Development and validation of an endoscopic myringotomy technique to treat otitis media and interna in a case series of three guinea pigs (Cavia porcellus)

Background: Medical treatment of clinical otitis media and interna in guinea pigs is often unsatisfactory. Total ear canal ablation and lateral bulla osteotomy are used successfully in dogs, cats, and rabbits to treat chronic, medically nonresponsive ear disease. However, in guinea pigs this surgery can cause death. This study aimed to evaluate and describe a standardized myringotomy technique to treat guinea pigs with otitis media and interna. Methods: Ear dissections and endoscopically assisted myringotomy were evaluated on guinea pig carcasses to choose the most suitable endoscope and optics. Three client-owned guinea pigs with chronic otitis media and interna had a myringotomy with bacteriological sampling and therapeutic irrigation of the tympanic cavity performed. Anesthesia for the procedures was 25 minutes, the patients were recovered and eating within 2–6 hours, and discharged on targeted antibiotic therapy within 24 hours. Videotoscopy was performed at 7- and 14-days follow-up to assess the ear canal, healing of the tympanic membrane, and to evaluate the tympanic cavity. Repeat lavaging of the tympanic cavity was performed until the tympanic membrane incision was healed. Further follow-up occurred at 21- and 154-days postmyringotomy. Results: Two out of three guinea pigs had complete resolution of clinical signs, and the other showed clinical improvement from a 90° head tilt to a 30° head tilt. Conclusions and case series relevance: Videotoscopy assisted myringotomy under general anesthesia was a quick and straightforward endosurgical technique in three guinea pigs with chronic otitis media and interna. It allowed the collection of fluid for bacteriological culture and provided symptomatic relief.