A young, adult basset hound presents to you for evaluation of chronic recurrent ear pruritus and a strong “musty” odor. Historically, when the ears are cleaned, the odor and discharge respond well but the ear remains inflamed and recurrence is rapid. Repeated bacterial culture and sensitivity test results have been unremarkable. Upon otoscopic examination, you find a brownish waxy discharge. Which of these diagnostic tests would be most useful initially?
What is your diagnosis?
Acknowledgement: The author wishes to thank Ross Bond, DVM, BVMS, PhD, DVD, MRCVS, DECVD, for the use of the photo in this quiz and for his technical guidance.