Department of Comparative Medicine, College of Veterinary Medicine, The University of Tennessee, Knoxville, TN, USA
Abstract
The fat-soluble vitamin, vitamin E, is a biologic antioxidant that protects cellular membranes from lipid peroxides and free radicals. The clinical appearance of hypovitaminosis E is extremely variable and may include steatitis, myopathy, hemolytic anemia, encephalomalacia, paralysis, paresis, tremors, ataxia, torticollis, exudative diathesis, and/or reproductive problems such as decreased hatchability or fertility.1-6
Pansteatitis due to vitamin E deficiency occurred in three 10-week-old boat-billed heron chicks (Cochlearius cochlearius) at Knoxville Zoological Gardens despite daily vitamin supplementation. The heron diet was prepared in layers and offered free choice. Silversides fish (Menidia menidia) and a vitamin-mineral supplement were placed on top of a commercial bird of prey diet and dry dog food. Chicks presented weak and lethargic. Physical findings included emaciation, yellow-brown subcutaneous nodules, a firm distended coelom, erosions covered by a diphtheritic membrane along the roof of the mouth, and yellow-white, submucosal pharyngeal nodules. Although all adult boat-billed herons behaved normally, mild to moderate amounts of subcutaneous fat were found in all birds. One adult also had a slight distended, firm coelom. Clinical pathology revealed heterophilic leukocytosis, anemia, hypoproteinemia, and low plasma alpha-tocopherol levels (1.94–2.14 µg/ml). Dierenfeld reported a mean plasma alpha-tocopherol level of 9.53 µg/ml ±0.96 (reported range: 7.9–14.2 µg/ml) in six clinically normal, captive boat-billed herons.2 Two of three chicks died. Necropsy revealed coeloms distended with a mass of yellow-brown to golden-yellow, firm, nodular fat. The fat surrounded many abdominal organs as well as the heart and compressed the diameter of the gastrointestinal tract significantly. The chicks also had granulomatous pneumonia and air sacculitis due to Aspergillus fumigatus.
Literature Cited
1. Combs G.F. and M.L. Scott. 1997. Nutritional interrelationships of vitamin E and selenium. Bioscience 7:467–473.
2. Dierenfeld E.S. 1989. Vitamin E deficiency in zoo reptiles, birds and ungulates. J Zoo Wildl Med 20:3–11.
3. Jones T.C., Hunt R.D., King N.W. 1997. Nutritional deficiencies. In: Jones TC, Hunt RD, King NW (eds). Veterinary Pathology. Baltimore: Williams and Wilkins; Pp. 789–793.
4. Lowenstein, L.J. 1986. Nutritional disorders of birds. In: Fowler M.E. (ed). Zoo and Wild Animal Medicine. Philadelphia: WB Saunders; Pp. 209–210.
5. Nichols D.K., Montali R.J. 1987. Vitamin E deficiency in captive and wild piscivorous birds. Proc First Int Conf Zool Avian Med., Turtle Bay, Hawaii. Pp. 419–421.
6. Quesenberry K. 1997. Disorders of the musculoskeletal system. In: Altman RB, Clubb SL, Dorrestein GM, Quesenberry K (eds). Avian Medicine and Surgery. Philadelphia: WB Saunders; Pp. 527–528.