Diet and Heart Disease

Heart disease is common in dogs and cats, especially in older animals. As many as 10 percent of all dogs can have heart disease. Until the 1980s little was known of any relationship between diet and heart disease. Since then some important nutrients have been documented as important in preventing several forms of heart disease. Also as has been known for years, nutrition is important in managing fluid retention caused by chronic heart failure.

Taurine and Heart Disease¹

Animals manufacture the amino acid taurine that is essential for normal structure and function of the retina, platelets and heart. With taurine deficiency, cats can develop feline taurine-deficient dilated cardiomyopathy. The problem can be suspected from physical examination and thoracic radiographs showing heart enlargement. The problem is diagnosed by low plasma taurine (less that 20 micromol/L). Normal plasma taurine ranges between 50 and 120 micromol/L. Dilated cardiomyopathy also affects some American Cocker Spaniels which have low plasma levels of both taurine and L-carnithine (see below). Heart disease in other animals may be related to deficiency of these nutrients.

Most animals make enough taurine that deficiency doesn't develop. Cats cannot make enough to meet their needs, however. Cats depend on dietary taurine to supply adequate amounts. Diets containing animal proteins usually provide cats with enough taurine. There are some exceptions. Animal proteins in cheese and eggs contain little or no taurine. Cats cannot be fed these proteins unless they are supplemented with taurine. Plants also do not manufacture taurine so plant proteins in tofu or other soy products, beans, and cereals cannot be fed without added taurine supplements. Plant-produced proteins can be fed to dogs because they produce taurine from other amino acids. Taurine unlike other amino acids is not incorporated in protein structure but is free in body fluids. Meat processing that results in loss of its juices causes loss of taurine. Feeding processed nutrients can cause taurine deficiency in cats.

Feline taurine-deficient dilated cardiomyopathy was not recognized before cats were fed commercial pet foods. Cats living primarily on a carnivorous diet do not develop the problem; they consume enough taurine. Since the pet food industry recognized that taurine deficiency was a cause of medical problems, cat foods were supplemented with taurine. The first problem recognized was blindness caused by retinal degeneration. Addition of taurine to the diet solved that problem. Not enough taurine was added to prevent cardiomyopathies, however. With the recognition that heart problems were caused by taurine deficiency, more taurine was added to cat diets. Dry foods need high taurine, 1000 to 1200 mg taurine/kg dry weight. Canned foods need twice this amount to maintain normal taurine in body tissues. Cats with cardiomyopathy are treated with taurine, giving initial doses of 250 to 500 mg twice a day. If heart disease resolves, 6 to 12 weeks of therapy are required. (Other medications such as diuretics and vasodilators are also needed.) With improvement, taurine supplementation can be reduced to 250 mg daily. Recovered cats’ diets should always contain adequate taurine.

Despite awareness of problems caused by taurine deficiency, some cats may be fed inadequate taurine, especially if their diets contain primarily cereals or a single processed food. It is unknown if all commercial cat foods contain adequate taurine. All diets for feeding normal cats in website contain enough taurine. Vegetarian diets have taurine added in a powder or capsule form.

Carnitine and Heart Disease¹

Animals use lysine and methionine to synthesize L-carnitine. This compound is classified as a water-soluble vitamin or a nonessential amino acid. It is needed to transport free fatty acids into mitochondria of cardiac muscle. Carnitine is esterified with fatty acids to facilitate their movement across cell membranes. Inside mitochondria, oxidation of fatty acids generates energy in the form of ATP. Carnitine remaining after fat oxidation forms esters with potentially toxic waste products and transports them from mitochondria.

Carnitine deficiency is associated with heart problems in some Boxer, Doberman Pinscher and American Cocker Spaniel dogs with dilated cardiomyopathy. Some of these dogs improve and live longer with oral L-carnitine supplements. No one knows why some animals suffer from carnitine deficiency. It may result from inadequate dietary carnitine, lysine, or methionine or from intestinal malabsorption of these nutrients. Deficiency could also result from excess renal loss of these nutrients. Defective transport of carnitine esters across mitochondrial membranes could be a factor.

