Training rhesus macaques for venipuncture using positive reinforcement techniques: a comparison with chimpanzees

Abstract

As more emphasis is placed on enhancing the psychological well-being of nonhuman primates, many research facilities have started using positive reinforcement training (PRT) techniques to train primates to voluntarily participate in husbandry and research procedures. PRT increases the animal's control over its environment and desensitizes the animal to stressful stimuli. Blood draw is a common husbandry and research procedure that can be particularly stressful for nonhuman primate subjects. Although studies have demonstrated that chimpanzees can be trained for in-cage venipuncture using PRT only, fewer studies have demonstrated success using similar techniques to train macaques. It is often assumed that macaques cannot be trained in the same manner as apes. In this study, we compare PRT data from singly housed adult rhesus macaques (Macaca mulatta; n = 8) with data from group-housed adult chimpanzees (Pan troglodytes; n = 4). All subjects were trained to place an arm in a 'blood sleeve' and remain stationary for venipuncture. Both facilities used similar PRT techniques. We were able to obtain repeated blood samples from 75% of the macaques and all of the chimpanzees. The training time did not differ significantly between the 2 species. These data demonstrate that macaques can be trained for venipuncture in a manner similar to that used for chimpanzees.

Figure 1.

Adult male rhesus macaque with arm in blood sleeve. The monkey was trained to put his arm in the blood sleeve and hold onto the peg at the distal end until released by the trainer. While 1 trainer worked with the monkey, another provided the secondary reinforcement (clicking) and the juice bottle, which was removed if the monkey did not perform the appropriate behavior. The blood sleeve for the chimpanzees was similar.

Figure 2.

Blood sleeve used for training adult male rhesus macaques. The sleeve was designed for the cages used at the macaque facility. The back plate, which was cut so that it covered the cage door, was made of 0.5-in. acrylic, and the arm sleeve was made of 0.125-in. acrylic. The arm sleeve was 9.5 in. long, with a diameter of 2.75 in. Illustration credit: J. Gregory Johnson.

Figure 3.

Amount of time (min; A) and number of sessions (B) needed to train 6 rhesus macaques and 4 adult chimpanzees to put their arm in a blood sleeve and remain stationary for blood draw. Overall, training took 4 to 7 mo for the rhesus and 4 to 12 mo for the chimpanzees. Error bars represent SE.

Figure 3.

Amount of time (min; A) and number of sessions (B) needed to train 6 rhesus macaques and 4 adult chimpanzees to put their arm in a blood sleeve and remain stationary for blood draw. Overall, training took 4 to 7 mo for the rhesus and 4 to 12 mo for the chimpanzees. Error bars represent SE.