Alopecia, Noninflammatory-Dogs PDF

Canine and Feline, Seventh Edition 69 Alopecia, Noninflammatory—Dogs A...

Canine and Feline, Seventh Edition 69 Alopecia, Noninflammatory—Dogs A lack of normal shed. Males with hyper- diffuse pattern of alopecia. Sebaceous estrogenism may attract other male dogs. adenitis—inflammatory cause of alopecia Physical Examination Findings more common in specific breeds (Samoyed, ­ BASICS Akita). Hypothyroidism and Alopecia—usually diffuse and bilaterally DEFINITION symmetric truncal alopecia sparing the head hyperadrenocorticism—may cause very Uncommon alopecic disorders that are and distal extremities; uncommon with similar pattern of diffuse alopecia associated associated with abnormal hair follicle cycling. hyperandrogenism. Hair coat—may be dry with lack of hair follicle cycling. Follicular Both endocrine and nonendocrine diseases or bleached. Secondary seborrhea, pruritus, dysplasia including color dilution alopecia can be associated with alopecia. Definitive pyoderma, comedones, ceruminous otitis and black hair follicular dysplasia—alopecia diagnosis often requires ruling out the more externa, and hyperpigmentation—variable. should be color restricted. Patterned common endocrine alopecias. Enlargement of nipples, mammary glands, alopecia of various breeds (dachshund, vulva, prepuce—may be associated with Boston terrier, greyhound, water spaniel, and PATHOPHYSIOLOGY hyperestrogenism. Macular melanosis and others)—breed-specific alopecia of unknown Many factors affect the hair cycle, both linear preputial dermatitis—may be associ- cause. Seasonal/cyclic/canine flank alopecia— hormonal and nonhormonal. Increased ated with hyperestrogenism. Abnormal- alopecia of flank and dorsum, often serpiginous sex hormones can affect the hair cycle. sized or different-sized testicles—may be patterns with hyperpigmentation, more often Estrogen is a known inhibitor of anagen, associated with hyperestrogenism or in short-coated breeds (boxer, English the growth phase of the hair follicle. The hyperandrogenism. Testicles may also bulldog, Airedale) and may recur seasonally. mechanism by which alopecia X influences appear normal in size. Tail gland Postclipping alopecia—hair fails to regrow the hair cycle is not known. Exposure to hyperplasia and perianal gland hyperplasia— following clipping; however, hair regrowth human exogenous hormone replacement usually associated with hyperandrogenism. occurs within one year. Telogen therapy. Systemic signs (polyuria/polydipsia [PU/ defluxion—alopecia occurs 1–2 months SYSTEMS AFFECTED following illness or severe stressful episode PD]/polyphagia) are usually not present. Behavioral. Endocrine/metabolic. Hemic/ and usually more sudden in onset, with lymphatic/immune. Skin/exocrine. CAUSES relative ease of epilation. GENETICS Hyperestrogenism—Females CBC/BIOCHEMISTRY/URINALYSIS Breed predispositions exist for alopecia X; Estrogen excess associated with cystic ovaries, Usually unremarkable. Anemia, however, the mode of inheritance is unknown. ovarian tumors (rare), exogenous estrogen hypercholesterolemia associated with severe supplementation, or exposure to human hypothyroidism. Anemia and/or bone INCIDENCE/PREVALENCE topical hormone replacement. marrow hypoplasia or aplasia can be Hyperestrogenism and hyperandrogenism are uncommon to rare causes of alopecia. Hyperestrogenism—Males associated with hyperestrogenism. Alopecia X is relatively common in Estrogen excess due to Sertoli cell tumor OTHER LABORATORY TESTS predisposed breeds. (most common), seminoma, or interstitial cell Serum sex hormone concentrations—often tumor (rare), or exposure to human topical normal, treat according to suspected GEOGRAPHIC DISTRIBUTION