Recently there has been some controversy about feeding dogs and cats foods that substitute legumes (often peas) for grain in prepared dry and canned foods. This started in early 2018 when a young adult Beagle/Lab mix developed heart disease. He was diagnosed with dilated cardiomyopathy (DCM) meaning his heart was growing too large to efficiently pump blood. This disease is fairly common in older dogs and some cats but is unusual in a relatively young (4 YO) dog.
DCM symptoms in dogs and cats include:
- acting tired
- a bloated abdomen
- abnormally rapid breathing
- poor appetite
DCM can result in abnormal heart rhythms, congestive heart failure (a build-up of fluid in the lungs or abdomen), or sudden death. When a pet develops an enlarged heart it is natural to assume that if it was bigger there would be more force–like a bigger bicep in a human leads to more strength. Unfortunately, that is not how it works.
Unlike other muscles, the heart becomes weaker and weaker when it enlarges. This leads to a thinning of the heart walls; the organ becomes more like a flabby balloon than the powerful muscle it is. The heart simply cannot efficiently pump blood out to the body and so much of it remains in the heart with each beat. In the beginning, the body can compensate for this poor blood flow. Eventually, these homeostatic mechanisms are overwhelmed and DCM develops.
The idea that a large heart muscle was actually weak was a difficult concept to grasp when I was learning about the human body in my nursing and nurse practitioner education. Without going into an involved and complicated review of cardiac physiology, you will just have to trust me when I say that a big heart is a good thing when it comes to love, but not so good when it happens to your dog…or to you.
Heart Disease Affects 10-15% of all dogs and cats
Several dog breeds are well known for developing DCM. These include:
- Cavalier King Charles Spaniels
- Doberman Pinschers
- Irish Wolfhounds
- Great Danes
Before 1987, no one knew why cats developed DCM. However, research done at the University of California – Davis School of Veterinary Medicine found it is due to a deficiency in taurine, an essential amino acid. Because cats are carnivores and taurine is found in meat, cats never developed the ability to make their own taurine and must get this protein from their diet.
The number of cats with DCM decreased dramatically since the late 80s after pet food manufacturers began supplementing cat foods with taurine. However, vets still see taurine deficiency-induced DCM in cats. Usually, this is when owners are feeding a vegetarian or home-prepared diet or a diet made by a manufacturer with inadequate nutritional expertise or quality control.
Does Diet Cause Heart Disease?
There is not much information on how diet causes heart diseases like DCM in humans or in our pets. However, there are definite links between feeding a grain-free diet that includes protein from legumes and dogs that develop an enlarged heart. In the case of the Beagle cross I mentioned earlier, his owner was feeding a boutique, grain-free diet that contained kangaroo and chickpeas.
Many veterinarians and veterinary nutritionists report they are seeing more cases of nutritional deficiencies in pets. They attribute this to feeding unbalanced raw, vegetarian and other homemade diets. These nutritional deficiencies are also present in some branded pet food products as marketers jump on the latest fads, like exotic ingredients.
The growing evidence is that in both the breeds typically at risk for DCM and in other breeds and mixes, the dogs who develop it are more likely to be eating boutique or grain-free diets. These foods are made up of exotic meats and ingredients such as kangaroo, lamb, buffalo/bison, venison, salmon, duck, lentils, peas, fava beans, tapioca, barley, and/or chickpeas. Vegan and vegetarian diets are strongly associated and it was found in dogs eating raw or home-prepared diets, too.
Like cats, Golden Retrievers and Cocker Spaniels were found to be at risk for DCM caused by taurine deficiency, and one study showed that Cocker Spaniels with DCM improved when given taurine supplementation. Vets have studied the issue intensely. Additional studies show taurine deficiencies associated with foods containing lamb and rice bran, as well as high fiber and very low protein diets.
Breeds found to have an increased risk for taurine deficiency causing DCM include:
- St. Bernards
- English Setters
- Irish Wolfhounds
- Portuguese Water Dogs
The reasons why some dog breeds develop a taurine deficiency are not fully understood. Theories are that it could be reduced levels of taurine production due to a deficiency in the diet, reduced availability of taurine or its building blocks within the body, increased losses of taurine in the feces, or altered metabolism of taurine in the body.
Is This One Problem Or Two?
It’s not as simple as it looks. It appears there may be two separate problems–one related to a taurine deficiency and a separate problem with another group of dogs getting DCM that is completely unrelated to taurine in the food. Isolating and identifying the dietary factors contributing to DCM in the non-taurine deficient dogs is proving to be difficult. However, DCM is more likely to occur in dogs eating grain-free, vegan/vegetarian or exotic ingredient diets.
We’ve been told by popular articles, websites, and pet food manufacturers that especially dogs with allergies (or the potential to develop an allergy) should avoid grains like wheat and substitute ingredients totally foreign to the dog, like salmon or buffalo. Faced with thousands of diet choices, persuasive marketing and opinions all over the internet, pet owners don’t know if what they are feeding will lead to nutritional deficiencies or even toxicities that potentially could cause disease.
The first step is to begin reading the pet food label, as I discuss in this post. It is vitally important to your pet’s health that the food meet minimal nutritional standards as defined by the American Association of Feed Control Officials.
Grain-free and Exotic Is Not The Answer To Allergies
According to veterinary websites, while food allergies are a possible cause for an itchy skin, ear infections or diarrhea, there are many more likely causes which may have nothing to do with food.
Let’s review. An allergy to a food happens when the immune system identifies a protein found in food to be an invader instead of a nutrient. The end result can be itchy skin, vomiting or diarrhea. Some unfortunate dogs and cats will have both skin and gastrointestinal symptoms.
But just observing these signs does not automatically mean your pet has a food allergy. Instead, there are more common causes of these issues such as parasites, viruses, bacterial infections, pancreatitis, eating something they shouldn’t, and many others.
When a pet has symptoms only with certain foods, it could be an allergy but is more likely due to an intolerance to that specific diet. Perhaps the kibble or can has too much fat, too much or too little fiber or has some other thing that doesn’t agree with a particular pet.
Fleas, allergies to fleas and environmental allergies like dust mites, pollen and grasses are much more common in pets than food allergies even though they have similar symptoms.
What Should A Responsible Pet Owner Do?
While vet schools across the country and the Food and Drug Administration are intensively looking at this issue, pet owners do have ways to manage the risk to their dogs and cats.
Most vets recommend reassessing what you feed, especially if you are buying a boutique, grain-free, or exotic ingredient kibble or canned food. The same is true if you cook up your own home-made or raw diet. They say sticking to a company with a proven track record of providing a quality product is the best way to avoid potential heart problems.
Be on the lookout for early signs of heart disease if you’re feeding your dog a boutique, grain-free, or exotic ingredient diet. At the first sign of slowing down, unusual shortness of breath, or coughing make an immediate appointment with your veterinarian. The vet will listen for a murmur or abnormal heart rhythm first. Depending on what they hear and the physical findings, they may do additional tests, such as x-rays, blood tests, electrocardiogram (EKG), an ultrasound of the heart (echocardiogram) or even refer you to a veterinary cardiologist.
What we know about pet nutrition sometimes lags behind the marketing of pet foods. We can move in the wrong direction when advertising outpaces science. Hopefully, now that we have seen what happens when a diet is marketed for purely commercial reasons, even though it is adopted with the best intentions, we can follow a more science-based approach to the best nutrition for our pets.
Let us know your experiences and thoughts. Leave a comment below.