Skin parasites, layers of skin, derma lesions, disorders of skin

• Sample site: Periphery of lesion at alopecic–hair junction, scrape until minimal capillary oozing for burrowers.

• Prep: Mineral oil on slide → specimen → coverslip → microscopy.

• Record: Species, presenting sign, lesion description, specimen/site, elements seen, diagnosis, management.

• Sample site: Periphery of lesion at _____–hair junction, scrape until minimal _____ oozing for burrowers.

• Prep: _______ oil on slide → _____ → coverslip → microscopy.

• Record: ______, presenting sign, lesion ______, specimen/site, elements seen, diagnosis, management.

1. Otodectes cynotis (ear mites)

2. Notoedres cati (notoedric mange / feline scabies)

3. Sarcoptes scabiei (sarcoptic mange / scabies

4. Demodex (demodectic mange)

5. Cheyletiella (walking dandruff)

ONSDC

Mites and mange

1. Ctenocephalides spp. (fleas)

2. Argas persicus (fowl tick / poultry tick)

3. Rhipicephalus sanguineus (brown dog tick)

4. Dermanyssus gallinae (poultry red mite)

5. Ancylostoma caninum larvae

CARDA

Other ectoparasites

Common ear mite of dogs and cats; highly contagious by direct contact, especially among housemates. Causes ear scratching, head shaking, and dark waxy/ceruminous discharge. Feeds mainly on desquamated epithelial cells, cerumen, and aural exudates in the ear canal; outside the ear, it may feed on blood, serum, and lymph. Slide treatment note: Otodex TX.

Otodectes cynotis (ear mites): Common ear mite of dogs and cats; highly contagious by direct contact, especially among housemates. Causes ear scratching, head shaking, and dark waxy/ceruminous discharge. Feeds mainly on desquamated epithelial cells, cerumen, and aural exudates in the ear canal; outside the ear, it may feed on blood, serum, and lymph. Slide treatment note: Otodex TX.

Otodectes cynotis (ear mites): Common ear mite of dogs and cats; highly contagious by direct contact, especially among housemates. Causes ear scratching, head shaking, and dark waxy/ceruminous discharge. Feeds mainly on desquamated epithelial cells, cerumen, and aural exudates in the ear canal; outside the ear, it may feed on blood, serum, and lymph. Slide treatment note: Otodex TX.

Notoedres cati (notoedric mange / feline scabies

Primarily a feline burrowing mite; may occasionally affect dogs. Produces intense pruritus, crusting, scaling, and alopecia, often beginning on the head, ears, and face. Slide treatment note: ivermectin.

Notoedres cati (notoedric mange / feline scabies): Primarily a feline burrowing mite; may occasionally affect dogs. Produces intense pruritus, crusting, scaling, and alopecia, often beginning on the head, ears, and face. Slide treatment note: ivermectin.

Notoedres cati (notoedric mange / feline scabies): Primarily a ______ burrowing mite; may occasionally affect dogs. Produces intense _____, _____, scaling, and _____, often beginning on the ____, ____, and face.

Slide treatment note: _______.

Sarcoptes scabiei (sarcoptic mange / scabies)

Highly contagious burrowing mite; can temporarily affect humans. Mites burrow into the skin, lay eggs, and feed on epidermal debris, blood, and skin material, causing intense pruritus, alopecia, crusts, and excoriations.

Sarcoptes scabiei (sarcoptic mange / scabies): Highly contagious burrowing mite; can temporarily affect humans. Mites burrow into the skin, lay eggs, and feed on epidermal debris, blood, and skin material, causing intense pruritus, alopecia, crusts, and excoriations.

Sarcoptes scabiei (sarcoptic mange / scabies): Highly ______ burrowing mite; can temporarily affect _____. Mites burrow into the ___, lay eggs, and feed on ______ debris, _____, and skin material, causing intense pruritus, alopecia, crusts, and ______.

Demodex (demodectic mange)

Follicular mite living mainly in hair follicles and sebaceous glands. Usually associated with underlying immune compromise; feeds on follicular/sebaceous secretions including sebum, keratin, and host cells. Slide note: “male” and “female” are life-cycle/sex stages of the mite, not different species.

Demodex (demodectic mange): Follicular mite living mainly in hair follicles and sebaceous glands. Usually associated with underlying immune compromise; feeds on follicular/sebaceous secretions including sebum, keratin, and host cells. Slide note: “male” and “female” are life-cycle/sex stages of the mite, not different species.

