Figure 1: Diagnosing Allergic Skin Disease in the Canine Patient
Figure 1 shows an algorithm for diagnosing allergic skin disease in dogs, which consists of the following steps:
- Clinical History and Dermatologic Physical Examination
A detailed history, including a review of previous medical records, should be obtained. Information regarding seasonality, pruritus level, ectoparasite prevention, and response to previous therapies are all paramount in the workup of the pruritic dog. A complete physical examination, including flea combing and otoscopic examination, should be performed. Remember to assess the skin in areas where inflammation may be less obvious, like paws, claws, skin folds, and perianal, axillary, and inguinal regions.
- Minimum Dermatologic Database
A minimum dermatologic database should be collected including skin cytology, skin scrapings, ear cytology (if ear disease is present), and DTM (Dermatophyte Test Medium) culture if indicated.
- Treat Pruritus
This is a key aspect of managing both the patient’s and pet caregiver’s quality of life. Consider antipruritics and/or topical therapy, keeping in mind that these therapies may be less effective if an active infection is present.
- Treat Secondary Infections and Ectoparasites
Secondary bacterial and yeast infections and otitis externa must be treated concurrently with controlling pruritus and diagnosing the underlying allergic disease. Prescribe a flea and tick preventive and discuss compliance with the client.
- Recheck, Verify Medication, and Assess Response to Treatment
Response to therapy should be assessed 14 days after initiation, and it is recommended to discontinue one medication at a time to help determine which, if any, were responsible for the response.
- Diet Trial
Diet trials should be conducted for 4-12 weeks, and a food challenge performed to confirm the diagnosis if there is a positive response. (see Section 1 of the Guidelines for more information on conducting and assessing diet trials).
MDB, minimum dermatologic database; OE, otitis externa.