Dilated Cardiomyopathy
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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