Conductive hearing loss in bighorn sheep

Area of Science:

• Veterinary medicine
• Animal audiology
• Wildlife ecology

Background:

• Psoroptic mange (Psoroptes ovis) is a parasitic infestation affecting various animals.
• External ear canal lesions can potentially impact auditory function.
• Bighorn sheep (Ovis canadensis mexicana) are susceptible to various health challenges in their natural habitat.

Purpose of the Study:

• To investigate if external auditory canal lesions, such as those caused by psoroptic mites, can lead to conductive hearing loss in Mexican bighorn sheep.
• To simulate conditions mimicking mite infestations to assess auditory effects.

Main Methods:

• Conductive hearing loss was simulated in three Mexican bighorn sheep by introducing bone wax or saline solution into the ear canals.
• Auditory brainstem response (ABR) testing was employed to assess hearing function before and after the simulated manipulations.
• The effects of saline solution (loading the tympanic membrane) and bone wax were compared.

Main Results:

• Saline solution in the ear canal resulted in a more pronounced effect on the auditory brainstem response compared to bone wax.
• These findings suggest that alterations in the external auditory canal can significantly impact hearing sensitivity.
• The auditory brainstem response demonstrated measurable changes indicative of hearing impairment.

Conclusions:

• Simulated lesions of the external auditory canal can induce conductive hearing loss in bighorn sheep.
• Psoroptic scabies lesions may compromise hearing sensitivity in bighorn sheep.
• Impaired hearing could increase the susceptibility of bighorn sheep to predation.