Skin scraping can be used for ectoparasites and dermatophytes. Superficial Skin Scrapes are suitable for scabies and short body Demodex mites. Deep Skin Scrapes are needed for long body Demodex mites. Start by clipping a large area of hair at the site of interest. Apply a thin layer of paraffin oil. If required, sample 2–5 separate areas. For a Superficial Skin Scrape, use a scalpel blade to scrape all scale in a wedge to a collection point. Sampling should not cause bleeding. For a Deep Skin Scrape, lift the skin and squeeze firmly. Sampling should result in capillary bleeding. The paraffin and expressed material should be collected. For both methods, the sample should be mixed with a drop of paraffin oil on a glass slide. A cover slip should be applied and the slide examined under low power (x40 or x100 magnification). SKIN SCRAPING The photomicrograph shows degenerate neutrophils with intra- and extracellular cocci diagnostic for bacterial infection, most likely associated with Staphylococcus pseudintermedi us. Bacterial overgrowth with numerous cocci in the absence of any inflammatory reaction can sometimes be found. Tip: Although antibiotic therapy improves the condition, it is important to identify and treat the underlying disease. Stain the slide, using a modified Wright’s staining system such as DiffQuik ® or RAPI DIFF ® , according to the manufacturers’ instructions. Dip 5-10 times in each solution, starting with fixative solution, followed by stain solution 1 (red eosin dye) and stain solution 2 (blue thiazine dye or methylene blue dye). Rinse with water, then air-dry or dry gently with a hairdryer. Warning: Wear gloves or use forceps to protect your hands from long-lasting stains. STAINING THE SLIDE Examine under a microscope, starting with the lowest magnification. Initially, choose an area showing copious purple material, then use the lenses with higher magnification. Closely examine under the oil immersion lens (x 1,000 magnificatio n) to search for cells and infectious organisms. Tip: To avoid light scatter, which would cause slight blurring of the image, apply a drop of mineral or immersion oil over the stained material. Cover with a cover slip andthen examinemicroscopically. MICROSCOPY Adhesive tape sampling is ideal for sampling greasy or scaly lesions. It is commonly used to find Malasseziaand bacteria, but mites and lice may also be seen. Use a good quality, clear sticky tape and press firmly against the skin. Repeatedly press the tape onto the area to be sampled until the tape is no longer sticky. Fasten the sticky end of the tape to a glass slide, then add a drop of purple DiffQuik ® or RAPI DIFF ® stain and stick the tape down over it. Squeeze out the excess stain and blot away. Alternatively , stain using the conventional DiffQuik ® or RAPI DIFF ® method. Examine under oil immersion (x 1,000 magnification), using the tape as a cover slip. Image and text courtesy of Dermcare-V et, Australia. TAPE SAMPLING Cytology is a quick and easy tool in the diagnosis and management of otitis and skin infections, allowing the presence of organisms to be determined by microscopic examination of prepared slides. This process ensures more accurate targeting of the causal organisms and, as a result, a faster resolution rate. Cytology only takes a few minutes and provides invaluable information that is helpful for both initial assessment and in monitoring the success of therapy. Cytology IMPORTANT: Although the colour, consistency and smell of the otic discharge can give you some idea of what to expect, mere visual and olfactory examination cannot replace cytology. Typical Results It is easier to decide what is abnormal after having examined cytology slides from a few normal sites. Occasional cocci and yeasts are within normal limits, but most fields will only contain translucent, large, polygonal cells without a nucleus i.e. keratinocyte s or skin cells. Some of these keratinocytes are stained purple and may be cigar shaped. Tip: You should send duplicates of your slides to an experienced cytologist when starting out, and compare the cytology report with your own findings. Malasseziapachydermatis