The Heat Cycle

Signs of Heat

The first sign of a female (dam) coming "into season" is often swelling of the vulva. This swelling can occur a week before bleeding, or the day before. Other signs of heat are behavioral changes; your dam may start to hump other dams, or pups or even your leg. She may also begin to lick herself a lot.

If you own more than one dam, they will usually cycle together; one dam in heat will bring other dams into heat.

Finger pointing to a dog's vulva

Small vulva—dam not in heat

Dog's Vulva

Small vulva—dam not in heat

The back end of a female dog in full standing heat swelled up

A female dog in full-standing heat swollen up

finger pointing to a dam in heats vulva

A dam in heat and almost ready to be bred. You really need to stand your girl up, and look at the vulva. It will tip upwards and change position slightly to make it easier for the male to penetrate, also if you insert a gloved finger it will squeeze your finger inward. When a female ovulates, she will try to mount the male. She will have a very STRONG, distinct smell that dogs from MILES around can smell. Her discharge will have changed from dark red to a more faint color.

Canadian coin next to a swollen dog's vulva

Dam in heat. The vulva is swollen, sticking out from the body and three times the normal size.

Swollen dog's vulva with a little bit of blood

Dam in heat. The vulva is swollen, sticking out from the body and three times the normal size.

Canadian coin next to a swollen dog vulva

Dam in heat. The vulva is swollen, sticking out from the body and three times the normal size.

A human finger holding a Canadian coin next to a swollen dog vulva

Dam in heat. The vulva is swollen, sticking out from the body and three times the normal size.

Close Up - Swollen Dog Vulva

Female dog in heat

Swollen Dog Vulva with blood coming out

Female dog in heat dripping blood and vaginal fluid.

Other signs of being "ready to breed," are her willingness to stand for the male and she will hold her tail off to the side, called "flagging." She will often back her butt up to your leg as well..

A vet has ways to tell when she is fertile, but you still have to watch for the swelling and bleeding.

You will notice after her first heat that her teats will be more noticeable.

Dogs chest

Nine-month-old female before heat—no boobies

Dogs chest with a visible nipple

After heat—tiny, pink, more noticeable boobies

Your dog has come into heat

It is most common for the dam to come into heat at six months of age and then every six months thereafter. Some dams come in at four months and some at twelve months for their first heat, while some are every six months and some every five to 11 months. All dams vary, so you should keep track of what your dam is doing and when.


When is she fertile?

If you have the male with you he will tell you. Normally it is about 12 days after the bleeding starts, when the bleeding has slowed and thinned to pink. The male will know, he will regularly check, lick, analyze in with his built-in lab in his nose ;-)

On day 5 you will want to do your first blood progesterone test on the female. Then you will know exactly when the peak is. This is the type of testing the vet does if they are doing artificial insemination or a surgical implant.

This blood test measures in nonamoles and nanograms. Each measurement is different. It tests her progesterone levels, and lets you know when she drops eggs and when the eggs will ripen.

Recently we bred our girl; the following were her blood test measurements (nanomoles per liter):

2.5 on day seven, 4.2 on day nine

7.0 on day 11, 16.1 on day 13 (time to do first breeding)

A smear, can be done earlier in the cycle, will test for cornification. It is not as accurate, but when she is fully cornified, she is ready to breed.

Puppies are born 63 days from ovulation. (Not 63 days from breeding, as the male can breed her several days before, and after ovulation)

Fresh sperm can live five days (maybe seven days at most). Chilled sperm last 12 (max 24) hours after insertion. Frozen sperm last one (two) hours after inserted.

An egg lives five days. But on day one the egg is immature and cannot be penetrated. On day three the egg will be ripe, and this is the best day to inseminate. On day four, eggs are still ripe, and on day five the eggs are dying.


Generally the dog comes into heat, and the experienced breeder notices right away, while the newbie may not notice till day four.

Normally they are breedable on approximately day 12 to day 18, but they can remain in heat till day 21.

Each dog is different, and heat averages two to three weeks. They start to bleed, and then by day 12 it goes pink, and by day 16 they stop bleeding. Unfortunately many people think when they stop bleeding, they are out of heat, but in a dog, it means they ovulated. So...many unplanned breeding's happen.

Note: you cannot spay a female when she is in heat, or just after, as everything swells up and there is too much blood. Six weeks after is usually fine. Always ask your vet.