Transcript Skin Scrapes and Their Parasitic Friends

Skin Scrapes and Their
Parasitic Friends
Clinical Pathology
Skin Scrape
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Fast and easy diagnostic tool
Inexpensive
Should be one of the first diagnostics
performed when diagnosing
dermatologic disorders.
Items needed for a skin scrape
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Blade (15 or 10)
Mineral oil
Microscope slide
Microscope
Skin Scraping Technique
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Drop mineral oil on skin and/or slide.
• Some prefer just to pass blade through oil
instead of applying to skin.
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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
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Scrape areas that have lesions
Scrape typical sites for particular
ectoparasite
• Ex: ear margins for Sarcoptic mange
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Do multiple skin scrapes
Microscopic exam of the Skin
Scrape Sample
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Identify any ectoparasites.
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Determine live:dead ratios
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Determine life cycle stage
• Eggs, immature, adults
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Determine numbers found
Classification
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Class
• Acarina (mites and ticks)
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Family: Sarcoptidae and Psoroptidae
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Sarcoptidae
• Mites that burrow through epidermis
 Sarcoptes, Notoedres, Knemidocoptes species
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Psoroptidae
• Mites that reside on the skin surface
 Psoroptes, Chorioptes, Otodectes species
Sarcoptes Scabei
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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
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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
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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
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Revolution every 2 weeks (off label).
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Ivermectin orally (extra-label).
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Paramite dips every 7-10 days
(discontinued product).
NEVER USE PARAMITE CONTAINING
DIP IN CATS!!!!!!!!!!!!!!!!!!!!!!!!!!!
Notoedres cati
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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
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Revolution/ Ivermectin
Keep isolated from other cats
Knemidocoptes Species
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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
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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)
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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
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Diagnosis:
• Grossly see with otoscope or with ear
swab
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Treatment:
• Ivermectin
• Acarexx topical
• Pyrethrins
• Revolution
Demodex Species
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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 species
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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
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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
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Cats
• Round, blunt body
• Contagious
• Pruritic
• Treatment: lymesulfur dips
Demodex canis clinical signs
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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
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Location of lesions:
• Face, muzzle, legs/feet, occasionally
trunk.
• Localized or generalized
• Peripheral lymphadenopathy is common
due to secondary infection.
Demodex treatment
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Correct/treat underlying conditions
Neuter/spay
Treat secondary bacterial infections
Topical treatment
• Benzoyl peroxide
• Mitaban (Amitraz) dips
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Ivermectin SID
• Increasing oral dose
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Mibemycin
• (interceptor SID)
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Continue treatment one month beyond a
negative skin scrape.
Malassezia Dermatitis
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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
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Causes moderate to intense pruritis
with regional or generalized alopecia.
Chronic changes:
• Hyperpigmented
• Lichenificiation
• Hyperkeratosis
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Odorous skin
Malassezia diagnosis
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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
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Correct underlying cause
Shampoos
• Ketoconazol
• Miconazol
• Chlorhexidine
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In severe cases use systemic
ketoconazole, iatroconazole