Listed below are several of the more prevalent cardiac diseases of cats and dogs. This is article is intended to be used as a summary of some of the common cardiac diseases. The article was not written by a cardiologist and is for general knowledge only. Please consult with your veterinarian for any cardiac conditions diagnosed.

The heart is a muscular organ consisting of four chambers- a right and left atrium and right and left ventricles. Valves are located between the atrium ,ventricles, and the two major vessels leading to the heart to prevent blood from flowing abnormally. Blood is circulated through the body by the pumping action of the heart. Deviations in the size of the chambers, or strength or elasticity of the muscle, or disease of the valves, will affect the flow of blood in the body and subsequently the dynamics of all the organs in the body. Once the heart begins to malfunction a vicious cycle develops and abnormal fluid build-up begins in different areas of the body depending on which side and part of the heart are involved. Thus, congestive heart failure develops.

Cardiomyopathy in cats

Dilated cardiomyopathy is a disease of the ventricular muscle, characterized by a loss of muscle tone of the heart. The heart loses its strength and tone and becomes enlarged, filled with blood and unable to contract properly. Before the mid 1980’s this was one of the most commonly diagnosed heart diseases of cats. Most cats probably had secondary cardiomyopathy as a result of taurine deficiency. Due to changes in diet formulation, this is now an uncommon cause of heart disease in cats. There may also be a genetic component in Siamese, Abyssinian, and Burmese cats.

Clinical signs are related to low cardiac output: loss of appetite, weakness, depression, difficulty breathing, and thromboemboli causing painful paralysis.

Diagnosis is made by x-ray and ultrasound. Ultrasound is the definitive diagnostic tool.

Treatment is that of congestive heart failure, with the use of digoxin, diuretics such as furosamide, and supplementation of taurine. Prognosis is poor despite intensive therapy.

Hypertrophic cardiomyopathy:

Hypertrophic cardiomyopathy is a thickening of the heart muscles causing a decrease in the size of the chambers of the heart. As a result, the heart cannot supply the body the amount of blood it needs due to the decreased volume of blood in the chambers. Hypertension develops and pulmonary edema (fluid in the lungs) develop. Congestive heart failure, thromboemboli, and abnormal heartbeats (arrythmias) develop.

Clinical signs include difficulty breathing, loss of appetite, exercise intolerance, vomiting, collapse, or sudden death, . In the early stages the physical exam is normal. We have observed sudden death in some kittens and cats during routine anesthetic induction. Post mortum exam reveals cardiomyopathy as the cause of death. This is similar to the sudden death seen in some young athletes.

Physical signs seen during exams in cats with more developed cardiomyopathy include an abnormal heart- beat, murmur, muffled heart sounds, rapid heart sounds, difficulty breathing, weakened pulses, and early stages of hypertension.

Differential diagnosis includes that of hyperthyroidism, valvular disease, hypertension, trauma, feline asthma, and cancer of the chest.

Diagnosis is based upon x-ray and, most importantly, ultrasound.

Treatment is palliative. In people, heart transplant is the treatment of choice. In cats, we treat with low sodium diets, medications to treat congestive heart failure such as diltiazem, or atenelol, and aspirin to prevent blood clots. Diuretics may also be used. Low salt diets may be used, but palability may be an issue. The prognosis varies from good to poor depending upon the severity of the disease.

Restrictive cardiomyopathy of cats:

This is a poorly defined heart disease involving selected areas of the ventricles of the heart. Scarring of the heart muscle results in both contraction and relaxation difficulties of the heart leading to congestive heart failure. Cats with restrictive cardiomyopathy have clinical and functional signs similar to both of the other forms of cardiomyopathy. Dilatation of all cardiac chambers may be evident.

Signs are those of congestive heart failure-poor appetite, weight loss, difficulty breathing, blood clots and paralysis of the limbs.

Differential diagnosis is that of hypertrophic cardiomyopathy, dilated cardiomyopathy, hyperthyroidism and hypertension .

Diagnosis is confirmed by xray-disproportionate atrial enlargement, abnormal lung shadows, and ultrasound. Ultrasound might show an abnormal right atrial enlargement and other changes too complex to discuss on this handout.

Treatment includes diuretics, nitroglycerine application, calcium channel blockers,such as diltiziam, and possible use of beta blockers, such as atenelol. The diuretic furosamide may also be recommended as well as low dose aspirin. Low salt diets are recommended, but as stated above palatability may be an issue.

Most cats with restrictive cardiomyopathy live for 3-12 mos.