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

This research investigated the impacts of chronic mercuric chloride intoxication in an older horse, revealing signs of severe respiratory difficulty and kidney disease, similar to Fanconi syndrome in humans. Despite the removal of the mercury source, the horse’s health did not improve, and it had to be euthanized due to deterioration.

Key Findings

• Chronic exposure to mercuric chloride resulted in severe respiratory distress and kidney disease in the horse, persisting even after the source of mercury was removed.
• The renal symptoms included high sugar and moderate protein levels in the urine, increased phosphorus in the urine, low urine concentration, increased urine production, decreased kidney filtration rate, and ultimately, the presence of waste products in the blood.
• The overall condition of the horse bore similarities to Fanconi syndrome, a disorder affecting the kidney’s proximal tubules in humans.
• Urine samples showed inconsistent levels of gamma-glutamyl transpeptidase, alkaline phosphatase, and amino-aspartate transferase, indicating possible inconsistency in indicators of kidney tubular damage due to prolonged mercury exposure.

Pathological Findings

• A granulomatous reaction, a form of chronic inflammation, was observed throughout the horse’s lungs and to a lesser extent in the kidneys, liver, and bone marrow.
• In the kidneys, apart from the granulomatous inflammation, there was marked degeneration of the proximal tubules, the part of the kidney involved in the process of urine formation.
• Despite widespread inflammation in the lungs, mercury levels were negligible there. In contrast, the highest concentration of mercury was found in the kidney’s cortex, the outer layer that plays a significant role in kidney function.
• Unlike previous studies of mercury toxicity in horses, this study observed a granulomatous reaction, suggesting a potential individual sensitivity to mercury in this specific horse.