Several species of Senecio are widely distributed on pasture lands in Southern Brazil. Farmers from this region are known to complain about declines in reproductive rates in cattl from undetermined causes. Several poisonous plants can cause direct and indirect reproductive disorders in cattle in several countries, including Brazil. However, their pathogenetic mechanisms are still poorly understood. The aim of this study is to describe ovarian lesions in cows with chronic seneciosis, from farms located in the Southwest Mesoregion of Rio Grande do Sul, a southern state in Brazil. Twenty-one cases of bovine chronic seneciosis diagnosed between 2011 and 2014 were analyzed. The study showed that chronic seneciosis is the major cause of death in adult cattle in the region. Four pregnant cows showing classical necropsy large luteal cells (LLG) from the ovaries of these four cows had marked megalocytosis and nuclear pseudo-inclusions. Some LLG showed nuclei with up to 23.69μm in diameter and the increase in size of these nuclei was significantly greater than measured those of control cows. It is concluded that the ingestion Senecio spp. induces ovarian changes in cows and the intoxication should be considered as a possible cause of reproductive failure in cattle herds from this region.
Diseases of cattle; Senecio spp.; seneciosis; pyrrolizidine alkaloid; corpus luteum; megalocytosis.
