A 1.5 year old male adult guinea pig (Cavia porcellus) presented with acute vestibular disease, consisting of a right head tilt, circling, and ataxia. The head tilt was non-responsive to initial empirical antimicrobial therapy for presumptive otitis media. Video otoscopy and a myringotomy were performed under general anesthesia. A large amount of purulent debris was flushed from the middle ear and submitted for culture. Treatment with appropriate systemic and topical antibiotics was pursued for 4 weeks. Near complete resolution of clinical signs was achieved by the end of treatment with only a minor residual head tilt. This is the first described use of a diagnostic and therapeutic myringotomy for the treatment and resolution of otitis media in a guinea pig. Based on the clinical success seen in this case and the relative ease of the procedure, myringotomies should be considered for diagnosis and treatment of otitis media in guinea pigs.