Otoscopic, cytological, and microbiological examination of the equine external ear canal.

The research article is about an examination of horse external ear canals via otoscopy, cytology and microbiology to understand its diseases and conditions and to encourage practitioners to conduct such examinations.

Objective of the Research

• The main aim of this study was to highlight the usefulness and feasibility of otoscopic examinations and cytology in diagnosing several diseases in horses such as head trauma, headshaking, otitis externa, vestibular disease, aural neoplasia and aural pruritus.
• The research intends to disprove the stigma in the veterinary field about the perceived difficulty and inconvenience in conducting otic examinations of horses.

Methodology

• The researchers used a handheld otoscope to examine the proximal external ear canal in live horses, and video otoscopy for examining cadaver heads.
• The study found that while the proximal ear canal could be viewed using a handheld otoscope for a sedated horse, further sedation or general anesthesia and a video otoscope would be needed for a comprehensive visualization of the tympanic membrane in the live horse.
• Cytological examinations and aerobic culture were performed on the proximal ear canals of 18 horses, with both ears sampled in three horses. Computed Tomography (CT) imaging and histopathology were used to examine equine cadaver heads in cross-section.

Results

• No cells or organisms were detected in 11 out of 21 ears upon cytological examination. Nine of the ears were sterile when cultured, implying no bacterial growth.
• Low numbers of organisms were observed in 10 of 21 ears, with Corynebacterium sp. being the most common.
• Two of the 21 ears exhibited significant growth of a single organism – Corynebacterium sp. and Staphylococcus intermedius, respectively.

Conclusion

• The research concluded that otic examinations can yield important diagnostic information, therefore equine practitioners should consider it as a vital part of their clinical evaluations.
• The study also emphasized the need to better understand the anatomy of the equine external ear canal, which can be made possible through more advanced diagnostic methods like CT scans and histopathology.