Ancylostoma caninum

Ancylostoma caninum is a species of nematode known as a hookworm, which principally infects the small intestine of dogs. The result of A. caninum infection ranges from asymptomatic cases to death of the dog; better nourishment, increasing age, prior A. caninum exposure, or vaccination are all linked to improved survival. Other hosts include carnivores such as wolves, foxes, and cats, with a small number of cases having been reported in humans. Warm and moist conditions are important to allow survival of A. caninum during the free-living stages of its lifecycle, so it is largely restricted to temperate, tropical, and subtropical regions. In parts of the world where these climatic requirements are met such as Sri Lanka, Southeast Asia, and Malaysia, A. caninum is the main cause of hookworm disease in canines. A. caninum females are typically long and wide, while the males are smaller at in length and in width. Males have a copulatory bursa , which consists of spine-like spicules positioned on three muscular rays that grasp the female during mating. As with other nematodes, the sperm lack flagella. The copulatory bursa is a unique feature of Strongylida members, thus making it a useful means for identifying members of this suborder; it is also used to distinguish members within the suborder due to differences in bursa appearance between species. The vulva of A. caninum females is located at the boundary of the second and final thirds of the body. The teeth of A. caninum are found in the buccal capsule and divided into three sets. Two ventral sets form a lower-jaw equivalent, while a further set projects from the dorsal side and loosely equates to an upper jaw. Each ventral set has three points, with those furthest to the sides being the largest. While the ventral sets are prominent, the dorsal set is hidden deeper in the buccal capsule. A. caninum bends its head end upward (dorsally), which has been noted to be a potential source of confusion when determining how the hookworm is oriented. If it has recently ingested blood, A.