Differential diagnosis of feline symmetricalalopecia (Proceedings)

Feline symmetrical alopecia

• Etiology

• A symptom of several possible underlying diseases; Not a specific disease entity. A result of excess symmetrical licking with the “barbs” of the tongue fracturing the hair shafts; Rarely is the alopecia spontaneous.

• Clinical Features

• A non-inflammatory, symmetrical alopecia.

• Most commonly affects the ventral abdomen, inguinal region, perineum, dorsal lumbosacral region, medial and posterior thighs; May also affect the entire ventrum, anterior and medial forelegs.

• May affect “anywhere the cat can lick”.

• Close inspection reveals diffuse thinning of hair rather than “total” alopecia. Owner often unaware of excess grooming behavior.

• May be “secretive” or nocturnal groomers; Problem with “hair balls”.

• Flea Allergy Dermatitis

• Most commonly affects the dorsal lumbo-sacral region, caudo-medial thighs, ventral abdomen, and flanks.

• Warm weather seasonal or non-seasonal pruritus – geographic differences.

• Cutaneous Adverse Food Reactions - “Food Allergy”

• Often affects the ventral abdominal, inguinal regions.

• May also have “miliary lesions” in the pre-aural region, pinnae, neck, periorbital region, and face.

• Non-seasonal pruritus, concurrent GI signs rare!

• Atopic Dermatitis (“Catopy”)

• Most commonly affects the medial thighs, entire ventrum, forelegs.

• May mimic the distribution patterns of Flea Allergy or Food Allergy.

• May be warm weather seasonal, present year round with exacerbations in warm weather, or non-seasonal.

• Parasitic Causes

• Cheyletiellosis (“Walking Dandruff”) - affects primarily the dorsal trunk with excess scaling a major sign. Symmetrical alopecia of the ventral abdomen.

• Demodicosis - Demodex gatoi – short stubby mite. Symmetrical alopecia of the ventral abdomen.

• Otoacariasis (Ectopic Ear Mites) - may mimic the distribution patterns of Flea Allergy, Food Allergy, or Atopy. Usually has concurrent otitis externa.

• Pediculosis (Lice) - Felicola subrostrata. Affects primarily the dorsal trunk. Presence of “nits” on hair shafts.

• Cat Fur Mite - Lynxacarus radovsky. Affects primarily the dorsal trunk. “Salt and pepper” like scale.

• Intestinal Parasite Hypersensitivity - roundworms, hookworms, whipworms, tapeworms, Coccidia. May mimic the distribution patterns of Flea Allergy, Food Allergy, or Atopy.

• Fungal Causes

• Dermatophytosis - most commonly has areas of “patchy” alopecia, scales. History of other pets or humans in the household with skin lesions.

• Malassezia Dermatitis - secondary complication. Brownish discoloration to the skin.

• Miscellaneous Causes

• Hyperthyroidism - excess grooming from “hyperexcitable” behavior.

• Lower Urinary Tract Infections - affects the ventral abdomen.

• Impacted anal glands (Anal sacculitis) - affects the perineal, perianal region.

• Endocrine Causes

• Hyperadrenocorticism - spontaneous symmetrical, truncal alopecia, easily epilated hairs. May have concurrent “skin fragility”.

• Hypothyroidism - ????

• Neoplastic Causes

• Pancreatic Paraneoplastic Alopecia - geriatric cats. Alopecia most commonly on the ventrum and legs. Skin takes on a “shiny” appearance. Easily epilated hairs. Concurrent anorexia, lethargy.

• Psychogenic Causes

• Feline Psychogenic Alopecia - an anxiety neurosis. Often due to a disturbing influence. New puppy or kitten, barking dogs, new baby, recent move, etc. Emotional breeds: Burmese, Siamese, Abyssinian. Sequela to previous pruritic skin disease. Most commonly affects the easiest areas to reach; medial thighs, ventral abdomen, medial forelegs. Darkened hair color in Siamese cats due to melanin pigment increase with cooler skin temperature.

