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==1. What is Arginine?==

==1. What is Arginine?==

Arginine is an essential amino acid for dogs and cats. It is classified as a gluconeogenic amino acid and contains a positively charged nitrogen side chain that can be used as a binding site for other molecules. Dietary arginine is absorbed by a dibasic amino acid transporter in the small intestine (particularly the jejunum) and plasma arginine is actively reabsorbed in the proximal tubule of the kidney. Species that do not require dietary arginine (such as humans) are able to endogenously synthesise adequate amounts of this amino acid through the conversion of glutamate into ornithine; ornithine is ultimately converted into arginine in the urea cycle through the activity of pyrroline-5-carboxylate synthase and ornithine aminotransferase. Low activity these enzymes are found in dogs and cats<ref name="Burns">Burns RA, et al.  Arginine: An Indispensable Amino Acid for Mature Dogs. J Nutr 1981; 111:1020-1024.</ref><ref name="Morris">Morris JG. Nutritional and Metabolic Responses to Arginine Deficiency in Carnivores J Nutr 1985;115:524-531.</ref>. Dogs and cats have an absolute requirement for dietary arginine.

Arginine is an '''essential amino acid''' for dogs and cats. It is classified as a '''gluconeogenic''' amino acid and contains a positively charged nitrogen side chain that can be used as a binding site for other molecules. Dietary arginine is absorbed by a dibasic amino acid transporter in the small intestine (particularly the jejunum) and plasma arginine is actively reabsorbed in the proximal tubule of the kidney. Species that do not require dietary arginine (such as humans) are able to endogenously synthesise adequate amounts of this amino acid through the conversion of glutamate into ornithine; ornithine is ultimately converted into arginine in the urea cycle through the activity of pyrroline-5-carboxylate synthase and ornithine aminotransferase. Low activity of these enzymes are found in dogs and cats<ref name="Burns">Burns RA, et al.  Arginine: An Indispensable Amino Acid for Mature Dogs. J Nutr 1981; 111:1020-1024.</ref><ref name="Morris">Morris JG. Nutritional and Metabolic Responses to Arginine Deficiency in Carnivores J Nutr 1985;115:524-531.</ref>. '''Dogs and cats have an absolute requirement for dietary arginine'''.

==2. Why is it Important?==

==2. Why is it Important?==

Arginine plays a critical role in the detoxification of ammonia, resulting from the turnover and breakdown of proteins. It is an important intermediate in the urea cycle which converts ammonia to urea. In the cats the arginine dietary protein in order to handle the increased need for detoxifying ammonia released from amino acid catabolism a<ref name="Taylor">Taylor TP, et al. Increasing dispensable amino acids in diets of kittens fed essential amino acids at or below their requirement increases the requirement for arginine. Amino Acid 1997;13:257-272.</ref>. Cats are also highly sensitive to dietary arginine deficiency, feeding an arginine free diet to cats can result in hyperammonemia and death within a few hours<ref>Morris JG and Rogers QR. Ammonia intoxication in the near-adult cat as a result of a dietary deficiency of arginine. Science 1978 Jan 27;199(4327):431-2</ref>.

Arginine plays a critical role in the detoxification of ammonia, resulting from the turnover and breakdown of proteins. It is an important intermediate in the urea cycle which converts ammonia to urea. In cats the arginine dietary protein in order to handle the increased need for detoxifying ammonia released from amino acid catabolism a<ref name="Taylor">Taylor TP, et al. Increasing dispensable amino acids in diets of kittens fed essential amino acids at or below their requirement increases the requirement for arginine. Amino Acid 1997;13:257-272.</ref>. Cats are also highly sensitive to dietary arginine deficiency, feeding an arginine free diet to cats can result in hyperammonemia and death within a few hours<ref>Morris JG and Rogers QR. Ammonia intoxication in the near-adult cat as a result of a dietary deficiency of arginine. Science 1978 Jan 27;199(4327):431-2</ref>.