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[[File:Feline taurine.jpg|300px|right]]

[[File:Feline taurine.jpg|300px|right]]

[[File:Taurine.jpg|300px|right|thumb|Role of taurine in the cat]]

[[File:Taurine.jpg|300px|right|thumb|Role of taurine in the cat]]

Taurine (2-aminoethanesulfonic acid) is a '''naturally occurring sulphonic acid produced in the liver''' as an end product of [[Methionine and Cysteine - Nutrition|cysteine]] metabolism. Taurine is not incorporated into proteins but found free in animal tissues; the highest concentrations are found in brain, heart, and skeletal muscle. Although commonly referred to as an amino acid it lacks a carboxyl group and is not classified as a true amino acid. '''Dogs can synthesise taurine from dietary precursors''' and are typically able produce amounts sufficient to meet daily needs. '''Cats are unable to produce adequate amounts of taurine to meet requirements and pre-formed taurine is required in the diet.'''

Taurine (2-aminoethanesulfonic acid) is a '''naturally occurring sulphonic acid produced in the [[Liver - Anatomy & Physiology|liver]]''' as an end product of [[Methionine and Cysteine - Nutrition|cysteine]] metabolism. Taurine is not incorporated into proteins but found free in animal tissues; the highest concentrations are found in brain, heart, and skeletal muscle. Although commonly referred to as an amino acid it lacks a carboxyl group and is not classified as a true amino acid. '''Dogs can synthesise taurine from dietary precursors''' and are typically able produce amounts sufficient to meet daily needs. '''Cats are unable to produce adequate amounts of taurine to meet requirements and pre-formed taurine is required in the diet.'''

==Why is it Important?==

==Why is it Important?==

The importance of taurine is related to its roles in many different organ systems, especially brain and heart. Deficiency results in serious and sometimes irreversible conditions. Therefore it is important to have an understanding of how animals may develop deficiencies and be aware of strategies to avoid or treat deficiencies.  

The importance of taurine is related to its roles in many different organ systems, especially brain and [[Heart Structure - Anatomy & Physiology|heart]]. Deficiency results in serious and sometimes irreversible conditions. Therefore it is important to have an understanding of how animals may develop deficiencies and be aware of strategies to avoid or treat deficiencies.  

==Roles in the Body==

==Roles in the Body==

'''Taurine is used in the conjugation of bile acids into bile salts in both dogs and cats'''. Cats only use taurine to form bile salts while dogs are able to conjugation bile acids to either taurine or glycine depending on availability of either amino acid<ref>Rabin J, et al. Dietary influences on bile acid conjugation in the cat. J Nutr 1976;106:1241-1246.</ref><ref>Wildgrube HJ, et al. Naturally occurring conjugated bile acids, measured by high-performance liquid chromatography, in human, dog, and rabbit bile. J Chrom. 1986;353:207-13.</ref>. Cats are unable to switch conjugation to glycine like dogs and other species and have an obligate loss of taurine in faeces. Bile salts are deconjugated in the intestinal lumen by bacteria and the deconjugated bile acids return to the liver via enterohepatic circulation. Taurine is then either absorbed by enterocytes, excreted in faeces, or further utilized by intestinal bacteria.  

'''Taurine is used in the conjugation of bile acids into bile salts in both dogs and cats'''. Cats only use taurine to form bile salts while dogs are able to conjugate [[Bile acids|bile acids]] to either taurine or glycine depending on availability of either amino acid<ref>Rabin J, et al. Dietary influences on bile acid conjugation in the cat. J Nutr 1976;106:1241-1246.</ref><ref>Wildgrube HJ, et al. Naturally occurring conjugated bile acids, measured by high-performance liquid chromatography, in human, dog, and rabbit bile. J Chrom. 1986;353:207-13.</ref>. Cats are unable to switch conjugation to glycine like dogs and other species and have an obligate loss of taurine in faeces. Bile salts are deconjugated in the intestinal lumen by bacteria and the deconjugated bile acids return to the liver via enterohepatic circulation. Taurine is then either absorbed by enterocytes, excreted in faeces, or further utilized by intestinal bacteria.  

Taurine also plays a role in normal retinal and myocardial function, osmoregulation, platelet aggregation, modulation of calcium flux within cells, reproduction, and immune response. There are three established clinical syndromes related to taurine deficiency: feline central retinal degeneration (FCRD), dilated cardiomyopathy (DCM), and reproductive failure.  

Taurine also plays a role in normal retinal and myocardial function, osmoregulation, platelet aggregation, modulation of calcium flux within cells, reproduction, and immune response.  

 

There are three established clinical syndromes related to taurine deficiency:  

#feline central retinal degeneration (FCRD),  

#[[Dilated Cardiomyopathy|dilated cardiomyopathy]] (DCM), and  

#reproductive failure.  

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====Recognised Syndromes Related to Taurine Deficiency====  

====Recognised Syndromes Related to Taurine Deficiency====  

#'''Feline Central Retinal Degeneration (FCRD)''':  Taurine deficient cats develop hyper-reflective lesions in the area centralis of the retina, which progresses to complete photoreceptor degeneration and ultimately blindness<ref>Anderson PA, et al. Biochemical lesions associated with taurine deficiency in the cat.  J Anim Sci 1979;49:1227-1234.</ref>. This condition is not reversible, but is very rare in cats fed diets with adequate taurine content.