Carnitine deficiency is often difficult to diagnose. Dilated cardiomyopathy causes specific physical findings and radiographic changes. They do not prove carnitine deficiency, however. Plasma carnitine can be measured but that can be normal and not necessarily reflect carnitine levels in cardiac muscle. Up to 80 percent of dogs with carnitine deficiency in cardiac muscle have normal or increased plasma carnitine concentrations. Deficiency is proven only by measuring carnitine in cardiac muscle biopsies.Carnitine deficiency is treated with L-carnitine given orally at a dose of 2 grams mixed with food three times a day. This treatment appears to have few adverse side-effects. With success, appetite and activity improve after 1 to 4 weeks of therapy. Carnitine supplementation increases its level in heart muscle in most, but not all, dogs.Dilated cardiomyopathy caused by carnitine deficiency may be prevented by feeding diets high in carnitine. Carnitine is most abundant in red meat and dairy products. Feeding non-meat based commercial pet food results in dogs having plasma carnitine levels 50 percent lower than those consuming meat-based diets. Thus, although dogs are said not to be strictly carnivores and they can be fed vegetarian diets, feeding the cereal-based commercial dog foods is not likely to support adequate carnitine levels in heart muscle. Furthermore, heat may inactivate carnitine, something possible during processing of commercial dog food. Dilated cardiac myopathy caused by carnitine deficiency is prevented and treated best by feeding foods high in L-carnitine. The meat- and dairy product-based diets in this website provide dogs with abundant carnitine.

Hypertension, Sodium, Potassium, Magnesium and Heart Disease¹

Although hypertension is a circulatory problem, it is usually caused by renal rather than heart disease in dogs and cats. The renal causes and their management are described in the section on renal disease. Feeding low sodium diets is an important part of management. Because renal disease impairs all kidney functions, dietary intake of other salts must also be restricted.

Sodium Content of Foods mg/110 grams food
Foods from plants	mg sodium	Foods from animals	mg sodium
Barley (pearled)	3	Beef hamburger	200
Rice (white)	3	Beef chuck	104
Farina	2	Chicken, light meat	190
Wheat	2	Chicken, dark meat	255
Oatmeal	5	Cottage cheese	1,055
Baked breads	500-1000	Egg yolk	51
Potatoes (sweet)	28	Egg, whole	311
Corn flakes	1,045	Beef kidney	730
Crackers	1,100	Beef liver	453
Pretzels	1,361	Beef heart	382
Squash	trace	Bacon and ham	1,100-1,800
Soybean (tofu)	7	Frankfurter	2,477
Corn meal	1	Cheese (processed)	1,890
Potatoes (white)	5	Canned beef stew	2,349

Source: Morris (1995)

Recipes for this management are found in the section on renal disease.

Congestive heart failure develops when the heart no longer sustains normal circulation. Compensatory mechanisms attempt to restore normal circulation. The mechanisms attempt to maintain blood pressure, fluid volume, sodium concentration, delivery of oxygen and nutrients, removal of carbon dioxide and other waste products as well as delivery of regulating agents and hormones. Circulating blood volume depends on total body sodium which determines extracellular fluid. Regulation to maintian normal body sodium is lost with congestive heart failure and also with some heart disease that is not causing clinical signs. Renal sodium excretion is reduced below normal and sodium is retained, resulting in water retention. Clinical signs are not apparent in early cases. Ascites and edema appear in severe retention. Pulmonary edema can develop and cause respiratory failure.

Sodium retention is managed by feeding a low sodium diet, beginning before signs of congestive heart failure appear. Low sodium diets are usually effective. When dietary management begins after clinical signs appear, improvement may not be evident without other treatment such as diuretics. Diuretics can cause loss of enough sodium to produce hyponatremia which can result in neurological signs. Low sodium diet should be tried first and diuretics should be used only when dietary management alone fails.

