Hutchinson, E. K., Freeman, Z., Rice, K. A. et al. 2012. Objective assessment of self-injurious behavior in rhesus macaques and successful treatment with guanfacine. American Association for Laboratory Animal Science [AALAS] Meeting Official Program, 647-648 (Abstract #PS78).
Self-injurious behavior (SIB) occurs sporadically in 5% to 15% of captive nonhuman primates, with over-representation among males and those animals housed in single caging prior to adulthood. Though SIB may manifest as a range of specific behaviors, the most clinically relevant and potentially devastating to research is self-biting with associated wounds. This wounding is often progressive in frequency, severity, and distribution, and may lead to euthanasia due to humane and ethical concerns. The sporadic nature and difficulty in objectively measuring SIB have made it difficult to evaluate potential treatments. Our institution’s Research Animal Resources obtained 20 adult male rhesus macaques with 100% prevalence of SIB, with and without wounding, at the termination of a longitudinal experiment. We designed a method of quantifying wounds according to their severity and distribution, with each limb scored on a 1 to 4 scale according to the most severe wound present on that limb. This wound scoring was much quicker and more reliable between observers than total wound counts, significantly correlating with total wounds (Spearman r = 0.845, P < 0.0001) and demonstrating significant matching over time within individual animals (P < 0.001). A treatment efficacy study was also conducted using guanfacine, an α2-adrenergic agonist used to treat nonhuman primate SIB in a previous case report and our own clinical experience. Sixteen animals were given an oral vehicle for 4 wk, then guanfacine (10 mg twice daily, n = 12) or placebo (n = 4) for 4 wk, then vehicle only for an additional 4 wk. Animals receiving a full course of guanfacine treatment (n = 9) had a significant improvement in wound scores over those receiving placebo, (MW P = 0.0305) with those animals having higher wounds scores at the start of the study experiencing larger improvements (Spearman r = −0.7606, P = 0.0173). Furthermore, the positive effect of guanfacine on wound score persisted for 8 wk after cessation of drug treatment, despite a short half-life of the drug. This suggests that guanfacine is not only effective in treating SIB, but may also be used in a pulse-therapy fashion for animals on experiments in which they cannot actively be on study while receiving such a drug.