A 4-year old crossbred Pointer, with observable vaginal prolapse was brought to our hospital at the 47th day of gestation. The prolapse reoccurred next day despite of the vulval suturing. During the examination of the prolapsed mass towards the cranium via palpation, it was observed that gestational sacs and urinary bladder were also in the prolapsed mass as well. Ultrasonographic imaging of the tissue revealed that puppies were presented into one-third section of the prolapsed vagina and there were no signs of vitality in the puppies. Although it is rare, vaginal prolapse might occur in association with simultaneous dilation of urinary bladder with a part of uterus in the third trimester of the gestation in dogs. In this case, the probability of true vaginal prolapse during gestation was restated and it was revealed that as an innovation ultrasound was a beneficial and guiding technique for the diagnosis of this case.