Common internal parasites found in the stomach, large intestine, and cranial mesenteric artery of thoroughbreds in Kentucky at necropsy (1985 to 1986).

A total of 278 Thoroughbreds (less than 1 to 31 years old) were examined at necropsy (July 9, 1985, to Feb 2, 1986) in Kentucky for various internal parasites. Examination was not made of all the horses for each of the parasites. Specific parasites recovered from the stomach of foals (n = 30) and yearlings and older horses (n = 96) and percentage (in parentheses) of each age category infected, respectively, were as follows: Gasterophilus intestinalis 2nd instar (53% and 32%) and 3rd instar (37% and 24%); G nasalis 2nd instar (7% and 8%) and 3rd instar (7% and 10%); Habronema spp immature (7% and 13%); H muscae (3% and 8%); Draschia megastoma (3% and 5%) and lesions (0% and 2%); and Trichostrongylus axei (0% and 3%). Parasites in the large intestine included Anoplocephala perfoliata, which was found in the cecum of 30% of the foals (n = 87) and in 60% of the yearlings and older horses (n = 186). Probstmayria vivipara and immature Oxyuris equi were not found in the colon and rectum of any of the horses (n = 53 foals and n = 101 yearlings and older); mature O equi were not sought. Examination of the cranial mesenteric artery for Strongylus vulgaris revealed immature and/or mature specimens in 9% of foals (n = 87) and 14% of yearlings (n = 44); lesions of S vulgaris were present in 25% of foals (n = 87) and 34% of yearlings (n = 44).