ClinQuiz: Equine parasites, answer 3B
3) B — Correct.
This is Otobius megnini, the spinose ear tick, a fairly common and profoundly irritating pest found in the ears of horses, cattle, and, occasionally, cats and people. Populations of Otobius species are reported in horses and cattle throughout the world. In North America, this tick is most commonly seen in the western and south central United States and Mexico but is found less commonly in the eastern United States (east of Louisiana, Arkansas, or Missouri).11 However, horses that have traveled to the western or south central states will occasionally return infested. Only immature stages of Otobius species larvae and nymphs; infest animals; the breeding adults are free-living and have vestigial mouthparts.12