Some effects of chronic mercuric chloride intoxication on renal function in a horse

Chronic mercuric chloride intoxication in an aged horse given 0.8 mg Hg/kg/day for 14 weeks was manifest by signs of progressive respiratory difficulty and renal disease. The effects were not self-limiting after mercury was withdrawn, and the animal was destroyed six weeks later. Renal function changes included heavy glycosuria, modest proteinuria, phosphaturia, reduced urine osmolality, gradually increasing urine production, reduced glomerular filtration rate, and terminally, azotemia. The condition bore similarities to the Fanconi syndrome in man. Urinary gamma-glutamyl transpeptidase, alkaline phosphatase and amino-aspartate transferase activities were inconsistent indicators of tubular damage in random samples at this dose rate. The pathologic response was characterized by extensive granulomatous infiltration throughout the lungs, in particular, and to a lesser extent in the kidneys, liver and bone marrow. The renal changes included this marked interstitial reaction and proximal tubular degeneration. Mercury levels were negligible in the lungs and highest in the renal cortex. The granulomatous reaction was not encountered in previous mercury toxicity studies in horses and may indicate an individual sensitivity to the agent.