Alopecia in Cats PDF - Blackwell's Five-Minute Veterinary Consult

Canine and Feline, Seventh Edition 65 Alopecia—Cats A...

Canine and Feline, Seventh Edition 65 Alopecia—Cats A Alopecia universalis (normal in sphynx cats): ◦◦ Hereditary, complete absence of primary ­ BASICS ­ DIAGNOSIS hairs; decreased secondary hairs. DEFINITION DIFFERENTIAL DIAGNOSIS ◦◦ Sebaceous and apocrine ducts open onto Common problem, seen as abnormal lack of skin surface; oily feel to skin. Infectious hair coat. ◦◦ Wrinkled foreheads; gold eyes; no Dermatophytosis. whiskers; downy fur on paws, tip of tail, PATHOPHYSIOLOGY Parasites and scrotum. Specific and unique for each cause. ◦◦ Mites—Demodex gatoi, cheyletiella, ◦◦ Comedones with or without secondary SYSTEMS AFFECTED notoedres are often pruritic and scaly; folliculitis. Endocrine/metabolic. Demodex cati cause hair loss with minimal Feline hypotrichosis: Hemic/lymphatic/immune. inflammatory change in many cases. ◦◦ Siamese and Devon Rex cats (autosomal ◦◦ Fleas can cause alopecia if patient is Skin/exocrine. recessive alopecia). hypersensitive and pruritic; severe on caudal SIGNALMENT ◦◦ Poorly developed primary telogen hair dorsum, abdomen, and around ears. Age, breed, or sex predilections specific to follicles. ◦◦ Tick attachment sites can cause alopecic each condition. ◦◦ Born with normal coat, which becomes granuloma. Neoplastic- and paraneoplastic-associated thin and sparse as young adult. Bacterial: alopecias generally recognized in older cats. ◦◦ Alopecia secondary to deep bacterial Environmental SIGNS infection. Solar damage—skin can be damaged Depends on specific diagnosis. Knowing ◦◦ Superficial bacterial infections secondary with prolonged sun exposure; most whether cat is pruritic is a very important part to underlying cause. common in outdoor light-colored cats. of workup for alopecia. Viral: Areas with thin hair most affected: ears, ◦◦ Herpesvirus can cause neuralgia, pruritus, eyes, and nose; early signs alopecia, scaling, CAUSES alopecia, and ulcerated eosinophilic skin and erythema; can transform to squamous Infectious—dermatophytosis, parasitic lesions, most commonly on the face. cell carcinoma. (mites, fleas), superficial and deep ◦◦ FIV- and FeLV-associated giant cell Burns/frostbite—burns are location bacterial infections, viral: herpesvirus, dermatosis. dependent’ sometimes have a drip-like papillomaviral plaques, feline immuno- ◦◦ Papillomaviral plaques in older cats may pattern if caused by hot liquid; affect pressure deficiency virus (FIV)– and feline leukemia transform to squamous cell carcinoma. points if due to heating pad. Third-degree virus (FeLV)–associated giant cell burns will have permanent scars. Frostbite dermatosis. Hypersensitivities commonly affects ear tips and causes alopecia Hypersensitivity—atopy/allergy, oral Food, flea bites, or environmental allergens and necrosis. medication reaction, topical medication (atopy)—ears, face, and abdomen are most Scarring is loss of hair follicles and usually reaction. affected. pigment from area of skin. Disorders of hair follicle cycling—telogen Oral medication reactions—severe facial effluvium, Cushing’s (iatrogenic and hyper- pruritus caused by methimazole: symptoms Ischemic adrenocorticism), hypothyroidism resolve when medication discontinued. Post matting/traction—caused by loss of (iatrogenic). Topical parasite preventives—rare cause of blood supply to hair follicle due to tight Congenital—hair follicle dystrophy, alopecia at site of application; usually temporary. prolonged matting or pulling of hair; usually