Dermatology - Feline Pruritic Skin Disorders

sihirlifil's version from 2017-09-25 15:36

Traumatic Induced Alopecia

Question Answer
Traumatic induced alopecia caused by?Allergic
Miscellaneous (urinary cystitis, impacted anal sacs)
Traumatic induced alopecia results from?Cats barbering, licking, grooming excessively
Traumatic induced alopecia looks…Symmetrical! hardly ever endocrine-related
Diagnostic tools for traumatic induced alopeciaHistory
Trichogram (pluck hair, mineral oil)
Intradermal flea antigen test
What does a trichogram tell you?If hair is broken off, shows that the cat has been barbering instead of hair falling out naturally
What’s the problem with intradermal flea antigen test?Flea allergy could be type I or type IV, so you can’t rule it out if you get a negative (test only works for type I)
Stress in the clinic causes cortisol release which may suppress the test
Allergic alopecia: Distribution pattern?Pre-aural, lateral canthus of eye, head and neck (alone or with back half of body too)
Pre-aural alopecia ddx?Atopy, food allergy
Atopy: diagnostics?Blood allergy test (cortisol and endorphins mess with intradermal test)
Atopy: treatment options?Steroids
Antihistamines (chlorpheniramine)- work well
Immunotherapy- allergy shots great for cats! easier than pilling
Is atopy common in cats?Yes!
Food allergy: diagnostics?Food trial for 8 weeks (Purina HA hydrolyzed chicken, Royal Canin)
Diets: novel protein, hydrolyzed, home cooked (hard to do for cats- taurine)
Are food allergies common in cats?No!
Flea allergy: distribution?Head& neck, back ½
Flea allergy: txSteroids short-term
Avoidance (keep inside)
Flea products
Cyclosporine not helpful!!!
Malassezia: CS?Excessive grooming (periorbital), thick crusts, scale (chin)
Malassezia: treatment optionsSteroid- Methylprednisolone acetate injection (Depo)
Miconazole drops
Is malassezia common in cats?No
Demodex gatoi: location?Surface! not follicle
Demodex gatoi: CS?Pruritis!!!
Is demodex gatoi contagious?Yes. Treat all cats in household (some can only be carriers)
Demodex gatoi: Diagnosis?Short stumpy mite of superficial scrape (epidermis)
Treatment of demodex gatoiLSD (also for scabies & dermatophyte)
Behavioral: diagnosis?By exclusion, history (cause & effect)
Most have underlying cause
Which neoplasia common for cat skin?Mast cell tumor (solitary or diffuse)
MCT causes what CS?Pruritis
MCT: diagnosis?Biopsy
CS of impacted anal sacs/urinary cystitis?Increased scale around the butt from barbering/grooming, potential cause of pruritis

Eosinophilic Reactions

Question Answer
Types of eosinophilic reactionsMiliary dermatitis
Eosinophilic plaque
Eosinophilic granuloma
Indolent ulceration
Most common cause of eosinophilic reactionsEctoparasites
Can be associated with allergies
What must you do after the infection resolves?Biopsy! Relapse is likely unless underlying cause is identified
Miliary dermatitis: CS?Millet-like crusted papules
Miliary dermatitis: DdxHypersensitivity (flea, food, aeroallergens)
Dermatophytosis- must do DTM
Bacterial infection
Ectoparasites (e.g. ear mites)
Miliary dermatitis: Diagnostic tests?Fungal culture
Impression cytology
Skin scrapings
Flea antigen test
Miliary dermatitis: treatment?Methylprednisolone
Depo Medrol (2 weeks)
Fatty acids?
Antihistamines not effective!!! (not the same granules as mast cells)
(Cyclosporine if underlying atopy)
Eosinophilic plaque: CS?Most intense pruritis (moist dermatitis), 2ry infections common (staph)
Eosinophilic plaque: what is it essentially?Like 1000 miliary lesions all coalescing together. Well-demarcated, not self-induced
Eosinophilic plaque: dx?Biopsy
Eosinophilic plaque: DifferentialsMast cell tumor
Eosinophilic plaque: treatment optionsNeed steroids (Methylprednisolone)
Depo Medrol (Walter case)
Concurrent antibiotics if 2ry infection (Cefovecin good)
Eosinophilic granuloma: CS?Not pruritic
Linear granulomas, usually oral, chin, back of throat, down backs of legs
Eosinophilic granuloma: dx?Biopsy
Eosinophilic granuloma: differentials?Kerion form of ringworm
Oral allergy syndrome/flea allergy
Atopy, food allergy
Eosinophilic granuloma: if not steroid-responsive, do what?BIOPSY! Rule out neoplasia
Eosinophilic granuloma: tx?Difficult!
May need like 6 injections of Depo Medrol instead of 1-2
Indolent ulceration: CS?Nonpruritic ulcerations and erosions on lips (not usually planum nasale)
Indolent ulceration: DdxHypersensitivities
Indolent ulceration: If not steroid-responsive what do?Biopsy to rule out SCC


Question Answer
How does Cyclosporine A work? SEffx?Inhibits T-helper cells. Nephrotoxic so don’t use if hx of kidney disease, monitor UA & PU/PD, culture as needed (2ry infections common)
Plasma cell pododermatitis: Signalment & hx?Middle-aged, history of puffy footpads (cat doesn’t notice)/ulcers +/- pain, not progressive
Plasma cell pododermatitis: DdxAutoimmune
Contact reaction
Plasma cell pododermatitis: DiagnosticsBy CS, can biopsy from side of foot (100% diagnostic)
Plasma cell pododermatitis: treatment optionsCyclosporine
Depo Medrol
Doxycycline (give with water and careful of esophageal strictures)
Mosquitos like to bite where?Footpad, nose, ears

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