Fetotoxicity of Astragalus lentiginosus (Locoweed) in Spanish Goats

Locoweed species—Astragalus and Oxytropis spp. that contain the indolizidine alkaloid swainsonine— are widely distributed on rangelands in North and South America, Mexico, China, and other rangelands throughout the world. Other range plant species including Sida spp. (Seitz et al. 2005), Ipomoea spp. (Damir et al. 1987), and Swainsona spp. (Laws and Anson 1968) from Brazil, Africa, and Australia, respectively, also contain swainsonine and other metabolic toxins that poison livestock and have been problematic for ranchers. Swainsonine poisons livestock by inhibiting the metabolic enzymes lysosomal α-mannosidase and mannosidase II (Dorling et al. 1980). Inhibition of these enzymes results in abnormal oligosaccharide accumulation in cellular lysosomes with accompanying characteristic neurovisceral vacuolation in multiple organ systems (Stegelmeier et al. 1995). Clinically, locoweeds cause intention tremors, generalized depression, nervousness, proprioceptive deficits, aberrant behavior, reproductive dysfunction, emaciation, and death (James et al. 1970). Poisonings with similar etiologies have been reported in Brazil and Mozambique from Ipomoea carnea (Damir et al. 1987, De Balogh et al. 1999) and in Australia from Darling Pea (Swainsona galegiofolia) (Hartley 1978). Swainsonine is found in these plant species and is believed to be partially responsible for the reported toxicoses. The manifestation of clinical effects varies somewhat, depending on the animal species involved. Additionally, locoweeds cause embryo and fetal death, abortions, generalized reproductive dysfunction, and occasional birth defects. There has been a substantial amount of research in sheep fed locoweeds at various stages of gestation (James 1971, Panter et al. 1999); however, there has been relatively no research done on goats, particularly pregnant Spanish goats. Thus, the purpose of this study was to describe the clinical effects of locoweed ingestion on pregnant goats, focusing with ultrasound on the embryo/fetotoxic effects during the late first trimester and early-second trimester of pregnancy using Spanish goats.