#'''Feline Central Retinal Degeneration (FCRD)''':  Taurine deficient cats develop hyper-reflective lesions in the area centralis of the [[Eye - Anatomy & Physiology#The Wall (retina, uvea and sclera)|retina]], which progresses to complete photoreceptor degeneration and ultimately blindness<ref>Anderson PA, et al. Biochemical lesions associated with taurine deficiency in the cat.  J Anim Sci 1979;49:1227-1234.</ref>. This condition is not reversible, but is very rare in cats fed diets with adequate taurine content.

#'''Dilated Cardiomyopathy''': Taurine deficiency in now an uncommon cause of DCM in cats as commercial diets are supplements with adequate taurine levels. Cats with taurine-deficient DCM may present with subclinical disease or in overt heart failure. Echocardiography usually demonstrates left atrium enlargement, dilation of both ventricles (see image), and decreased left ventricular contractility<ref>Pion PD, et al. Myocardial failure in cats associated with low plasma taurine: a reversible cardiomyopathy. Science 1987;237:764-768.</ref>. Supplementation with oral taurine (250 - 500 mg orally twice a day) may improve clinical signs in 1-3 weeks.  

#'''[[Dilated Cardiomyopathy - Feline Cardiomyopathies|Dilated Cardiomyopathy]]''': Taurine deficiency in now an uncommon cause of DCM in cats as commercial diets are supplements with adequate taurine levels. Cats with taurine-deficient DCM may present with subclinical disease or in overt heart failure. Echocardiography usually demonstrates left atrium enlargement, dilation of both ventricles (see image), and decreased left ventricular contractility<ref>Pion PD, et al. Myocardial failure in cats associated with low plasma taurine: a reversible cardiomyopathy. Science 1987;237:764-768.</ref>. Supplementation with oral taurine (250 - 500 mg orally twice a day) may improve clinical signs in 1-3 weeks.  

#'''Decreased Immune Response''': Prolonged taurine deficiency in cats can result in a range of abnormalities in the immune system, including leukopenia, neutrophil dyfunction depletion of cells from B-cell areas of lymph nodes and spleen<ref>Schuller-Levis G, et al. Immunologic consequences of taurine deficiency in cats. J Leukoc Biol 1990;47:321-331.</ref>. The clinical significance of immune dysfunction related to taurine deficiency is not well described.  

#'''Decreased Immune Response''': Prolonged taurine deficiency in cats can result in a range of abnormalities in the immune system, including leukopenia, neutrophil dyfunction depletion of cells from B-cell areas of lymph nodes and spleen<ref>Schuller-Levis G, et al. Immunologic consequences of taurine deficiency in cats. J Leukoc Biol 1990;47:321-331.</ref>. The clinical significance of immune dysfunction related to taurine deficiency is not well described.  

#'''Poor Reproductive Performance''': Although taurine-deficient cats come into oestrus normally dietary taurine deprivation adversely affects feline pregnancy<ref name="Sturman">Sturman JA. Dietary taurine and feline reproduction and development. J Nutr 1991;121:S166-S170.</ref>:  it is associated with abortion, stillbirths, reduced litter size, low birth weight, and poor kitten survival. Taurine deficiency in queens has also been associated with congenital defects in kittens such as hydrocephalus and anencephaly, cerebellar dysgenesis, abnormal hind-limb development and thoracic kyphosis<ref>Sturman JA, et al. Feline maternal taurine deficiency: Effect on mother and offspring. J Nutr 1986;116:655-667.</ref><ref>Sturman JA and Lu P. Role of feline maternal taurine nutrition in fetal cerebellar development: and immunohistochemical study. Amino Acids 1997;13:369-377.</ref>. Taurine-deprived, live-born kittens have a poor postnatal survival rate, maturational delay, and reduced growth rates<ref name="Sturman"/>. Surviving kittens are often small and weak and are prone to various complications.   

#'''Poor Reproductive Performance''': Although taurine-deficient cats come into [[Oestrous Cycle - Cat|oestrus]] normally dietary taurine deprivation adversely affects feline pregnancy<ref name="Sturman">Sturman JA. Dietary taurine and feline reproduction and development. J Nutr 1991;121:S166-S170.</ref> it is associated with:

#'''Deafness''': Taurine deficiency has been associated with delayed auditory brainstem- evoked response maturation in cats resulting in hearing loss<ref>Vallecalle-Sandoval MH, et al. Comparison of the developmental changes of the brainstem auditory evoked response (BAER) in taurine-supplemented and taurine-deficient kittens. Int J Dev Neurosci 1991;9(6):571-9.</ref>.

*abortion,  

*stillbirths,  

*reduced litter size,

*low birth weight, and  

*poor kitten survival.  

