A Non-Metal Cage for Small Animals.

Abstract

The increasing use of small laboratory animals, especially the albino rat, in studies involving precise measurements has emphasized the importance of the care required in the technic of caging and feeding. Largely in response to the demands imposed by the recent investigations of nutritional anemia, several suggestions have been made for the design of cages in which the experimental animal has no access to metal. In connection with metabolism studies with a dietary regime extremely poor in inorganic salts, the same need for a metal-free cage arose in this laboratory and, because of the difficulty in cleaning the cages of the designs already suggested, the one herein described was devised. It has the advantages of being simple in construction, easy to wash and sterilize and consisting of parts which are standard and easily replaced (see accompanying illustrations).

The main portion of the cage consists of a Pyrex cylinder 21 cm. inside diameter, 22 cm. outside diameter and 16.5 cm. high. This rests on a grid made of a circular collar of galvanized iron 22.8 cm. in diameter and 5 cm. high, across which are bars consisting of glass tubing 3 mm. outside diameter. Copper wire No. 20 is run through the tubing for support and added strength and passes through holes in the collar at a distance of 1.5 cm. below the upper edge. There is a space of 0.7 cm. between the tubes forming the grid; this, however, can easily be varied to suit experimental conditions. The tubes are slightly bent so that urine dropping upon them tends to flow towards the center. A similar grid forms the top of the cage. If care is taken to make the tubes touch the metal collar, the animal has no opportunity to lick or chew metal.