Potassium depletion is common in patients with heart disease. Potassium deficiency follows because poor appetite reduces intake and diuretics, hyperaldosteronism and persistent chloride depletion increase renal loss. Very low sodium diets stimulate aldosterone release to conserve sodium, but aldosterone stimulates renal potassium excretion. Potassium losses are reflected by hypokalemia but they can be predicted even when plasma potassium levels are normal. Hypokalemia increases toxicity to drugs such as cardiac glycosides. Also hypokalemia reduces efficacy of some of anti-arrhythmic drugs. Unless plasma electrolyte measurements show hyperkalemia, animals with heart disease should receive higher than NRC recommended dietary levels of potassium.<span class="style18">

Magnesium depletion is often unrecognized in animals with heart disease. The causes include reduced intake and increased renal loss due to diuretics or chronic use of other drugs that promote renal magnesium excretion. Cardiac glycosides promote renal wasting of magnesium. Magnesium like potassium is largely intracellular. Plasma magnesium concentrations accounting for only one percent of total magnesium do not reflect body stores. Magnesium depletion is difficult to prove by plasma levels. Muscle biopsy magnesium measurement reliably reflect total body amounts. Low normal plasma magnesium during cardiac glycoside and diuretic therapy justifies magnesium replacement therapy.

Cardiac Cachexia¹

Cardiac cachexia is loss of body fat and skeletal muscle with chronic congestive heart failure. Its causes include reduced appetite, poorer assimilation of food, increased energy expenditure and drugs for treating heart disease and its complications. Animals with chronic congestive heart failure often become anorectic for reasons poorly understood. Anorexia is worsened by unpalatable diets. Severe sodium and protein restriction can reduce food intake. Appetite can be normal but malabsorption of nutrients can be great enough to cause weight loss. Congestive heart failure causes hypertension in intestinal capillaries, veins and lymphatics. In addition to reducing nutrient absorption, hypertension causes plasma and lymph fluid loss into the intestine. This protein-losing enteropathy results in protein depletion as well as other substances lost in plasma. Metabolic rates increase with chronic congestive heart failure. Increased energy is needed to support greater efforts to sustain respiration and circulation. Drugs commonly used to chronic congestive heart failure, such as cardiac glycosides, can reduce appetite, cause vomiting and impair intestinal absorption. Diuretics can cause electrolyte imbalances which can affect appetite and intestinal absorption.

Ideal Diets for Dogs and Cats with Chronic Heart Disease¹

Diets for management of heart disease must contain normal amounts of taurine and L-carnitine. Beef-based diets provide more L-carnitine than chicken-based diets. Both beef and chicken provide taurine. Sodium-restricted diets must be used with sodium and fluid retention, hypertension or congestive heart failure. Potassium supplementation is necessary with suspected or proven potassium depletion. With increased plasma potassium, dietary potassium should be low. Magnesium is often lost so dietary magnesium should be higher than usual. Diets should be highly palatable. Vitamin B₁₂ should be given by tablet several times a month or by feeding a food such as sardines that contains abundant amounts.

Dietary Management of Chronic Heart Disease in Dogs

Beef, Potato and Chicken Fat Diet
Normal Protein, Minimum Sodium, High Potassium, High fat

8 ounces (raw weight) lean ground beef, cooked (228 grams)
3 cups potatoes boiled in skin (369 grams)
1 tablespoon chicken fat (14 grams)
2/3 teaspoon bone meal powder (4 grams)
1/5 tablet B complex vitamin-trace mineral (made for humans)

provides 909 kcalories, 47.8 g protein, 37.9 g fat
supports caloric needs of 31 pound dog
provides sodium 105 percent, potassium 254 percent, magnesium 212 percent of dog's needs

Beef and Potato Diet
Normal Protein, Minimum Sodium, High Potassium, Lower Fat

8 ounces (raw weight) lean ground beef, cooked (228 grams)
3 cups potatoes boiled in skin (369 grams)
2/3 teaspoon bone meal powder (4 grams)
1/5 tablet B complex vitamin-trace mineral (made for humans)

provides 792 kcalories, 47.8 g protein, 24.9 g fat
supports caloric needs of 31 pound dog
provides sodium 112 percent, potassium 262 percent, magnesium 229 percent of dog's needs

