December 10th, 2020
There are different types of heart disease that dogs can suffer from. Some are present from birth and others develop over time. We’ve written about some of the different types in our earlier article. However, in this article we will focus on diet and how alterations to the dog’s diet may help to slow progression of the disease and increase quality of life. There are several nutrients deemed to be important for dogs with heart disease and these are:
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Sodium
Taurine
L-carnitine
Fatty acids (Omega 3)
Antioxidants
Co-Enzyme Q10
Sodium
The European Pet Food Industry Federation (FEDIAF) guidelines for sodium levels for healthy adult dogs are 0.10% minimum (on a dry matter basis or DM) and 1.80% (DM) maximum. For an explanation of dry matter please see the end of this article.
However, it is recommended that dogs suffering from heart disease eat a diet with reduced sodium levels. Sodium helps the body retain water. By reducing the sodium, the fluid accumulation that occurs with heart disease can be controlled. In turn, reducing the fluid can help reduce the associated discomfort and coughing the dog is suffering from.
The amount of sodium restriction depends on the stage of heart disease and the exact figures are still unclear. However, as a general guideline for early-stage heart disease the ideal diet should contain less than 0.40% sodium on a dry matter* (DM) basis and that once clinical signs/symptoms appear the sodium should be reduced to less than 0.30% DM which is the level found in most senior diets anyway. Extreme sodium restriction would be 1.5% DM and under.
Taurine
Taurine is an amino acid that is essential for cardiac health. Unlike cats, that require a dietary source of taurine (from meat or fish), dogs can synthesise taurine themselves as long as their diet contains adequate amounts of protein and the amino acids methionine and cysteine. However, recent research into heart disease in dogs has suggests that breeds with genetic heart problems may also have difficulty maintaining the right balance of taurine in the body.
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American Cocker Spaniels, Golden Retrievers and Newfoundlands, especially those fed on a high fibre, low protein or a lamb and rice diet (lamb is relatively low in taurine) are breeds that all suffer from DCM but that also appear to have a predisposition to taurine deficiency.
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For dogs that are already suffering from heart disease a taurine supplement is often recommended. Especially for dogs with DCM. The recommended dose for dogs with taurine depletion is 250-1000 mg every 8-12 hours. Pet foods for dogs with cardiac disease should contain at least 0.1% taurine on a dry matter* basis.
L-Carnitine
Carnitine is a vitamin like substance produced in the liver from amino acids methionine and lysine. In normal, healthy dogs the liver should produce all the carnitine a dog requires but a carnitine deficiency has been linked to dogs with DCM. The heart ‘prefers’ a certain type of fat as its energy supply to contract and relax.
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Carnitine helps to break down this fat into energy and studies show that supplementing the diet with L-Carnitine (or other active forms of the substance) can help to improve blood flow. The recommended dose for dogs is currently 50-100mg per kg of body weight every 8 hours and dog food specifically marketed for heart disease should contain at least 0.02% L-carnitine on a dry matter* basis.
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Omega 3 fatty acids
Omega 3 is just one type of essential fatty acid (EFA). They are called essential as they cannot be synthesised in the body and must be obtained by diet. Dogs and cats need several types of omega oils, including 6 and 3. Omega 3 fatty acids are recommended for heart disease for several reasons.
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Firstly, they reduce inflammatory proteins called cytokines, but a diet supplemented with omega 3 fatty acids has also been shown to improve appetite and reduce muscle loss in dogs with heart failure. Further studies have shown that Omega 3 fatty acids appear to supress abnormal heart rhythms (antiarrhythmic effect).
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The best sources of omega 3 fatty acids are fish oil, marine algae and shellfish such as green lipped mussel. Salmon oil is usually the preferred source of fatty acids than cod liver oil due to the high levels of vitamins A and D in cod liver oil. The recommended dose for dogs with heart disease that have a poor appetite and weakness/muscle wastage is 40mg per Kg of body weight of EPA omega 3 and 25 mg/Kg of DHA omega 3.
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Potassium and Magnesium
These are important minerals for a dog with chronic heart failure. A deficiency of magnesium or phosphorus can exacerbate the potential side effects of cardiac medications and may cause other problems such as muscle weakness and cardiac arrhythmias.
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Magnesium levels should be monitored in your dog and if he/she becomes deficient then a diet with higher levels may be recommended. However, whether the dog requires a diet higher or lower in potassium depends completely on the individual animal. Again, your vet will need to check your dog regularly and moderate the diet when and if necessary.
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Phosphorus
Some of the specialist diets specifically developed for cardiac disease have a reduced phosphorus content too. Phosphorus, along with calcium is a major component of bone. Phosphorus is also found in the soft tissues and plays a role in almost all of the body’s metabolic processes. However, phosphorus restriction is important once kidney failure has been diagnosed.
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During renal failure, the kidney’s ability to filter and excrete phosphorus declines and the build-up of phosphorus in the body can be toxic. Reducing dietary phosphorus for dogs with kidney failure has been shown to increase their lifespan by 2-3 times compared to dogs fed on a standard food.
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As many dogs with heart disease also have kidney disease, some companies have chosen to restrict phosphorus in the diet as well as minerals such as sodium. However, phosphorus restriction is not necessary to aid patients with heart disease if their kidneys are functioning correctly.
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Antioxidants
During normal cell metabolism (oxidation) the body produces unstable molecules called free radicals. Free radicals are responsible for normal aging but if they are able to increase in numbers, they can cause disease and illness too. Contaminants such as pollution and damage from sunlight (sun burn) can increase the amount of free radicals the body produces.
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Antioxidants including Vitamins C and E help to neutralise free radicals and therefore reduce the destruction caused by free radicals. However, studies have shown that dogs with either Dilated cardiomyopathy or Mitral Valve disease have an imbalance between free radical production and the amount of antioxidant protection available.
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Therefore, it has been recommended that the diet of a dog with heart disease is supplements with antioxidants such as Vitamins C and E, however scientific evidence to support the need for supplementation is still weak.
Co-Enzyme Q10
Co-Enzyme Q10 is produced naturally in the body and is a vitamin-like substance that is involved in the production of cellular energy. It has antioxidant properties and supplementation has been reported to help with heart disease, however more research is required to substantiate these claims.
*What is dry matter?
Vet’s Kitchen dry food contains 8% moisture, the rest of the food (92%) is called dry matter, and this is where all the nutrients in the food are. Different brands of dry food and types of foods e.g. wet food or semi moist food all contain different moisture contents. These differences in moisture content make it difficult to do a direct comparison on nutrient levels, therefore nutrients are usually only compared on a dry matter basis instead of an ‘as fed’ basis.
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