Nematodes in the order Oxyurida are classified into two superfamilies. members of the Superfamily Oxyuroidea are found in vertebrates and the Thelastomatoidea in herbivorous arthropods such as cockroaches. The Oxyurida is the only significant group of nematodes with adult members in both vertebrates and invertebrates.

The only oxyurid of significance in domestic animals is Oxyuris equi found in the cecum and colon of horses. However, a number of species are of importance in humans and laboratory animals.



Predilection sites
Enterobius vermicularis Humans & other primates (gibbons, chimpanzees & marmosets) Cecum & appendix
Passalurus ambiguus Rabbits & hares Cecum & colon
Skrjabinema ovis Sheep & goats Colon
Syphacia obvelata Mice(laboratory & wild) Cecum
Aspiculuris tetraptera Mice (laboratory & wild) & rats Small & large intestines
Oxyuris equi Horses & donkeys Cecum & colon


Oxyuris equi

O. equi is found worldwide in horses and donkeys. The esophagus has a prominent posterior bulb.  They are commonly called pinworms because of their pointed tails and the single pin-shaped spicule of males. Females are larger than males, measuring from 5 to 15 cm in length while males are approximately 1 cm long. The female vulva is situated anteriorly. Oxy1ath.jpg (13708 bytes)
Oxyuris equi - male



Parasites and Parasitic Diseases of Domestic Animals
Dr. Colin Johnstone (principal author)
Copyright 1998 University of Pennsylvania
This page was last modified on January 24, 2000