Merck Manual

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Psychological Well-being and Environmental Enrichment of Nonhuman Primates


Terri Parrott

, DVM, St. Charles Veterinary Hospital

Last full review/revision Jan 2020 | Content last modified Feb 2020
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Providing for the psychological as well as the physical well-being of nonhuman primates maintained in captivity is a high priority. Psychological well-being is enhanced by appropriate social companionship (ie, compatible conspecifics); opportunities to engage in behavior related to foraging, exploration, and other activities appropriate to the species, age, gender, and physical condition of the animal; and housing that allows typical movement and resting postures.

Sensory capabilities should be constantly addressed, taking into account a primate's sense of vision, smell, taste, hearing, and touch. As with their human counterparts, they need constant stimulation and exercise. When enclosures are of the minimum legal size, enlargements or added exercise areas should be encouraged, taking into account the species of primate in the enclosure and their natural movements in the trees as well as on the ground.

Interactions with human caretakers should be generally positive and not a source of undue stress. Voluntary presentation of body parts can be taught with positive reinforcement and will build a bridge of trust between the nonhuman primate and its caretakers.

Well-designed and implemented environmental enrichment programs should meet basic requirements. These include but are not limited to perching areas, limbs and ropes for climbing and brachiation, visual barriers for seclusion and rest, and hiding boxes with clean flooring or substrate.

If an animal displays stereotypic or self-injurious behaviors, these need to be addressed. Repetitive behavior such as pacing, flipping, floating limb attacks, hair-plucking, and overgrooming the extremities are a result of inadequate mental stimulation. Drug therapy and behavioral redirection can be instituted, and frequent reassessments are recommended. Fluoxetine is a selective serotonin reuptake inhibitor and can be started at a dosage of 0.2 mg/kg daily and increased as needed. If the animal is in pain due to some of these behaviors, meloxicam can be added to the regimen as well. Ameliorating preexisting abnormal behaviors is important and may take several months.

Socialization (both with similar species and their caretakers) may involve visual and auditory stimuli as well as physical contact. Positive reinforcement for desired behaviors appears to provide substantial benefit to most species of nonhuman primates and should be provided within the constraints of research protocols and daily management practices.

Additional enrichment options include forage boards or other food-related enrichment devices, manipulation mirrors, and a variety of cage toys provided on a rotating schedule to maintain novelty. Animal behavioral assessments as well as periodic review and evaluation of the effectiveness of enrichment program components should be performed by appropriately trained individuals every 3–6 months.

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