INTOXICAÇÃO POR UREIA EM BOVINOS NO BRASIL: UMA ABORDAGEM DIAGNÓSTICA

Abstract

GIMELLI, A. Urea poisoning in cattle: a diagnostic approach. MESTRADO – Programa de Pós-Graduação em Ciências Veterinárias. Faculdade de Medicina Veterinária e Zootecnia, Universidade Federal de Mato Grosso do Sul, Campo Grande, MS, 2022. Urea is a solid, hygroscopic and soluble in water substance. It stands out as a source of non-protein nitrogen (NNP) and it is widely used as a partial replacement of protein in cattle feed, which is due to the ability of the ruminal microbiota to use nitrogen (N) in the synthesis of microbial protein that later is used by the host. Despite the advantages involving its use, urea also has limitations, the main one being the narrow margin between metabolizable and toxic or fatal doses. Therefore, to be used safely, an adaptation period is necessary, with a gradual increase in consumption and not exceeding the maximum dose. Urea intoxication is characterized by rapid, and usually fatal, evolution, being frequent in non-adapted animals, but can occur in those with previous adaptation. The aim of this study is to review the clinical, epidemiological and pathological aspects of urea intoxication. In addition, interviews were carried out with veterinarians that frequently send material for diagnosis to LAP-FAMEZ in order to assess their perception of the outbreaks of urea poisoning, in the hope to obtain a comparative picture between the cases received by the laboratory and published surveys and the situation of this condition in the field. In the period of the retrospective study, only four outbreaks were followed, and only in one of them was it possible to prove the ingestion of toxic amounts of urea, through experimental reproduction. Of the 35 participants in the interviews, 88.9% said they had already seen more than one case compatible with urea intoxication, but 87.5% of them reported not having performed a necropsy and/or sent material to confirm the diagnosis. The most cited factors for not sending material were “not deemed it necessary” (63%) and animals found in autolysis (17%). Consumption after rain was the most cited intoxication circumstance by the interviewees (56.3%), followed by the animals' lack of adaptation (43.8%), which is also the most frequent in outbreaks monitored by the laboratory (3/4). Through this study it was possible to observe that the reality of urea intoxication may be very distant from that reported in previous studies, and due to the difficulty often observed in the diagnostic approach, we hope that it constitutes a useful guide for field veterinarians.