Do laboratory rats benefit from more cage space? (2004)

Foulkes, A.

Abstract

The porphyrin scores were significantly higher in rats housed in small or large cages that were barren than in rats housed in small or large cages that were furnished with a PVC tube. The lowest porphyrin scores were found in rats living in the large PVC tube-furnished cages. This housing environment was the least stressful one of the four test situations. The animals stress status was reflected in their food consumption with rats living in barren cages eating much more food and gaining significantly more weight than rats living in the enriched cages. Rats kept in the typical, barren standard cages very often become obese. The present findings indicate that this problem is related to stressful living conditions, similarly to obesity in modern people living in stressful environments. "Laboratory rats do not benefit from more cage space, unless the space is provisioned with proper enrichment such as a PVC tube. Being confined in a small standard cage is a much more stressful experience for rats than being confined in a larger cage furnished with a PVC tube. Access to a PVC tube reduces a rat's stress level in a small cage, but the stress is still much higher than in a large cage with PVC tube."