yeast is a very common causal organism, often isolated alongside Staphylococcuspseudintermedius (x 2,000 magnification). Note the peanut/footprint/ snowman/Russian doll shape of the yeast. Malassezia pachydermatis is commonly found in patients with atopic dermatitis, but also in other otitis cases. The discharge is often brown/waxy and has a characteristic yeasty odour. Although some yeast organisms can be found in healthy ears, treatment is advised even when relatively small numbers of yeast cells can be seen, if the clinical signs (erythema and/or pruritus) suggest they play a role in the disease. Whenever rod shaped bacteria are seen on cytology, bacterial culture should be performed, because the organisms could be Pseudomonas aeruginosa. Infections with Pseudomonas spp. may require intense medical therapy and carry a cautious prognosis. The antibiotic chosen should always be based on sensitivity testing. It is prudent t o reserve some types of antibiotics for conditions which have responded poorly, or are expected to respond poorly, to other classes of antibiotics. Keratinocyte(cigarshaped) NORMAL CYTOLOGY MALASSEZIA SPP. PSEUDOMONAS SPP. MALASEB ® SHAMPOO CANAURAL ® FUCIDERM ® GEL Dechra Veterinary Products Ltd would like to thank Ariane Neuber (DrMedVet, CertVD, DipECVD, MRCVS) and Dermcare-Vet, Australia for their help in preparing this information sheet. The material should then be gently transferred onto a microscope slide by rolling the cotton bud along the glass surface. Do not rub the swab backwards and forwards because this will disrupt the cellular components. Tip: If marked properly, material from both ears can be spread onto the opposing sides of a single slide, saving time and slides. PREPARING THE SMEAR Depending on the quality of the material, the slide should be air-dried (purulent material) or gently heat fixed with low heat (waxy/oily discharge). Tip: A hairdryer can be used for gentle heat fixation and will also be useful for drying the slide after rinsing. See ‘STAINING THE SLIDE’. FIXING THE PREPARATION It is easy to obtain a sample from the ear by gently removing the otic discharge with a cotton bud. Cotton bud sampling is also suitable for collecting samples from the skin and in areas such as between the toes. Warning! Cotton buds should not be inserted into ears for any reason other than for collecting samples. This could lead to damage to the lining of the ear canal and/or push ceruminous material down toward the tympanic membrane. Tip: If ear mite infestations are suspected, an additional slide should be prepared and examined microscopically, unstained and under low power. COTTON SWAB SAMPLING Bacterial overgrowth Neutrophilwith engulfed cocci BACTERIAL INFECTION/OVERGROWTH Interpretation of cytological slides requires some experience and practice. Examine the sample under high-power x 400 magnification to detect inflammatory cells (mainly neutrophils and macrophages) and under x 2,000 magnification with oil immersion to detect cocci, rods and yeasts. Tip: Make sure you don’t confuse cocci (perfectly round, similarly sized and purple in colour) with melanin granules (black/brown/yellow colour) or irregularly shaped stain aggregates, when focusing up and down. INTERPRETING THE SLIDES Cells (x 400) Yeasts Cocci (x 2,000) Rods (x 2,000) Making a difference to your day CANAURAL: Each g of Canaural contains Fusidic acid (diethanolamine fusidate) 5 mg, framycetin 5 mg, nystatin 100,000 units, prednisolone 2.5 mg. UK: POM-V IE: POM FUCIDERM: Fuciderm Gel contains 0.5% w/w F usidic acid and 0.1% w/w beta methasone valerat e. UK: POM-V IE: POM MALASEB: Malaseb Shampoo contains 2% w/v chlorhexidine and 2% w/v miconazole. UK: POM-V IE: P OM Further informatio n is available on request from: Dechra V eterinary Produc ts Ltd, Cartmel Drive, Harlescott, Shrewsbury, Shropshire SY1 3TB. Tel: +44 (0)1743 441632. Fax: +44 (0)1743 462111. Dechra Vete rinary Products Ltd is a trading division of Dechra Ltd. Registere d Office: Dechra House, Jamage Industrial Estat e, Talke Pits, Stoke-on-Trent, Staffordshir e ST7 1XW. Register ed in England No: 5 385888. www .dechra. com/derma