Small Animal Dermatology, 3rd edition

CHAPTER 14 BEHAVIORAL OR SELF-INJURIOUS DERMATOSES 229

Often a singular lesion; multiple lesions have a poorer prognosis for complete

resolution

Development of multiple lesions supportive of a primary behavioral disorder

Early lesion: well-circumscribed area of alopecia and erythema

Typical lesion: proliferative, eroded, crusted and firm plaque; previous lesions

may heal with palpable scarring as new areas are traumatized

Severe lesion: extensive area of ulceration and exudation; thickened and prolif-

erative tissue may surround a central crateriform ulcer

Severe lesions may cause lameness

Initiating triggers include allergic dermatitis, localized trauma, arthropathy,

endocrinopathy, neuropathy, and neoplasia

Perpetuated by secondary deep bacterial infection, secondary arthritis and/or

osteomyelitis, altered sensation within scar tissue, and learned behavior.

 Feline symmetric alopecia (Figures 14.4–14.6):
Also called feline psychogenic alopecia or neurodermatitis
Often associated with allergic dermatitis; behavior as a primary cause is uncom-

mon

Skin often remains undamaged; suspect other conditions if associated with sig-

nificant dermatitis

Alopecia results from overgrooming and is less often seen as chewing or hair

pulling; hair coat is barbered, resulting in short stubble emerging from follicles

Rarely lesions of eosinophilic plaque may develop

Behavior may be obvious or secretive to avoid a negative response; if clandestine,

the owner may deny that hair loss is due to removal as opposed to lack of growth

Evidence of self-grooming may be noted by frequent vomiting of hair balls,

excessive hair in feces, and visualization of short stubble in areas of alopecia

Well-demarcated patches of alopecia develop in accessible areas; patches may

initially appear asymmetric

Regrowing hair may appear darker in breeds with darkened “points”

Common regions affected: ventral abdomen, thighs (medial, lateral, and caudal),

ventral trunk, and dorsal aspects of the forelegs

Diagnosis as a psychodermatosis requires exclusion of other causes; significant

history may include hair coat regrowth in response to use of an Elizabethan

collar or administration of a corticosteroid; see differential diagnosis list below.

 Flank sucking:
May occur in response to a specific trigger or be a generalized (displacement)

activity

Dogs suck or nurse on a portion of the flank fold

Skin often remains undamaged; alopecia and lichenification may result from

chronic behavior

Secondary bacterial folliculitis and reaction to topical treatments may perpetuate

the process.

 Tail biting or chasing (Figures 14.7, 14.8):
Most dogs chase, but do not catch, the tail
Tail trauma may be severe in some patients