hormone replacement. Associated with diagnosis based on clinical signs and ruling None male pseudohermaphrodism in miniature out other disorders. Serum estradiol SIGNALMENT schnauzers. concentrations—sometimes elevated in male Species Hyperandrogenism—Males dogs with testicular tumors or female dogs Dogs Androgen-producing testicular tumors with cystic ovaries; however, normal fluctuation (especially interstitial cell tumors). of estradiol occurs throughout the day, making Breed Predilections interpretation of estradiol concentrations Hyperestrogenism and hyperandrogenism— Alopecia X difficult. Adrenal sex hormone panel not no breed predilections. Alopecia X— Hairs fail to cycle, but underlying endocrine useful for diagnosis of alopecia X. miniature poodle and plush-coated breeds cause has not been identified. such as Pomeranian, chow chow, Akita, IMAGING RISK FACTORS Radiography, ultrasonography, and Samoyed, keeshond, Alaskan Malamute, and Intact male and female dogs at increased Siberian husky; recently described in laparoscopy—identify cystic ovaries, ovarian risk for developing testicular tumors and tumors, testicular tumors (scrotal or Schipperke breed. ovarian cysts/tumors, respectively. abdominal), adrenal tumors, sublumbar Mean Age and Range Cryptorchid males at increased risk for lymphadenopathy, and possible thoracic Hyperestrogenism and hyperandrogenism— developing testicular tumors. Exogenous metastases of malignant tumors. middle-aged to old intact dogs. Alopecia estrogen supplementation. Exposure to X—1–5 years of age; however, older dogs human exogenous hormone replacement DIAGNOSTIC PROCEDURES may develop the condition. therapy. No known risk factors for alopecia Preputial cytology—may demonstrate X other than breed predisposition. cornification of cells in males with hyper­ Predominant Sex estrogenism (similar to bitch in estrus). Hyperandrogenism, primarily intact males. Skin biopsy. Hyperestrogenism, primarily intact females or males. Alopecia X, neutered or intact PATHOLOGIC FINDINGS dogs of either sex. ­ DIAGNOSIS Histologic changes associated with endocrine dermatoses (telogen hairs, follicular keratoses, SIGNS DIFFERENTIAL DIAGNOSIS hyperkeratosis, excess trichilemmal keratini- Historical Findings Inflammatory causes of alopecia zation [flame follicles], thin epidermis, and Overall change in hair coat—dry or (pyoderma, demodicosis, and dermato­ thin dermis) may also be seen with bleached because hairs not being replaced; phytosis)—usually cause patchy rather than noninflammatory alopecias including  70 Blackwell’s Five-Minute Veterinary Consult A Alopecia, Noninflammatory—Dogs (continued) hyperestrogenism and alopecia X. Histopathology 4 treatments. Hair regrowth can take up to treatment. Therefore, if hair regrowth will help rule out inflammatory causes of 6 months. Effective in approximately occurs, discontinue treatment to preserve alopecia (pyoderma, demodicosis, 40–50% of cases. treatment for future recurrence of dermatophytosis, sebaceous adenitis) and some CONTRAINDICATIONS alopecia. Risk of treatment should be of the other differentials listed above. None weighed with the fact that this is a cosmetic disease. PRECAUTIONS Melatonin at high doses can cause insulin resistance. Use caution in treating dogs with ­ TREATMENT diabetes mellitus. Medroxyprogesterone DIET acetate can cause mammary nodules and ­ MISCELLANEOUS None cystic endometrial hyperplasia with long-term ASSOCIATED CONDITIONS use. Diabetes mellitus has been reported in a Pyoderma, seborrhea, comedones may be CLIENT EDUCATION few dogs. Alopecia X is a cosmetic condition resulting in associated with alopecia. Behavioral changes coat loss only and there is no definitive cure