## Overview The spinose ear tick (Otobius megnini) infests the external ear canal of horses, particularly in dry regions of the western United States and Mexico. Larvae and nymphs feed for weeks to months, causing intense irritation, head shaking, and secondary infection. ## Causes Exposure to environments where the tick is present. Nymphs attach deep in the canal. ## Diagnosis Otoscopic visualization of blue-gray nymphs in the ear canal, plus clinical signs of irritation. ## Treatment Manual removal when possible, acaricides labeled for equine use, and treatment of secondary bacterial otitis. Environmental control reduces reinfestation. ## Recovery and Prognosis Excellent once ticks are eliminated and secondary infection resolves. ## Prevention Regular ear inspection in endemic areas and appropriate environmental management.
head shaking; ear rubbing; ear-shy behavior; dropping feed; visible nymphs in the canal; secondary discharge
## Overview The spinose ear tick (Otobius megnini) infests the external ear canal of horses, particularly in dry regions of the western United States and Mexico. Larvae and nymphs feed for weeks to months, causing intense irritation, head shaking, and secondary infection. ## Causes Exposure to environments where the tick is present. Nymphs attach deep in the canal. ## Diagnosis Otoscopic visualization of blue-gray nymphs in the ear canal, plus clinical signs of irritation. ## Treatment Manual removal when possible, acaricides labeled for equine use, and treatment of secondary bacterial otitis. Environmental control reduces reinfestation. ## Recovery and Prognosis Excellent once ticks are eliminated and secondary infection resolves. ## Prevention Regular ear inspection in endemic areas and appropriate environmental management.
head shaking; ear rubbing; ear-shy behavior; dropping feed; visible nymphs in the canal; secondary discharge