A Tribute to Nick Short
It is with extreme sadness that we share the news that one of WikiVet’s founders, Nick Short, has passed away.
Nick was the driving force behind WikiVet and all that it stood for, and it is thanks to his vision, innovative approach and tireless enthusiasm and belief, that WikiVet is available as a free resource to veterinary professionals around the world today. Nick’s dedication and passion for veterinary education were truly inspirational and his very many friends, colleagues and students across the world have lost a true gem. He was an exceptional human being: gentle, good-natured, charming, generous and kind: he has left many legacies which will ensure that he will be remembered for many years.
Our thoughts are with his friends and family at this heartbreaking time. A book of remembrance has been set up for anyone that would like to leave a message of condolence for Nick and his family have asked that anyone who wishes to do so make a donation to BipolarUK, a charity that was close to Nick’s heart.
Arginine - Nutrition
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 of these enzymes are found in dogs and cats. Dogs and cats have an absolute requirement for dietary arginine.
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 cats, the arginine dietary protein requirement is higher in order to handle the increased need for detoxifying ammonia released from amino acid catabolism a. 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.
Roles in the Body
Arginine is a structural component of proteins; serves as a key substrate for the detoxification of ammonia; stimulates the release of hormones, such as insulin, glucagon, and gastrin; and is a precursor to nitric oxide (NO), which is used as a cell signalling mediator.
Consequences of Arginine Deficiency
Puppies fed an arginine deficient diet containing adequate total protein will experience a decreased food intake and hyperammonemia resulting in vomiting and ptylism, with an increase in urinary orotic acid excretion and muscle tremors. There are also reports of puppies developing cataracts after being fed an arginine-free milk replacer. Feeding an arginine deficient diet to adult dogs results in a decreased food intake.
Feeding of an arginine deficient diet to kittens results in diarrhoea, weight loss, food refusal, ataxia, hyperammonemia, and urinary orotic aciduria. Feeding a diet that has no arginine but contains substantial levels of other amino acids can result in death within a few hours.
There are no studies on either acute or chronic toxicity related to feeding high doses of arginine to dogs and no reports of safe upper limits. Kittens fed purified diets containing arginine at 5-10 times above the requirement had a decrease in growth rate, but immediate adverse effects were not noted. Toxicity studies in adult cats are lacking.
Sufficient arginine is found in plant and animal protein sources, such as muscle meat, eggs, dairy protein (i.e. casein), cereal grains, and pulses (i.e. legumes).
Diagnosing Arginine Deficiency
Diagnosis of arginine deficiency is based on fasting plasma amino acid levels and the presence of urinary orotic acid.
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- 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
- National Research Council (NRC). Protein and Amino Acids. In Nutrient Requirements for Dogs and Cats. 2006 Washington, DC: National Academies Press p. 120-122.
- Ha YH, et al. Arginine requirement in immature dogs. J Nutr 1978;108:203-210.
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- Ranz D, et al. Nutritional lens opacities in two litters of Newfoundland dogs. J Nutr 2002;132:1688S-1689S.
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- Taylor TP, et al. Optimizing the pattern of essential amino acids as the sole source of dietary nitrogen supports near maximal growth in kittens. J Nutr 1996;126:2243-2252.
Date reviewed: 18 May 2015
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