiency.