The distribution and urinary excretion of sulfamethoxazole were investigated in healthy buffalo calves. After a single iv dose (100 mg/kg), the blood level peaked at 103.8+-4.3 ug ml-1 at 15 min and declined to 12 ug ml-1 at 24 h. The minimum inhibitory concentration of drug (25 ug ml-1) was maintained up to 12 h. The extent of penetration of sulfamethoxazole in erythrocytes was calculated to be 19-35 %. Fulfamethoxazole rapidly distributed in cerebrospinal fluid (CSF) and interstitial fluid, with concentrations of 8.1-40.7 ug/ml and 11.8-64.7 ug/ml from 15 to 720 min of administration, respectively.

The hematologic parameters (total red blood cell count, hematocrit, hemoglobin concentration, erythrocyte sedimentation rate, mean corpuscular hemoglobin, mean corpuscular volume, mean corpuscular hemoglobin concentration, total white blood cell count, relative and absolute differential white blood cell count) were examined in three (3) castrated male Swamp buffaloes 3-5 years old harnessed to loads of 100 kg, 200 kg, 300 kg and allowed to travel 1,000 meters over an asphalt road for a period of 30 days per load. Blood samples were collected and examined every seventh day of the test period. Except for blood hemoglobin concentration, no significant alterations in the values of most blood parameters examined were observed. The hemoglobin concentration of the animals under test were significantly decreased after harnessing to 100 kg and 200 kg but did not significantly differ from the pre-test values obtained after harnessing to the 300 kg load.