Variations in body temperature in the late stage of pregnancy and parturition in bitches.

Abstract

Body (rectal) temperature was taken in 45 pregnant bitches in the late stage of pregnancy to study a chronological relationship between variations in body temperature and the initiation of parturition. The average body temperature was 38.0°C 2 and 3 days before parturition. It declined clearly with the lapse of time, to 37.4 and 37.0°C 20 and 10 hr, respectively, before parturition (P<0.001). After that, it rised gradually with the lapse of time, reaching 37.4°C 1hr before parturition (P<0.001). In the 45 bitches, the minimum body temperature was 37.5°C at the highest when body temperature level had declined in the late stage of pregnancy. This was lower than the minimum one (37.7-38.1°C) in the diurnal variations of body temperature of non-pregnant bitches observed simultaneously with the 45 bitches in the present investigation. Then, the time when body temperature fell to 37.5°C in the late stage of pregnancy was detected as the starting-time of reckoning. The interval between this time and the initiation of parturition in these bitches ranged from l3 to 33 hr, being 2l.5±0.8 hr (mean±standard error). Therefore, it was concluded that a distinct decline of body temperature to 37.5°C or less in the late stage of pregnancy could be an indicator predicting the occurrence of parturition in the bitch. In other words, it was of practical value for the clinical diagnosis of parturition to take body temperature in bitches in the late stage of pregnancy.