The reaction of anæstrous hedgehogs to experimental conditions

Abstract

Between Oct. and March anestrous [male] and [female] hedgehogs were kept in the laboratory (a) without treatment, (b) at an environmental temp, of 70-75[degree] F, (c) with additional evening illumination, (d) receiving injections of estrin, (e) receiving injections of urine of pregnancy extract. Changes characteristic of the breeding season were induced in the majority of experimental animals. The [female][female] showed follicular growth and enlargement of the uterus and vagina, such as normally do not occur until April or May. In several animals there was full estrus development, but only 3 ovulated. In untreated [male][male] kept in the laboratory, the testes became active in Dec. Full activity was reached 2-4 weeks earlier by the animals given extra warmth, extra light or injections of urine of pregnancy extract. The accessory glands were like the normal anestrous ones in the untreated [male][male], but were stimulated by the experimental conditions. The anestrua of the hedgehog is therefore unstable in comparison with the definite period of quiescence of animals like the ferret. This conclusion is of some theoretical importance in its bearing on the fixity or non-fixity of the breeding season in various spp., especially in those with a wide climatic range.