Chapter 3. Maladaptive behaviors (2007)

LAREF [Laboratory Animal Refinement and Enrichment Forum]

Abstract

Animals kept in legally minimum-sized, unstructured enclosures very often exhibit stereotypical behaviors. Traditionally, these repetitive movement patterns without obvious goals or functions are categorized as abnormal. A healthy animal kept in a small, barren enclosure has little choice of expressing his or her biologically inherent drive to engage in species-typical behaviors, other than pacing back and forth, running in circles, somersaulting, rocking, self-biting, bar-biting, wood-gnawing, ear-pulling, hair-pulling, eye-poking and other bizarre activity patterns. There is nothing really abnormal, except the abnormally restrictive and abnormally boring housing conditions that induce the stereotyped expression of these activities.Hair pulling-and-eating reflects maladjustment to a distressing condition in primates. The inherent constraints of permanent confinement makes it very difficult to cure affected animals from this behavioral pathology. I have been working with several hundred macaques over a number of years, and I have offered them all types of natural foraging and occupational enrichments, but I did not have much success in reducing, let alone eradicating, hair pulling behavior. At best, enrichment may provide a short-term distraction to deep-seated psychological maladjustment problems. Some of these problems may have their origin in a lack of basic environmental stimuli during early infant development, such as social deprivation or barren living quarters. This lack of appropriate external feedback may cause the animals to resort to self-directed strategies to get some relief of their tension. Once these critters are hard-wired it is almost impossible to change a well-entrenched behavioral pathology such as hair pulling. Self-injurious biting is a serious behavioral pathology that reflects gross insufficiencies in the rearing, housing and care of an animal. In my own experience with rhesus and stump-tailed macaques, self-biting occurs in the following two sequences of events and circumstances: 1. The subject is extremely bored, shows no signs of excitation, and repeats the same movement patterns over and over again-for example, circling, pacing or somersaulting-interjected by sham biting of specific body parts (Figure 9). This behavior often goes unnoticed because there is no visible abrasion or laceration, plus the subject usually does not show the behavior when there is a distraction, for example when personnel is present. 2. The subject is extremely frustrated-with high emotional arousal, e.g., shaking, intense staring, piloerection-for example, when fear-inducing personnel approach the cage, with the subject having no option of escape or attack. The animal will predictably attack specific sites of arms or legs, perhaps always the right wrist or always the left upper thigh. This typically leads to noticeable abrasion over time-first local alopecia, followed by mild inflammation-but may also result in serious wounds. Typically an animal self-inflicts lacerations of the same body part several times on different occasions, often necessitating the amputation of the repeatedly injured limb.