Abstract: Otitis externa is a condition of the outer ear canal in mammalian animals, especially dogs and cats, marked by inflammation and infection of tissue, buildup of ear wax, and draining of ear exudate. Symptoms of infection are, among others, excessive cerumen, alopecia in the ear flap, crusts, and ear pruritis. Typical causes of otitis externa are fungi, bacteria, and mites. A medicating mixture in accordance with the invention, comprising cold-pressed citrus oil, deionized water, and, optionally, hydrolysates of milk proteins, when applied topically to an infected ear canal can produce significant reduction in symptoms. In a clinical study, 95% of an infected population of dogs were normalized without other or further treatment.