Page 159 - Problem-Based Feline Medicine

9 – THE CAT WITH ABNORMAL HEART SOUNDS AND/OR AN ENLARGED HEART 151

● Blalock–Taussig shunt can be recommended (artifi- In cats fed commercially available feline diets, DCM is
cial shunt from the left subclavian artery to the pul- a rare form of cardiomyopathy.
monary artery). This increases blood flow through
All cardiac chambers are dilated. Atrophy of papil-
the pulmonary circulation.
lary muscles is present.
● Other modified techniques have been described.
Consult with an experienced surgeon. Myocardial sections on post-mortem show patchy
white areas. Microscopically there is myocyte atrophy
Prognosis with interstitial fibrosis.

Most cats can reach middle age and some even have The hemodynamic hallmark is severe systolic dys-
a normal lifespan. function.

Long-term prognosis depends on the severity of blood
flow. Clinical signs
There is no age or sex predilection.
DILATED CARDIOMYOPATHY
Usually cats with dilated cardiomyopathy have a his-
tory of being fed a non-commercial diet, or dog food.
Classical signs
A heart murmur is often present, but in some cases may
● Heart murmur (in some cases may not be
not be. When present, a systolic murmur varies in loca-
present).
tion and intensity with variations in heart rate.
● Gallop rhythm.
● Arrhythmia. Gallop rhythm is commonly heard. It is identified when
● Dyspnea. more than two heart sounds are present on auscultation.
● Hypothermia.
Arrhythmias can be heard as premature heart beats with
● Collapse.
pulse deficits.
● Lameness, paralysis or paresis from
systemic thromboembolism. Dyspnea is seen in symptomatic cats with an increased
respiratory rate (greater than 30 breaths/ min) at rest or
with open-mouth breathing in extreme cases. Pleural effu-
Pathogenesis
sion may be present and result in muffled heart sounds.
This disease in most cats is due to a deficiency in tau-
In symptomatic cats, hypothermia is common.
rine concentration. Taurine supplementation in com-
mercially available diets has reduced significantly its Collapse may result from impaired cardiac output (ven-
incidence. tricular tachycardia)
Any cat fed a non-commercial diet should have tau- Lameness, paralysis or paresis are usually the result of
rine supplementation. Cats fed home-made vegetarian systemic thromboembolism.
diets are at high risk of taurine deficiency. However,
Most cats with aortic saddle thrombosis present for
not all cats experimentally fed a taurine-deficient diet
acute onset of hindlimb paralysis, pain, absent femoral
have developed dilated cardiomyopathy.
pulses, cool extremities and cyanosis of the nail bed. In
Dilated cardiomyopathy (DCM) is not always the some cases a history of episodic lameness is given.
result of taurine deficiency. Currently most of the
Ascites is found in a small minority of cases.
cases are idiopathic.
Retinal degeneration changes consistent with taurine
Diagnosis
deficiency are present in 33% of cats.
Other potential causes for DCM include a late expres- Radiographic findings
sion of chronic myocarditis, genetic abnormalities, and Severe generalized cardiomegaly and enlarged pul-
in some cats, the cause is unknown. monary veins are seen. Pulmonary edema with or without