Metabolic cages

Metabolic cages create both welfare and scientific challenges and their use should be limited to procedures which are strictly necessary. Kalliokoski et al. (2013) concluded that mice do not habituate to metabolic cages.

Introduction

An elevated level of albumin in the urine is a result of leakage across the kidney barrier and the use of 24h urine collection to calculate albumin leakage into the urine is an established measurement of kidney injury in rodent models. The time spent in the metabolic cages for urine collection is stressful for the animals. The animals are single housed with limited space, without a shelter on grid flooring and without bedding and environmental enrichment in the metabolic cage. Weight loss, lowering of the body temperature and ruffled fur coat can be seen in mice after metabolic caging. Prolonged stress is generally acknowledged to affect factors like kidney function and pharmacokinetics, so reducing stress in caged animals would likely result in more reliable research data.