PARASITIC DERMATOSES : DEMODICOSIS - FELINE
- At a glance
- WHAT DOES IT LOOK LIKE?
- WHAT ELSE LOOKS LIKE THIS?
- HOW DO I DIAGNOSE IT?
- HOW DO I MANAGE IT?
- COMMENTS
AT A GLANCE
- Rare overgrowth of skin commensal mite, Demodex cati, generally associated with underlying immunosuppressive or metabolic disease
- Contagious pruritic demodectic mite, Demodex gatoi
WHAT DOES IT LOOK LIKE?
- Demodex cati: alopecia, scaling, erythematous lesions, most common on head, ceruminous otitis
- Demodex gatoi: self induced alopecia of ventrum, forelegs or hips
WHAT ELSE LOOKS LIKE THIS?
- Allergic skin disease with self trauma
- Otic ectoparasites
- Dermatophytosis
- Difficult to distinguish from other pruritic skin diseases leading to over-grooming and self-induced alopecia: flea allergy, food allergy, atopic dermatitis
HOW DO I DIAGNOSE IT?
- Superficial and deep skin scrapes
- Superficial skin scrapes of affected and other household cats, fecal.
- Positive response to 3 lime sulfur dips 5-7 days apart as is a diagnosis of exclusion.
- Should be ruled out prior to diagnosing "psychogenic alopecia".
HOW DO I MANAGE IT?
- Doramectin .2-.6mg/kg SQ q 7 days.
- Lime sulfur dips 2-4% 2X/week for 4-8 weeks. Must treat all in contact cats.
COMMENTS
- Very rare and most often associated with an immunosuppressive or metabolic disease and/or immunomodulatory therapies
- Primary clinical feature is pruritus leading to self induced ventral alopecia
- Contagious
- Only effective treatment is topical lime sulfur
- Diagnosis of exclusion made by response to topical lime sulfur
- Miller, WH, Griffin CE, Campbell KL (eds): Small Animal Dermatology, 7th ed, St Louis, Saunders, an imprint of Elsevier 2013 pp 304 -315.
- Morris DO, Beale KM: Feline Demodicosis. In Bonagura JD (ed): Kirk's Current Veterinary Therapy VIII. Philadelphia, W. B. Saunders. 2000 pp 580-582
abscess
A discrete swelling containing purulent material, typically in the subcutis
alopecia
Absence of hair from areas where it is normally present; may be due to folliculitis, abnormal follicle cycling, or self-trauma
alopecia (“moth-eaten”)
well-circumscribed, circular, patchy to coalescing alopecia, often associated with folliculitis
angioedema
Regional subcutaneous edema
annular
Ring-like arrangement of lesions
atrophy
Thinning of the skin or other tissues
bulla
Fluid-filled elevation of epidermis, >1cm
hemorrhagic bullae
Blood-filled elevation of epidermis, >1cm
comedo
dilated hair follicle filled with keratin, sebum
crust
Dried exudate and keratinous debris on skin surface
cyst
Nodule that is epithelial-lined and contains fluid or solid material.
depigmentation
Extensive loss of pigment
ecchymoses
Patches due to hemorrhage >1cm
epidermal collarettes
Circular scale or crust with erythema, associated with folliculitis or ruptured pustules or vesicles
erosion
Defect in epidermis that does not penetrate basement membrane. Histopathology may be needed to differentiate from ulcer.
erythema
Red appearance of skin due to inflammation, capillary congestion
eschar
Thick crust often related to necrosis, trauma, or thermal/chemical burn
excoriation
Erosions and/or ulcerations due to self-trauma
fissure
Excessive stratum corneum, confirmed via histopathology. This term is often used to describe the nasal planum and footpads.
fistula
Ulcer on skin surface that originates from and is contiguous with tracts extending into deeper, typically subcutaneous tissues
follicular casts
Accumulation of scale adherent to hair shaft
hyperkeratosis
Excessive stratum corneum, confirmed via histopathology. This term is often used to describe the nasal planum and footpads.
hyperpigmentation
Increased melanin in skin, often secondary to inflammation
hypopigmentation
Partial pigment loss
hypotrichosis
Lack of hair due to genetic factors or defects in embryogenesis.
leukoderma
Lack of cutaneous pigment
leukotrichia
Loss of hair pigment
lichenification
Thickening of the epidermis, often due to chronic inflammation resulting in exaggerated texture
macule
Flat lesion associated with color change <1cm
melanosis
Increased melanin in skin, may be secondary to inflammation.
miliary
Multifocal, papular, crusting dermatitis; a descriptive term, not a diagnosis
morbiliform
A erythematous, macular, papular rash; the erythematous macules are typically 2-10 mm in diameter with coalescence to form larger lesions in some areas
nodule
A solid elevation >1cm
onychodystrophy
Abnormal nail morphology due to nail bed infection, inflammation, or trauma; may include: Onychogryphosis, Onychomadesis, Onychorrhexis, Onychoschizia
onychogryphosis
Abnormal claw curvature; secondary to nail bed inflammation or trauma
onychomadesis
Claw sloughing due to nail bed inflammation or trauma
onychorrhexis
Claw fragmentation due to nail bed inflammation or trauma
onychoschizia
Claw splitting due to nail bed inflammation or trauma
papule
Solid elevation in skin ≤1cm
papules
Solid elevation in skin ≤1cm
paronychia
Inflammation of the nail fold
patch
Flat lesion associated with color change >1cm
petechiae
Small erythematous or violaceous lesions due to dermal bleeding
phlebectasia
Venous dilation; most commonly associated with hypercortisolism
plaques
Flat-topped elevation >1cm formed of coalescing papules or dermal infiltration
pustule
Raised epidermal infiltration of pus
reticulated
Net-like arrangement of lesions
scale
Accumulation of loose fragments of stratum corneum
scar
Fibrous tissue replacing damaged cutaneous and/or subcutaneous tissues
serpiginous
Undulating, serpentine (snake-like) arrangement of lesions
telangiectasia
Permanent enlargement of vessels resulting in a red or violet lesion (rare)
ulcer
A defect in epidermis that penetrates the basement membrane. Histopathology may be needed to differentiate from an erosion.
urticaria
Wheals (steep-walled, circumscribed elevation in the skin due to edema ) due to hypersensitivity reaction
vesicle
Fluid-filled elevation of epidermis, <1cm
wheal
Steep-walled, circumscribed elevation in the skin due to edema