Feeding the Cardiac Patient
Heart disease most commonly results in abnormalities of physiology that require special dietary considerations. The American College of Veterinary Nutrition (ACVN) is comprised of a group of veterinarians with special training and certification in nutrition. Information on this page principally reiterates recommendations of those specialists. Veterinary Nutritionists (see web link) and pet food manufacturers are other potential sources of dietary information.
Click HERE to see the Tufts University School of Veterinary Medicine Heart Smart webpage for more information for pet owners about treating heart disease.
Click HERE for more information about reduced sodium diets and feeding pets with heart disease
Here are some diet lists / click to download
Compiled by Charity Callicoat / Cardiology Department, Medvet – Cincinnati
It's about the Salt!
Animals (including humans) with sufficiently severe heart disease lose the ability to adequately excrete sodium (salt) from the body. Severe heart disease causes a cascade of changes in kidney function and the central nervous system whereby sodium and water are retained. The increased blood volume acts to distend the heart and is one mechanism by which the system attempts to return heart function towards normal when heart disease exists. This system works well for short-term problems, such as blood loss or dehydration, but causes serious problems in the long run when heart disease is present. The increased distention of the veins eventually causes pressure to rise to a degree that literally forces fluid through the walls of the smallest blood vessels and into the surrounding tissues. This constitutes the condition known as "congestive heart failure" (CHF) and it is very serious! Part of the treatment of CHF involves restriction of sodium intake in the diet and it is of the utmost important that owners of pets with cardiac disease observed this restriction! Failure to do so can result in fluid accumulation in the lungs, difficulty breathing (human patients describe a sensation of drowning), a trip to the emergency room, or even death!
While it isn't the only issue, a large part of formulating a diet suitable for a heart patient revolves around the sodium content. The bottom line is that a dog or cat cannot be allowed to ingest excessive sodium, but must continue to ingest an appropriate amount of protein, calories, vitamins, and other nutrients. For this reason, nutritionists often prefer to express the sodium content of a diet in terms of milligrams (mg) per unit of caloric energy. When the patient ingests an appropriate amount of energy, it also takes in an appropriate amount of salt; this plan applies to many other nutrients as well. This ratio of sodium to caloric density works out roughly as follows:
A limited number of canine and feline diets (below) show their sodium content in terms of the above parameters. For other diets and treats, you may be able to determine if the diet is acceptable given the following 2 pieces of information:Unfortunately this desired information is not always readily available for all pet foods and it may be necessary for you to switch your pet to a higher-quality brand for which diet analysis data is available. We recommend manufacturers that engage in nutritional research, employ veterinary and nutritional experts, and publish diet analytical information of the type shown above. This turns out to entail a rather select group of manufacturers including Hill's, Iams/Eukanuba, Purina, Royal Canin (Mars), Innova (Iams), and Nutro (Mars).
1. % sodium in the diet on an AS FED basis.
2. kilocalories of metabolizable energy per kilogram (as fed) of the diet.
Divide item #1 by item #2 and multiply by 1000000 (1 million) to obtain the sodium content in milligrams (mg) per 100 kcal.
Hill's Prescription Diet, Canine Advanced Protection Adult diet:
Sodium percentage ( as fed ): 0.28%
Metabolizable Energy ( kcal/kg, as fed ): 3,794
0.28 ÷ 3794 x 1,000,000 = 73.8 (moderate sodium restriction)
This will also work if you have BOTH the sodium as a percentage of DRY MATTER AND the Metabolizable energy (kcal/kg) in terms of DRY MATTER; the calculation is the same including multiplying by 1,000,000 but DON'T mix dry mater and as fed information.
ALTERNATIVELY, (if there is insufficient information to perform the above calculation or you can't figure out how to do it) look specifically for the SODIUM CONTENT AS A PERCENTAGE OF DRY MATTER. An approximate guide to sodium content is as follows (for products with typical caloric density) :
If the manufacturer does not provide this information on the label, website, or by contacting them directly, then we cannot determine the sodium content either. Please do not ask us to track down this information for you.
