Loxoscelism is a disease caused by envenomation by spiders belonging to the genus Loxosceles. Loxoscelism (also known as "necrotic arachnidism" or "gangrenous spot") has been mentioned as a disease in humans since the 1870'S,1 but the etiological agent was not discovered until 1934.2 Since the 1930's there has been an abundance of material published on loxoscelism in humans in South America. However, this literature remained mostly unknown in North America until 1957, when a report implicated Loxosceles reclusa as the possible etiological agent of spider-bite in Missouri and other midwestern states. 2 Subsequently a significant amount of research has been reported in the United States on the condition in humans, but no reports have been found in veterinary journals. The lack of reports in the veterinary literature may be responsible for loxoscelism being overlooked or misdiagnosed in animals.