Dilated Cardiomyopathy

Also know as: DCM — Congestive Cardiomyopathy

Introduction

This disease is the most common form of cardiomyopathy in dogs.

Dilated cardiomyopathy (DCM) is characterized by progressive systolic dysfunction (loss of myocardial contractile function) and ventricular dilation (eccentric hypertrophy).

Signalment

Giant and large breeds (e.g. Doberman Pinscher, Irish Wolfhound and Great Dane) are most at risk.

Prevalence increases with age and the typical age at diagnosis is 6-8 years.

Male dogs are more frequently affected than females, particularly in Doberman Pinschers.

Clinical Signs

The natural history of the disease is described in two phases.

The asymptomatic (occult) phase is when no clinical signs are apparent, but there may be structural, functional or electrical abnormalities. These include increased left ventricular and left atrial internal diameter, reduced myocardial contractility and ventricular premature contractions. The duration of this occult phase is variable and can last from months to years.

The overt clinical phase is when clinical signs, such as congestive heart failure (CHF), syncope and exercise intolerance, develop. Arrhythmias are common in this stage.

Diagnosis

History and clinical signs suggest heart failure.

Physical examination will show presence of a systolic murmur, a gallop rhythm, S3 heart sound, arrhythmias, pulse deficits and pulmonary crackles.

Blood tests will show azotemia, elevated liver enzymes (+ liver congestion), signs of congestive heart failure, signs of thromboembolism (cats) and plasma taurine reduction (cats).

Radiography will show left ventricular hypertrophy (seen in Dobermans & Boxers), left atrial enlargement (seen in Dobermans & Boxers), generalised cardiomegaly (seen in giant breeds), left sided congestive heart failure signs e.g. pulmonary congestion & edema and right sided congestive heart failure signs e.g. pleural effusion and ascites.

Electrocardiography (ECG) will show rhythm disturbances e.g. atrial fibrillation (giant breeds), ventricular arrhythmias (Doberman Pinchers, Boxers), conduction disturbances and characteristic signs of hypertrophy.

Echocardiography will show a hypokinetic left ventricle (i.e. reduced fractional shortening therefore reduced contractility), reduced ejection fraction (i.e. % end diastolic volume ejected at systole), decreased ventricular wall thickness, left atrial enlargement and mitral regurgitation.

Treatment and Control

Treat congestive heart failure (reduce preload & afterload; improve systolic function; control cardiac arrhythmias), therapeutic thoracocentesis (to remove pleural effusion in cats) and taurine supplementation (cats).

Prognosis

Dogs:

Poor: Most breeds survive 6-12 months and in Dobermans and Boxers the prognosis is grave.

Cats:

Good: When cardiomyopathy results from taurine deficiency, but grave in other causes of cardiomyopathy.

Dilated Cardiomyopathy Learning Resources
Vetstream To reach the Vetstream content, please select	Canis, Felis, Lapis or Equis
Flashcards Test your knowledge using flashcard type questions	Myocardial Pathology Flashcards

References

Ettinger, S.J. and Feldman, E. C. (2000) Textbook of Veterinary Internal Medicine Diseases of the Dog and Cat Volume 2 (Fifth Edition) W.B. Saunders Company

Ettinger, S.J, Feldman, E.C. (2005) Textbook of Veterinary Internal Medicine (6th edition, volume 2) W.B. Saunders Company

Fossum, T. W. et. al. (2007) Small Animal Surgery (Third Edition) Mosby Elsevier

WikiVet® Introduction - Help WikiVet - Report a Problem