Life Cycle of the Bloodworm

This diagram appeared in the Summer 1978 issue of the Small Farmers’ Journal. It was not an advertisement, but actually part of an article on new methods for deworming horses. Parasitic worms have long been a major problem among horses in domestic environments, up to today. In fact, some studies have suggested that they might be related to ~50% of horse deaths on farms. Bloodworms, the subject of this diagram, are the most dangerous and common of these parasites. They are extremely difficult to deal with because they live in and reproduce through the horse’s digestive system.

Before the advent of veterinary medicine, people devised all kinds of crazy methods of deworming horses. Some of the most dubious of these included feeding horses mercury, tobacco, liquorice, and even their own blood. Beginning in the 1890s, however, veterinarians began to develop and propagate herbal remedies, to various degrees of success. Chemical deworming remedies became quite popular and widespread in the 1940s; but these were largely abandoned by the 1960s as the worms developed resistances and the toxic of effects the chemicals had on horses became more widely known. The 1970s witnessed the invention of a number of important pharmaceuticals that proved much more effective and safe than their chemical counterparts. It was these remedies that were being promoted in this article in the Small Farmers’ Journal.