INTRODUCTION
Skin scrapes may be performed as a useful diagnostic aid in cases of dermatitis and pruritis. Confirmation of an ectoparasitic infestation and the subsequent identification of the parasite present means that suitable treatment can be promptly administered.

EQUIPMENT

• Protective gloves and apron.
• Assistant - to restrain the animal
• Surgical clippers - to prepare the site for sampling.
• Sterile scalpel blade (size 10) - to collect the sample.
• Liquid paraffin or 10% Potassium hydroxide (KOH) - to facilitate collection of the sample, and to separate debris from parasites and aid their motility (which improves microscopic visualisation).
• Sterile container - in which to store the sample.
• Pencil - to label the sample.
• Microscope slides - to prepare smears.
• Bunsen burner (optional) - to speed up the process of "clearing" (enabling improved microscopic visualisation).
• Microscope - for examination of the prepared slides.

METHOD

1. Put on protective gloves and apron; remember that some ectoparasites are zoonotic.
2. Ask an assistant to restrain the patient.
3. Select a suitable site for sampling. The area may be gently clipped prior to sampling, but take care not to cause further irritation or excoriation. The area/s of the animal affected may also aid in diagnosis since different ectoparasites may tend to favour different parts of the body. (Sarcoptes lesions are most commonly found on the ventrum, ears and elbows; scrapes should be avoided in excoriated areas, instead locate small raised papules from which to obtain your sample).
4. Squeeze a fold of skin between the thumb and forefinger in order to extrude material from the hair follicles.
5. Place a drop of liquid paraffin onto the skin to facilitate the removal of material.
6. Make several scrapings until petechial bleeding (capillary ooze) is present. The depth of the scraping depends upon the type of mite suspected. Deep scrapings are necessary for Demodex which lives in deep epidermal burrows, whilst Notoedres are found nearer to the surface.
7. Place the scalpel bade in a labelled sterile container ready for dispatch to an external laboratory or later in-house examination.
8. Repeat steps 3-6 selecting a new sampling site. As many as 20 scrapings may be
   necessary in order to confirm a Sarcoptes scabiei infestation.
9. Gently smear the sample onto a labelled microscope slide and add 1 drop of
   liquid paraffin.
10. The smear may be heated over a Bunsen flame in order to speed up the clearing process.
11. Apply a cover slip.
12. Examine under the microscope using the x4 or x10 objective.

NOTES
Samples for surface mite investigation are collected using an acetate strip, hair brushing or hair pluck method. Smears may be prepared using the same technique.