Dilated Cardiomyopathy

CARDIOLOGY ()Map CARDIOVASCULAR CONDITIONS (Map)

a.k.a. Congestive Cardiomyopathy

• Common in dogs

• Rare in cats (with adequate taurine supplementation)

Signalment

Dog: Giant and Large Breeds (e.g. Dobermann pinscher, Boxer, Great Dane); Male>Female; Risk increases with age

Cat: Greatest risk in: Siamese, Burmese, Abyssinian; Male>Female; Middle Age & Old Age

Description

• Dilated cardiomyopathy (DCM) occurs when there is a progressive reduction in systolic myocardial contractility. Decreased myocardial contractility affects the removal of blood from the ventricle at systole. A larger volume of blood increases the end diastolic pressures causing dilation of the ventricle and the development of eccentric hypertrophy.

Diagnosis

History & Clinical Signs

-Asymptomatic (Occult) DCM: See in predisposed breeds (e.g. Doberman pinschers)

-Right-Sided Congestive Heart Failure Signs

• Giant Breeds usually prone to these

-Left-Sided Congestive Heart Failure Signs

• Boxers and Doberman pinschers have a higher risk

-Syncope

-Weight Loss

-Dyspnoea

-Lethargy

-Weakness

-Hindlimb Paresis (cats with saddle thrombi)

Physical Exam

-Systolic Murmur

-Gallop Rhythm

-S3 Heart Sound (+/-)

-Arrhythmias

-Pulse Deficits

-Pulmonary crackles

Laboratory Findings

-Azotemia

-Elevated Liver Enzymes (+ Liver Congestion)

-Signs of congestive heart failure

-Signs of thromboembolism (cats)

-Plasma taurine reduction (cats)

Radiography

-Left Ventricular Hypertrophy (Seen in Dobermans & Boxers)

-Left Atrial Enlargement (Seen in Dobermans & Boxers)

-Generalized Cardiomegaly (Seen in Giant Breeds)

-Left-Sided Congestive Heart Failure signs (pulmonary congestion & edema)

-Right-Sided Congestive Heart Failure signs (pleural effusion, ascites)

Electrocardiography (ECG)

-Rhythm Disturbances (e.g. Atrial fibrillation (Giant Breeds); Ventricular Arrhythmias (Doberman pinchers, Boxers))

-Conduction Disturbances

-Characteristic signs of hypertrophy

Echocardiography

-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

-Mitral regurgitation

Treatment

-Treat congestive heart failure (Reduce Preload & Afterload; Improve Systolic Function; Control Cardiac Arrhythmias)

-Therapeutic thoracocentesis (To remove pleural effusion) (cats)

-Taurine Supplementation (cats)

Prognosis

Dogs

-Poor: Most breeds survive 6-12 months

-Grave: Dobermans and Boxers

Cats

-Good: When cardiomyopathy results from taurine deficiency

-Grave: Other causes of cardiomyopathy