Setting up a cage for tethered infusion can be difficult. If not done right, you may face a range of problems such as twisted tethers, tethers destroyed by biting, seromas caused by repeated impact of the VAB™ on the cage, or restricted movement, all of which can ruin your experiment and impact animal welfare.
In this post we'll start with a good conventional rat cage from Tecniplast and turn it into an infusion cage with these critical features:
When we are done it will look like this:
For our cage we've chosen the Tecniplast 1291H Eurostandard Type III H rat cage and a series -123 raised wire lid. The 1291H is 185mm tall, which you need to have clearance for the VAB™. (We do not recommend the shorter 1290D.) The raised wire lid works perfectly with standard 12in/30cm tethers, plus rats can stand on hind legs which is good for their welfare. If you have a flat -116 lid you will probably need to use shorter tethers. You must have the divider in the feed hopper to keep pellets from interfering with the tether.
For more details or to order this cage, download the brochure on the Tecniplast Conventional Housing for Small Rodents webpage.
Next we'll show you how to slot the lid so that the tether can move freely.
Step 1: Mark Cage Top for Cutting
Firmly secure the cage top to a stable surface, find the center point (or as close to center as possible), and mark the segments of cage to be cut. You will be cutting four separate segments.
Step 2: Spread Wire for Tether
Insert your pliers centered between the two cross sectional bars on top of your cage, then rotate your pliers 90 degrees so the width of the pliers spreads and bends the wire caging. Check to be sure your tether connector easily slides in and out of the gap.
Step 3: Cut Wire
While wearing your safety glasses and gloves, use your Dremel tool and cutting disk to cut the wires at all four locations. Cut each cross section in two places, as closely to the perpendicular cross-wire as possible. Grind any sharp edges.
The Instech CM375KRP mount is ideal for this kind of cage, assuming you are working with rats and will use tethers with plastic swivels. The simple spring arm removes slack from the tether and minimizes forces on the animal and the surgical site. It is safe for cage washers and swivels snap in and out easily with no tools required.
The height of this cage with the CM375KRP mount is a good fit with our standard 12in/30cm spring tethers. You'll know you have a good fit when the arm is fully upright when the animal is in the center of the cage and there is no slack in the tether; when the animal is in a far corner the spring arm should be bent down, but not so much that the bottom of the swivel or the tubing loop enters the cage. If you are using our rat Vascular Access Button™ system, these tethers are compatible: