Today's Veterinary Practice

MAY-JUN 2014

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Today's Veterinary Practice May/June 2014 46 | DermaTology DeTails tvpjournal.com notion that affected dogs have an autoimmune disease. Any of the bacteria listed previously can cause surface, su- perficial, or deep pyoderma. HOW DO WE DIAGNOSE PYODERMA? Pyoderma is diagnosed by history and clinical examination, and supported by cytologic findings. Cytology is important for several reasons; it: • Identifies coexistent staphylococcal and Malassezia infec- tions; in order to resolve the infections, both need to be treated • Confirms the presence of bacteria and white blood cells • Helps to differentiate pyoderma from other cutaneous dis- eases that mimic, or may coexist with, pyodermas, such as pemphigus foliaceus. Samples can be obtained for cytology in several ways. • Clear tape is an excellent way to collect materials from feet and skin folds, as well as from collarettes. See Step by Step: Using Clear Tape for Cytologic Evaluation of Pyoderma. • Direct impression smears can be obtained from moist lesions and pustule exudate, allowed to dry, and then stained. • A dry #10 blade can collect crusts from very dry lesions, which are then placed on a slide and minced into sterile saline. Once dried, the slide can be stained and examined. Culture and sensitivity is recommended for all general- ized deep pyodermas and if treatment with 2 different class- es of oral antibiotic, repeated courses of a previously effective antibiotic, or one injection of cefovecin 18 fail to resolve any su- perficial or deep infections (Figure 1, page 44). Table 2. antibiotics for Treatment of canine Pyoderma ANTIBIOTIC DOSE AMINOGLYCOSIDES Amikacin 15 mg/kg sc Q 24 H AMPHENICOLS Chloramphenicol 50 mg/kg Po Q 8 H CEPHALOSPORINS (FIRST GENERATION) Cephalexin* 22–30 mg/kg Po Q 8 or 12 H CEPHALOSPORINS (THIRD GENERATION) Cefovecin (convenia)* 8 mg/kg sc; repeat in 2 weeks if necessary Cefpodoxime (simplicef)* 5–10 mg/kg Po Q 24 H (higher doses best) LINCOSAMIDES Clindamycin 11 mg/kg Po Q 12 H Lincomycin 20 mg/kg Po Q 12 H PENICILLIN COMBINATIONS Amoxicillin–Clavula- nate (clavamox)* 20 mg/kg Po Q 8–12 H QUINOLONES/FLUOROQUINOLONES (SECOND GENERATION) Ciprofloxacin (not recommended)† 30 mg/kg Po Q 24 H Enrofloxacin (baytril) 10–20 mg/kg Po Q 24 H QUINOLONES/FLUOROQUINOLONES (THIRD GENERATION) Marbofloxacin (Zeniquin) 5.5 mg/kg Po Q 24 H RIFAMYCINS Rifampin‡ 5–10 mg/kg Po Q 24 H SULFONAMIDES Ormetoprim–Sulfad- imethoxine (Primor) 27.5–30 mg/kg Po Q 24 H Trimethoprim/ Sulfamethoxazole 20–30 mg/kg Po Q 12 H TETRACYCLINES Doxycycline (if sensitive) 10 mg/kg Po Q 12 H Minocycline (if sensitive) 5–10 mg/kg Po Q 12 H * For methicillin-sensitive infections only † Ciprofloxacin, while inexpensive, is a second genera- tion fluoroquinolone with less activity against gram- positive bacteria than desired. In 2 separate studies, it has been very inconsistent in absorption, potentially leading to lack of efficacy and resistance. 19,20 ‡ Keep dose at maximum of 10 mg/kg/day to reduce risk of hepatic damage, including necrosis and death; avoid use with other hepatotoxic drugs. CHALLENGES OF COMPLIANCE • compliance is likely a bigger problem in veterinary medicine than we have realized, 21 and lack of compli- ance is a common factor in treatment failure and/or recurrence of pyoderma. • a component that is often ignored, but very important, is whether the antibiotics are administered correctly and for the full course of therapy. • Poor compliance may allow for selection of more resistant bacteria, contributing to the potential for development of a methicillin-resistant infection. Step by Step: Using Clear Tape for Cytologic Evaluation of Pyoderma 1. Press the tape—sticky side down—onto the lesion, then stain with a modified Wright's giemsa stain, such as Diff- Quick. Do not fix the tape with methanol as it will cloud the tape. 2. after staining, rinse with water and lay—sticky side down—onto a glass slide. 3. Press out excess water with a paper towel; then examine the slide. 4. While the slide can be scanned at lower powers, the oil immersion lens is recommended for examination of bac- teria and yeast. TVP_2014-0506_DermDetails_Infections.indd 46 5/23/2014 3:24:56 PM

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