There is a bit of blood with the delivery of each pup and a bit afterwards when the uterus is sloughing off the remainder of the placentas and the uterus contracts to shrink itself down to normal. If there is excessive bleeding you would need to take your dog to the vet quickly. The quantity of blood depends on the size of the dog. A small dog would loose less than 1/4 cup of blood if even that if delivering about 6 pups. The amount of blood loss during birth depends on the size of the dog and the size of the litter of pups she has.