Today's Veterinary Practice

JUL-AUG 2017

Today's Veterinary Practice provides comprehensive information to keep every small animal practitioner up to date on companion animal medicine and surgery as well as practice building and management.

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32 DERMATOLOGY DETAILS Dermatology Diagnostics: Cutaneous Biopsy Sarah Bartlett, DVM, MS, DACVD Animal Dermatology Clinic, Marietta, Georgia DERMATOLOGY DETAILS Biopsy is often an important diagnostic step in determining the cause of cutaneous disease. An accurate diagnosis requires appropriate timing of the biopsy, careful site selection and biopsy technique, selection of a dermatopathologist, good communication between the clinician and the pathologist, and correlation of the results with the clinical picture. In general, biopsy is indicated when a dermatosis is acute and severe, is unusual in appearance, or is not responding to appropriate therapy after 3 weeks. Persistent ulcerations, suspected neoplasms, or vesicular dermatitis should always be biopsied. Biopsy should also be chosen for suspected conditions easily diagnosed by biopsy, such as follicular dysplasia, zinc-responsive dermatosis, sebaceous adenitis, and immune-mediated disease. Biopsy is also indicated in any suspected condition for which therapy is expensive, dangerous, or time consuming. 1 SITE SELECTION At least 3 to 4 biopsy sites should be chosen, unless only a focal lesion is present. A variety of types of lesions should be sampled. Primary lesions, such as pustules, nodules, papules, vesicles, bullae, and tumors, are more likely to provide an answer. However, secondary lesions may also be diagnostic, especially crusts. Scale, comedones, alopecic areas, the margins of ulcers, and hypopigmentation (especially at the nasal planum or mucocutaneous junctions) may also be helpful. Typical locations for a suspected disease should be biopsied, but any atypical locations that are affected should also be included. PREPARATION Timing of the biopsy is important. Active disease is required in order to obtain an accurate diagnosis, and in some cases lesions may be transient. If pemphigus foliaceus is suspected and pustules were previously present, it may be helpful to wait for pustule recurrence. In general, it is better to consider biopsy before the development of secondary changes that may cloud the diagnosis. Withdrawal of corticosteroids and treatment of bacterial infections for several weeks prior to taking biopsy samples is usually necessary to avoid masking of primary pathology. Biopsies can often be performed without sedation. However, sedation may be necessary to minimize patient movement and to increase patient comfort. Biopsies from the nasal planum and paws almost always necessitate deep sedation or anesthesia. I often use a combination of dexmedetomidine and butorphanol for biopsy in these sensitive areas. DERMATOLOGY DETAILS

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