Aspectos clínico-patológicos e laboratoriais do envenenamento crotálico experimental em bovinos

Abstract

Crotalus poisoning was experimentally reproduced by inoculation of Crotalus durissus terrificus (South American Rattlesnake) venom by subcutaneous via in ten clinically healthy mixed breed bovine, weighing between 125 and 449 kg and aged 12 to 36 months. Two bovine of the same age range and breed standard were used as controls. The bovine that received a 0.03 mg/kg p.v. dose died 7h40min after inoculation. A 0.015 mg/kg p.v. dose provoked death in four out of seven inoculated bovine, while two bovine experimentally poisoned with 0.0075 mg/kg p.v. became mildly sick and recovered. Onset of symptoms occurred between 1h30min and 13h45min after inoculation. Evolution oscillated between 5h25min and 44h59min for bovine deaths and between 33h15min and 17 days for bovine that recovered. The principal nervous signs observed were diminished response to external stimuli, hypotonic reflexes, dragging of hooves along the ground, apparent lethargy, difficulties in moving around obstacles, ocular globe paralysis, lateral and sternal decubitus and tongue paralysis. Constant adypsia and petechiae in the conjunctival and vaginal mucosa was also verified. A discrete to moderate increase in bleeding time was verified in six bovine and a moderate increase in partial thromboplastin time was activated in seven bovine. Moderate leukocytosis with neutrophilia, relative lymphopenia, eosinopenia and monocytosis occurred and a discrete increase in the number of rods. A significant increase in creatine kinase serum levels was observed, of a ten-fold order. No significant alterations were observed at urinalysis. At necropsy there were minimal edema at the inoculation site, discrete petechiae and suffusions in the epicardium, omentum, biliary vesicle and bladder mucosa. Histopathological examination revealed necrosis (hyalinization) of groups or isolated myocytes in ten different muscles examined, both close and distant from the inoculation site. Faced with the clinic-pathological picture, observations were made regarding the diagnosis of crotalus envenomation and its differentiation from deseases which course with paralysis and muscular necrosis in cattle in Brazil.