Cor Pulmonale in Dogs and Cats: Symptoms, Treatment, and Prevention

1 Symptoms

Cor pulmonale is heart disease caused by disease of the lung tissue, chest wall, or pulmonary arteries, which raises pulmonary arterial pressure, overloads the right side of the heart, thickens the right ventricle, and can end in right-heart failure. It is divided into acute and chronic forms.

Acute cor pulmonale can result from caval syndrome caused by heartworm. Chronic forms arise from chronic heartworm infection, emphysema, chronic bronchitis, interstitial pneumonia, or chest-wall and spinal deformities.

Before the heart fails, dogs and cats cough, breathe with effort using the abdominal muscles, stretch the head and neck forward, and splay the front legs. A loud second heart sound is heard. In decompensation, swelling, ascites, pleural fluid, and an enlarged liver appear.

2 Causes and Transmission

The root problem is sustained elevation of pulmonary vascular resistance. Lung and airway diseases (chronic heartworm, emphysema, chronic bronchitis, interstitial pneumonia, bronchiectasis), chest-wall motion disorders (muscle or skeletal abnormalities, spinal curvature), and pulmonary vascular disease (including lung tumors) all contribute.

Heartworm-associated cor pulmonale is transmitted by mosquitoes carrying Dirofilaria immitis, so parasite prevention is central to avoidance.

3 Diagnosis

A history of chronic respiratory or chest-wall disease with signs of right-heart failure guides suspicion. Thoracic radiographs reveal an enlarged right heart and underlying lung changes, while echocardiography assesses right-ventricular size and pulmonary pressures.

Electrocardiography may show right-axis shift and arrhythmias, and heartworm testing plus bloodwork identify infectious or parasitic drivers. Cardiac biomarker testing supports the diagnosis.

4 Treatment

Treatment targets the primary lung disease, removes the underlying cause, protects the heart, and eases breathing. Veterinary-directed care may include sedation and cough suppressants, airway mucus modifiers, bronchodilators, and anti-inflammatory corticosteroids for reactive airways.

Loop diuretics relieve fluid overload, and when heartworm is the cause, appropriate antiparasitic (adulticide) therapy is begun carefully under veterinary supervision because dying worms can worsen obstruction. Oxygen and rest are essential during acute distress.

5 Prevention

Year-round heartworm prevention and regular parasite control remove a major cause. Managing chronic bronchitis, emphysema, and obesity reduces pulmonary strain.

Avoid exposing pets to cigarette smoke and poor air quality, keep them at a healthy weight, and seek early care for persistent cough or breathing difficulty so lung disease is treated before the heart is damaged.