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Latest health and behavior news and advice from the veterinarians at Tufts University.

Features May 2015 Issue

Canine Diet for Heart Disease

When your dog’s heart begins to decline, certain nutrients take on special significance.

Last month we discussed the fact that because unlike people, dogs don’t get the kind of heart disease in which fatty deposits clog the arteries and hinder blood flow, the fat and fat-like substances in their diet are not a big heart disease issue. Instead, dogs’ heart disease tends to be in the form of faulty heart valves, which allows blood to leak backward rather than flow forward like it’s supposed to. Still, what a dog eats has a major impact on heart disease progression and symptoms. Herewith, the nutrients you need to be concerned about.

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It's important to feed a dog with heart disease a food with the right mix of ingredients.

Sodium. As we said last month, keeping down sodium consumption will control a dog’s blood pressure as well as reduce fluid build-up in those cases where heart disease has progressed to congestive heart failure and fluid builds up around the lungs or chest, making it harder to breathe.

While the condition is still moderate, sodium restriction should be moderate also. “If you go too low in sodium too fast,” says Cummings School veterinary nutritionist Deborah Linder, DVM, DACVN, “the body may actually rebound and make it worse.” That is, the dog may hold onto too much fluid in an effort to combat the sodium restriction.

Fortunately, moderate sodium restriction, not a bad idea for any dog, is easy to achieve with a number of over-the-counter foods produced by large, reputable companies. What’s tricky is that unlike with foods for people, sodium levels are not required to be listed on dog food labels. You can find out by talking with your vet or calling pet food manufacturing companies directly. (If a company can’t or won’t tell you, don’t buy their food; it could be a red flag about quality control.) You’re looking for no more than 100 milligrams of sodium per 100 calories of food. You might be surprised to learn that some dog foods contain as much as 600 milligrams of sodium per 100 calories.

You can also look on HeartSmart, the Cummings School of Veterinary Medicine’s website for owners of dogs with heart disease. The list was updated last October, but as it says right at the top, “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.” The list is at least a place to start, however, and the HeartSmart website — vet.tufts.edu/heartsmart — also contains information on symptoms, diagnostic tests, and treatments for heart disease along with nutrition information, at-home monitoring, and exercise.

As the heart disease becomes more severe, you will want to speak with your dog’s veterinarian about dropping to 80 milligrams of sodium per 100 calories of food, or even 50. Over-the-counter options are not as plentiful at that level, but they are certainly out there. You don’t have to start cooking up the dog’s meals at your stove.

“One hundred milligrams of sodium per 100 calories and then 80 milligrams or 50 milligrams per 100 calories are not hard and fast rules,” Dr. Linder says. “They’re based on our clinical experience here at Tufts. There need to be more studies to find out the exact numbers — but these are good general guidelines. They’re what we’ve seen works best.”

Protein. “There is not necessarily a specific number of grams of protein that I would want people to watch for,” Dr. Linder says. “But it is important to be mindful of protein. As a dog’s heart disease becomes more severe, she can have cachexia — a loss of lean body mass. “You don’t want to combine that with not consuming enough protein in the diet. That makes for chaos. In fact, if you don’t provide enough protein in the dog’s food, her body will be even more likely to break down its own muscle mass to get it.”

Decades ago, it used to be argued that dogs should be fed a low-protein diet if they had heart problems. It was thought that extra protein put an extra demand on the heart to work harder. But studies have since shown that’s not the case. In fact, the call for enough dietary protein is strong enough that Dr. Linder says that if there are no medical concerns that would necessitate a low-protein diet, like advanced kidney disease, it’s even “okay to go with an above-average-protein food plan.”

Any dog food with a statement from AAFCO — the Association of American Feed Control Officials — declaring that the food is complete and balanced will have an appropriate amount of protein for a dog with heart disease. “But you want to go on the high side,” Dr. Linder stresses. “Ask your vet. She may be able to tell you about the number of grams of protein in a food per so many calories.

“It’s very individual,” she adds. “It’s not like sodium, for which through clinical experience we can name cutoff points. What’s a high enough amount depends on the particular pet with heart disease.”

At the very least, she says, you definitely want to make sure you’re not going low-protein. Foods labeled ‘senior diets’ vary considerably, but some tend to be on the lower side, supposedly to stave off kidney disease (although unless a dog has advanced kidney disease, protein in the diet should not be reduced).

