Ultrasound is a good modality to ensure that the puppies are alive and to detect gross defects in the puppies and uterus but is a poor modality to determine litter size. Radiographs taken with high resolution machines can accurately determine the litter size in almost 100% of small to medium breeds and very accurately in most large and giant breeds. Knowledge of the litter size may help the breeder to know how many puppies they are waiting for during the whelp.