alopecia universalis (normal in sphynx cats), hair regrows with time. Disorders of Hair Follicle Cycling feline hypotrichosis (Siamese and Rex cats), Post traumatic—rare, alopecia with little Telogen effluvium: pinnal hypotrichosis. inflammation can be seen with injuries where ◦◦ Caused by severe stressful situation or Environmental—solar damage, burns, nerve or blood supply interrupted to the skin. hormonal change such as anesthesia/ frostbite, scarring. surgery, parturition, severe illness, drugs. Autoimmune Ischemic—post matting alopecia, post ◦◦ Sudden onset of large symmetric areas of Alopecia areata—rare, alopecia with little traumatic. hair thinning or alopecia. outward inflammation, most common on Autoimmune—alopecia areata, pemphigus ◦◦ Hair regrows over weeks. face and head. foliaceus. Cushing’s syndrome: Pemphigus foliaceus—crusting and alopecia Neoplastic—epitheliotropic lymphoma, ◦◦ Long-term (months) corticosteroid on ears, sometimes nose, feet, and other areas; mastocytosis, squamous cell carcinoma administration, oral or injectable. pruritus variable. in situ. ◦◦ Megestrol acetate administration. Neoplastic Manifestation of internal disease— ◦◦ Hyperadrenocorticism from adrenal Epitheliotropic lymphoma—scaly alopecia, sebaceous adenitis (thymoma-associated tumor or pituitary tumor. eventually plaques and nodules. exfoliative dermatitis), paraneoplastic ◦◦ Causes symmetric alopecic and atrophic/ Squamous cell carcinoma in situ—papillo- alopecia, mural lymphocytic folliculitis, thin skin, sometimes skin fragility/tearing, maviral plaques: in older cats, scaly, crusty, hyperthyroidism, hyperadrenocorticism, ear tips droop. often pigmented, multifocal, sometimes diabetes. Hypothyroidism—iatrogenic is most pruritic. Psychogenic—compulsive disorder. common cause, due to treatment of hyper- Manifestation of Internal Disease RISK FACTORS thyroidism. Thymoma-associated exfoliative dermatitis: FeLV/FIV—reported risk for demodicosis Congenital ◦◦ Nonpruritic dramatic scaling dermatitis (not all cases associated with viral Hair follicle dystrophy/sebaceous gland that starts on head and neck. infection). dystrophy can cause thin hair diffusely or ◦◦ Surgical removal of thymoma resolves waxy accumulations on the hairs. dermatitis over 4–5 months.  66 Blackwell’s Five-Minute Veterinary Consult A Alopecia—Cats (continued) Paraneoplastic alopecia: EXPECTED COURSE AND PROGNOSIS ◦◦ Most cases associated with pancreatic Determined by specific diagnosis. adenocarcinomas, bile duct carcinomas. ◦◦ Nonpruritic alopecia has acute onset, ­ TREATMENT progresses rapidly; bilaterally symmetric, See specific chapters for full list of ventrally distributed (also located along medications, doses, and other therapies. bridge of nose and periocular); hair epilates If pet is compliant, shampoo and topical ­ MISCELLANEOUS easily; dry fissuring footpads; skin often therapy may relieve secondary problems such ZOONOTIC POTENTIAL thin and hypotonic; rapid weight loss. as hyperkeratosis, crusting, or secondary Dermatophytosis—can cause skin lesions in Mural lymphocytic folliculitis—sometimes bacterial infections. humans. paraneoplastic: alopecia of face, eyelids, Cheyletiellosis—can cause irritation in muzzle; skin has thick, waxy feel; histologic humans. lymphocytic invasion of follicular outer root SEE ALSO sheath and epidermis. ­ MEDICATIONS Cheyletiellosis. Hyperthyroidism—alopecia due to DRUG(S) OF CHOICE Demodicosis. self-barbering; can see weight loss as well. Dermatophytosis. Hyperadrenocorticism—symmetric, Demodicosis—fluralaner topically