Cat owners frequently have many questions about what to feed their pets. The pet store, grocery store, and even convenience store have a dizzying variety of dry, moist, canned and pouch-style foods made for a wide variety of lifestyle situations. It’s no wonder that people become confused when there are hundreds of foods to choose from!
When choosing a food for your pet, it is important to get your veterinarian’s input. It’s also important to carefully consider the natural history of the cat species and think about what cats are designed to eat in the wild. Cats are strictly carnivorous animals, and aside from munching on a little grass, which has no nutritional value, they eat other animals. This is a very high-protein, low-carbohydrate diet with a moderate amount of fat (as long as their prey animals are well-fed!)
Thousands of years of eating this diet have shaped the cat’s metabolism to be as efficient as possible, but some of those adaptations make it very difficult for a cat to survive on alternate food sources. For example, cats, like all animals, use protein in their food to build body proteins such as muscle tissue and blood components. However, because protein is so abundant in their natural diet, they also break down proteins into amino acids that are then converted to sugar for energy. People and dogs have the capacity to do this when protein is abundant in the diet, but also have the capacity to shut down this pathway when protein is scarce. Cats do not have this option, and will continue to break down protein for energy when they are starving or on a low-protein diet, and so they begin to cannibalize their own tissue protein for energy. This can occur even if their overall calorie intake is sufficient.
Cats also require several amino acids (building blocks of protein) that are only found in animal protein, such as taurine, arginine, methionine, and cysteine. They have lost the ability to make these amino acids because they are abundant in their natural diet. Attempting to feed cats a vegetarian diet can result in dangerous deficiencies unless supplements are carefully added to the diet.
Cats have limited amounts of the enzymes found in the digestive tract and liver to digest and process carbohydrates in their diet. Increased amounts of carbohydrate in the diet leads to rapid swings in blood sugar, which can lead to diabetes, but it also leads to the excess carbohydrates being stored as fat.
Cats normally take in a moderate amount of fat in their carnivorous diet, which they rely on for energy, but also for the building blocks of cell membranes, certain chemicals which cells use to signal each other, hormones, and skin oils. They are unable to make certain fatty acids, since they expect to be able to obtain them in their food.
When we take all of these evolutionary adaptions into account, it becomes obvious that we should be trying to feed cats a diet that most closely matches what they would be eating in the wild. The commercial foods that most closely fit this description are canned and pouch foods. When choosing a food for your cat, the most important thing to do is to read the fine print on the label. A scan of the label on a canned or pouch (wet) food should reveal that the primary ingredients are meat, poultry, and/or fish and their byproducts. Further down the list, you may see a small amount of carbohydrate thickener, such as guar gum, seaweed, tapioca starch, or wheat gluten. (Wheat gluten was the subject of the food recall two years ago—it seems safe now, but many people choose to avoid it anyway.) Beyond that, you should see a list of the vitamins and minerals that are added to food to make it a complete and balanced diet. You should try to avoid ingredients like rice, corn, soy, or wheat in canned food, even if the manufacturer uses whole grains to make it sound healthy.
Feeding your cat canned food will help make sure that he is receiving the proper amount of protein to maintain his muscles and keep him healthy. It also provides the fat he needs for a healthy coat, and low carbohydrates to prevent obesity. It will help keep his blood sugar levels steady to stave off diabetes, but also to help him feel more satisfied with amount of food you are providing. Feeding canned food has the added benefit of providing moisture in the diet, which helps to support a healthy urinary tract and prevent kidney disease.
A small amount of dry food per day can help provide cats with the satisfying “crunch” they love and may provide some benefit for their teeth, but the supply of this higher-carbohydrate food should be limited to prevent obesity. It can be helpful to think of dry food as being the cat equivalent of potato chips—a small portion per day can be part of a healthy diet, but having a bowl available at all times would lead most of us to a larger waistline! Talk to your veterinarian about the right portions of canned and dry food that would be healthy for your cat.