Unless concurrent medical conditions dictate otherwise, we suggest mild sodium reduction for most middle age and older dogs and cats; this recommendation is flexible, however, after the full health profile is known. Our pets are like us: excessive sodium in the diet can predispose to hypertension ( high blood pressure ) which can result in serious damage to the heart, kidney, and eyes if severe enough. Elevated blood pressure increases the work of the heart and typically increases the amount of heart valve leakage, if any is present. Fortunately (for dogs and cats), our four-legged friends do not share our human predisposition for stroke or coronary artery disease that can be provoked by hypertension.
For animals with more severe heart disease, sodium restriction is a necessity. Moderate sodium restriction is recommended for pets with moderate heart disease ( with heart enlargement ), and marked sodium restriction for those with congestive heart failure. Animals with refractory congestive heart failure may require extreme sodium restriction to help maintain their comfort when symptoms cannot be well-controlled with medication and more moderate sodium restriction.
Why not just restrict sodium intake the same for all heart patients? Shouldn't we just minimize sodium intake for everybody? This is definitely not the case. For one thing, low sodium diets tend to be less palatable. We all know that a dash of salt tends to bring out the flavor in many of the things we like to eat. However restricting sodium unnecessarily actually provokes the body to conserve sodium to its utmost ability. Too little salt in the diet activates detrimental sodium conservation mechanisms – it's not a good thing!
Sodium restriction is not just about the diet but salt intake from ALL sources including treats, medications, and whatever the grandchildren or visitors might be using to bribe the family pet. If your dog or cat is a cardiac patient, everyone involved must understand that they are NOT being kind to give the wrong kinds of treats. In approximate terms, this comes down to an amount of allowable sodium per day FROM ALL SOURCES that should not be exceeded.
Scroll down to the bottom of the article for lists of low-sodium diets for dogs and cats.
But It's Not ONLY about the Salt
Dogs and cats with heart disease need to maintain adequate calorie intake with an appropriate distribution of calories from fat, carbohydrate, and protein. It's been determined that inadequate protein intake, or deficiencies of specific amino acids, can actually cause serious heart disease and the Cardiology Subspecialty of the ACVIM has recommended avoidance of protein restricted diets ( specifically for dogs with old-age heart valve disease ). While older dogs and cats do not need as much protein as do young, growing animals, certain diets are specially formulated to be quite restrictive in their protein content. Example diets to avoid include ones formulated for specific types of bladder stones, kidney disease, or liver disease. Diets formulated for otherwise healthy adult dogs usually contain more than 4-5 grams per 100 kcal of metabolizable energy at a minimum and greater amounts may be preferable; cats require more protein in the diet and adult diets usually contain more than 7-8 g/100 kcal at a minimum.
Calories and Cachexia
It's extremely important for cardiac patients to maintain a normal body weight. Excessive weight, in the form of body fat, places additional stress on the heart and in more than one way. Besides the additional work of the heart that's required for normal ambulation and exercise, excess fat causes an oxidative stress. Oxidative stress disrupts normal metabolism in many ways and impairs the ability of blood vessels to expand and deliver nutrients in a normal way. Hence part of the lack of exercise capacity in a cardiac patient is due to impairment of the blood vessels themselves! Current opinion is that modest exercise is beneficial for cardiac patients under most circumstances. It helps to maintain an appropriate weight level and also healthier blood vessels as well as improve overall health of the heart itself.
The flip side of this coin is equally important. Animals with more severe heart disease may begin a pathological sequence of weight loss. The reasons for this are multi-factorial. Cardiac patients typically are prescribed potent medications that can have a negative impact on appetite. These negative side effects are often highly dosage dependent so that adjustments in medications may be required. If your pet begins to lose appetite, it's very possible that medication dosages need adjustment; you should seek veterinary attention or advice for your pet as soon as practical in this situation! The first step in treating loss of appetite and a cardiac patient is to check for toxic effects of drugs.