Taurine deficiency in queens has also been associated with congenital defects in kittens such as [[hydrocephalus]] and anencephaly, cerebellar dysgenesis, abnormal hind-limb development and thoracic kyphosis<ref>Sturman JA, et al. Feline maternal taurine deficiency: Effect on mother and offspring. J Nutr 1986;116:655-667.</ref><ref>Sturman JA and Lu P. Role of feline maternal taurine nutrition in fetal cerebellar development: and immunohistochemical study. Amino Acids 1997;13:369-377.</ref>. Taurine-deprived, live-born kittens have a poor postnatal survival rate, maturational delay, and reduced growth rates<ref name="Sturman"/>. Surviving kittens are often small and weak and are prone to various complications.   

#'''[[Ear - Anatomy & Physiology#Deafness|Deafness]]''': Taurine deficiency has been associated with delayed auditory brainstem- evoked response maturation in cats resulting in hearing loss<ref>Vallecalle-Sandoval MH, et al. Comparison of the developmental changes of the brainstem auditory evoked response (BAER) in taurine-supplemented and taurine-deficient kittens. Int J Dev Neurosci 1991;9(6):571-9.</ref>.

==Toxicity==

==Toxicity==

==Dietary Sources==

==Dietary Sources==

Taurine is found in animal proteins, with highest concentrations in skeletal and heart muscle, though concentrations will vary by species<ref name="Spitze">Spitze AR, et al. Taurine concentrations in animal feed ingredients; cooking influences taurine content. JAPAN(Berl) 2003 Aug;87(7-8):251-62.</ref>. Taurine is also lower in dairy and egg proteins and it limited to absent in plant proteins. Vegetarian andvegan diets will cause taurine deficiency in cats if not supplemented adequately; vegetarian and vegan diets for dogs often contain inadequate sulphur amino acid precursors and are at a high risk for causing taurine deficiency in dogs. Synthetic forms of taurine are available for vegetarian and vegan diets. Diets severely restricted in protein may provide insufficient quantities of amino acids to support adequate taurine production in dogs<ref>Sanderson SL, et al. Effects of dietary fat and L-carnitine on plasma and whole blood taurine concentrations and cardiac function in healthy dogs fed protein-restricted diets. AJVR 2001;62:1616-1623.</ref>.

Taurine is found in animal proteins, with highest concentrations in skeletal and heart muscle, though concentrations will vary by species<ref name="Spitze">Spitze AR, et al. Taurine concentrations in animal feed ingredients; cooking influences taurine content. JAPAN(Berl) 2003 Aug;87(7-8):251-62.</ref>. Taurine is also lower in dairy and egg proteins and it limited to absent in plant proteins. Vegetarian and vegan diets will cause taurine deficiency in cats if not supplemented adequately; vegetarian and vegan diets for dogs often contain inadequate sulphur amino acid precursors and are at a high risk for causing taurine deficiency in dogs. Synthetic forms of taurine are available for vegetarian and vegan diets. Diets severely restricted in protein may provide insufficient quantities of amino acids to support adequate taurine production in dogs<ref>Sanderson SL, et al. Effects of dietary fat and L-carnitine on plasma and whole blood taurine concentrations and cardiac function in healthy dogs fed protein-restricted diets. AJVR 2001;62:1616-1623.</ref>.

Processing and cooking of foods will also influence taurine content and animal requirements. Wet food diets promote higher intestinal bacterial population and will increase loss of taurine in cats<ref>Anantharaman-Barr G, et al. Fecal bile acid excretion and taurine status in cats fed canned and dry diets. J Nutr 1994;124:2546S-2551S.</ref><ref>Kim SW, et al. Dietary antibiotics decrease taurine loss in cats fed a canned heat-processed diet. J Nutr 1996;126:509-515.</ref>; boiling increases meat taurine loss compared to roasting or baking<ref name="Spitze"/>, and dietary fibre content will influence rate of taurine loss<ref name="Torres"/><ref>Stratton-Phelps M, et al. Dietary rice bran decreases plasma and whole-blood taurine in cats. J Nutr 2002;132:1745S-1747S. </ref>. Vegetarian diets are deficient in taurine, in addition to other key nutrients for cats, and should not be fed without proper supplementation.

Processing and cooking of foods will also influence taurine content and animal requirements. Wet food diets promote higher intestinal bacterial population and will increase loss of taurine in cats<ref>Anantharaman-Barr G, et al. Fecal bile acid excretion and taurine status in cats fed canned and dry diets. J Nutr 1994;124:2546S-2551S.</ref><ref>Kim SW, et al. Dietary antibiotics decrease taurine loss in cats fed a canned heat-processed diet. J Nutr 1996;126:509-515.</ref>; boiling increases meat taurine loss compared to roasting or baking<ref name="Spitze"/>, and dietary fibre content will influence rate of taurine loss<ref name="Torres"/><ref>Stratton-Phelps M, et al. Dietary rice bran decreases plasma and whole-blood taurine in cats. J Nutr 2002;132:1745S-1747S. </ref>. Vegetarian diets are deficient in taurine, in addition to other key nutrients for cats, and should not be fed without proper supplementation.

[[Category:To Do - Nutrition]]

[[Category:To Do - Nutrition]]

[[Category:To Do - Nutrition GGP]]

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