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Skin Scrapes and Their Parasitic Friends. Clinical Pathology. Skin Scrape. Fast and easy diagnostic tool Inexpensive Should be one of the first diagnostics performed when diagnosing dermatologic disorders. Items needed for a skin scrape. Blade (15 or 10) Mineral oil Microscope slide

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Skin Scrapes and Their Parasitic Friends

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Skin scrapes and their parasitic friends

Skin Scrapes and Their Parasitic Friends

Clinical Pathology

Skin scrape

Skin Scrape

  • Fast and easy diagnostic tool

  • Inexpensive

  • Should be one of the first diagnostics performed when diagnosing dermatologic disorders.

Items needed for a skin scrape

Items needed for a skin scrape

  • Blade (15 or 10)

  • Mineral oil

  • Microscope slide

  • Microscope

Skin scraping technique

Skin Scraping Technique

  • Drop mineral oil on skin and/or slide.

    • Some prefer just to pass blade through oil instead of applying to skin.

  • Gently squeeze the skin area that you are scraping. Hold the blade perpendicular to the skin.

  • Scrape until a small of amount of capillary blood oozes. (careful to not cut).

  • May place coverslip if you like.

  • Examine entire slide in a systematic fashion (start with 10x objective)

Skin scrape hints

Skin Scrape Hints

  • Scrape areas that have lesions

  • Scrape typical sites for particular ectoparasite

    • Ex: ear margins for Sarcoptic mange

  • Do multiple skin scrapes

Microscopic exam of the skin scrape sample

Microscopic exam of the Skin Scrape Sample

  • Identify any ectoparasites.

  • Determine live:dead ratios

  • Determine life cycle stage

    • Eggs, immature, adults

  • Determine numbers found



  • Class

    • Acarina (mites and ticks)

      • Family: Sarcoptidae and Psoroptidae

      • Sarcoptidae

        • Mites that burrow through epidermis

          • Sarcoptes, Notoedres, Knemidocoptes species

      • Psoroptidae

        • Mites that reside on the skin surface

          • Psoroptes, Chorioptes, Otodectes species

Sarcoptes scabei

Sarcoptes Scabei

  • Oval with 8 legs

  • Long unjointed pedicles with suckers on the end.

  • Terminal anus

  • Eggs are oval/brownish

  • Entire life cycle is on host

  • Female mites burrow through epidermis

  • Over 10-15 day period 40-50 eggs are deposited in tunnels

  • Larva emerge in 3-10 days.

Sarcoptes scabei symptoms

Sarcoptes scabei symptoms

  • EXTREME pruritis

  • Erythema, papules, scaling, crusting excoriations.

  • Location: Ears, lateral elbow/hock, ventral abdomen (termed ventral “blowout”).

  • Scratch reflex: When scratch on ear margin, dog scratches.

Sarcoptic transmission etc

Sarcoptic Transmission, etc

  • Transmitted through direct contact

  • Diagnosis is through physical exam and history.

  • Since mites burrow into skin is very easy to get negative skin scrapes.

  • May have to do repeated skin scrapes

  • Zoonosis- mites are self-limiting in humans (Scabies).

Sarcoptic treatment

Sarcoptic Treatment

  • Revolution every 2 weeks (off label).

  • Ivermectin orally (extra-label).

  • Paramite dips every 7-10 days (discontinued product).

  • NEVER USE PARAMITE CONTAINING DIP IN CATS!!!!!!!!!!!!!!!!!!!!!!!!!!!

Notoedres cati

Notoedres cati

  • Roundish shape, smaller than scabie mite

  • Dorsal anus

  • Same type of legs as scabie mite

  • Mainly found in cats and occasionally in rabbits.

  • Location: Head, neck, ears, back of head and sometimes feet.

  • Crusts, excoriations, scales

  • Pruritis

  • Is contagious

Notoedres cati treatment

Notoedres cati Treatment

  • Revolution/ Ivermectin

  • Keep isolated from other cats

Knemidocoptes species

Knemidocoptes Species

  • Scaly leg mite of birds

  • Burrows under the scales of legs and toes

  • Some species may cause depluming around head/neck.

