Euthanasia of a macaque with self-injurious behavior in a visual neuroscience laboratory

The causes of self-injurious behavior (SIB) in primates are not well understood, but a relatively impoverished physical environment, deficiency of normal social interactions, lack of novel stimulation, nursery rather than maternal rearing, and an intrinsically susceptible temperament are potential contributing factors. An important issue, seldom addressed, is what level of SIB is severe enough to warrant euthanasia. In this case report, a healthy 5-year-old macaque is described who was euthanized 11 d after developing SIB. The episodes occurred about 0.5% of the time and were rated SIB 1 (mild) per the United States National Primate Research Center Scoring System. The factors that may have led to the emergence of SIB, the efforts made to address it, and the decision to euthanize the monkey are reviewed. Recommendations are made for management of future cases, along with a suggestion that self-injurious behavior should conform to category SIB 2 (moderate) or SIB 3 (severe) before euthanasia is considered.