The aims of this study were to evaluate in the canine foetus the growth of the deep portion of the telencephalic vesicle (DPTV) and to estimate the day of parturition by means of its ultrasonographic measurements in small and medium size bitches. The results showed that the growth of DPTV can be investigated during pregnancy with ultrasonography, but accuracy in the prediction of the day of parturition by means of its measurements is not as precise as those of gestational inner sac and biparietal diameters. However, it may contribute to the estimation of gestational age if combined with the biparietal diamete