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Alopecia, Dog 47

Alopecia, Dog
VetBooks.ir BASIC INFORMATION vaccination (post-rabies vaccination pan- • Inflammation in or around hair follicles (e.g., Diseases and Disorders

Definition niculitis), drug administration (e.g., topical alopecia areata, sebaceous adenitis, infectious
corticosteroid)
folliculitis with staphylococci, dermatophytes,
Complete or partial loss or absence of hair in or Demodex)
areas where it is normally present. Alopecia PHYSICAL EXAM FINDINGS • Breakage of hair due to trauma (e.g., pru-
can be localized, multifocal, or generalized. • Is alopecia diffuse or localized/multifocal? ritus), structural hair defects (e.g., CDA),
Symmetrical? Location? or direct infection (e.g., dermatophytosis)
Synonyms • Is the hair absent (e.g., endocrine disease), • Dysplasia of hair follicles
Excessive shedding, hair loss, hypotrichosis broken (e.g., self-trauma), or miniaturized • Diminution of hair follicle size (pattern
(e.g., pattern alopecia)? alopecia)
Epidemiology • Does hair epilate easily (e.g., folliculitis)? • Ischemia (e.g., post-rabies vaccination pan-
SPECIES, AGE, SEX • Is there skin inflammation, skin lesions, or niculitis, dermatomyositis)
Common; signalment depends on cause. Age pruritus? • Telogen effluvium (defluxion): synchronous
of onset is clinically important. • Are there follicular casts (e.g., sebaceous arrest of the hair cycle caused by drugs,
adenitis, demodicosis)? pregnancy, or other stressors
GENETICS, BREED PREDISPOSITION • What color is the hair (e.g., CDA)? • Anagen effluvium (defluxion): sudden inter-
Breed predispositions exist for many causes of • Is the skin thickness normal (e.g., reduced: ruption of anagen resulting in an abnormal
alopecia: hyperadrenocorticism; increased: inflamma- hair shaft and hair loss within days, not well
• Alopecia X (p. 44): plush-coated dogs (e.g., tory conditions)? documented in dogs
Pomeranian), arctic breeds, miniature poodle • Is there evidence of endocrine disease (e.g.,
• Breed-specific follicular dysplasia (p. 344): obesity, muscle atrophy) or other abnormal
Chesapeake Bay and curly-coated retrievers, findings such as lymph node enlargement DIAGNOSIS
Portuguese water dog, Irish water spaniel (e.g., pyoderma, leishmaniasis)?
• Color dilution alopecia (CDA): blue or fawn Diagnostic Overview
Doberman pinscher, others Etiology and Pathophysiology The distribution of alopecia and the degree of
• Pattern alopecia: Boston terrier, dachshund The mechanism of hair loss varies with the inflammation are helpful for prioritizing dif-
• Canine (recurrent) flank alopecia (p. 869): underlying cause: ferential diagnoses and selecting diagnostic tests
boxer, English bulldog, others • New hair failing to grow when old hairs are (p. 1091).
• Congenital hypotrichosis is normal in certain lost (e.g., endocrine)
breeds (e.g., Chinese crested)
• Post-rabies vaccination panniculitis and
alopecia: miniature poodle, other small dogs
CONTAGION AND ZOONOSIS
• Dermatophytosis
• Ectoparasites, including Sarcoptes, Cheyletiella,
and fleas

GEOGRAPHY AND SEASONALITY
Seasonal: canine (recurrent) flank alopecia,
self-inflicted alopecia due to atopic dermatitis
or flea bite hypersensitivity
ASSOCIATED DISORDERS
• Hypothyroidism: lethargy, obesity
• Hyperadrenocorticism: Cushing’s syndrome
• Sertoli cell tumor: male feminization
• Bacterial folliculitis or Malassezia dermatitis:
often associated with underlying hypersen-
sitivity dermatitis
Clinical Presentation
DISEASE FORMS/SUBTYPES
• Congenital or acquired
• Generalized or localized/multifocal
• Inflammatory or non-inflammatory
HISTORY, CHIEF COMPLAINT
• Determine age of onset and progression
• Question degree of pruritus
• Question other clinical signs (e.g., polyuria/
polydipsia)
• Ask about recent pregnancy, serious illness,
anesthesia (causes of telogen effluvium), ALOPECIA, CANINE Post-rabies vaccination panniculitis and alopecia in a Bichon frisé.

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