Caracterização epidemiológica e clinicopatológica de casos de salmonelose em bovinos em Minas Gerais (2014-2024)

Abstract

Cattle ranching is one of the main sectors of Brazilian livestock production and depends on maintaining herd health to ensure productivity, welfare, and biosecurity. Among the bacterial diseases with the greatest impact is salmonellosis, which can cause enteric and septicemic presentation with high morbidity and mortality, especially in young animals. Considering the importance of this disease and the need for up-to-date regional data, this study aimed to characterize cases of salmonellosis diagnosed in cattle at the Setor de PatologiaVeterinária of the Universidade Federal de Lavras (SPV-UFLA) from 2014 to 2024. This is a retrospective study based on the analysis of necropsy files. Epidemiological information (age, sex, breed, production system, and municipality of origin), macroscopic and histopathological findings, bacterial culture and immunohistochemistry data were collected, with histological revaluation of selected cases. The data were reorganized into tables and analyzed descriptively, allowing the systematization of findings from cases over an eleven-year period. During the 2014-2024 period, 865 cattle necropsies were performed, of which 53 (6.1%) were diagnosed with salmonellosis. Among these, 47 cases were classified as septicemic and six as enteric form. The affected cattle derived from 28 municipalities in the Campo das Vertentes, West, South, and Southwest regions of Minas Gerais State. Most cases involved dairy cattle (69.8%), predominantly females (86.8%) and of the Holstein breed (60.3%). The disease primarily affected suckling calves (41.5%) and weaned calves aged 3 to 6 months (30.2%). Cases occurred throughout the year, with higher incidence from september to february, a period associated with higher environmental temperature and humidity. The main necropsy findings included hepatic alterations (66%), gallbladder wall thickening (47.2%), splenomegaly (56.6%), pulmonary reddening and exudation (56.6%), and highlighting of peyer patches (52.8%). Histological exam revealed fibrinoid necrosis, lymphohistiocytic infiltration, hyperemia, thrombosis, and intralesional bacterial collections in various organs, including the intestine, gallbladder, liver, and lungs. Bacterial culture and immunohistochemical analysis, positive in four and five cases respectively, confirmed Salmonella sp., with one culture-positive case identifying the Dublin serovar in liver and lung samples, reinforcing the clinicopathological correlation. The results demonstrate the endemicity of salmonellosis in the region and its higher occurrence in young cattle from dairy systems. Characterization of clinicopathological findings over eleven years contributes to the understanding of disease dynamics and highlights the need for integrated diagnostic, prevention, and control strategies.