RAISING LABORATORY MICE AND RATS 5 
mouse leaves the nest and begins to eat solid food. Young mice may be re- 
moved from their dam at 3 weeks of age and the dam rebred. A female is not 
usually productive after 15 months, but may live much longer. Male mice 
have been known to live 214 to 3 years. : 
Care and Management 
HOUSING 
The temperature in the building in which mice are housed should be kept 
at 70° to 80° F. Dampness and drafts should be avoided. ‘There should be 
good ventilation, however. A variety of types of cages are used, depending on 
the needs and fancy of the individual. Cages should be of metal, however, to 
stand sterilization at least monthly by steam or by dipping in a solution of 
disinfectant. For general purposes the “shoe box” type of cage is satisfactory 
(fig. 1). The sides and bottom are of sheet metal. The dimensions are 
7 by 12 by 5inches. ‘The cover fits like the cover to a shoe box. A rectangular 
area in the cover is cut out and the metal replaced with %4- to 34-inch mesh 
hardware cloth. Some absorbent material such as shavings, sawdust, or 
peanut hulls should be kept in the cages to absorb moisture. Pregnant 
females should be provided with shredded paper for nesting material. A 
Y%-inch mesh hardware-cloth feed cup is hung over the edge by hooks so 
that feed is before the mice at all times. This type of feed cup can be used 
only with the compressed dog biscuit type of food. A glass drinking tube of 
6- to 8-millimeter bore extends from an inverted water bottle, into the cage, 
through a reinforced opening in the top (fig. 1). 
Figure 1.—A metal ‘‘shoe box’’ mouse cage for general use 
having ¥2-inch-mesh hardware cloth in the cover. From 
the inverted water bottle a glass tube extends into the cage. 
The feed cup is shown at right. 
When used to house breeding animals, this cage will accommodate a male 
and three to five females. This type of cage is also suitable for housing preg- 
nant females and females with their litters to weaning age. Asa holding pen 
for weaned mice, it will accommodate 10 animals. 
Another popular type of cage has the same dimensions as the one just 
described except for the depth, which is 7inches. The sides are made of %4- 
to ¥g-inch mesh hardware cloth. The top of the cage slopes so that the front 
is about 2 inches lower than the rear. In the top of the cage is a metal door 
which is slightly smaller than the top. The door is held shut by the weight of 
the water bottle, which is clipped to it. The water bottle is of the same type 
as that used with the “shoe-box” type of cage. The glass drinking tube ex- 
tends from the bottle into the cage through a small circular hole in the metal 
door. This type of cage has no bottom, but is set in a galvanized iron pan 
342 inches deep, two cages to a pan. Sawdust or shavings are placed in the 
pan to absorb moisture. When the cages are to be cleaned, the mice are 
