Spinose ear ticks are a constant source of annoyance and irritation for their definitive hosts. Their tendency to occur in large numbers can cause ulceration of the inner ear, high sensitivity of the ears, large amounts of blood loss, and even deafness. Heavily infested animals often shake and rub their heads, which can cause their outer ears to become excoriated and raw. Several cases of human infestation have been reported, and the tick has been incriminated in some instances of pathogen transmission
As with many soft ticks, the mouthparts of O. megnini are not visible from the dorsal view. The nymph is somewhat violin shaped with tiny, backward-projecting spines covering the body, which are the reason for the description spinose in the common name. The adult may achieve 10 mm (0.4 in) in length, is brown, and has a slightly granular body cuticle. The male and female close resemble each other; neither possesses a scutum.