Description of lesions in lambs intoxicated with sodium selenite included in intraruminal boluses: Lambs intoxicated with selenium.

Selenium is an essential micronutrient for ruminants, which participates in the optimal functioning of proteins and enzymes that can combat oxidative stress in the body; however, its toxicity is documented in different species. The objective of this work was to describe macroscopic and microscopic lesions in lambs intoxicated with selenium administered through intraruminal boluses. The main lesions at necropsy were pulmonary oedema; the myocardial surface presented multifocal pale areas; the thyroid and thymus glands were decreased in size, and areas of necrosis, haemorrhage and hyperkeratosis were observed in the reticulum and rumen. At the microscopic level, congestion, haemorrhage, oedema and hyaline membranes were observed in the lung; hepatic congestion, haemorrhage, degeneration and necrosis; degeneration and necrosis of the reticulum mucosa, as well as areas of hyperplasia and hyperkeratosis; myocardial degeneration, necrosis and fibrosis; congestion, haemorrhage, degeneration and renal tubular necrosis; thyroid follicular atrophy and thymic cortical atrophy. This study evidenced the main lesions related to selenium poisoning in lambs supplemented with the mineral through intraruminal boluses.