Nutritional therapy in the treatment of heart disease in dogs - Heart Disease in Dogs

Alternative Medicine Review,  Sept, 2001  by Robert S. Dove

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Abstract

A number of diseases affecting the heart are prevalent in canines. Acquired diseases, those which develop over the course of an animal's lifetime (rather than congenital defects present at birth), have recently been the subject of several studies to determine the efficacy of dietary supplementation on symptom presentation, disease severity, and mortality rates. Specifically, coenzyme Q10 (CoQ10), vitamin E (as alphatocopherol), L-carnitine, taurine, and fish oil (omega-3 fatty acids) have all been evaluated in the prevention and treatment of many types of heart disease in dogs. Other supplements with preliminary evidence, meriting further investigation, include magnesium, Crataegus, and the B vitamins. Both clinical observation and interventional trials with various breeds have provided clear evidence for the benefit of numerous supplements on canine heart disease. Appropriate levels of certain dietary nutrients have been shown to increase life span, improve life quality, reduce symptoms and physical evidence of disease, and decrease mortality rates in these animals. (Altern Med Rev 2001;6(Suppl):S38-S45)

Introduction

Decades of research on human cardiovascular disease and its successful treatment have provided insight into the relationship of certain dietary nutrients and their function in maintaining heart health. There is recent evidence suggesting these vitamins and micronutrients, both as adjuvant use and possibly as replacement for some traditional medications, also deserve attention in veterinary applications. (1) A review of the current literature and research studies provides a good basis from which to determine the usefulness of many cardioprotective compounds for animals. These compounds include the antioxidant vitamins such as E and the B complex vitamins, in addition to nutrients such as coenzyme Q10 (CoQ10), L-carnitine, taurine, magnesium, fish oil, and Crataegus extract. Investigation into the important role of nutrition in the pathogenesis and treatment of heart disease in dogs has provided new therapeutic options for the veterinarian and pet owner alike.

Types and Symptoms of Acquired Heart Disease in Dogs

Canine cardiovascular disease can involve one or more heart structures. There are a number of primary disease types for which nutritional supplementation is considered effective treatment. These include diseases of the heart valves (mitral regurgitation and valvular disease), ventricles (primary diastolic dysfunction), heart muscle tissue (cardiac hypertrophy, dilated and restrictive cardiomyopathy, congestive heart failure), and those due to abnormal electrical activity (cardiac arrhythmias), ischemic and reperfusion damage, and non-fatal infarcts. Unless a specific disease state is designated, "heart disease" will be used throughout this article to refer to a generic state of acquired heart dysfunction leading to compromised health.

Heart failure is the state wherein the heart cannot meet the metabolic needs of the body's tissues. This usually occurs in the presence of elevated left ventricular pressures at end diastole. Heart failure may occur in conditions where the heart is producing a normal cardiac output, but is still insufficient to meet the metabolic needs of the dog due to increased tissue requirements, such as in states of anemia. In these instances, heart disease can occur secondary to conditions where the strength of the heart muscle appears normal. However, most conditions that result in heart failure occur as a result of a significantly weakened left or right ventricle, or both.

Congestive heart failure occurs when the volume of blood introduced into the heart is in excess of the heart's capacity to pump it back out to the body. If this inability is due to left ventricle dysfunction, it typically results in elevated pulmonary venous pressures and pulmonary congestion leading to edema as fluid builds up behind the heart. This can lead to pleural and abdominal effusion. If the impairment exists in the right ventricle or the pulmonary arteries, congestion occurs behind the right heart (causing pleural effusion and/ or ascites). Many, but not all, cases of heart failure include congestive heart failure.

In some dogs, no evidence of illness is apparent, especially in the early stages of heart disease. However, signs of left-sided congestive heart failure (fluid accumulation in the lung or pulmonary edema) are often present. These signs can include lethargy, decreased activity level or exercise ability, dyspnea, wheezing, cough, and orthopnea. Abrupt weakness, collapsing episodes, and even sudden death due to disturbances in heart rhythm can also occur. The development of left- and right-sided congestive heart failure with ascites can create greater respiratory effort and cause abdominal distention. Once fluid accumulations have occurred, clinical heart failure is present and intervention must be taken.

Cause and Prevalence of Acquired Heart Disease in Dogs

According to information disseminated by the American Veterinary Medical Association, one in ten dogs has heart disease. (2) While some animals have a genetic predisposition toward the development of heart disease, many develop degenerative heart conditions as a result of multiple dietary factors, including nutritional deficiencies, obesity, or cachexia. The pathology of one of the most commonly investigated canine cardiac diseases, idiopathic dilated cardiomyopathy, characterized by left ventricular dilation and systolic dysfunction, may have a direct correlation to deficiencies of taurine and L-carnitine in many breeds. (3-4) Similar findings reveal a relationship between the development of congestive heart failure and inadequate levels of CoQ 10. (5)