Multiple bovine abortions with evidence of fetal locoism from pre-clinically intoxicated dams

Abstract

Chronic consumption of specific plant species from the genera Oxytropis, Astragalus, lpomeoa, and Swainsonia, commonly known as locoweeds, is well known to induce locoism in grazing animals. Locoism in cattle is characterized by sensory deficits, ataxia, behavior changes, loss of condition, and failure to grow. The toxic principle swainsonine is rapidly absorbed and distributed through the bloodstream to multiple organs where it inhibits cellular lysosomal alphamannosidase and Golgi mannosidase II, leading to lysosomal dysfunction and disruption of glycoprotein processing. Excessive mannose-rich oligosaccharide accumulations cause cytoplasmic vacuolation and cellular dysfunction. In addition to neurologic disease, chronic consumption of locoweeds is known to induce abortion and embryonic death in neurologically affected dams. We describe multiple cases of bovine abortion associated with chronic locoweed ingestion in non-clinical dams from a herd in southeastern Colorado. Neurons from the cerebral cortex, brainstem, cerebellum, and renal tubular epithelial cells displayed the characteristic cytoplasmic vacuolation observed in adult cases of locoism in the aborted animals. Although chronic ingestion of locoweed is widely known to cause early gestation embryonic death, late-term hydrops amnii, and fetal fluid accumulation, locoweed-induced abortion should be considered as a differential diagnosis for cases ofnon-infectious abortion in grazing cattle, even in the absence of maternal clinical signs. These findings indicate that the bovine fetus may be more sensitive to the abortive effects of swainsonine than previously thought.