Chicken, Potato and Chicken Fat Diet
Normal Protein, Minimum Sodium, High Potassium, Low Fat

1 cup cooked chicken breast (285 grams)
3 cups potatoes boiled in skin (369 grams)
1 tablespoon chicken fat (14 grams)
2/3 teaspoon bone meal powder (4 grams)
1/5 tablet B complex vitamin-trace mineral (made for humans)

provides 735 kcalories, 49.3 g protein, 17.8 g fat
supports caloric needs of 23 to 24 pound dog
provides sodium 111 percent, potassium 267 percent, magnesium 244 percent of dog's needs

Beef, Rice and Chicken Fat Diet
Normal Protein, Minimum Sodium, Low Potassium, High fat

8 ounces (raw weight) lean ground beef, cooked (228 grams)
2 cups cooked rice, white polished, long-grain (320 grams)
1 tablespoon chicken fat (14 grams)
1/2 teaspoon bone meal powder (3 grams)
1/5 tablet B complex vitamin-trace mineral (made for humans)

provides 913 kcalories, 47.6 g protein, 37.3 g fat
supports caloric needs of 31 pound dog
provides sodium 94 percent, potassium 61 percent, magnesium 135 percent of dog's needs

Beef and Rice Diet
Normal Protein, Minimum Sodium, Low Potassium, Low fat

8 ounces (raw weight) lean ground beef, cooked (228 grams)
2 cups cooked rice, white polished, long-grain (320 grams)
1/2 teaspoon bone meal powder (3 grams)
1/5 tablet B complex vitamin-trace mineral (made for humans)

provides 796 kcalories, 47.6 g protein, 25.3 g fat
supports caloric needs of 26 pound dog
provides sodium 101 percent, potassium 65 percent, magnesium 146 percent of dog's needs

Chicken, Rice and Chicken Fat Diet
Normal Protein, Minimum Sodium, Low Potassium, Moderate Fat

1 cup cooked chicken breast (285 grams)
2 cups cooked rice, white polished, long-grain (320 grams)
1 tablespoon chicken fat (14 grams)
1/2 teaspoon bone meal powder (3 grams)
1 multiple vitamin mineral tablet

provides 739 kcalories, 49.5 g protein, 18 g fat
supports caloric needs of 23 to 24 pound dog
provides sodium 103 percent, potassium 65 percent, magnesium 159 percent of dog's needs
add salt substitute (potassium chloride, 1/4 teaspoon) to bring potassium to 136 percent of needs

Chicken and Rice Diet
Normal Protein, Minimum Sodium, Low Potassium, Low Fat

1 cup cooked chicken breast (285 grams)
2 cups cooked rice, white polished, long-grain (320 grams)
1/2 teaspoon bone meal powder (3 grams)
1 multiple vitamin mineral tablet

provides 624 kcalories, 49.5 g protein, 5.25 g fat
supports caloric needs of 26 pound dog
provides sodium 103 percent, potassium 56 percent, magnesium 173 percent of dog's needs
add salt substitute (potassium chloride, 1/4 teaspoon) to bring potassium to 147 percent of need

Dietary Management of Chronic Heart Disease in Cats

Beef, Rice, Clams and Chicken Fat Diet
Normal Protein, Normal Potassium, Minimum Sodium

8 ounces (raw weight) lean ground beef, cooked (228 grams)
1/2 cup cooked rice, white polished, long-grain (80 grams)
1 ounce clams, chopped in juice (28.5 grams)
1/2 tablespoon chicken fat (7 grams)
1/4 teaspoon bone meal powder (1.5 grams)
1/2 calcium carbonate tablet (calcium 200 mg)
1 multiple vitamin mineral tablet

provides 590 kcalories, 48.7 g protein, 31.6 g fat
Use table on cat caloric requirements to determine how much to feed
provides potassium 164 percent, sodium 276 percent, magnesium 167 percent of cat's daily needs

