Polioencephalomalacia induced with amprolium in buffalo calves--clinicopathologic findings.

Polioencephalomalacia was induced in eight buffalo calves, 6-12 months old, by drenching amprolium (300 mg/kg body weight per day) for 29-55 days. Four buffalo calves of the same age group were drenched with tap water only and served as control. Blood samples were collected at different intervals during amprolium administration until the onset of clinical signs. Cerebrospinal fluid was also collected prior to amprolium administration and at the onset of clinical signs. A significant progressive decrease in erythrocyte transketolase (TK) activity and an increase in the percent of thiamine pyrophosphate (TPP) effect were observed in amprolium-fed calves during amprolium administration until the onset of clinical signs. There was a significant increase in blood lactate and blood pyruvate concentrations and a significant decrease in lactate/pyruvate ratio at the onset of clinical signs. Serum electrolyte (Na, Ca, P, Mg) concentrations showed no significant changes. However, the serum potassium concentration had decreased significantly at the onset of signs. The cerebrospinal fluid analyses revealed a significant increase in lactate and pyruvate concentrations and lactate/pyruvate ratio in amprolium-fed calves. The electrolytes (Na, K, Ca, P and Mg) of cerebrospinal fluid did not show any change. It is concluded that oral administration of amprolium (300 mg/kg body weight daily) for 4-6 weeks produces biochemical changes characteristic of polioencephalomalacia in buffalo calves.