A 7-year-old rabbit was presented for scratching the right ear. Examination was consistent with otitis externa. Clinical signs resolved after 1 month of topical treatment with enrofloxacin but recurred 1 month after cessation of treatment. Periosteal reaction was noted in both bullae on radiographic evaluation and culture of the right ear revealed Pseudomonas aeruginosa susceptible to marbofloxacin, amikacin, and gentamicin, with intermediate sensitivity to enrofloxacin. Oral marbofloxacin was administered for 1 month and topical enrofloxacin for 2 months, after which the rabbit began to exhibit signs of pain. Computed tomography (CT) of the skull revealed that the right tympanic bulla was enlarged, misshapen, and filled with material consistent with an exudate. The rabbit was anesthetized and a unilateral total ear canal ablation and lateral bulla osteotomy were performed. Polymethylmethacrylate (PMMA) beads containing either gentamicin or cefazolin were placed within the bulla or surrounding soft tissue. Within 2 weeks, the rabbit was exhibiting normal behavior and was not scratching its ear.
Commentary: Most literature on treatment of otitis in rabbits is in exotic animal or laboratory medicine journals or books. This excellent descriptive article on the management of otitis externa/media is a truly helpful contribution. For example, rabbits do not have a horizontal ear canal. The vertical ear canal extends ventrally to the external acoustic meatus without changing direction.
Several major take-home points are also made: First, the overall approach to otitis externa/media for rabbits is similar to that for dogs and cats. Second, apparently recognition of otitis media in rabbits can be equally as difficult. Although the rabbit in this study reportedly had clinical signs for about 4 months, the findings on CT suggested that the problem had existed much longer. Finally, rabbits are different from cats and dogs with respect to otic exudate, which must be considered when selecting treatment measures. Rabbits produce caseous debris that increases chances for recurrent infection; thus PMMA beads must be used for local antimicrobial treatment.—Karen Moriello, DVM, Diplomate ACVD
Total ear canal ablation and lateral bulla osteotomy for treatment of otitis externa and media in a rabbit. Chow EP, Bennett RA, Whittington JK. JAVMA 239:228-232, 2011.