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

This study examined internal parasites in Thoroughbred horses in Kentucky, detailing the parasites found in different parts of their bodies. The study involved necropsy on 278 horses ranging in age from less than a year to 31 years old.

Study Methods and Participants

• The researchers performed necropsy on 278 Thoroughbred horses in Kentucky from July 1985 to February 1986.
• The sample consisted of horses of various age groups, ranging from less than 1 year old to 31 years old. However, not all horses were examined for each type of parasite.

Parasites Found in the Stomach

• The examination of the stomach of foals and older horses revealed several parasites of varying prevalence, including Gasterophilus intestinalis, G nasalis, Habronema spp, H muscae, Draschia megastoma, and Trichostrongylus axei.
• The prevalence of the different parasites varied between the two groups, with Gasterophilus intestinalis being the most common in both foals (53% and 37% in 2nd and 3rd instars, respectively) and older horses (32% and 24% in 2nd and 3rd instars, respectively).

Parasites Found in the Large Intestine

• In the large intestine, the most common parasite found was Anoplocephala perfoliata, found in the cecum of 30% of the foals and 60% of older horses.
• Two other parasites, Probstmayria vivipara and immature Oxyuris equi were not found in the colon or rectum of any of the examined horses. The mature form of O equi was also not sought.

Parasites Found in the Cranial Mesenteric Artery

• The cranial mesenteric artery of the horses was examined for the presence of the parasite Strongylus vulgaris.
• Both immature and mature specimens were found in 9% of foals and 14% of yearlings.
• Lesions of S vulgaris, an indicator of the presence of this parasite, were found in 25% of foals and 34% of yearlings.