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==4. Consequences of Taurine Deficiency==
==4. Consequences of Taurine Deficiency==
===Dogs:===
===Dog:===
Taurine-deficient DCM has been reported in dogs<ref name="Fascetti">Fascetti AJ, et al. Taurine deficiency in dogs with dilated cardiomyopathy: 12 cases (1997-2001). JAVMA 2003;223:1137-1141.</ref><ref name="Belanger">Belanger MC, et al. Taurine-deficient dilated cardiomyopathy in a family of golden retrievers. JAAHA 2005;41:284-91.</ref><ref name="Kittleson">Kittleson MD, et al. Results of the multicenter spaniel trial (MUST): taurine- and carnitine-responsive dilated cardiomyopathy in American cocker spaniels with decreased plasma taurine concentration. JVIM 1997;11:204-211.</ref><ref name="Backus">Backus RC, et al. Low Plasma Taurine Concentration in Newfoundland Dogs is Associated with Low Plasma Methionine and Cyst(e)ine Concentrations and Low Taurine Synthesis. J Nutr 2006;136:2525-2533.</ref>. This can occur despite being fed commercial diets labelled as complete and balanced when the diet provides inadequate supply of sulphur amino acids without additional taurine supplementation; contains poorly digestibly proteins<ref name="Torres">Torres CL, et al. Taurine status in normal dogs fed a commercial diet associated with taurine deficiency and dilated cardiomyopathy. JAPAN(Berl) 2003;87:359-72.</ref>; contains a higher fibre content that promotes a high faecal losses of bile salts<ref>Delaney SJ, et al. Plasma and whole blood taurine in normal dogs of varying size fed commercially prepared food. JAPAN(Berl) 2003 Jun;87(5-6):236-44.</ref>; or is fed to a large breed dog with a low capacity for synthesis of taurine<ref name="Backus"/><ref>Ko KS, et al. Differences in taurine synthesis rate among dogs relate to differences in their maintenance energy requirement J Nutr 2007;137:1171–1175.</ref>. Regardless of cause, taurine supplementation in these dogs appears to reverse some of the changes in cardiac function<ref name="Fascetti"/><ref name="Belanger"/></ref><ref name="Kittleson"/>. Taurine supplementation is recommended for all dogs presenting with DCM until taurine deficiency has been ruled out.
Taurine-deficient DCM has been reported in dogs<ref name="Fascetti">Fascetti AJ, et al. Taurine deficiency in dogs with dilated cardiomyopathy: 12 cases (1997-2001). JAVMA 2003;223:1137-1141.</ref><ref name="Belanger">Belanger MC, et al. Taurine-deficient dilated cardiomyopathy in a family of golden retrievers. JAAHA 2005;41:284-91.</ref><ref name="Kittleson">Kittleson MD, et al. Results of the multicenter spaniel trial (MUST): taurine- and carnitine-responsive dilated cardiomyopathy in American cocker spaniels with decreased plasma taurine concentration. JVIM 1997;11:204-211.</ref><ref name="Backus">Backus RC, et al. Low Plasma Taurine Concentration in Newfoundland Dogs is Associated with Low Plasma Methionine and Cyst(e)ine Concentrations and Low Taurine Synthesis. J Nutr 2006;136:2525-2533.</ref>. This can occur despite being fed commercial diets labelled as complete and balanced when the diet provides inadequate supply of sulphur amino acids without additional taurine supplementation; contains poorly digestibly proteins<ref name="Torres">Torres CL, et al. Taurine status in normal dogs fed a commercial diet associated with taurine deficiency and dilated cardiomyopathy. JAPAN(Berl) 2003;87:359-72.</ref>; contains a higher fibre content that promotes a high faecal losses of bile salts<ref>Delaney SJ, et al. Plasma and whole blood taurine in normal dogs of varying size fed commercially prepared food. JAPAN(Berl) 2003 Jun;87(5-6):236-44.</ref>; or is fed to a large breed dog with a low capacity for synthesis of taurine<ref name="Backus"/><ref>Ko KS, et al. Differences in taurine synthesis rate among dogs relate to differences in their maintenance energy requirement J Nutr 2007;137:1171–1175.</ref>. Regardless of cause, taurine supplementation in these dogs appears to reverse some of the changes in cardiac function<ref name="Fascetti"/><ref name="Belanger"/></ref><ref name="Kittleson"/>. Taurine supplementation is recommended for all dogs presenting with DCM until taurine deficiency has been ruled out.
====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 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, 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''': 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. <span style="color:red">Echocardiography usually demonstrates left atrium enlargement, dilation of both ventricles (image to be provided),</span> 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 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.