Hypervitaminosis A in the Young Pig

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Abstract
Two experiments were conducted to study characteristics of hypervitaminosis A and to determine levels necessary to evoke symptoms of toxicity in young pigs. Gross toxicity symptoms observed in their general order of appearance included malaise, roughened hair coat, scaly skin, hyperirritability and sensitivity to touch, lacrimation, marked petechial hemorrhages over the legs and abdomen, bleeding from cracks in the skin about the hooves, blood in the urine and feces, loss of strength and control of the legs accompanied by inability to rise, periodic tremors and death. Observations at necropsy included hemorrhage into limb joints, in the mucosa, submucosa, subpericardium and at the corticomedullary junction of the kidney. Cartilage cell columns were disorganized in the enlarged costochondral junctions, which also appeared to be decalcified. Severe toxicity early in life prevented surviving pigs from reaching normal size. Vitamin A toxicity decreased weight gains, feed consumption and feed efficiency. Increased dietary levels of vitamin A had a significant effect on serum inorganic phosphorus and alkaline phosphatase, as well as on plasma hydroxyproline. Alkaline phosphatase, ether extract and phosphorus in bone were also significantly affected. No significant effects on hemoglobin, hematocrit, serum calcium, bone ash or calcium content of bone ash were discernible. Average time required for symptoms of hypervitaminosis A to appear in pigs fed diets containing 1,100,000, 880,000, 660,000 and 440,000 I.U. of added vitamin A per kg. was 16, 17.5, 32 and 43 days, respectively. No symptoms of hypervitaminosis A appeared at 8 weeks in pigs fed diets containing 220,000 I.U. per kg. Copyright © 1966. American Society of Animal Science . Copyright 1966 by American Society of Animal Science

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