Evolution of cattle intoxications in southern Rio Grande do Sul: Spatial distribution and trends over 42 years

Abstract

Several toxic diseases cause mortality in cattle in southern Rio Grande do Sul State, Brazil. The aim of this study was to carry out a comparative analysis to determine the evolution of the main intoxications that occurred in cattle in southern Rio Grande do Sul from 1979 to 1999 and from 2000 to 2020. The spatial distribution and trend of occurrence of these intoxications over the 42 years in southern Rio Grande do Sul were determined using data from the Regional Diagnostic Laboratory of the Faculty of Veterinary Medicine at the Federal University of Pelotas (LRD-UFPel), which will make it possible to predict their occurrence in the coming years. From January 1979 to December 1999, 3,753 bovine materials were received for diagnosis at LRD-UFPel, and 3,653 cases were received from 2000 to 2020. Of the total number of materials received, 394 were diagnosed as intoxications, with 140 cases from 1979 to 1999 and 252 cases from 2000 to 2020. Out of 140 cases diagnosed in the first 21 years of operation of the LRD-UFPel, 113 (80.7%) were poisoning by plants, 22 (15.7%) by fungi outbreaks, and five (3.57%) by chemical substances. From 2000 to 2020, of the 252 diagnosed outbreaks 224 (88.8%) were caused by toxic plants, 10 (3.96%) by fungi, 12 (4.76%) by chemical substances, and six (2.38%) by insects. In the temporal trend analysis, a significant linear trend was observed with values of p=0.03 and an annual percentage change (APC) of 2.5 for the increase in the number of diagnoses of poisoning in general over the 42 years of the study. When analyzing the temporal trend of poisoning by Senecio spp., there was an increase in the occurrence of the diagnosis, with different characteristics and inflection points over time, with an annual growth rate of 9% in diagnoses during the first 21 years. There was a decrease in the occurrence of poisoning by Solanum fastigiatum, Echium plantagineum, and Claviceps paspali. Furthermore, poisoning by Ramaria flavo-brunnescens and Baccharis coridifolia maintained a similar percentage throughout the study period. It is concluded that toxic diseases will likely remain important causes of cattle death in the region.