Canine and Feline Alopecia - Dogs PDF

Canine and Feline, Seventh Edition 67 Alopecia—Dogs A...

Canine and Feline, Seventh Edition 67 Alopecia—Dogs A RISK FACTORS Epitheliotropic lymphoma—diffuse, Chronic corticosteroid use causes hair cycle generalized truncal alopecia with scaling and arrest with other signs of iatrogenic Cushing’s. intense erythema; later nodule and plaque ­ BASICS formation. DEFINITION Pemphigus foliaceus—hair loss associated Common disorder. with scale and crust formation. Characterized by complete or partial loss of Sebaceous adenitis—hair straightening, hair in areas where it is normally present. ­ DIAGNOSIS thinning, with dry hyperkeratosis; standard May be associated with multiple causes, be DIFFERENTIAL DIAGNOSIS poodles and crosses, Havanese, other breeds. the primary problem, or be secondary to an Allergic dermatitis with secondary Multifocal Alopecia underlying cause. Demodicosis—partial to complete alopecia infections and self-trauma due to pruritus. PATHOPHYSIOLOGY with erythema, comedones, and mild scaling; Specific Locations Multiple causes. lesions may become inflamed and crusted. Pinnal alopecia/pattern baldness— Represents removal of hair or disruption in Dermatophytosis—partial to complete miniaturization of hairs and progressive the growth of the hair from hypersensitivity, alopecia with scaling, with or without alopecia; dachshund, greyhound, American infection, genetic abnormality, trauma, erythema, not usually ring-like. water spaniel, Portuguese water spaniel, immunologic attack, mechanical “plugging,” Staphylococcal folliculitis—circular patterns Boston terrier, Manchester terrier, whippet, endocrine abnormalities, neoplasia, drug of alopecia with epidermal collarettes, erythema, Italian greyhound, Chihuahua. reaction, and/or blockage of receptor sites for crusting, and hyperpigmented macules. Pinnal alopecia with crusting or necrosis— stimulation of hair growth cycle. Injection/topical medication reactions— consider vasculitis, which can have many inflammation with alopecia and/or cutaneous triggers. SYSTEMS AFFECTED atrophy from scarring. Traction alopecia—hair loss secondary to Endocrine/metabolic. Rabies vaccine vasculitis—well-demarcated having barrettes or rubber bands applied to Hemic/lymphatic/immune. patch of alopecia observed 1–3 months post the hair, or prolonged tight matting of the Skin/exocrine. vaccination. Small-breed dogs more predisposed. hair. SIGNALMENT Alopecia areata—noninflammatory areas of Post-clipping alopecia—failure to regrow Age, breed, and sex predilections are specific complete alopecia. after clipping associated with slow or arrested to each cause listed. Sebaceous adenitis of short-coated breeds— hair cycle. SIGNS annular to polycyclic areas of alopecia and Melanoderma (alopecia of Yorkshire May be acute in onset or slowly progressive. scaling. terriers)—symmetric alopecia of pinnae, Multifocal patches of alopecia are associated Symmetric Alopecia bridge of nose, tail, and feet. with folliculitis caused by demodicosis, Seasonal/cyclic/canine flank alopecia— Hyperadrenocorticism—truncal alopecia dermatophytosis, or, most commonly, associated with atrophic skin, comedones, serpiginous flank alopecia with hyperpig- staphylococcus infection. and pyoderma, as well as other systemic signs. mentation; boxer, English bulldog, Airedale Large, more diffuse areas of alopecia may Hypothyroidism—thinning of truncal terrier. indicate follicular dysplasia or metabolic Black hair follicular dysplasia—alopecia of haircoat; generalized alopecia is uncommon component. presentation; alopecic “rat” tail. black-haired areas only. Pattern and degree of hair loss, along with Dermatomyositis—alopecia of face, tip of Noninflammatory alopecia (alopecia presence of pruritus, are important for X)—symmetric truncal alopecia associated ears, tail, and digits; associated with scale establishing differential diagnoses. with hyperpigmentation; alopecia often starts crusting and scarring. CAUSES along collar area of neck; Pomeranian, chow Breed-Related Alopecia Infectious—dermatophytosis, parasitic chow, Akita, Samoyed, Keeshonden, Alaskan Alopecic breeds—Chinese crested, Mexican (mites, fleas), superficial and deep bacterial Malamute, and Siberian husky. hairless, Inca hairless, Peruvian Inca orchid, infections. Hyperestrogenism (females)—symmetric American hairless terrier (often associated Hypersensitivity/reaction—atopy/allergy, alopecia of flanks and perineal and inguinal with comedones, folliculitis, and furunculosis). oral medication reaction, topical medication regions with enlarged vulva and mammary Congenital hypotrichosis—cocker spaniel, reaction. glands; may also be associated with exogenous Belgian shepherd, poodle, whippet, beagle, Disorders of hair follicle cycling—telogen hormone exposure. French bulldog, Yorkshire terrier, Labrador effluvium, Cushing’s (iatrogenic and hyper- Male feminization from Sertoli cell tumor— retriever, bichon frise, Lhasa apso, basset hound. adrenocorticism), hypothyroidism alopecia of perineum and genital region with Color dilution alopecia—blue or fawn (iatrogenic), alopecia X, seasonal flank gynecomastia. Doberman