as per label every 3 months; lime sulfur dips at Diabetes Mellitus Without Complication— nonpruritic; older cat if natural, any age if Cats. iatrogenic; can have severe skin fragility. weekly intervals for six dips; other mites and fleas also respond to appropriate topical or Feline Paraneoplastic Alopecia. Diabetes—unkempt and unhealthy coat, oral treatments. Flea Bite Hypersensitivity and Flea Control. skin infections. Hyperadrenocorticism (Cushing’s Syndrome)— Allergic dermatitis—antihistamines only Psychogenic rarely helpful; novel restricted-ingredient diet; Cats. Although anxiety may make overgrooming corticosteroids; cyclosporine (5–7 mg/kg/day Hyperthyroidism. worse from any underlying condition, a pure initially); allergen-specific immunotherapy; Lymphoma, Cutaneous Epitheliotropic. compulsive disorder is very rare; all other ectoparasite control. Pemphigus. causes of alopecia must be ruled out prior to Hyperthyroidism—methimazole, Sebaceous Adenitis, Granulomatous. considering. thyroidectomy, or radioactive iodine Squamous Cell Carcinoma, Skin. CBC/BIOCHEMISTRY/URINALYSIS therapy. Thymoma. Abnormalities may be noted with diabetes Diabetes mellitus—regulation of glucose ABBREVIATIONS mellitus, hyperadrenocorticism, and levels (insulin, weight loss, diet). FeLV = feline leukemia virus. hyperthyroidism. Hyperadrenocorticism—discontinue FIV = feline immunodeficiency virus. glucocorticoids if iatrogenic; if natural, OTHER LABORATORY TESTS ­Suggested Reading FeLV and FIV—risk factors for demodico- trilostane, mitotane, and surgery are options. Backel K, Cain C. Skin as a marker of general Paraneoplastic alopecia—surgical excision sis and other infections. feline health: cutaneous manifestations of Thyroid hormones—document hyperthy- of neoplasia; but neoplasia often fatal. infectious disease. J Feline Med Surg, 2017, Epitheliotropic lymphoma—corticoster- roidism/hypothyroidism. 19(11):1149–1165. oids, lomustine. IMAGING Diesel A. Cutaneous hypersensitivity derma- Sebaceous adenitis—surgical removal of Abdominal ultrasound—assess adrenals in toses in the feline patient: a review of allergic thymoma, corticosteroids, cyclosporine. hyperadrenocorticism and look for neoplasia skin disease in cats. Vet Sci, 2017, 4(2):25. Squamous cell carcinoma in situ—surgical in animals with paraneoplastic syndrome. Mecklenburg L, Linek M, Tobin DJ. Hair excision, retinoids (topical and oral), topical Chest radiographs/ultrasound to rule out Loss Disorders in Domestic Animals. imiquimod cream. thymoma. Chichester: Wiley, 2009. CT scan—look for pituitary or other PRECAUTIONS Vogelnest LJ. Skin as a marker of general neoplasia tumors in animals with hyperadreno- Toxicity with griseofulvin and itraconazole feline health: cutaneous manifestations of corticism. (see Dermatophytosis). systemic disease. J Feline Med Surg, 2017, 19(9):948–960. DIAGNOSTIC PROCEDURES Author Melissa N.C. Eisenschenk Skin scrapes. Consulting Editor Alexander H. Werner Dermatophyte culture. Resnick Parasite treatment trials, since negative skin ­ FOLLOW-UP Acknowledgment The author and editors scrapes do not rule out all parasites. PATIENT MONITORING acknowledge the prior contribution of Karen Skin biopsy. Determined by specific diagnosis. Helton Rhodes. Shirts/collar to prove self-trauma if pruritus is questioned. PREVENTION/AVOIDANCE Food elimination trials if parasites and Determined by specific diagnosis.  Client Education Handout dermatophytes are ruled out. POSSIBLE COMPLICATIONS available online Intradermal allergy testing. Determined by specific diagnosis.