DIFFERENTIAL DIAGNOSES
Table 1. Differential Diagnoses Associated with Self-directed Behaviors in Dogs and Cats
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Once you have assessed that a self-directed behavior is present, consider all appropriate differential diagnoses (Table 1). In concert with a careful review of the animal's behavioral history, directly observing the patient is essential to appreciate
potential behavioral etiologies. Although a videotape of the patient's behaviors does not preclude direct observation, it
can provide an opportunity to observe the animal engaging in any associated behaviors in its home environment and to study
specific behaviors in detail.
Primary medical conditions
Although self-directed behaviors by definition exclude primary medical causes, patient evaluation should include a thorough
physical examination, a complete blood count, a serum chemistry profile, and any additional diagnostics that may be clinically
indicated by other findings (e.g. skin scraping, dermatophyte culture, acetate tape preparation, cytology, histology).7 If clinically relevant abnormalities are noted, you must determine whether the findings are most consistent with a primary
or secondary medical cause. Secondary behavioral disorders may result from primary medical conditions that affect an animal's
normal behavior patterns and social functioning. As with stressful environmental and social stimuli, medical conditions that
cause pain, discomfort, lassitude, or malaise may result in reduced coping strategies, increased reactivity, anxiety, or aggression.
Displacement activities
Beyond normal maintenance purposes, grooming in dogs and cats may occur as a displacement behavior. This type of activity
is performed out of context as a result of conflict (the tendency or state of motivation to simultaneously perform more than
one type of activity), frustration (engagement in a sequence of behaviors that cannot be completed because of physical or
psychological obstacles), or anxiety in response to social or environmental stressors. Displacement grooming can distract
an animal from stressors, lower its level of arousal, or deflect social conflict or agonistic interactions. Displacement grooming
may also occur as a stress response in the absence of sufficient social or environmental stimuli. Displacement grooming is
a normal adaptive response to transient stressors; however, with recurrent or sustained stress, excessive grooming (over-grooming)
may result.1
Stereotypic behavior and compulsive disorders
Stereotypic self-directed behaviors are characterized by sequences of movements that serve no obvious function and occur repetitively,
out of context, or at an excessive frequency or duration. A diagnosis of a compulsive disorder applies when these sequences
of movements not only meet the above criteria but also fail to achieve any real or potential goal and interfere with an animal's
ability to function normally.1,2 Self-directed compulsive disorders in dogs include a number of syndromes that are descriptive of lesions (e.g. acral lick dermatitis, psychogenic alopecia) or behavior patterns (e.g. flank sucking, tail chewing, tail chasing, self-nursing, preputial licking, excessive chewing of the feet or nails, excessive
scratching or rubbing). Self-directed compulsive disorders in cats also include syndromes that are descriptive of lesions
(e.g. psychogenic alopecia) or behavior patterns (e.g. hyperesthesia syndrome, tail chewing, excessive chewing of the feet or nails, excessive scratching or rubbing). Correctly
diagnosing a stereotypic behavior or compulsive disorder requires evaluating the behavior pattern and frequency, the contexts
in which the behavior occurs, and the degree to which such behavior interferes with an animal's ability to function normally.
Redirected behaviors
Redirected behaviors may result when activity directed toward a target is thwarted or interrupted. The redirection may result
from a tangible physical obstacle (e.g. a window, confinement to a leash) or a virtual obstacle (e.g. social anxiety, fear). Although redirected behaviors are generally directed toward another individual or environmental objects,
I have observed several animals redirect their behavior toward themselves. The redirected behavior may or may not manifest
as self-directed aggression. While redirected behaviors may initially occur in the presence of a specific provocative stimulus,
over time the animal may generalize and become responsive to a number of different stimuli. A precise behavioral history that
identifies specific provocative situations in which the redirected behavior occurs is necessary to confirm this diagnosis.
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