Demodex (demodectic mange): ______ mite living mainly in ____ follicles and _____ glands. Usually associated with underlying ______ compromise; feeds on follicular/sebaceous secretions including _____, _____, and host cells.

Slide note: “____” and “______” are life-cycle/sex stages of the mite, not different species.

Sarcoptes burrows in the skin, is highly contagious, spreads by direct contact or contaminated items, and may temporarily affect humans as scabies. Demodex lives in hair follicles/sebaceous glands and is usually linked with immune compromise.

_______ burrows in the skin, is highly contagious, spreads by direct contact or contaminated items, and may temporarily affect humans as scabies. ______ lives in hair follicles/sebaceous glands and is usually linked with immune compromise.

Cheyletiella (walking dandruff)

Surface mite causing cheyletiellosis; dandruff-like scaling may appear to move because of mite movement on the skin surface.

Cheyletiella (walking dandruff): Surface mite causing cheyletiellosis; dandruff-like scaling may appear to move because of mite movement on the skin surface.

Cheyletiella (walking dandruff): _______ mite causing cheyletiellosis; _____-like scaling may appear to move because of mite movement on the skin surface.

Feature	Sarcoptic mange	Demodectic mange
Agent	Sarcoptes	Demodex
Contagious?	Yes; highly contagious	Usually no; linked with immune issues
Mite location	Burrows in skin	Hair follicles / sebaceous glands
Treatment focus	Antiparasitic medication	Antiparasitic medication + manage underlying immune problem

Feature	Sarcoptic mange	Demodectic mange
Agent	Sarcoptes	Demodex
Contagious?	Yes; highly contagious	Usually no; linked with ______ issues
Mite location	Burrows in ____	_____ follicles / _____ glands
Treatment focus	_____ medication	Antiparasitic medication + manage underlying _______ problem

Ctenocephalides spp. (fleas)

External parasites that feed on blood; may cause pruritus, irritation, flea allergy dermatitis, anemia in heavy infestations, and secondary skin lesions.

Argas persicus (fowl tick / poultry tick)

Small soft-bodied tick found mainly on domestic fowl such as chickens and ducks.

Rhipicephalus sanguineus (brown dog tick)

Important dog tick and vector; commonly associated with tick infestation on skin and ears.

Dermanyssus gallinae (poultry red mite)

Poultry mite that can cause irritation and blood loss.

Ancylostoma caninum larvae

Infective hookworm larvae may penetrate the skin and cause cutaneous larva migrans; lesions often appear on body parts that contact the ground. Slide note: larvae are migrating.

1. Macule

2. Patch

3. Papule

4. Plaque

5. Nodule

6. Cyst

7. Vesicle

8. Bulla

9. Pustule

10. Hematocyst

11. Petechiae

12. Purpura

13. Ecchymoses / bruises

MPPPN CVBPH PPE

Primary lesions

Macule

Small, flat, circumscribed color change; slide note: macule is less than 1 cm.

Patch

Larger flat discolored lesion; slide note: patch is a macule greater than 1 cm.

Papule

Small solid raised lesion; slide note: papule is elevated and less than 1 cm.

Plaque

Elevated, palpable, broad/flat-topped lesion larger than 10 mm or greater than 1 cm; may form by coalescing papules.

Nodule

Small solid bump / deeper solid lesion, usually involving dermis or subcutis.

Cyst

Sac-like cavity filled with solid, semisolid, liquid, air, or other material; slide note: a true cyst has a lining sac, while a false cyst lacks a lining and may be related to trauma or inflammation.

Vesicle

Small fluid-filled blister.

Bulla

Larger fluid-filled blister, usually greater than 1 cm.

Pustule

Elevated lesion filled with pus / purulent exudate.

Hematocyst

Blood-filled cyst-like or blister-like lesion; compare with bulla because both may look blister-like but contain different material.

Petechiae

Smallest hemorrhagic lesions; pinpoint non-blanching red to purple spots in skin or mucous membranes.

Purpura

Larger hemorrhagic lesions, about 4–10 mm, that may be multifocal or coalescing.

Ecchymoses/ bruises

Largest hemorrhagic lesions, usually greater than 1 cm.

