An open air holding system for chimpanzees in medical experiments

Chimpanzee models often impose severe mental and physical suffering on these animals. We have developed an alternative system which provides for considerably more three dimensional movement and animal-to-animal interaction. It has been used for a period of 20 months in nonexperimental and 8 months in experimental animals. Presently 24 experimental animals, previously held in isolation cages for up to 4 years, are held on outside pads. Animals were transferred from isolation to large outdoor cages for readjustment prior to being put out on pads. Animals that had acquired behavioral abnormalities during their stay in isolation had a longer period of adjustment but now appear happy and are capable of normal interaction with their companions. Chimpanzees approaching sexual maturity and individuals over 5 years that have undergone hepatitis B and non-A, non-B infections are being transferred to a 6 hectare island situated in a river 10 km from the laboratory. Six animals present on the island since October 1978 are in good physical health and are the beginning of a future semi-free-ranging colony. They are fed daily on the same regimen as the main colony and receive monthly anthelmintic treatment in milk. There are presently no caged animals in the colony.