POSSIBILITIES OF THE DIAGNOSIS OF HEAT AN D OVULATION IN DOGS

Oestrus cycle of 67 bitches with histories of infertility has been mon itored to evaluate the accuracy of vaginoscopy and the characteristic response of receptivity, vaginal cytology and RIA progesterone assay t o determine the optimal time for mating. The usual procedure was to ta ke vaginal smears and blood samples and carry out vaginoscopy every tw o to four days during the heat period. Vaginal smears were stained wit h Schorr-Papanicolaou's method and evaluated for the percentage of cor nified (eosinophil) cells. The first day of oestrus was defined as day on which 80% or more of the vaginal epithelial cells were cornified. Ovulation occurred 6 to 7 days after the first day of oestrus. Blood s amples were assayed for plasma progesterone by radio-immunoassay (RIA) . Ovulation was estimated to occur when the progesterone concentration reached a level of 5 ng/ml. In the present study, in 62.5% of bitches (20 of 32 bitches) the difference between the time of ovulation deter mined by vaginal cytology and plasma progesterone assay was not substa ntial (the difference was not more than 2 days). It was found that vag inoscopy could be used only to differentiate the two stages of heat pe riod (prooestrus and oestrus). In the present study, the following hea t/ovulation problems were detected: short heat period, split oestrus, early oestrus behaviour, late oestrus behaviour, failure of oestrus be haviour, early ovulation, late ovulation, failure of ovulation (''subo vulation''). These problems have been illustrated by typical cases' di agrams (Figs). Based on the results of the present study, RIA progeste rone assay and vaginal cytology are useful methods in the management o f bitches with histories of infertility and also to raise the litter s ize.