Most cases of acute otitis externa are pruritic.

The pet is presented to the veteri­narian for scratching at the ear, erythematous pinnae, head shaking, or pain when the ears are manipulated. The differential diagnosis for pruritus is extensive and is dealt with in other textbooks on dermatology.

This chapter contains a “rapid-fire” clinical approach to the treatment of the itchy pet with or without otitis externa. Using this approach, treatment for several different etiologic causes of pruritus are addressed at once. Not only does this regimen prom­ise the best chance at fast and lasting relief from pruritus, but it also allows the veterinarian to make a rapid clinical diagnosis based on the response to the various elements involved in the trial. Protocols to treat most known types of ear problems, including Malassezia and bacterial (e.g., Pseudomonas) otitis, follow the discussion of treating pruritus.

Perhaps the most common etiology for acute otitis externa is hypersensitivity. The most common hypersensitivities encountered in small animal practice are flea allergy, food allergy, and atopy. Dogs with atopic dermatitis are presented to the veterinarian with a clinical history of pruritus of the feet, face, axilla, and ears. It has been estimated that as many as 80% of dogs with atopy have otitis externa and pruritic ears. In dogs and cats with food hypersensitivity, otic pruritus may be the only clinical sign. Flea allergy may contribute to overall pruritus, but rarely causes otic pruritus singularly.

If the clinician suspects atopy, then prior to starting this pruritic clinical trial, which involves the use of some corticosteroids, a pretreatment blood sample for in vitro allergy testing should be drawn. The blood should be spun and the serum frozen. Frozen serum can be submitted for in vitro allergy testing for as long as 60 to 90 days without affecting the results. Testing and therapy for atopy is both tedious and expensive. The treatment is lifelong. The following clinical trial affords clients proof that their pet is suffering from hypersensitivity, making the decision to test and hyposensitize easier.

Of course, a good physical examination and observational skills are not to be neglected in attempting to sort out the etiology of dermatologic disease. It is prudent to do skin scrapings, fecal analysis, heartworm testing, fungal culture, skin and ear cytology, and other tests as indicated by clinical common sense during the initial examination.

In addition, recheck visits and the observational skills of the client are crucial to securing an accurate diagnosis. Have the client keep a daily diary of the pet’s response using a scale of 1 to 10 to quantify the intensity of pruritus, erythema, pain, any discharge from the ear, and head shaking.