Innovation: wellbeing for rodents in preclinical studies
Monday 16 March 2009 by Raafat Fares , Laurent Bezin
MARLAU™ cage (patent n° FR09/00544). This cage (figure 1) was engineered in the laboratory to standardize procedures of enrichment for rodents. Two cage dimensions exist, a large one for rats, and a smaller one designed for mice.
Marlau™ cage provides welfare by introducing crucial features of the wild, such as novelty, complexity, and physical activity. The cage is divided into 2 floors. The ground floor (G) is divided into 2 sections including one section (G1) with food pellets, and another (G2) with 3 water bottles. G2 also contains a red rectangular house with 4 lateral windows and 2 opened extremities and 3 running wheels. G2 is connected to the upper floor via a ramp. The upper floor, which contains a labyrinth, is connected to G1 via a tunnel. When rats are in G1, they can access to G2 using 2 one-way opening doors. Exposure to complexity is assured by imposing all rats to go through the labyrinth once they are in G2 to reach food. Physical activity is encouraged by the enlarged exploration area (9-fold greater than in “E” cages [length 405 mm, depth 255 mm, height 197 mm, total exploration surface = 800 cm2], Charles River) and free access to running wheels. Finally, increased social interactions are promoted by the possibility to house together a larger number of animals (12 rats or 18 mice / cage). At each change of the bedding material (made of aspen wood: half of Litaspen Premium 6 and half of Litaspen Premium 8/20), paper wool and aspen wood wool are added in G1 and G2, respectively.
Standardization of novelty is assured by changing the labyrinth configuration 3 times a week (Monday, Wednesday and Friday) at 17:30, using 6 labyrinths (A-F), each offering 2 different configurations (1 and 2; e.g. A1 and A2 for labyrinth A) (figure 2).
Labyrinth changes are made in a defined order to offer reproducibility across experiments (starting with the series of A1, B1, C1, and ending with the series of D2, E2, F2). After F2 configuration has been used, another series is restarted from A1. When the terms “A1” or “D2” are employed, it signifies that the side 1 of the labyrinth A, or the side 2 of the labyrinth D, is positioned facing the ramp, respectively. To avoid territorial dominance, rats can enter and exit the labyrinth using 2 gates on each side.
The movie * illustrates the behavior of young adult Sprague-Dawley rats (2 month old) just after labyrinth change. Housing in MARLAU™ cage started at weaning (21 day old).
