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