Ethylene glycol monomethyl ether effects on health and reproduction in male rabbits

Male Dutch rabbits were weighed and randomly assigned within each weight group to five groups of six animals each (plus one more in the highest dose group). They received 0, 12.5, 25.0, 37.5, or 50.0 mg of ethylene glycol monomethyl ether (EGME) per kg of body weight in the drinking water 5 d/week for 12 weeks. Feed and water consumption were monitored daily and body weight weekly. All animals consumed the water and feed, maintained body weight, and were in good health throughout the experiment. Semen was collected twice weekly for 12 weeks, and 96% of the ejaculates were obtained. By weeks 6 and 9, most males in groups receiving 50.0 or 37.5 mg of EGME per kg were oligospermic. Only minor changes in other characteristics of sperm obtained from treated animals were found, as measured by computer-assisted sperm analysis. Fertility of the males still producing sufficient sperm during week 12 to use for insemination was tested with 96 does producing 2839 oocytes, and fertility of treated males (41%) was not lower (P > 0.05) than 47% in controls. At necropsy, all vital organs were grossly normal, with no notable histopathology. However, the groups of animals receiving 37.5 and 50 mg of EGME per kg of body weight produced fewer sperm and had smaller testes than controls (P < 0.05). Although all rabbits appeared grossly normal, there was a marked disruption of spermatogenesis as ingestion of EGME increased above 25 mg/kg of body weight. Rabbit testes appear to be more sensitive to EGME than testes of rats or mice.