Skin Scrapings/KOH Digestion

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Parasitology


Skin Scrapings/KOH Digestion

Test Code: SSE
Test Name: Skin Scraping KOH Digestion

Contact Name: Dr. Mani Lejeune
Contact Telephone: 607-253-3581
E-mail: ml872@cornell.edu

Test Method: Microscopic Examination and Digestion
Sample Required: Representative sample of skin lesion
Collection container: plastic escape proof container or ointment tin
Transport: Ship on cold packs
Test Day: M-F
Lag Time: 1-4 days
Species: All species

Results Format: Identification of parasite recovered, or No Ectoparasites Detected

Interpretation

Skin scrapings for ectoparasites must be submitted in an escape proof container such as a plastic container with a screw top or an ointment tin. All samples must be representative of the lesions on the animal.

Skin scrapings for the diagnosis of mange must be collected in a way that takes into account the nature of the lesion and the location of the mite causing the lesion.

Deep dwelling mites (such as Sarcoptes, Demodex) that cause minimal epidermal hyperplasia and lesions may be recovered by doing the following: dip a scalpel blade in mineral oil, pinch a fold of skin between the thumb and forefinger, hold blade at right angles to the skin, scrape until blood begins to seep from the abrasion, and place the scalpel blade with material removed into an escape proof container. Remember that unless you draw blood, you are not doing a good scraping!!!

Surface dwelling mites (such as Chorioptes) or lice that produce epidermal hyperplasia and exfoliation and lesions may be recovered by scraping the detritus into an ointment tin using the cover as a scraper, or by scraping the detritus with a scalpel blade into an escape proof container.

All skin scrapings are examined grossly using a dissecting microscope. If no arthropods are detected, the entire sample is put into a 5% potassium hydroxide solution and digested. This releases any arthropods that may be caught in tissue exudates or skin. The digested material is then prepared for microscopic examination and identification of any parasites detected.