  • Intense pruritis

  • Diagnose through skin scrape

  • Treatment: Ivermectin????

Family psoroptidae psoroptes cuniculi

Family Psoroptidae: Psoroptes cuniculi

  • Ear canker mite of Rabbits

  • Lesions are dried, flaky crusts within the ear canal.

  • Pruritic

  • Treatment: Ivermectin Subcutaneously or topically at 2 week intervals.

  • Do not clean ears- they are very painful and will bleed

Otodectes cynotis ear mites

Otodectes cynotis (ear mites)

  • Mainly in ear canal, but may be found on any area of the body

  • Mite feeds on epidermal debris

  • Produces intense irritation

  • Usually bilateral

  • Contagious

Otodectes cynotis

Otodectes cynotis

  • Diagnosis:

    • Grossly see with otoscope or with ear swab

  • Treatment:

    • Ivermectin

    • Acarexx topical

    • Pyrethrins

    • Revolution

Demodex species

Demodex Species

  • Host specific

  • Reside in hair follicles and sebaceous glands

  • Small numbers are part of the normal skin flora of all dogs

  • In immunodeficiencies, these mites increase in numbers

  • Possible genetic predisposition.

Demodex species1

Demodex species

  • Demodex canis-dogs

  • Demodex cati-cats

  • Dmodex gatoi-cats

  • Demodex bovis-bovine

  • Demodex ovis-sheep

  • Demodex caprae-goat

  • Demodex equi-horse

Demodex canis and cati

Demodex canis and cati

  • Elongated, spindle shape

  • Adults: 8 stubby legs

  • Larvae: 6 stubby legs

    • When diagnosing demodex cati need to rule out underlying disease like Feline Leukemia/FIV, etc.

Demodex gatoi

Demodex gatoi

  • Cats

    • Round, blunt body

    • Contagious

    • Pruritic

    • Treatment: lyme-sulfur dips

Demodex canis clinical signs

Demodex canis clinical signs

  • Often begin with localized lesions that spread.

  • Patchy, multifocal or diffuse alopecia

  • Variable erythema

  • Silver/grayish scales

  • Papules or pustules

  • Variable pruritis-localized usually not pruritic unless infected

  • Secondary lesions- hyperpigmented, lichenification, crusty, ulcerated, folliculitis from secondary bacteria.

Demodex canis

Demodex canis

  • Location of lesions:

    • Face, muzzle, legs/feet, occasionally trunk.

    • Localized or generalized

    • Peripheral lymphadenopathy is common due to secondary infection.

Demodex treatment

Demodex treatment

  • Correct/treat underlying conditions

  • Neuter/spay

  • Treat secondary bacterial infections

  • Topical treatment

    • Benzoyl peroxide

    • Mitaban (Amitraz) dips

  • Ivermectin SID

    • Increasing oral dose

  • Mibemycin

    • (interceptor SID)

  • Continue treatment one month beyond a negative skin scrape.

Malassezia dermatitis

Malassezia Dermatitis

  • Yeast found in low numbers in the ear canal, peri-orally, peri-anally, and moist skin folds

  • Almost always associated with underlying disease (atopy, food allergy, endocrine disorders)

  • Common in dogs- rare in cats

Malasezzia continued

Malasezzia continued

  • Causes moderate to intense pruritis with regional or generalized alopecia.

  • Chronic changes:

    • Hyperpigmented

    • Lichenificiation

    • Hyperkeratosis

  • Odorous skin

Malassezia diagnosis

Malassezia diagnosis

  • Skin scrape and stain, skin imprint, tape prep

  • Lesions may involve interdigital spaces, axillary region, neck.

  • Cytology reveals budding yeast (round to oval)

Malassezia treatment

Malassezia treatment

  • Correct underlying cause

  • Shampoos

    • Ketoconazol

    • Miconazol

    • Chlorhexidine

  • In severe cases use systemic ketoconazole, iatroconazole

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