pinscher, silver Labrador, cream alopecia. Seasonal/cyclic/flank alopecia—common, chow chow, blond Irish setter, blue pit bull Congenital—hair follicle dystrophy. serpiginous flank alopecia with hyperpig- terrier, other breeds with dilute coat colors. Environmental—solar damage, burns, mentation; boxer, English bulldog, Airedale Melanoderma with alopecia—Yorkshire frostbite, scarring. terrier. terrier. Ischemic—post-matting alopecia, barrette Color mutant/dilution alopecia—brittle or Seasonal/cyclic/canine flank alopecia— or rubber band too tight, dermatomyositis, coarse hair, thinning of blue or fawn-colored serpiginous flank alopecia with hyperpig- post vaccine, vasculitis. hair coat, and secondary folliculitis; other mentation; boxer, English bulldog, Airedale Autoimmune—alopecia areata, pemphigus colors of hair normal. terrier. foliaceus, sebaceous adenitis, vasculitis. Follicular dysplasia—slowly progressive Pinnal alopecia/pattern baldness— Neoplastic—epitheliotropic lymphoma. alopecia affecting one color of hair. miniaturization of hairs and progressive Manifestation of internal disease—hypo- Anagen defluxion and telogen defluxion— alopecia; dachshund, greyhound, American thyroidism, hyperadrenocorticism. acute onset of alopecia due to stressful event. water spaniel, Portuguese water spaniel, Boston  68 Blackwell’s Five-Minute Veterinary Consult A Alopecia—Dogs (continued) terrier, Manchester terrier, whippet, Italian Dermatophytosis—terbinafine, ketoconazole, SEE ALSO greyhound, Chihuahua. fluconazole, itraconazole, lime sulfur dips, Demodicosis. Noninflammatory alopecia (alopecia griseofulvin. Dermatophytosis. X)—symmetric truncal alopecia associated Staphylococcal folliculitis—investigate and Flea Bite Hypersensitivity and Flea with hyperpigmentation; alopecia often starts treat underlying cause, shampoo and antibiotic Control. along collar area of neck; Pomeranian, chow therapy. Hyperadrenocorticism (Cushing’s chow, Akita, Samoyed, keeshond, Alaskan Sebaceous adenitis—topical therapy, Syndrome)—Dogs. Malamute, Siberian husky. essential fatty acid supplementation, Hypothyroidism. CBC/BIOCHEMISTRY/URINALYSIS cyclosporine. Lymphoma, Cutaneous Epitheliotropic. Rule out metabolic causes such as hyperadreno- Iatrogenic Cushing’s—stop all glucocorti- Pemphigus. corticism. coids. Sebaceous Adenitis, Granulomatous. Natural hyperadrenocorticism—trilostane, Sertoli Cell Tumor. OTHER LABORATORY TESTS mitotane, surgical removal of tumor. Thyroid panel—do not rely on low T4 ABBREVIATIONS Hypothyroidism—levothyroxine supple- (total thyroxine) alone); diagnose hypo- ACTH = adrenocorticotropic hormone. mentation. HDDST = high-dose dexamethasone- thyroidism. Follicular dysplasia—control concurrent Adrenocorticotropic hormone (ACTH)- suppression test. allergies and infections. LDDST = low-dose dexamethasone- response test, low-dose dexamethasone- Alopecia X and seasonal flank alopecia— suppression test (LDDST), and high-dose suppression test. sometimes responds to melatonin. T4 = Total thyroxine. dexamethasone-suppression test (HDDST)— Ischemic lesions—consider pentoxifylline. evaluate for hyperadrenocorticism. ­Suggested Reading Sex hormone profiles (questionable CONTRAINDICATIONS Behrend EN, Kooistra HS, Nelson R, et al. validity, often not useful for diagnosis or N/A Diagnosis of spontaneous canine therapy). POSSIBLE INTERACTIONS hyperadrenocorticism: 2012 ACVIM IMAGING None consensus statement (small animal). J Vet Ultrasonography—evaluate adrenal glands for ALTERNATIVE DRUG(S) Intern Med, 2013 27(6):1292–1304. evidence of hyperadrenocorticism. None Mecklenburg L, Linek M, Tobin DJ. Hair Loss Disorders in Domestic Animals. DIAGNOSTIC PROCEDURES Chichester: Wiley, 2009. Cytology. Moriello KA, Coyner K, Paterson S, Mignon Skin scraping. B. Diagnosis and treatment of dermatophytosis Fungal culture. ­ FOLLOW-UP in dogs and cats: clinical consensus Skin biopsy—very useful to evaluate status guidelines of the World Association for of follicle/hair growth as well as epidermal PATIENT MONITORING Determined by cause. Veterinary Dermatology. Vet Dermatol, changes associated with specific conditions. 2017, 28(3):266–e68. POSSIBLE COMPLICATIONS Morris DO. Ischemic dermatopathies. Vet N/A Clin North Am Small Anim Pract, 2013, 43(1):99–111. ­ TREATMENT Vandenabeele S, Declercq J, De Cock H, Treatments depend on the underlying Daminet S. Canine recurrent flank alopecia: causes of alopecia; see specific chapters for ­ MISCELLANEOUS a synthesis of theory and practice. Vlaams each condition. Diergeneeskd Tijdschr, 2014, ASSOCIATED CONDITIONS 83(6):275–283. Bathing can be useful as adjunctive therapy N/A Author Melissa N.C. Eisenschenk for many conditions. AGE-RELATED FACTORS Consulting Editor Alexander H. Werner N/A Resnick Acknowledgment The author and editor ZOONOTIC POTENTIAL acknowledge the prior contribution of Karen ­ MEDICATIONS Dermatophytosis can cause skin lesions in Helton Rhodes. humans. DRUG(S) OF CHOICE Demodicosis or other external parasites — PREGNANCY/FERTILITY/BREEDING Avoid retinoids and griseofulvin in pregnant  Client Education Handout isoxazoline antiparasitics as per label. available online animals.