Otobius megnini is a one-host tick with larval and nymphal stages parasitic and the adult stage non-parasitic. Mating occurs off the host and eggs are laid in the environment. The larvae hatch in 3-8 weeks and can survive in the environment for 2-4 months before attaching to a host. Larvae typically develop into nymphs in the ear and nymphs remain on the host from 1-7 months, after which they leave the host and develop into adults. The entire life cycle can be completed in as little as 5 months, but in Canada O. megnini typically has an annual life cycle.
Otobius megnini can cause waxy exudate and severe inflammation in and around the ear, and can lead to secondary bacterial infection which can cause irritation and subsequent skin trauma. Heavy infections can result in ulceration in and around the ear, perforation of the eardrum and occasionally meningitis. In the horse O. megnini infection can cause sweating, pawing, muscle tremors and muscle fasciculations which can be misinterpreted as symptoms of colic. Otobius megnini is not associated with tick paralysis and is not known to transmit any pathogens.
Diagnosis can be made by discovery and identification of the ticks in the ear. Treatment usually relies on the application of acaricides directly to the ear.