PATHOLOGY OF SUBACUTE METHYLMERCURIALISM IN CATS

  • 1 January 1977
    • journal article
    • research article
    • Vol. 38  (1) , 59-67
Abstract
Clinical signs of toxicosis, neurologic lesions and increased tissue residues of methylmercury (MM, an environmental contaminant) were produced in 9 cats by oral administration of 1.29 and 0.86 mg of Hg/kg of body wt/day as methylmercuric hydroxide. Clinical signs, which began after 15 days of exposure, included anorexia, ataxia, hypermetria, proprioceptive impairment, blindness, vertical nystagmus and grand mal convulsions. Significant lesions occurred in cerebrum, brainstem and cerebellum and correlated well with clinical signs. Microscopic CNS lesions consisted of neuronal degeneration, necrosis and loss of neurons, swollen axons, demyelination, loss of nerve cell processes, vacuolation of neuropil, gliosis, neuronophagia, perivascular cuffs, endothelial hypertrophy and hyperplasia, leptomeningitis and infrequent vascular necrosis. Overall distribution of CNS lesions was unrelated to daily dose, but more advanced lesions were produced by the smaller daily dose. Mean tissue residues of MM were generally directly related to daily dose, and the average distribution among tissues was constant, with highest concentrations in liver, followed by kidney, spleen, muscle and brain. In utero exposure of kittens to MM revealed transplacental accumulation.

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