Higley, J. D., Davis, E., Woodward, R. A. et al. 2007. Self-injurious behavior in rhesus macaques: early history and present factors and the role of the serotonin system. American Journal of Primatology 69(S1), 39. (30th Meeting of the American Society of Primatologists Scientific Program, Abstract #21)

Self-injurious behavior (SIB) is a problem of virtually all nonhuman primate research facilities. Its incidence varies between institutions and with the strictness of the criteria that are used. Nevertheless, it is widely agreed that several variables are important for determining its prevalence, such as early experiences, and long-term single-cage housing. Until recently, mechanical methods such as collars or serious, long-term sedation were the typical treatments used. We will present data showing that the incidence of SIB leading to veterinarian intervention is low (less than 1%) at the NIH Animal Center (NIH-AC), where virtually all the monkeys are housed in social groups. Analyses show that since 1989, only 3 animals born in the NIH-AC engaged in injurious self-biting. Nevertheless, biting arms or legs does occur in a subset of the monkeys at the NIH-AC. Chi-Squared analysis [α=0.05] shows that when compared to animals reared by their mothers or in classic peer-reared groups, the probability of self-biting is significantly higher in the more impoverished surrogate-reared infant subjects which have only limited daily contact with other conspecifics. This less severe form of self-biting may be a risk factor for future incidents of severe SIB. When treated with serotonin acting medications, non-injurious self-biting rates decreased significantly from pre-treatment rates. Post-treatment rates of SIB returned to baseline levels following drug treatment. Our results suggest a role of rearing and CNS serotonin in the risk for SIB.