Lesion	Surface / content	Key size / feature
Macule	Flat discoloration	Less than 1 cm
Patch	Flat discoloration	Greater than 1 cm
Papule	Raised, solid	Less than 1 cm
Plaque	Raised, broad	Greater than 1 cm / larger than 10 mm
Vesicle	Fluid-filled	Small blister
Bulla	Fluid-filled	Large blister, greater than 1 cm

Lesion	Surface / content	Key size / feature
______	Flat discoloration	Less than 1 cm
______	Flat discoloration	Greater than 1 cm
______	Raised, solid	Less than 1 cm
_____	Raised, broad	Greater than 1 cm / larger than 10 mm
_____	Fluid-filled	Small blister
_____	Fluid-filled	Large blister, greater than 1 cm

Comedo

Follicular plugging with keratin and sebum (“blackhead”); slide examples include Schnauzer comedo syndrome and blackheads.

Excoriation

Self-induced superficial skin abrasion, erosion, or ulceration from scratching, biting, rubbing, or chewing, often due to intense pruritus.

Fissure

Linear crack or split through the epidermis and sometimes dermis, often from loss of skin elasticity.

Scale

Visible flakes of stratum corneum / dried skin or epithelial tissue from abnormal keratinization.

Crust

Dried serum, blood, pus, inflammatory exudate, or dead epithelium on the skin surface.

Epidermal collarette

Circular rim of scale from ruptured vesicles or pustules; often seen as peeling edges around lesions.

Erosion

Superficial epidermal loss that heals without scarring; may be seen with excoriation from scratching, biting, or rubbing.

Ulceration

Full-thickness epidermal loss extending into dermis that may scar; excoriation may progress into ulceration when scratching/chewing is severe.

Scar

Permanent fibrous tissue / mark replacing normal dermis after injury.

Sclerosis

Pathologic hardening from increased fibrous connective tissue; slide example also included nuclear sclerosis, an aging opacity of the lens in dogs.

Induration

Firmness due to edema, inflammation, or fibrosis in dermis/subcutis.

Lichenification

Thickened skin with exaggerated lines from chronic rubbing/licking.

Hyperpigmentation

Increased melanin or darkening of skin after inflammation or endocrine disease.

Folliculitis

Inflammation of hair follicles; slide note: papule = elevated, pustule = pus, and folliculitis lesions may show papules, pustules, and crusts centered on hair follicles.

Perifolliculitis

Inflammation around the hair follicle.

Furunculitis / furunculosis

Deep infection/inflammation of a hair follicle with follicular rupture, abscess formation, pus, and necrotic tissue. (boils or caruncles)

Intertrigo

Maceration and inflammation of skin folds due to moisture, friction, accumulated skin secretions, and secondary infection.

1. Keratosis

2. Hyperkeratosis

3. Orthokeratosis / orthokeratotic hyperkeratosis

4. Parakeratosis / parakeratotic hyperkeratosis

5. Acanthosis nigricans / hyperpigmentation

6. Epitheliogenesis imperfecta

7. Hypertrichosis

8. Ichthyosis

9. Solar dermatosis

10. Callus

11. Paronychia

12. Seborrhea

13. Spongiosis

14. Erythema

15. Urticaria / hives

16. Wheal & flare reaction

17. Alopecia

18. Lupus erythematosus

KHOPA EHISC PSSEU WAL

Pathologic disorders of skin

Keratosis

General term for abnormal keratin formation or thickening/keratin accumulation in the epidermis or stratum corneum.

Hyperkeratosis

Specific increase in thickness of the stratum corneum due to increased keratin.

Orthokeratosis / orthokeratotic hyperkeratosis

Excess keratin with mature keratinization; cornified cells lack retained nuclei.

Parakeratosis / parakeratotic hyperkeratosis

Hyperkeratosis with retained nuclei in the stratum corneum / cornified layer.

Acanthosis nigricans / hyperpigmentation

Hyperpigmented, thickened skin often in flexures; not a specific disease but a reaction pattern to certain conditions.

Epitheliogenesis imperfecta

Congenital absence/defect of skin or mucosa leading to ulcerated areas at birth.

Hypertrichosis

Excessive hair growth beyond normal for breed/region.

Ichthyosis

Inherited disorder of cornification causing generalized scaling

Solar dermatosis

UV-induced skin injury causing erythema, scaling, and potential neoplasia.

callus

thickening of skin due to friction

intertrigo

skin fold dermatitis

folliculitis

inflammation of hair follicle

perifolliculitis

inflammation of structures surrounding hair follicle

furunculosis (penetrating folliculitis)

due to rupture of hair follicle

keratosis

excessive formation of keratin

paronychia

inflammation of skin surrounding the nails

seborrhea

increased greasiness, scaling and crusting of skin

spongiosis

intercellular edema

wheal and flare reaction

edema and redness of skin due to hypersensitivity/ allergic reactions