If your vet doesn’t feel comfortable discussing the details of which diets are high in protein, comments Dr. Linder, seek a consultation with a board-certified veterinary nutritionist. “Some vets have excellent training in nutrition and can provide the answers you need; others would feel more comfortable referring you to someone board-certified in nutrition. But even a vet not comfortable with the ins and outs of nutrition would be mindful if a dog had cachexia. She’d know to make sure the dog got more protein in her diet. It wouldn’t make the lost muscle come back, but it would help as much as possible not to make things worse.”

Potassium. Potassium levels in a dog with heart disease can go high or low, Dr. Linder says. It’s very dependent on the pet’s situation. Sometimes it depends on what medications the dog is taking, and at what dosages. A vet would know which direction to go in with dietary potassium based on blood work. As with protein, there are no hard-and-fast rules for potassium levels in food. “If you have a pet who’s very potassium-depleted,” Dr. Linder says, “the vet will steer you toward a diet that has more potassium than other brands.

“What dog owners should not do,” she adds, “is start trying to tweak potassium levels on their own. That’s about blood work and drug-nutrient interactions, and it takes a medical professional to sort it out.”

Are supplements ever appropriate?

The nutrients discussed so far concern the food a dog eats. But there are things outside the main diet — supplements — that could also have an impact on heart disease, affecting its rate of progression and the dog’s quality of life.

Taurine. A deficiency of the amino acid taurine is much more common in cats, because they require it in their diet. Dogs, on the other hand, do not have a dietary taurine requirement because the body can produce it. That said, some dogs have a genetic predisposition to need more taurine than their body can produce. And if they don’t get enough and become taurine deficient, they can develop a kind of heart disease known as dilated cardiomyopathy that compromises the ability of the heart to contract vigorously enough with each beat. Those dogs with a taurine deficiency and dilated cardiomyopathy tend to do better with taurine supplements. However, it is unlikely to have a benefit if taurine levels are not deficient,” Dr. Linder says. Susceptible breeds include cocker spaniels, Newfoundlands, St. Bernards, English setters, and Labrador and golden retrievers.

“If your pet has dilated cardiomyopathy and is a susceptible breed, your vet may recommend testing taurine levels. That way, she will know if a deficiency exists, how bad the deficiency is, and how much to supplement,” Dr. Linder counsels.

Note: Lamb and rice diets in breeds predisposed to a lack of taurine may make it more likely for them to develop a deficiency.

Omega-3 fatty acids. In people, omega-3s are thought to help prevent coronary artery disease — the blocking of blood flow through the arteries. In dogs, who only very rarely get coronary artery disease, omega-3s seem to work best for those with a reduced or altered appetite as a result of a compromised heart, or muscle loss, or abnormal heart rhythms (arrhythmias). It’s also thought that omega-3s help ameliorate inflammation in the dog’s body.

“Side effects to consider,” says Dr. Linder “include diarrhea and, in extremely high doses, bleeding problems” because omega-3s “thin” the blood. Admittedly, the occurrence of such problems is on the rare side, but to insure your dog stays safe, give omega-3 supplements to your dog with your vet’s knowledge so she can monitor her for any untoward effects. Tufts Cummings School’s HeartSmart website advises that for every 10 pounds of body weight, a dog should get one gram of fish oil that contains 180 milligrams of EPA (eicosapentaenoic acid) and 120 milligrams of DHA (docosahexaenoic acid). The site also advises choosing a brand from ConsumerLabs.com, which does testing for quality. Don’t give your dog fish oil in the form of cod liver oil. It can be toxic in vitamins A and D.

Coenzyme Q10. Some dog owners think it’s important for dogs with heart disease, Dr. Linder says. They believe it has antioxidant effects. But to date, studies in dogs have shown minimal to no benefit. “If people really push for it,” she says, “I won’t tell them not to administer it. But we don’t really have good evidence that it helps.”

The bottom line

Providing a dog with heart disease proper nutrition truly is medical nutrition therapy. It can afford a pet more quality time. But also, Dr. Linder says, it allows a dog’s body to focus on coping with the disease rather than dealing with any nutrient deficiencies. “By giving the right nutrients,” she comments, “you’re making sure your dog has everything she needs to function as best as possible” in the face of compromised health.

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