FELINE DERMATOLOGY Karen L. Campbell, DVM, MS, DACVIM, DACVD Professor Emerita, University of Illinois Clinical Professor of Dermatology, University of Missouri Evaluation of the Pruritic Cat Itching is a PAIN • Parasites • Allergies • Inflammation • Neurogenic Parastic causes of feline itching • FLEAS • Demodex gatoi • Demodex cati • Notedres • Cheyletiella • Otodectes • Mosquitoes • Ticks Fleas • May be difficult to find on cats • Check fecal – fleas or tapeworms present? • Manifestations include pruritus, symmetrical hair loss, miliary dermatitis, eosinophilic granuloma complex • Treatment trials • Serum IgE to flea saliva • IDT flea reactivity Feline Demodicosis • Demodex cati • Demodex gatoi Demodex gatoi • Short bodied • Found in the stratum corneum • Contagious • Pruritic • May find mites on skin scrapings or fecal flotation Demodex gatoi • Distribution • Head, neck, elbows • Ventral abdomen • Clinical signs • Alopecia • Scale, erythema • Excessive grooming Demodex gatoi Therapy • Stop any glucocorticoid or progesterone tx • Treat all in-contact animals • Lime sulfur is tradional treatment of choice • improve in 3 weeks • treat for 4-6 weeks minimum • Bravecto for cats: one treatment may be curative • Ivermectin: 300 mcg/kg once weekly, variable response • Advantage Multi (q 7-14 days, variable response) • Amitraz: 125 ppm (1/2 normal strength) Demodex cati Localized follicular demodicosis • Rare condition • Eyelids, periocular, head, neck • Differential for feline acne • Usually responsive to lime sulfur or other mild parasiticides • Often self-limiting Demodex cati Generalized follicular demodicosis • Very rare • Siamese and Burmese at risk • Usually have an underlying condition • FIV, FeLV, Diabetes Mellitus, Bowen’s disease Demodex cati Treatment: generally much easier than K9 • Manage pyoderma • Lime sulfur dip weekly • Ivermectin 300 mcg/kg wkly + Lime sulfur dips • Bravecto for cats should be curative • Amitraz at 125 ppm (1/2 strength) Cheyletiella: “Walking Dandruff” • Large, surface dwelling mite • Highly contagious, poorly host specific (zoonotic) • 3 species • C. yasguri Dogs • C. blakei Cats • C. parasitivorax Rabbits Cheyletiella - Pathogenesis • Non-burrowing mite, lives on skin surface and occasionally pierces skin to feed • Entire life cycle (21 days) takes place on one host • Females may survive in environment for 10 days • Disease prevalence decreasing due to increased use of flea preventatives Cheyletiella – Clinical Signs • Dorsal distribution • Scale • Variable pruritus (possible hypersensitivity in severely pruritic animals) • Exfoliative erythema • Miliary dermatitis or “fur mowing” in cats Cheyletiella - Diagnosis • Visualization of parasite: • Larger than sarcoptes • Prominent mouth hooks • Visualization of eggs: • Small and attached to hair by fine strands (vs large louse nits firmly cemented to hairs) Cheyletiella Cheyletiella - Diagnosis • Methods of parasite visualization: • Direct examination of “walking dandruff” (naked eye or hand lens) • Superficial skin scrape • Acetate tape preparation • Fecal floatation • Flea combing • Vacuum test Cheyletiella • Treatment • All in-contact animals • Minimum of 6 weeks (ideally 2-4 weeks past clinical cure) • Treat environment (pyrethrin spray) • Keratolytic shampoo Treatment • Lime Sulfur: • Dip weekly for 6 weeks • Fipronil: • 0.25% spray: 1-2 pumps/lb q 2 weeks for 3-4 treatments • 10% spot on: apply 1-2 times/month for 3 treatments • Selamectin: • Apply once q 2 to 4 weeks for 3 treatments Otodectes cynotis – “Ear Mites” • Highly contagious, especially in young animals • Not species specific • Cause of >50% of all feline ear disease • 5% of canine ear disease • Asymptomatic carriers are common Otodectes cynotis Complete 3 week life-cycle on a single host Feed/breed in canal • Irritates tissues • Increased cerumen • Mechanical damage • “Coffee ground” debris Migrate all over body • tail base pruritus • miliary dermatitis Otodectes cynotis Diagnosis • Visualization of mites (otoscopy) • Mineral oil prep of debris • Diff-Quick prep of debris for concurrent infections • Response to therapy Otodectes cynotis - Treatment • Treat all in contact animals • Ear Cleaner • Topical or systemic parasiticide Parasites as causes of scaling • Lynxacarus radovsky = cat fur mite • Sarcoptes scabiei var canis • Notoedres cati • Felicola subrostratus Feline Scabies • Notoedres cati • Transient infestation of other animals (foxes, dogs, rabbits, humans) • Highly contagious Feline Scabies • Large numbers of mites are present (easily found on skin scraping) • Die rapidly off host • Smaller than S. scabiei with a dorsal anus (vs terminal anus in S. scabiei) Notoedres: Clinical Signs • Intense pruritus • Distribution: • Medial pinna • Upper ear, face, eyelids, neck • Feet and perineum • Lesions: • Erythematous papule (early) • Thickened, folded skin with extensive yellow crust (chronic) • Excoriations Notoedres - Diagnosis • Clinical signs are strongly suggestive • DDX: Pemphigus, Otodectes, Sarcoptes, Cheyletiella, dermatophytosis, atopy, food, lupus, drug eruption. • Positive skin scrape is diagnostic, mites are easily recovered Notoedres – Topical Treatment • Clip hair NOTE: Permethrin is toxic to cats!! • Keratolytic shampoo • Lime sulfur dip • Weekly for 6-8 weeks • Amitraz: • Increased toxicity in cats Notoedres – Systemic Treatment • Ivermectin: • 200-300 ug/kg SQ every 2 weeks for 3 treatments • Advantage Multi or Selamectin: • Q 2 weeks for three treatments • Bravecto • One dose should be effective Mosquito Bite Hypersensitivity • Erythema, edema, • Keep cats indoors crusting, hair loss, especially at dusk and depigmentation dawn • Antibiotic ointment or oral • Lesions may be pruritic • Topical/oral steroids and/or painful • May affect nose, ear pinnae, chin, eyelids, and/or footpads • Primarily affects outdoor cats during summer months From Clinicians Brief Allergies in cats TYPES OF ALLERGIES • Parasitic • Food • Environmental • “Atopic dermatitis” • Contact • Drug Allergies in Cats • Manifestations include • Pruritus • Feline Miliary Dermatitis • Eosinophilic Granuloma Complex • Feline Symmetrical Alopecia Facial Pruritus • Prior to diagnosis of allergies rule out • Otodectes • Demodicosis • Notedres • Viral/mycoplasma infections • Facial pruritus is most commonly associated with food allergies Feline Miliary dermatitis • Lesions • Variably Pruritic • Papulo-Crustous Eruptions • Location • Dorsum • Neck Feline Miliary Dermatitis Feline Miliary Dermatitis • Etiologies • Ectoparasites • Allergies (often flea allergy, also food allergies and environmental allergies) • Bacterial (usually 2o) • Dermatophytes (rare presentation) • Autoimmune (pemphigus) • Nutritional deficiency? Feline Miliary Dermatitis • Diagnostic workup • Examine for parasites • Woods light exam • DTM culture • Cytology (organisms? acantholytic cells? • Treatment trial • Flea control • if responds continue flea control • Evaluate for allergies • Diet trials • Intradermal allergy testing • Biopsy lesions Eosinophilic Granuloma Complex Three Syndromes Seen • Indolent Ulcers • Eosinophilic Plaques • Linear Granulomas Common Features • Chronic • Circumscribed • Inflammatory Lesions Eosinophilic Granuloma Complex • Diagnosis of underlying cause • History • Physical exam • Response to flea control • Restrictive diet trial • Intradermal allergy test • Skin Biopsies (rule out infections and neoplasia) Indolent Ulcer Indolent Ulcer • More common in females between 5-6 years • Lesion • Ulcer on upper lip • Often bilateral • May have oral ulcers Indolent Ulcers Indolent Ulcer • Histopath • hyperplastic ulcerative dermatitis with PMN, plasma cell, mononuclear cell infiltration • Differential Diagnosis • Squamous Cell Carcinoma • Fibrosarcoma Indolent Ulcer • Treatment • Identify and treat underlying cause • Flea control for flea allergies • Change diet • Environmental allergy control • Desensitization treatment • Antibiotics • Convenia or Clavamox • Systemic corticosteroids • Prednisolone 1mg/kg/day • DepoMedrol 5mg/kg/IM • Cyclosporine • 7 mg/kg/day Indolent Ulcer • Refractory/Recurrent • Tacrolimus topically • CO2 laser • Radiation treatment • Cryosurgery Eosinophilic Plaques Eosinophilic Plaque • More Common in Females • Mean Age 3 Years • Lesion • well-circumscribed • raised • ulcerative plaque Eosinophilic Plaque • Locations • abdomen • back • legs • head • neck Eosinophilic Plaque • Histopath • Eosinophilic and Mast cell infiltration Eosinophilic Plaque • Diagnostic W/U for EGC • Flea control • Restrictive diet trial • Intradermal allergy test • Biopsy Eosinophilic Plaque • Treatment • Identify and treat underlying cause • Flea control • Diet change • Environmental allergy control • Desensitization • Elizabethan collar or sweater (to stop self-trauma) • Antibiotics • Corticosteroid trial • Cyclosporine and/or tacrolimus Linear Granuloma • Either Sex • 1-5 years in age • Lesion • Linear plaque on the posterior aspect of hind legs • Less often found on chin or in mouth • Histopath • necrobiosis of collagen with histiocytic and multinuclear giant cell infiltration with or without eosinophils • Usually secondary to allergies, however must rule out inflammatory/infectious/neoplastic diseases Linear Granuloma Linear Granulomas Linear Granuloma • Treatment • Observation • Identify and treat underlying cause • Flea control • Diet change • Environmental allergy control • Desensitization • Antibiotics • Corticosteroid trial • Tacrolimus or cyclosporine Allergies in Cats • Common manifestations include •