Salt poisoning outbreak in sheep in the state of Para

摘要

This paper reports an outbreak of salt poisoning in sheep on a farm in the state of Para, northern Brazil. Eight (1.46%) animals were affected from a total of 545 sheep and four (50%) of them died. The evaluation of the facilities and the handling indicated as predisposing factors excessive intake of the mineral supplement and water restriction. The main clinical signs were recumbency, decrease or absence of cutaneous sensibility, absence of auricular, palpebral and menace reflex, mydriasis, nystagmus, opisthotonus, spasticity of limbs, somnolence and stupor. Beside these signs bloat, diarrhea, tachypnea, tachycardia, dehydration and polyuria were observed. The course of the disease in animals that died ranged from two hours and a half to 48 hours. The medium of serum concentration of sodium and potassium of 31 sheep from the same group affected on samples collected during the outbreak revealed hypernatremia (190mEq/l) and hyperkalemia (8.2mEq/l). At necropsy, there was flattening of the cerebral gyri in one sheep; in this animal was found vacuolization of the neuropil in the cerebral cortex with moderate intensity in the intermediary and mild on the superficial layers, with increased perineural and perivascular spaces. In these areas there were markedly swollen nucleus of astrocytes with acute neuronal necrosis. The dosage of sodium in the brain of a sheep revealed a high value of 3.513ppm. The diagnosis was made based on the epidemiology, clinical signs, macro and microscopic lesions and in the dosages of sodium in serum and brain.