Pondering Pet Protein: How much protein should my pet get?

by Cailin R. Heinze, VMD, MS, DACVIM (Nutrition)

December 30, 2019

in Pet Nutrition Basics, Petfoodology Blog, Trending Topics in Pet Nutrition

Protein is a very important nutrient for all animals. A large part of animals’ bodies is made of protein – muscles and organs as well as many hormones and enzymes critical to normal function. Protein can also be a source of energy – it provides the same amount of calories as carbohydrate but less than fat. Animals have requirements for a certain amount of daily protein as well as requirements for many amino acids independently. Amino acids are the building blocks of protein – when an animal eats protein, its body breaks the protein down into these amino acids which can then be used to build new proteins or be “burned” for energy.

Not all proteins are the same in terms of amino acid types and amounts. The best quality proteins will have the highest amounts of the essential amino acids (the ones that animals’ bodies cannot make on their own and must be obtained from food) and will be the easiest for the pet to digest. Typically, animal proteins have higher overall protein quality than plant proteins, but even within animal protein sources commonly used in pet foods, there is a lot variation in protein quality. To maximize protein quality, proteins sourced from both plants and animals may be combined to overcome limitations that the proteins may have independently.

What if my pet doesn’t get enough protein?

Pets who don’t get enough protein can experience a number of health problems including weight loss, muscle loss, weakness, poor digestion, and even fluid build-up in their chest or abdomen. Fortunately, protein deficiencies due to diet are rare in pets and do not typically occur when good quality commercial diets designed for the pet’s species and lifestage are fed (e.g. feeding good quality kitten food to a kitten). Pets fed diets containing no animal protein (i.e. vegan diets) or pets fed home-prepared diets that are not carefully designed are at higher risk of becoming deficient in protein or amino acids.

Protein requirements

To prevent protein deficiency in the average pet, the Association of American Feed Control Officials (AAFCO) nutrient profiles have a minimum protein of 4.5 g/100 kcal for adult dogs and 5.63 g/100 kcal for pregnant and nursing dogs and for puppies. Most commercial dog foods have well over this amount with some containing more than 2 times more than the AAFCO minimum. Wet diets are more variable in their protein content.

Cats have higher protein requirements than dogs. The AAFCO nutrient profiles have a minimum protein of 6.5 g/100 kcal for adult cats and 7.5 g/100 kcal for pregnant and nursing cats and kittens. Many commercial dry cat foods contain 1.5 -2 times more protein than the AAFCO minimum for adult cats. As with dog foods, wet cat diets are more variable but tend to be higher in protein than dry foods.

As long as your pet is eating a diet that has undergone feeding trials or is formulated to meet AAFCO and is eating an amount of food in the range recommended in the feeding directions on the label for his or her weight, then he or she is likely getting enough protein. If you are curious how much protein is in your pet’s food, you can use our pet food calculator to compare the amount to the AAFCO requirements.

What if my pet gets more protein than it needs?

Feeding a diet that is higher in protein than pets need does not result in any health benefits. However, for a healthy pet, excess protein is unlikely to be harmful, either. The extra protein will just be broken down by the body and eliminated in the urine. For some health conditions, excess protein can worsen the disease process or make the pet feel worse. Two common diseases where this occurs are kidney disease and some types of liver disease.

A higher protein diet may be beneficial in cases where there is a medical reason to lower one of the other major nutrients – fat or carbohydrate. As protein, fat, and carbohydrates provide all the calories in food, reducing the amount of one means increasing the amounts of one or both of the others. So, low fat or low carbohydrate diets are generally going to be higher in protein. High protein diets are often also used for pets that have diseases that cause them to lose protein into their intestines, are frequently associated with muscle loss, and for overweight pets that are on weight loss plans as more protein may help preserve muscle mass when calories are reduced to encourage weight loss.

Health effects aside, concerns about the environmental sustainability of feeding pets (and people) more protein than they need have been raised. Protein, especially animal protein, is a resource-intensive industry- it requires a lot of land, water, and food crops to produce. Avoiding excessively high animal protein diets and feeding a complementary mixture of plant and animal proteins can help reduce the environmental burden while ensuring good health for both dogs and cats.

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Cailin R. Heinze, VMD, MS, DACVIM (Nutrition)

Dr. Cailin Heinze is a Board-certified Veterinary Nutritionist® and the Executive Director and Chief Academic Officer of the Mark Morris Institute, a non-profit organization whose mission is to promote optimal companion animal health by providing educational opportunities for veterinary students and veterinarians in clinical nutrition. She has also done some consulting work for Balance IT, a company that makes software and supplements for home-cooked pet diets. She is an expert in home-cooked diet formulation and general pet nutrition and has a special interest in feeding pets with kidney disease and cancer.