by Charlotte Howard

Created on: May 21, 2008   Last Updated: February 26, 2011

Breeding from your dog is a big decision to make. It is important that you take into account the bitches age, health and weight before letting her mate. It is important to the remember that every pregnancy is different, some are easy and uncomplicated, others come with dreadful problems such as miscarriage, prematurity and still birth. Improvements in veterinary care and medicine reduce these risks remarkably.  The breed of dog can determine number of pups, as smaller breeds tend to have a small brood than larger bitches.

The miracle that is pregnancy generally lasts between 64 and 66 days in bitches, however it can be as short as 56 or as long as 72 days before the puppies are born. It all depends on when the mating occurs, as early mating may seem like a longer pregnancy, or late mating like a shorter one as sperm and eggs can survive for a few days before being fertilized.

Pregnancy diagnosis in bitches is by palpatation, usually performed approximately one month after mating has occured. An ultrasound will determine how many pups there are, although it is not always possible to see them all. Hormone tests are not generally used to diagnose pregnancy in bitches. You may notice certain symptoms such as increased vaginal discharge, production of milk and increased weight before the vet has given you the positive news. Other behavioural changes occur too. The bitch will begin to 'nest', building a bed and perhaps taking favourite toys to that area, although this does not usually occur until later on in the pregnancy. If she shows signs of 'nesting' early on after mating it is possible that she is actually having a phantom pregnancy.

Implantation occurs between 14 and 20 days after initial ovulation, this is when the zygote, or fertilized egg attaches itself to the uterus wall. Very rarely some bleeding can occur at this point, although you will probably not notice as the bitch will clean herself. This egg will split and form into an embryo, growing rapidly over the next few weeks. At first a yolk will feed the embryo before the placenta is large enough to take over.

Bitches have around five pairs of mammary glands running down the stomach. These will become swollen as the pregnancy progresses and will start to produce colostrum, an early milk filled with antibodies and calories to aid the new puppies digestive and immune system when they are born.

At 3 weeks old the embryo will measure at a tiny 5 mm long, and just a week later it has grown to 20 mm and now has little buds that will grow into the limbs. Colouring and markings begin to appear at about 7 weeks old as the embryo turns into a foetus. Two weeks later the pup is born with eyes and ears closed.

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