for POSSIBLE INTERACTIONS associated with hyperestrogenism or hyper- the hair loss. The risk of treatment should be None androgenism. emphasized. Hair regrowth will only occur in a ALTERNATIVE DRUG(S) AGE-RELATED FACTORS portion of dogs regardless of treatment chosen, Mitotane—15–25 mg/kg once daily as None and hair loss may recur months to years later in induction for 5–7 days, followed by twice ZOONOTIC POTENTIAL spite of continued treatment. weekly maintenance; hair regrowth occurs None SURGICAL CONSIDERATIONS in portion of dogs treated and can take up to 3 months to become evident. Use of this PREGNANCY/FERTILITY/BREEDING Hyperestrogenism/Hyperandrogenism drug can result in an Addisonian crisis and N/A—neutering usually recommended for Castration—scrotal testicular tumors. other side effects, as for treatment of managing these conditions. Exploratory laparotomy—diagnosis and Cushing’s syndrome. Trilostane—dosages SYNONYMS surgical removal (ovariohysterectomy and as described for treatment of Cushing’s Alopecia X—growth hormone-responsive castration) for ovarian cysts and tumors and syndrome; hair regrowth occurs in a portion alopecia, castration-responsive alopecia, abdominal testicular tumors. of dogs treated and can take up to 3 months adrenal hyperplasia-like syndrome, adrenal Alopecia X to become evident. Use of this drug can sex hormone imbalance of plush-coated Neuter intact animals—a certain number result in an Addisonian crisis and other side breeds, among others. will regrow hair following neutering; hair effects, as for treatment of Cushing’s ABBREVIATIONS regrowth may take up to 3 months to become syndrome. ACTH = adrenocorticotropic hormone. evident. Microneedling technique may PU/PD = polyuria/polydipsia. induce hair regrowth. INTERNET RESOURCES https://vetmed.tennessee.edu/vmc/ ­ FOLLOW-UP SmallAnimalHospital/Dermatology PATIENT MONITORING ­Suggested Reading ­ MEDICATIONS Medroxyprogesterone acetate—complete Frank LA. Endocrine and metabolic diseases. DRUG(S) OF CHOICE physical examination and chemistry panel In: Miller WH, Griffin CE, Campbell KL, General Treatments regularly. Mitotane—electrolytes and eds., Muller and Kirk’s Small Animal Topical antiseborrheic shampoos—for cortisol with adrenocorticotropic hormone Dermatology, 7th ed. Philadelphia, PA: comedones and seborrhea associated with (ACTH) stimulation testing regularly. W.B. Saunders, 2013, pp. 501–553. Trilostane—electrolytes and cortisol with Frank LA. Alopecia X in a Pomeranian. alopecia. Antibiotics and topical antimicrobial shampoos—for secondary skin infections ACTH stimulation testing regularly. Clinicians Brief, 2017, Nov:26–30. associated with alopecia. PREVENTION/AVOIDANCE Stroll S, Dietlin C, Nett-Mettler CS. None Microneedling as a successful treatment for Alopecia X alopecia X in two Pomeranian siblings. Vet Melatonin—implants (8 mg or 18 mg every POSSIBLE COMPLICATIONS Dermatol 2015, 26:387–390. 4–6 months) or oral (3 mg q12h for small None Author Linda A. Frank breeds and 6–12 mg q12h for large breeds); EXPECTED COURSE AND PROGNOSIS Consulting Editor Alexander H. Werner evidence of hair regrowth may take up to 3 Estrogen- and androgen-secreting Resnick months. Effective in approximately 40% of tumors—resolution of signs should occur cases. Because this treatment is benign, it is within 3–6 months after castration or considered the treatment of choice following ovariohysterectomy. Alopecia X—hair  Client Education Handout neutering. Once hair regrowth has occurred, regrowth will occur in only a portion of available online discontinue treatment. Medroxyprogesterone dogs regardless of treatment chosen and acetate—5–10 mg/kg SC q4 weeks for hair loss may recur in spite of continued