The heart is quite important to the health of the entire body and inadequate heart function, as occurs with serious late stage heart disease, can result in a wide range of symptoms that would seem to suggest some other problem. Abdominal distention resulting from fluid accumulation in the abdomen can be a sign of serious heart disease. This may also be associated with gastrointestinal disturbances; congestion of the abdominal organs from poor heart function can seem to cause a wide range of ills that would not normally be associated with the heart. Unremitting weight loss, known as cardiac cachexia, often accompanies serious heart disease. This appears as loss of muscle mass that can make the patient appear to be all skin and bone in the most severe cases. The problem is not due to inadequate calorie intake alone but results from a cascade of biochemical abnormalities that instruct the tissues literally to self-destruct in a process called apoptosis (the second 'p' is silent in the pronunciation). The process is initiated by biochemicals known as cytokines that promote inflammation. Besides increased calorie intake, this process may require "nutritional pharmacology" as part of concurrent therapy.
Omega-3 polyunsaturated fatty acid, present in relatively high concentration in fish oil, is a direct means of combating cardiac cachexia and the biochemical pathways involved in apoptosis; supplementation can also improve appetite. The recommended daily dosage is ~ 65 mg per kilogram of body weight with an appropriate distribution of eicosapentanoic acid (EPA, 40mg/kg) and docosahexanoic acid (DHA, 25 mg/kg). Over-the-counter products are available at many human pharmacies (e.g. CVS 180mg EPA / 120mg DHA capsules, 1 capsule per 10 pounds body weight daily).
Taurine is an amino acid that is required in the diets of cats for normal heart and eye function; deficiency in either dogs or cats can clearly result in serious heart disease. Failure to supply adequate taurine in the diet can have disastrous effects on the heart! This fact was recognized in the 1980s and pet food manufacturers responded by supplementing diets with taurine where necessary. Nevertheless, we occasionally see pets with heart disease resulting from taurine deficiency even when feeding a diet that is adequately supplemented. When there is any question of this, we will recommend evaluating a blood taurine level and/or supplementation of the diet with taurine.
Below are a few recommendable reduced sodium diets for dogs and cats.
REDUCED SODIUM FOODS - CANINE
NOTE: Hill's h/d and Purina canine CV are not included on this list because of the very low protein content of these diets – avoid using them in dogs with cardiac disease except on recommendation of a veterinarian. Please note:
1. These lists are not exhaustive.
2. Don't assume that the canned and dry versions of a food will be similar in nutrient content.
3. Different flavors of the same food can be very different in nutrient content. If these lists specify a flavor, they refer to that flavor only.
4. These lists were updated Feb, 2008 by Lisa Freeman DVM, PhD Diplomate American College of Veterinary Nutrition. The nutrient content of diets can change very often so this will be out of date soon. Check with the manufacturers for up-to-date information frequently!
REDUCED SODIUM FOODS - FELINE
Treats and Home Cooking
(The following has been modified slightly from the work of Lisa Freeman DVM, PhD Diplomate American College of Veterinary Nutrition)
Many pet owners like to give treats as special favors to the furry members of the family. It's important to recognize for the cardiac patient which foods are appropriately low in salt and which are not:
ACCEPTABLE TREATS AND FOODS ( do not add salt ! )
- Rice ( plain white or brown rice, not flavored)
- Maple syrup
- Low-sodium cheese ( Look for the Heart Healthy labeling )
- Lean, home-cooked meats (chicken, turkey, beef, fish)
- Eggs, cooked
- Homemade soup
- Low-salt breakfast cereal. The label should read "this is a low-sodium food"
- Fresh vegetables/fruit ( carrots, green beans, apple, orange, banana)
FOODS TO AVOID!
- Fatty foods ( meat trimmings, milk, cream, ice cream, and other milk products)
- Baby food
- Pickled foods
- Bread, pizza
- Condiments (ketchup, soy sauce, barbecue sauce, etc.)
- Sandwich and deli meats/cold cuts ( ham, corn beef, salami, sausages, bacon, hot dogs)
- Most cheeses including squirtable and spreadable types ( unless specifically labeled as "low sodium" )
- Processed foods ( such as potato mixes, rice mixes, macaroni and cheese)
- Canned vegetables ( unless labeled "no salt added")
- Potato chips, packaged popcorn, crackers, and other snack foods
- Packaged soups ( unless labeled "low sodium")
- Most commercially available dog and cat treats!