The developing canine embryo becomes a foetus after thirty-five days of gestation and growth in the uterus. It is then recognisable as a dog and major organ formation is accomplished. It will have grown to about 35 to 40mm (1’/4 to 1’/2in) of the 160 to 185mm (6 to 7in) length it will be at birth if it is an average-sized breed.

At about thirty-five days after fertilisation, eyelids, ear-flaps and sex organs are evident; at forty days, paws and claws are formed and eyelids closed together; at forty-five days, the dog’s colouring appears as hair begins to grow; and at fifty days the foetus is well-proportioned. Five days later the foetus is moving around in the uterus within the placental band with teeth well formed, and at sixty to sixty-three days it is no longer a foetus but a pup being born blind but well covered in hair.