DWR Diagnostics Laboratory


Sampling Procedures For Investigating Skin Disease

Skin Scrapes

Should be performed where there is evidence of crusting, scaling, alopecia, erythema or papular/pustular eruptions. To identify Sarcoptes spp, Cheyletiella spp or Demodex spp. Gently squeeze the skin between the thumb and forefinger. Apply 1 drop of liquid paraffin to the area. Scrape the skin area chosen, using a blunted number 10 blade until capillary ooze is created. Scrape the debris gathered on the blade put sample and blade into a sterile universal container. Repeat this in three to five sites and put in the same container, then post it.

Acetate Tape Strips

Used to sample dry, greasy or waxy lesions especially those where Malassezia is suspected. Using a piece of tape (Scotch clear tape preferred) 1 ½ times the length of a slide press the middle of the tape onto the area to be sampled several times. To ensure microorganisms are detected it is best to stain the tape strip using Diff Quik before submission.. The tape is made to form a loop (sticky surface on outside) and is dipped in the pink dye (3 dips) and then purple dye ( 6 dips). The fixative (pot 1 of the Diff Quik set) is not used. The dye is allowed to drip off and the tape is attached to a microscope slide and posted in a slide container.

Glass Slide Impression Smears

Impressions can be taken from any exudative lesion. Pustules should be pricked with a fine gauge needle and then a glass slide pressed to the pustule four or five times, moving the slide slightly every time. The slide should then be heat fixed using a match or lighter before posting in a slide container.

Hair Plucks

To identify Demodex spp, or dermatophte or for fungal culture. Using haemostat forceps pluck hair from the edge of alopecic areas, place in a universal container.

Cotton Swab

For ear cytology. Insert gently into the ear canal, rotate several times and then place in a universal container and post.