Search Menu

Chances are, eons ago, one of your parents sat you down, all strained smiles and adult awkwardness, and had that “birds and bees” talk.

But did anyone ever have that same conversation with you about your dog? If you’ve decided to get into casual breeding, you need to know how to tell if your bitch is ready to be bred.

If you know how reproduction works in our species, for dogs, the first thing you need to do is … forget all that. Dogs are completely different, from their physiology (their uteruses are shaped like a wishbone, with both long sections, or horns, designed to contain puppies, like peas in a pod) to the mechanics of conception, as you’ll soon see.

Pregnant French Bulldog standing in the garden.
Gorlov Alexander/Shutterstock

When Does a Dog Go into Heat?

Among us humans, when a female begins to bleed, it is a sign that she has not conceived: Menstruation marks the end of the fertility cycle. In canines, however, the opposite is true: When a bitch begins to bleed, it signals the beginning of her fertile period.

Female dogs do not “get their period.” Colloquially, breeders refer to a bitch’s fertile time as being “in heat” or “in season.”

Like people, all dogs are individuals, so the amount of bleeding can vary, but typically we are not talking about a lot of volume. Investing in a correctly fitted pair of dog diapers can keep the mess to a minimum.

If you are observant, you’ll notice signs of your bitch’s impending season before she starts bleeding. Swelling of the vulva is one early sign, as are increased neediness and clinginess. Although some dogs, particularly Toy breeds or first-time bitches, experience “silent heats,” in which these external symptoms are absent.

Another difference between our species is frequency: While human females cycle every month, bitches come into heat every six to 12 months – sometimes more or less often. Your dog’s breed is sometimes a factor in this. For example, some primitive breeds cycle only once a year: Tibetan Mastiff breeders will tell you their females come into heat at the end of the year, forcing them to schedule stud dog visits alongside their tinsel-stringing.

When Should You Breed Your Dog?

The timing of a bitch’s first heat can vary significantly as well: Some females come into heat at six months of age, while others might not experience their first cycle until a year or older. Even within a particular breed, different families of dogs can and do have different timing of their cycles.

Even if she has not been spayed, a bitch cannot get pregnant when she is not in heat. So, assuming you have a female that cycles every six months, she is only fertile two times a year – not every month. Heat cycles last two to four weeks – again, every dog is different – but it’s important to know that a female is only fertile for a short period within that time frame.

The start of a heat, which is marked by bleeding and lasts from seven to 10 days, is called proestrus. Male dogs will show interest in bitches at this time, but typically a female will ward off any advances, as she knows she is not fertile yet because she has not yet ovulated.

During the next phase, called estrus, the bloody discharge tapers off and lightens in color, from pink to a yellowish straw to eventually nothing. It’s during this time that the female ovulates and is receptive to breeding. Estrus can last from five to 10 days, prompting both males and females follow to their biological imperative and procreate.

The remaining two phases of a bitch’s cycle are diestrus, the period right after estrus when the female is no longer receptive, and anestrus, the time the body uses to prepare for the next pregnancy. A bitch cannot conceive during these phases.

Borzoi mom and puppy outdoors.
©Dogs -

Planning for Your First Breeding

In the days when breedings were largely planned and executed without veterinary intervention, breeders knew a female was ready to be bred the old-fashioned way: Their stud dogs told them by detecting the hormonal changes that signal the fertile period.

Today, veterinarians gauge those hormone levels with blood tests that measure a bitch’s progesterone level, which rises throughout estrus. Some veterinarians will also perform a vaginal smear to check for increased cornification of the epithelial cells under a microscope, but this is typically done with progesterone testing.

Ovulation is the ding-ding-ding moment we have been waiting for: Until a female releases those eggs, fertilization cannot take place. Some bitches can stall their progesterone rise, as many breeders have discovered when they drive or ship a bitch to the stud dog. Eventually, the bitch will resume her progesterone climb.

In scientific terms, when a bitch’s progesterone level reaches 5 nanograms per milliliter, she ovulates. But, like humans, once she releases those eggs, she can’t recall them.

Rather than the solitary egg release that is typical of human ovulation, canine mothers-to-be can release ova that number in the double digits. And unlike many other mammals — including humans — a bitch’s eggs are not ready to be fertilized as soon as she ovulates: Instead, they slowly mature, ripening anywhere from 24 to 36 hours after ovulation.

This hurry-up-and-wait phenomenon — along with the fact that the eggs mature at different times — explains why some litters can have multiple sires. Sorting out baby daddies then falls to DNA testing.

If you do plan to breed your female dog and don’t yet have an experienced, knowledgeable mentor guiding you, find one who can explain the nuances in more detail. An obvious mentor would be your bitch’s breeder, which is why it is important to buy your breeding stock from someone who is experienced and ethical.

For your bitch’s sake – and yours – become knowledgeable about how canine reproduction works: If you think the process of timing a breeding is unfamiliar and intimidating, it’s nothing compared to the real heart-in-your-throat challenge of whelping the ensuing litter.

Related article: What Breeders Learned From Their Very First Litter
Get Your Free AKC eBook

Breeder Education Courses

Training isn't just for pets - here's your chance to learn too. Visit the AKC Breeder Education Platform designed to support your continuing education needs. Course topics include introduction to breeding, genetics, anatomy, whelping and nutrition.
*Turn off pop-up blocker to download
*Turn off pop-up blocker to download