Protein is a hot topic in pet nutrition, so how much is enough and how much is too much? When people think of protein they typically think of meat, however there are many sources of protein. Some of these include grains, seeds, pulses, and vegetables.
It is the essential amino acids found in protein, rather than the protein itself, that is required by both dogs and cats. Both essential and non-essential amino acids are found in plant and animal protein in varying levels.
Each protein source varies in the amount and type of amino acids that it supplies. Although the structure of an amino acid is the same regardless of the protein source, the amount of amino acids that each protein supplies is unique. Depending on the type of diet, protein and essential amino acid requirements can be met by animal protein sources, complementary plant sources, or a combination of both animal and plant sources. Complete and balanced pet foods must contain all of the essential amino acids in the amounts required by the intended species.
Dietary essential amino acids are required by both dogs and cats. Amino acid requirements of dogs and cats are very different, as cats are obligate carnivores and use protein for energy, whereas dogs prefer to utilize carbohydrates and fats. Cats have an additional requirement for the amino acid-like compound taurine. For dogs, this amino acid is considered conditionally essential, meaning that it is only required in specific situations.
Taurine is only found in animal protein sources, so it is important for cats to consume at least some of their protein from meat.
How much protein is enough?
Historically, dog food has been around 22-26% protein and 28-32% for cats. This level is more than adequate to supply essential amino acids for most pets. There are a few cases where higher protein levels are needed, such as for performance animals or critically ill patients. Conversely, decreased levels of protein may be necessary for specific heath issues.
It is important to remember that dietary protein provided in excess of the pet’s requirements cannot be stored by the body. Rather, what is not utilized for tissue maintenance or energy production will be stored as fat and the products of protein metabolism will be excreted in the urine, which is a wasteful end to a costly ingredient and contributes to harmful environmental ammonia levels. For dogs specifically, excessive protein can cause gastrointestinal issues and may contribute to diarrhea in dogs by disrupting the “good bacteria” normally present in the digestive system.
This blog was originally published on October 1, 2015. Last revised July 2022.