Abstract
An attempt was made to apply tlae cosinor method to analysis of a circadianrhythm phenomenon observed in the rectal temperature of dogs. The following resultswere obtained.Body or rectal temperature was taken some time between 9:DO and 10:DO AM in 80mongrel puppies 1 to 5 months old and 212 adult montgrel dogs 7 months to 3 years old.The temperatures determined were normally distributed. Therefore, as commonly used, the mean (x) of the temperatures of the dogs at every clock hour was used as that at agiven time.The period of body temperature rhythm was calculated front measurenaents over a 48-hour period in 8 (4 male and 4 female) mongrel puppies 3.3 to 5.9 months old and 6 (51Il2LlC and l fenaale) mongrel dogs 9 to 13 months old. It was 23.88-l-1.64 hours for thepuppies and 23.67+0.82 hours for the adult dogs.The cosinor method could be applied to the clarification of canine body temperaturerhythm, because the rhythm was shown to be a one-cycle-per-24-hours periodic ptteno-menon. Applicat.ion oil the cosinor method to the clarification of body temperaturerhythm re-cealed that the periodic function of Halberg et al. exhibited by a cosine curvewell reprexented the diurnal rhytltm of canine body temperature. Further, it was clearlyshown that the cosinor diagram, which was expressed with amplitude and acrophase ofthe periodic functiota auad provided with a rejection ellipse, represented the characteristicsof the body temperature rhythm of dogs effectively.