Beef, Clams and Chicken Fat Diet
Normal Protein, Normal Potassium, Moderate Sodium

8 ounces (raw weight) lean ground beef, cooked (228 grams)
1 ounce clams, chopped in juice (28.5 grams)
1/2 tablespoon chicken fat (7 grams)
1/4- teaspoon bone meal powder (1 grams)
1 calcium carbonate tablet (calcim 400 mg)
1 multiple vitamin mineral tablet

provides 487 kcalories, 46.6 g protein, 31.4 g fat
Use table on cat caloric requirements to determine how much to feed
provides potassium 202 percent, sodium 362 percent, magnesium 174 percentof cat's daily needs

Chicken, Rice, Clams and Chicken Fat Diet
Normal Protein, Normal Potassium, Moderate Sodium

1 cup cooked chicken breast (285 grams)
1/2 cup cooked rice, white polished, long-grain (80 grams)
1 ounce clams, chopped in juice (28.5 grams)
1 tablespoon chicken fat (14 grams)
1/4- teaspoon bone meal powder (1 grams)
1 calcium carbonate tablet (calcium 400 mg)
1 multiple vitamin mineral tablet

provides 475 kcalories, 50.2 g protein, 18.1 g fat
Use table on cat caloric requirements to determine how much to feed
provides potassium 150 percent, sodium 308 percent magnesium 203 percent of cat's daily needs

Chicken, Clams and Chicken Fat Diet
Normal Protein, Normal Potassium, Moderate Sodium

1 cup cooked chicken breast (285 grams)
1 ounce clams, chopped in juice (28.5 grams)
1 tablespoon chicken fat(14grams)
1/4- teaspoon bone meal powder (1 grams)
1 calcium carbonate tablet (calcium 400 mg)
1 multiple vitamin mineral tablet

provides 372 kcalories, 48.1 g protein, 17.9 g fat
Use table on cat caloric requirements to determine how much to feed
provides potassium 189 percent, sodium 409 percent, magnesium 232 percentof cat's daily needs

Tuna, Rice and Clams Diet
Normal Protein, Normal Potassium, Minimum Sodium

5 1/2 ounces tuna, canned in water (low sodium) (157 grams)
1 ounce clams, chopped in juice (28.5 grams)
1/2 cup cooked rice, white polished, long-grain (80 grams)
1 tablespoon chicken fat (14 grams)
1/4- teaspoon bone meal powder (1 grams)
1 calcium carbonate tablet (calcium 400 mg)
1 multiple vitamin mineral tablet

provides 431 kcalories, 46.4 g protein, 16.6 g fat
Use table on cat caloric requirements to determine how much to feed
provides potassium 149 percent, sodium low depending on content in tuna fish, magnesium 605 percent of cat's daily needs

Tuna and Clams Diet
Normal Protein, Normal Potassium, Minimum Sodium

5 1/2 ounces tuna, canned in water (low sodium) (157 grams)
1 ounce clams, chopped in juice (28.5 grams)
1 tablespoon chicken fat (14 grams)
1 calcium carbonate tablet (calcium 400 mg)
1 multiple vitamin mineral tablet

provides 328 kcalories, 44.3 g protein, 16.4 g fat
Use table on cat caloric requirements to determine how much to feed
provides potassium 200 percent, sodium low depending on content in tuna fish, magnesium 808 percent of cat's daily needs

References

1. Stepien, Rebecca L. and Matthew W. Miller. 1994. Cardiovascular Disease. In The Waltham Book of Clinical Nutrition of the Dog and Cat. edited by J. M. Wills and K. W. Simpson, 353-371. Oxford: Pergamon Press.

2. Morris, James G. 1995. Nutrition and Nutritional Diseases in Animals. 10-1 to 10-27. Class Notes for Veterinary Medicine 408, School of Veterinary Medicine, University of California, Davis.