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== Consequences of Vitamin E Deficiency ==

== Consequences of Vitamin E Deficiency ==

====Dogs:====  

====Dogs:====  

Vitamin E deficiency in dogs can develop anorexia, reproductive failure, skeletal and endocardial muscle degeneration, retinal degeneration, dermatitis, and subcutaneous [[oedema]]<ref>Elvehjem CA, et al. The effect of vitamin E on reproduction of dogs on milk diets. J Pediatr 1944;24:436-441.</ref><ref>Van Vleet JF. Experimentally induced vitamin E-selenium deficiency in the growing dog. JAVMA 1975; 166:769-774.</ref><ref name="Davidson">Davidson MG, et al. Retinal degeneration associated with vitamin E deficiency in hunting dogs. JAVMA 1998;213:645-651.</ref>. Dogs with concurrent intestinal disease affecting absorption of dietary fat (i.e. a [[Protein Losing Enteropathy|protein-losing enteropathy]]) as well as dogs with [[:Category:Liver Pathology|liver disease]] are at a higher risk of developing relative α-tocopherol deficiencies despite adequate dietary intake.

Vitamin E deficiency in dogs can develop anorexia, reproductive failure, skeletal and endocardial muscle degeneration, retinal degeneration, dermatitis, and subcutaneous [[oedema]]<ref>Elvehjem CA, et al. The effect of vitamin E on reproduction of dogs on milk diets. J Pediatr 1944;24:436-441.</ref><ref>Van Vleet JF. Experimentally induced vitamin E-selenium deficiency in the growing dog. JAVMA 1975; 166:769-774.</ref><ref name="Davidson">Davidson MG, et al. Retinal degeneration associated with vitamin E deficiency in hunting dogs. JAVMA 1998;213:645-651.</ref>. Dogs with concurrent intestinal disease affecting absorption of dietary fat (i.e. a [[Protein Losing Enteropathy|protein-losing enteropathy]]) as well as dogs with [[Liver - Pathology|liver disease]] are at a higher risk of developing relative α-tocopherol deficiencies despite adequate dietary intake.

====Cats:====  

====Cats:====  

Clinical signs of vitamin E deficiency in cats and kittens include anorexia, depression, myopathy, and pansteatitis (i.e., painful nodular inflammation of adipose tissue)<ref>Gershoff SN and Norkin SA. Vitamin E deficiency in cats. J Nutr 1962;77:303-308.</ref><ref>Dennis JM and Alexander RW. Nutritional myopathy in a cat. Vet Rec 1982;111:195-196.</ref><ref name="Niza">Niza MM, et al. Feline pansteatitis revisited: hazards of unbalanced home-made diets. J Feline Med Surg 2003;5:271-277.</ref>. The level of vitamin E required to prevent clinical sign of deficiency is directly related to the level of dietary PUFAs.

Clinical signs of vitamin E deficiency in cats and kittens include anorexia, depression, myopathy, and pansteatitis (i.e. painful nodular inflammation of adipose tissue)<ref>Gershoff SN and Norkin SA. Vitamin E deficiency in cats. J Nutr 1962;77:303-308.</ref><ref>Dennis JM and Alexander RW. Nutritional myopathy in a cat. Vet Rec 1982;111:195-196.</ref><ref name="Niza">Niza MM, et al. Feline pansteatitis revisited: hazards of unbalanced home-made diets. J Feline Med Surg 2003;5:271-277.</ref>. The level of vitamin E required to prevent clinical sign of deficiency is directly related to the level of dietary PUFAs.

 

====Influence of Diet:====  

====Influence of Diet:====  

The metabolic requirement for vitamin E is dependent on the PUFA concentration in the diet as well as the degree of peroxidation that occurs during processing and storage<ref name="Chow"/><ref name="NRC"/>. '''Diets high in fat and specifically high in long-chain omega-3 PUFAs will increase the tocopherol requirements in the diet'''<ref name="Davidson"/><ref name="Niza"/><ref>Hendricks WH, et al. Vitamin E requirement of adult cats increased slightly with high dietary intake of polyunsaturated fatty acids. J Nutr 2002;132:1613S-1615S.</ref>. Recycling of α-tocopherol is also impaired with concurrent high intakes of vitamin C (a water-soluble vitamin that is not a dietary requirement for dogs and cats); supplementation with vitamin C may increase vitamin E requirements<ref>Chen LH. Interaction of vitamin E and ascorbic acid (review). In Vivo 1989;3:199-209.</ref>.

The metabolic requirement for vitamin E is dependent on the PUFA concentration in the diet as well as the degree of peroxidation that occurs during processing and storage<ref name="Chow"/><ref name="NRC"/>. '''Diets high in fat and specifically high in long-chain omega-3 PUFAs will increase the tocopherol requirements in the diet'''<ref name="Davidson"/><ref name="Niza"/><ref>Hendricks WH, et al. Vitamin E requirement of adult cats increased slightly with high dietary intake of polyunsaturated fatty acids. J Nutr 2002;132:1613S-1615S.</ref>. Recycling of α-tocopherol is also impaired with concurrent high intakes of vitamin C (a water-soluble vitamin that is not a dietary requirement for dogs and cats); supplementation with vitamin C may increase vitamin E requirements<ref>Chen LH. Interaction of vitamin E and ascorbic acid (review). In Vivo 1989;3:199-209.</ref>.

==Toxicity==

==Toxicity==

There are no published reports of vitamin E toxicity in dogs, though in cats high levels of dietary vitamin E can result in prolonged bleeding times<ref>Strieker MJ, et al. Vitamin K deficiency in cats fed commercial fish-based diets. J Small Anim Prac 1996;37:322-326.</ref>. High dosage of vitamin E supplementation in people has also been associated with increased risk of mortality<ref>Bjelakovic G, et al. Mortality in randomized trials of antioxidant supplements for primary and secondary prevention systematic review and meta-analysis. JAMA 2007;297:842-857.</ref>, though this effect has not been studied in dogs and cats.

There are no published reports of vitamin E toxicity in dogs, though in cats high levels of dietary vitamin E can result in prolonged [[Coagulation Tests|bleeding times]]<ref>Strieker MJ, et al. Vitamin K deficiency in cats fed commercial fish-based diets. J Small Anim Prac 1996;37:322-326.</ref>. High dosage of vitamin E supplementation in people has also been associated with increased risk of mortality<ref>Bjelakovic G, et al. Mortality in randomized trials of antioxidant supplements for primary and secondary prevention systematic review and meta-analysis. JAMA 2007;297:842-857.</ref>, though this effect has not been studied in dogs and cats.

==Dietary Sources==

==Dietary Sources==

Nuts, seeds and seed oils have high concentration of α-tocopherol.  

Nuts, seeds and seed oils have high concentration of α-tocopherol.  

Mixed-tocopherols (i.e., combination of δ- and α-tocopherol) are used in commercial pet foods due to increased stability with processing and storage compared to α-tocopherol alone. The concentration of the biologically active α-tocopherol in mixed-tocopherol can range from 10-40% of the total vitamin E content. Mixed-tocopherols are effective at preventing lipid oxidation that occurs during the processing and storage of foods, but depending on the source may not provide adequate concentrations of α-tocopherol to the diet.

Mixed-tocopherols (i.e. combination of δ- and α-tocopherol) are used in commercial pet foods due to increased stability with processing and storage compared to α-tocopherol alone. The concentration of the biologically active α-tocopherol in mixed-tocopherol can range from 10-40% of the total vitamin E content. Mixed-tocopherols are effective at preventing lipid oxidation that occurs during the processing and storage of foods, but depending on the source may not provide adequate concentrations of α-tocopherol to the diet.

==Diagnosing Vitamin E Deficiency==

==Diagnosing Vitamin E Deficiency==

==References==

==References==

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[[Category:Vitamins]]

[[Category:Vitamins]]