Counterbalanced system for single- and multi-axial swivel

When a fixed swivel stand is used, the various tubes that are long enough to reach the far corners of the cage can tangle in the center giving the animal a chance to eat them. Conversely, if the connections are too short to keep them from tangling, they will hold the animal back, causing unnecessary stress. With a uniaxial support, these problems are solved by rotating in the vertical plane to eliminate chain slack, but leaving enough length to reach all corners of the cage. The adjustable counterweight can be adjusted to balance the weight of swivel and rope. The multi-axial supports are designed to minimize stress on the microdialysis probes, are counterbalanced, and move vertically and horizontally with the animal to prevent loosening of the cable. While most other lever arms use a mass as a counterweight, these use adjustable springs to make them lighter and more responsive. The mounting plate can be adjusted to mount on the side or top of many types of cages. The MCLA is a 15-cm (6-inch) arm that is typically used with rats. The SMCLA is a 9-cm (9-cm) arm that is virtually essential for any study involving rats. Versions of these balancing arms are also available for metabolic cages, chambers operating for intravenous self-administration, and automated blood samplers from Instech (SMCLA and MCLA include only the lever arm: the swivel and other accessories are not included).