Feline symmetrical alopecia - diagnosis

• Spontaneous vs. Post-traumatic alopecia

• Physical exam - rarely is area completely alopecic, hairs do not easily epilate.

• Trichogram - anagen bulbs with broken distal ends vs. telogen bulbs with fine pointed ends.

• Feline Symmetrical Alopecia: Flea Allergy Dermatitis

• Distribution pattern of lesions - posterior 1/3 of the body.

• Seasonal pruritus.

• Intradermal testing with flea antigen or in-vitro testing for flea.

• Response to intense flea treatment protocol.

• Feline Symmetrical Alopecia: Cutaneous Adverse Food Reactions -“Food Allergy”

• Often affects the ventral abdominal, inguinal regions.

• Non-seasonal pruritus.

• Home cooked, novel protein and carbohydrate elimination diet 8-12 weeks in duration.

• Protein Hydrolysate Diets

• Reduced molecular weight (Daltons) of specific protein in diet.

• Most “allergenic” proteins are in range of 14,000 – 70,000 Daltons.

• Hydrolyzed proteins in the range of 1,000 – 12,000 Daltons.

• Feline Commercial Protein Hydrolysate Diets

• Royal Canin Veterinary Diet: Feline Hypoallergenic HP23 - hydrolyzed soy, chicken fat, rice, beet pulp, fish oil.

• Hill's Prescription Diets: Feline z/d Low Allergen – hydrolyzed chicken and chicken liver, rice, vegetable oil.

• Feline Symmetrical Alopecia: Atopic Dermatitis (“Catopy”)

• Most commonly affects the medial thighs, entire ventrum, and forelegs.

• Seasonal or non-seasonal pruritus.

• Intradermal testing with aeroallergens.

• Aeroallergen specific IgE immunoassay.

• Feline Symmetrical Alopecia: Parasitic Causes

• Most frequently Cheyletiellosis and Demodicosis.

• Skin scrapings, Scotch tape preparations, flea combing, fecal flotation, vacuum technique.

• Response to empirical parasiticidal treatments. Lime sulfur dips vs. selamectin vs. ivermectin vs. fipronil spray.

• Feline Symmetrical Alopecia: Dermatophytosis

• Most commonly have areas of “patchy” alopecia, scales.

• History of other pets or humans in the household with skin lesions.

• Wood's lamp examination, KOH prep, fungal cultures, skin biopsy.

• Feline Symmetrical Alopecia: Hyperthyroidism

• Basal total serum thyroxine (T4).

• Feline Symmetrical Alopecia: Lower Urinary Tract Infections

• Urine culture and susceptibility.

• Feline Symmetrical Alopecia: Impacted anal glands (Anal sacculitis)

• Anal gland extirpation.

• Feline Symmetrical Alopecia: Hyperadrenocorticism

• Spontaneous symmetrical, truncal alopecia, easily epilated hairs.

• May have concurrent “skin fragility”.

• Dexamethasone suppression test - 0.1 mg/kg – baseline, 4 & 8 hours post dexamethasone.

• ACTH stimulation test - measure both cortisol and progesterone.

• Feline Symmetrical Alopecia: Pancreatic Paraneoplastic Alopecia

• Geriatric cats with alopecia most commonly on the ventrum, legs.

• Skin takes on a “shiny” appearance.

• Histopathology - marked follicular atrophy with a mild mononuclear perivascular dermatitis.

• Abdominal ultrasound.

• Serum trypsin-like immonoreativity (TLI).

• Feline Symmetrical Alopecia: Feline Psychogenic Alopecia

• History of change in cat's environment.

• Non-responsive to Prednisolone.

• Elizabethan collar response test.

• Histopathology - normal or very mild superficial perivascular dermatitis.

Feline symmetrical alopecia – treatment

• Flea Allergy Dermatitis

• Environmental treatment - pyrethroid + pyriproxifin; boric acid or sodium polyborate powder.

• Patient treatment - Imidacloprid – q14d + leufenuron – q30d; Fipronil + methoprene – q21d.

