Page:The Golden Hamster Manual.djvu/59

 one litter may sometimes equal or exceed. In both number and usefulness the cavy’s average total yearly production. The hamster female may be mated again after as short a resting period as 4 to 8 days from weaning each litter. Usable in extensive medical and bacteriological work from 18 days onward, and ready for long-distance shipment at 20 to 22 days from birth. The animal develops so rapidly that it is ready for mature adulthood’s major dissection work at an early age. Physicians, technicians, and professors, as well as students, appreciate the ease with which this ulque animal may be handled, experimented upon, or dissected, since it weighs approximately one-quarter pound at 13 to 14 weeks. Such size takes it out of the laboratory mouse class for such work and permits the hamster to rival or excel the cavy and rabbit in much reearch, diagnosis, and hospital laboratory specimen anaysls.

Normally, unless badly mistreated, males of all ages may be handled freely at all times. Hamster females tend to become somewhat pugnacious from about 7½ weeks of age. They do not jump at one’s hands, but move quickly and at times bite while struggling for freedom. Care should be exercised to avoid being bitten by such females while using naked hands to handle them. A No. 2½ tin can is more practical than the bare hands. In clinical routine, the use of a laboratory animal holder on adult females is advised.

For routines requiring a larger ratio of either sex, give special consideration to nest culling for such purpose a directed in Chap. 30.

Marking, spotting, or painting laboratory animals for identification of individuals in routine and special tests: Aniline green, methylene blue and gentian violet, in purified form suitable for medicinal use, are satisfactory for identification dyes or stains after dissolved in alcohol and diluted with water to consistency of temporary stain. The three separate stains may be prepared for a few cents and in brief time.

A minor detail in technique: Cheek pouches should be avoided in all needle type administrations to hamsters.

Laboratory Pens and Cages: Small animal cages such as used to retain rats are satisfactory. Metal cages are highly satisfactory, more especially if modern self-cleaning floor type cages are used. Hamsters raised on self-cleaning floors handle better in laboratory, since already adapted to modern pens and cages. Hamsters may be retained, penned in groups, for long periods. Growing hamsters may be penned with rats, except that hamsters tend to chew rats’ tails until even large rats become afraid of hamsters. Group pennings of one to two dozen growing males continue to do well in pens approximately 2 by 3 feet. Once a mature female has been penned separately for any length of time she may fight others when first returned to a group pen.

The cost of hamster feeding, in either retaining pens or in full breeding production schedules, is only about one-third that of the eavy.

Progress may be notably advanced in junior high studies in elementary zoology, general sclence; etc., by use of hamsters. Natural tameness and adaptation.