NOW that we have fully discussed the germane issues pertaining to the roles, prerequisites and expectations of the brood bitch and the stud dog, we can proceed with answers to the salient question: “When to breed?”
This is not a straightforward issue. We must, first of all, understand the estrus cycle (when and for how long the female dog is in heat). Not understanding this heat cycle is perhaps the most common cause of an unsuccessful mating. Owners often put their dogs together at the wrong time. So, let us deliberate on this estrus cycle in some detail.

Firstly, please note that the female dog could show first signs of heat (estrus) as early as eight months of age, even earlier in some cases. Usually, the “heat” appears when she is about 10 months old. There are no fixed times. As we are all aware, a woman can be pregnant for 8½ months, 8¾ months, 9 months, 9½ months etc, before giving birth. This is because we are dealing with biology, and not the exact science of mathematics.
Secondly, unlike what the general feeling is, a bitch comes in heat only about twice a year (again, this can vary), but I have known bitches to come into heat every 4 months or so. This, however, is the great exception. I will now rely on a very adequate and simple text put together by veterinarians Drs. Carlson and Giffin.
As a general rule, estrus, the season of heat, lasts 21 days, as reckoned from the first sign of vaginal bleeding. The onset of heat (called pro-estrus) lasts six to nine days. A pink to dark bloody discharge and firm swelling of the vulva signal it. It is during this stage that the female begins to attract the male, who is able to detect chemical changes, called pheromones, which are discharged from her vulva and excreted in her urine. During this pre-ovulatory phase (before the eggs are released from the ovary) in the heat cycle, the female would not accept the male. If mating is attempted, she would jump away, sit down, growl, or snap at the male to drive him away.
The second phase of the estrus cycle is called the true estrus, or standing heat. It is the time during which the female is receptive. She begins to flirt with the male, raises her tail and flags it to the side. She lifts her pelvis and presents her vulva when touched in the rear. The vulva softens and the discharge becomes pinkish.
[A microscopic examination of the vaginal secretions carried out by the vet at this time would show a reduction in the number of red cells. a few white cells would be seen. Also, there are changes in the appearance of the surface cells of the vaginal lining. These changes enable a veterinarian to determine whether the bitch is ready to be bred]. Estrus, or standing heat, lasts 6 to 12 days. It ends when the female refuses to stand (be receptive) for the male.
The third phase in the reproductive cycle is called metestrus. It begins when the female refuses to stand for the male. After a bitch has gone into heat once, her breasts and vulva would remain slightly larger than before.
The fourth phase is called anestrus, which is a period of reproductive rest. It lasts 100 to 105 days.
The heat period usually comes every six to eight months. However, as I have said earlier, some bitches go into heat every four months, and others only once a year. Several factors, such as the time of year, hereditary tendencies, and emotional states, have a bearing. Some of these will be discussed when we write about infertility.
Having explained how the cycle works, the question remains: When does the breeder bring the brood bitch and the stud dog together? The simplest rule-of-thumb answer is 8, 10 and 12 days after one sees the first droplets of blood. Since the breeder might have missed the first signs of pinkish discharge emerging from the vagina, one may bring the animals together 7, 9 and 11 days after recognizing the discharge.
Of course there are those who advocate bringing the dogs together and allowing them to remain with each other for the entire period of pro-estrus and estrus. This is not a good idea, because
i) the male would constantly harass the female when she is not ready – using up a lot of energy in the process, and possibly being injured by the unwilling female, and
ii) the female may just be “turned off” by the constant attention of a too amorous male. In addition, it has been observed that when the female has taken up the role of the alpha animal in animals growing up together, she may be less receptive to the weaker, subservient male.