In pet food, arginine is a conditionally essential amino acid, and it is consumed by two major pathways. The first is creatine synthesis, catalysed by the enzyme: Arginine-glycine aminotransferase (AGAT), which produces guanidinoacetate and ornithine. This occurs primarily in the kidney. The second is the urea cycle, catalysed by arginase in the liver, which produces urea and ornithine.
Crucially, both pathways consume arginine and produce ornithine, which can regenerate arginine via urea cycle. Different from dog, cats have very high constitutive AGAT activity, meaning they constantly use arginine for creatine synthesis. Consequently, cats have an absolute dietary requirement for arginine, whereas dogs have a conditional requirement and can slowly synthesize arginine within the body. Cats develop hyperammonemia within 2 to 6 hours of an arginine deficient meal, while dog may take days to weeks to show reduced growth or mild hyperammonemia. Clinically, arginine -deficient cats exhibit vomiting, ataxia, and death, whereas deficient dogs show primarily reduced growth.
There are six arginine deficiency risk factors in pet food.
- Plant-based and single-source protein diet meal
Certain protein sources are inherently low in arginine or have poor arginine digestibility. Corn gluten meal is naturally low arginine and requires supplementation. It poses a high risk for cats and moderate risk for dogs. Pea protein has moderate arginine contents, but methionine is limiting, and arginine: glycine ratio may be suboptimal. Soy protein concentrates usually have adequate arginine, but methionine is first limiting. Faba bean protein had the lowest methionine score, but arginine itself is not limiting.
- High-carbohydrate, low-meat formulation
Vegetarian or vegan pet food that rely on exclusively on plant protein without complementary sources risk arginine inadequacy, particularly for cats. The solution is to supplement L-Arginine.
- Home-prepared and raw diets
Improperly formulated raw diets using a single meat source (for example, only chicken breast without organs) may be arginine deficient. Muscle meat contains arginine but at lower concentrations than organs like liver, which is arginine rich.
- Renal or hepatic disease (Functional deficiency)
In chronic kidney disease, some research suggests that arginine supplementation my improve glomerular filtration. In liver insufficiency, reduced urea cycle capacity increases vulnerability to even marginal arginine deficiency.
- Rapid growth and high metabolic demand
Kittens and puppies have higher arginine requirements per kilograms of body weight. Similarly, lactating queens and dams have elevated protein turnover and arginine demand.
- AAFCO minimum requirements
On a dry matter basis, the AAFCO minimum arginine for cats in growth or reproduction is 1.25%, and for adult maintenance, it is 1.04%. For dogs, growth/reproduction requires at least 0.62%, and adult Maintenance requires 0.51%. A survey of 55 commercial pet foods in South Korea found average arginine content of 1.79% in cat foods and 1.37 in dog foods. Therefore, deficiency is rare in commercial diets but a real risk in improperly formulated home-prepared or vegan diets.
In practice, usually supplementation of L-Arginine could achieve optimal arginine levels in pet food to (1) prevent hyperammonemia in high protein diets; (2) support creatine synthesis without compromising the urea cycle, as adequate arginine suppliers both pathways simultaneously; (3)enable nitric oxide production for vasodilation, immune function, and neurotransmission; (4) support growth and reproduction, as puppies and kittens have higher arginine demand per kilogram body weight.
A study compiled by our Redox Animal Nutritionists.