• Aqueous hyposensitization with flea salivary antigen.

• Cutaneous Adverse Food Reactions – “Food Allergy”

• Commercial diet avoiding the known offending food source.

• Royal Canin Veterinary Diet: Feline Sensitivity RD30 dry – duck, rice, chicken fat, vegetable oil         

• Royal Canin Veterinary Diet: Feline Sensitivity VR canned – venison, rice.

• Hill's Prescriptions Diets: Feline d/d – Canned – lamb and rice.

• IVD – Limited Ingredient Diets - Feline Diets – duck, rabbit, venison, or lamb and green pea – canned or dry.

• Home-cooked Treatment Diets - “novel” protein and carbohydrate source, essential fatty acid dietary supplement, safflower oil, dicalcium phosphate, non-flavored, additive free vitamin and mineral supplement, and taurine for cats.

• Atopic Dermatitis (Catopy)

• Allergen specific immunotherapy (ASIT).

• Prednisolone (not Prednisone) - 1 mg/kg q12h x 7 d, then q24h x 7 d, then q48h at lowest possible dose to control pruritus.

• Graham-Mize CA, Rosser EJ, Hauptman J: Absorption, bioavailability and activity of prednisone and prednisolone in cats. Adv Vet Derm, vol. 5: 152-158.Greater than a 6-fold difference in Cmax of oral prednisolone (Cmax= 1400 ng/ml) vs. oral prednisone (Cmax= 220 ng/ml); Cmax of oral prednisolone after oral prednisone only 122 ng/ml.

• Results indicate both a decreased gastrointestinal absorption of prednisone compared to prednisolone, and possible decreased conversion of prednisone (inactive form) to prednisolone (active form) by the liver in cats.

• Cyclosporine – 5 mg/kg q24h.

• Parasitic Diseases

• Lime sulfur – q7d x 4 weeks - Cheyletiella, Notoedres, Trombicula, Lynxacarus, Demodex gatoi, Felicola subrostrata.

• Selamectin – q14d x 3 treatments - Cheyletiella, Notoedres, Otodectes.

• Fipronil spray – q30d - Cheyletiella, Notoedres, Felicola subrostrata.

• Ivermectin - 200 ug/kg q7d x 4 weeks - Cheyletiella, Notoedres, Otodectes; 200-300 ug/kg q24h - Demodex cati.

• Amitraz – 125 ppm q14d - Cheyletiella, Notoedres, Trombicula, Lynxacarus, Demodex gatoi, Demodex cati, Felicola subrostrata.

• Dermatophytosis: Systemics

• Itraconazole - 5-10 mg/kg q24h with food for 4-6 weeks.

• Terbinafine - 30 mg/kg q24h for 4-6 weeks.

• Lufenuron - 60-100 mg/kg q30d x 2 treatments.

• Dermatophytosis: Topicals

• Lime sulfur - twice weekly for 4-6 weeks.

• Enilconazole topical solution (10%) - twice weekly for 4-6 weeks.

• Miconazole shampoo and leave on rinse 2% (ResiZole) - twice weekly for 4-6 weeks.

• Hyperadrenocorticism

• Unilateral/Bilateral adrenalectomy - Mineralocorticoid maintenance: Fludrocortisone acetate – 0.1-0.3 mg/cat or Desoxycorticosterone pivalate – 2.2 mg/kg SQ once monthly. Glucocorticoid maintenance: Prednisolone – 1.25-2.5 mg/cat/day

• Metyrapone – 65 mg/kg q12h.

• Pancreatic Paraneoplastic Alopecia

• Screen for evidence of metastasis.

• Radiographs and ultrasound - liver, diaphragm, lungs.

• Partial pancreatectomy.

• Feline Psychogenic Alopecia

• Correct or remove disturbing influence.

• Mood altering drugs

• Clomipramine – 1.25-2.5 mg/cat/d.

• Amitriptyline – 5 mg/cat q12h.

• Hydroxyzine – 10 mg/cat q12h.

• Paroxetine HCl – 2.5 mg/cat q24h.