VLD 411: Veterinary Clinical Biochemistry and Laboratory Diagnosis - I (0+1)

SKIN SCRAPING

Superficial skin scraping (epidermal surface examination)

• This technique can be used to identify surface mites and multiple scrapings should be taken to increase the likelihood of ectoparasites detection.
• It is important to remove hair coat in the area by gentle clipping (the hair can be mounted and examined separately). After clipping the hairs the area has to be sterilized with spirit. The surface of the skin can than be scraped using a blunt scalpel blade.
• Alternatively, a few drops of liquid paraffin can be applied and spread over the skin-scraping site and then scraped with a blunt scalpel blade.
• It is important to note that 10% KOH should not be applied to the skin directly.

Processing on slide if material is scanty

• The emulsion of scanty material (superficial epidermis) is spread over a microscope slide.
• 2 or 3 drops of 10% KOH is added to it and mixed.
• It is then warmed for about 3 minutes.
• Covered with a glass coverslip and examined under the microscope.
• This technique can be used to identify surface mites and multiple scrapings should be taken to increase the likelihood of ectoparasites detection.

Deep skin scraping (deep epidermal examination)

• The skin scraping procedure is repeated until capillary blood oozes out. This technique is useful in the diagnosis of burrowing and deep follicular mites such as Sarcoptes scabiei and Demodex spp. Multiple sites should be scraped to maximize detection of ectoparasites.

Preservation

• Despatch: The material can be preserved  in 10% potassium hydroxide (KOH) or liquid paraffin or 10% formalin.

Commom ectoparasites

Demodex sp		Elongated body(cigar shape/ carrot shape), short stumpy legs, transversly striated abdomen
Sarcoptes sp		Body is globose and striate with scaly and spinose areas, posterior pairs of legs short, not extending beyond body margin,pedicels bear sucker or bristle and not segmented, terminal anal opening.
Psoroptes sp		Oval in shape, all legs extend beyond body margin, long segmented pedicels with suckers on end of some legs. Anus is in terminal. Dorsal surface devoid of scales and spines.