Some Factors Influencing the Life Span of Golden Hamsters

The golden hamster has found increased use as a laboratory animal over the last two decades. It is of particular interest because it hibernates although its periods of dormancy are short compared to those of other hibernators (1). The complete spectrum of physiological norms should be determined for this common animal just as they were for the laboratory rat. In the list of normal values for the hamster there is little published information on life span (2). This paper will present records of life spans of 126 hamsters kept under controlled laboratory conditions. Approximately 43% of the colony were maintained with a daily light cycle in a coldroom (6 ± 2 ° C.) for about 4 months each winter. Other conditions of the experiment have been described earlier in detail (1). For the purposes of this analysis the cold-exposed group was treated as a homogenous population, in spite of the fact that some of the animals hibernated. This combining of animals was due to the fact that there was such variation in the total duration of hibernation over the winter periods. Some hamsters hibernated for one day, others were in hibernation for a total of 95 days. The systematic pattern of results justifies this approach to this analysis. To be specific, the data treated in this paper look as if cold-exposure with or without hibernation produced the same effects upon the animals, in most respects. Furthermore, the hibernators were distributed nearly equally among four groups of cold-exposed animals. Later analyses will attempt to consider the influence of hibernation as a separate factor. We will ref.er in this report only to the cold-exposed group: this means a mixed group of males and females of two strains of animals, most of which were coldexposed 4 months, but a few of which received only 3 months of cold-exposure at 6° C. and a few weeks at 16° C. About 12 of the males and 10 of the females hibernated for variable periods of time