Dogs and cats and ferrets, oh my!
- Mary Malucci
- Aug 13, 2023
- 4 min read
Updated: Dec 25, 2024
In recent decades, the pet food industry has become as trendy as the human food industry. One recent trend argues that our pet's ancestors would not have eaten grains so there are now dozens of grain free diets on the shelves. Other arguments in favor of grain free diets include food allergies and carbohydrate calorie reduction. Grain free diets may sound good in theory but, in practice, they are becoming linked to a rise in heart disease in dogs and cats.
Grains are clearly defined as the fruits of cereal grasses, like wheat, barley, corn and rice. They are used in pet foods to provide carbohydrates, proteins, vitamins, minerals, essential fatty acids and fiber. When formulating grain free diets, manufacturers turned mainly to legumes, like peas, chickpeas and lentils, to replace the grains. Potatoes, both white and sweet, have also been used as grain substitutes. Now let's review our arguments in favor of grain free diets for our pets. Legumes and potatoes are even less likely to have been a large part of our pet's ancestral diets. They can be equally high in carbohydrate calories. While food allergies are problematic for many people, food allergies in pets are rare and usually related to animal proteins.
Dogs are omnivores, like people. A dog's digestive system produces all the enzymes necessary to digest grains and most do fine on a diet that includes grains. As the grain free diets became increasingly popular, veterinarians began noticing an increase in dogs being diagnosed with dilated cardiomyopathy or DCM. Dilated cardiomyopathy weakens the heart muscle, decreasing the heart's ability to pump blood. Untreated, DCM leads to congestive heart failure. Several studies have shown it is the presence of legumes rather than the absence of grains that is causing this trend. One 2018 study suggested the legumes in these diets interfered with the dog's ability to absorb enough taurine from their food. Taurine is an amino acid found primarily in muscle meats and deficiencies been shown conclusively to lead to DCM, especially in cats. Dogs with diet induced DCM often recover when switched to a food without legumes and supplemented with taurine. Research is ongoing but, in the meantime, concerned dog owners may want to avoid diets with lots of legumes or potatoes.
Cats and ferrets are obligate carnivores, meaning they need more meat protein in their diets than do dogs and people. Obligate carnivores use proteins as an energy source in addition to body building and maintenance. Cats are able to digest grains, although not as efficiently as dogs.
Historically, cats have been very sensitive to dietary influences. Taurine was recognized as an essential nutrient for cats when research showed that insufficient levels in their diet leads to blindness and heart failure. Taurine levels in commercial cat foods were significantly increased, which greatly decreased cases of taurine related blindness and heart disease. On the flip side, propylene glycol was recognized as toxic to cats because it causes a specific form of anemia so it's been banned from commercial cat foods in the US. Recent studies have also linked the presence of legumes in grain free cat foods to an increase in DCM in cats. Like the dogs, cats with diet induced DCM often respond well to changing to a legume free food and taurine supplementation.
Unlike dogs and cats, ferrets are unable to digest grains and need a grain free diet. Large quantities of plant sourced carbohydrates and fiber can cause digestive problems for ferrets, including potential GI obstructions. Similar to dogs and cats, they also seem unable to tolerate legumes in their food. Historically, ferrets have been known to develop struvite bladder stones when their diet contains too many plant proteins. Processing these plant proteins alters the pH of their urine, allowing crystals to form. This can usually be addressed by replacing plant proteins with animal proteins in the ferret's diet. With the recent trend of using peas or lentils in place of grains, some ferrets being fed grain free cat foods are developing cysteine bladder stones that need to be surgically removed. Although cats and ferrets are both considered obligate carnivores, ferrets are even more restricted in their ability to digest non meat foods than cats are.
Now that you understand more about your pet's needs, let's read the labels. When assessing the ingredients in your pet's food, look closely at the nutritional breakdown on the back or side of the bag. The ingredients are always listed in order from most to least. The first five ingredients are the most important. Certainly some form of meat should be in the top five. In light of our current discussion, it may be prudent to avoid foods listing legumes in the top five.
In the US, The Association of American Feed Control Officials (AAFCO) is an independent organization that has been providing guidelines for animal food manufacturers for more than 110 years. A commercial pet food that meets AAFCO standards should provide complete and balanced nutrition for your pet. Recently, AAFCO has approved new labeling regulations that should make pet food labels easier to read and understand.
Consult your veterinarian about diet recommendations. If your pet has health issues, there are many prescription diets available. For healthy pets, factors like age and activity level should be considered when deciding which diet will be best for your pet.
AVMA News: Until more science is available, FDA will end public updates on potential link between certain diets and canine dilated cardiomyopathy. by Coco Lederhouse
Diet-associated dilated cardiomyopathy by Lisa M. Freeman DVM PhD DACVIM
Taurine deficiency and dilated cardiomyopathy in golden retrievers fed commercial diets
What Dog Owners need to know about the FDA's Grain Free Diet alert and DCM by Anna Burke
Understanding the Pros and Cons of Grain Free Dog food by Dr Laura Duclos DVM
What's in my Cat's Food? by Lynn Buzhardt DVM
Is Grain free Cat Food better? by Matthew Everett Miller DVM
Ferret Diet recommendations by Arizona Exotic Animal Hospital
Label Pea protein cat food as not for ferrets, vet says by Tim Wall DVM
Comments