Heart Problems Can be Diet Related

Thirty years ago, veterinarians recognized deficiency of an amino acid (taurine) as the most common cause of dilated cardiomyopathy in cats.  This is a very specific type of heart disease where the heart muscle stretches, gets thinner and cannot properly contract. 

Cats fed taurine-free diets were unknowingly given cardiac complications. Felines are unable to make their own taurine (just like people can’t make their own vitamin C) and must ingest it to stay healthy.  Taurine is plentiful in most animal tissues, so feral and wild cats that hunt for their food derive adequate taurine from their diet.  But 30 years ago, not all commercial cat foods contained sufficient amounts of taurine, leading some cats to develop dilated cardiomyopathy and other health issues.  

This discovery resulted in pet food companies adding more taurine to the foods they manufacture. Subsequently, taurine-associated dilated cardiomyopathy in cats has become a thing of the past.  It is occasionally diagnosed when cat owners feed unbalanced diets (e.g., boiled poultry or vegetarian diets) or dog food only, which does not have enough taurine.

A few years later, certain breeds of dogs were found to also have dilated cardiomyopathy in association with taurine deficiency.  This was unexpected because dogs, unlike cats, are able to synthesize taurine from other sulfur-containing amino acids in their food.  Investigators suspected that these breeds were unable to synthesize taurine in amounts needed to replace losses. Taurine is typically efficiently recycled in the small intestine, but various dietary factors can affect this process. When supplemented with high doses of taurine, these dogs resolved their cardiomyopathy in many cases.

Since that time, specific categories of diets have been sporadically implicated in heart disease.  One group of Newfoundlands that were fed a commercial lamb-and-rice diet developed taurine deficiency and, luckily, reversible cardiomyopathy.  Other dogs have also been found to have taurine deficiency when fed similar lamb-and-rice diets.  Occasionally, dogs fed vegan or vegetarian diets have been taurine deficient and suffering heart disease.

Most recently, Golden Retrievers have been identified as having a taurine-deficiency associated cardiomyopathy.

Are Grain-Free Foods Implicated with Recent Cardiomyopathy Caused by Taurine Deficiency?

The current evidence suggests that the recent “outbreak” of cardiomyopathy in dogs is likely not primarily related to taurine deficiency.  Blood assays of taurine in many affected dogs show normal taurine concentrations.That said, there are concerns from some veterinary researchers about the methods used to assess taurine status in the studied populations, so we cannot completely rule out the role of taurine deficiency at this time. Time and more research will tell.

If it’s not taurine, what is the cause?

The simple answer is, we don’t know.  The only common link that investigators have observed is “grain-free” diets that use lentils and other legumes (peas) as the “base ingredient.” There are currently many theories, but no definitive answers explaining how these diets cause the cardiomyopathy.  

Are all “limited ingredient” or “grain free” diets at fault?

Some dogs are prescribed diets to diagnose and treat allergies (skin or gastrointestinal diseases).  Such diets might include a limited number of novel protiens and carbohydrates such as as salmon, kangaroo, duck, potatoes, peas, etc.  Currently, none of the limited-ingredient diets manufactured by the major pet food manufacturers – Hills, Purina, Royal Canin – have been associated with current cases of diet-associated cardiomyopathy.

While we are trying to discern the relation between grain-free and cardiac disease, it’s important to remember that there isn’t a good reason to feed “grain free” in the first place. While a few gain-free diets may also contain proteins novel to that dog, they are chosen for that, not because they lack grain. Grain free is simply a marketing category and there is no specific benefit.

What to do if your dog eats a grain-free legume based or other implicated diet?

First, check the ingredient label.  If peas or lentils are the main ingredient or main carbohydrate source, consider changing to a diet that contains grains.

Second, if you are reluctant to change the diet, consult your veterinarian about having a cardiac ultrasound (echocardiogram) to see if your dog has evidence of cardiomyopathy.  If your dog is found to be affected, even if it’s showing no clinical signs, change the diet to a grain-based commercial diet. Most nutritionists recommend using the WSAVA guidelines for selection of commercial diets, which are available to the public through a simple online search.

Third, if you have a dog that is “at risk” for taurine deficiency (American Cocker Spaniel, Golden Retriever, Newfoundland, Dalmatian) and eating an implicated diet, either change the dog to a food that is not grain-free or have the blood taurine levels checked by having your veterinarian measure both whole blood and plasma. If those are low, determine if the dog has cardiomyopathy with a cardiac ultrasound, change the diet, and supplement taurine as directed by your veterinarian.

Your veterinarian might suggest measuring taurine in other breeds as well.  The more data collected, the more likely researchers will be able to resolve whether taurine deficiency plays a primary or secondary role in causing this diet-associated cardiomyopathy.

Your veterinarian or veterinary cardiologist is the one best able to advise you about the most appropriate course of action for your dog.

What about cats?

A few cat cases have been reported to the FDA, but the numbers are too small to say anything definitive. This appears to be primarily a dog problem. But remember to feed your cat, food formulated for cats. Otherwise it may not be balanced.

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