How Long Does the Bleeding Phase Last in Dogs in Heat?

A female dog who isn't spayed goes into what's called "heat," or "being in season." This means she is receptive to mating. A dog heat cycle calculator can be helpful in determining when your dog is entering the various phases of her heat.

Woman holding her pet dog
A dog in her reproductive cycle is called in heat.
credit: Sally Anscombe/Moment/GettyImages

When a female comes into heat, her body is ready for the possibility of mating. This is when she is most sexually receptive, and if you are trying to breed a dog, this time period will be the best for successful mating. Even though young dogs do enter into heat, ethical breeders wait until they are about two years old — this will reduce the stress on a breeding dog's body and allow her to have a more successful pregnancy and birth.

When does heat start?

According to VCA Hospitals, a female dog entering her heat for the first time is equivalent to a human entering puberty. For most dogs, they will enter their heat cycle for the first time at around six months of age, but different breeds will vary slightly on this time. Smaller breed dogs tend to enter their dog heat cycle earlier, while the largest breeds may take up to 18 months or even two years of age before they reach sexual maturity.

Dog heat cycle calculator

A dog's heat cycle, also known as the estrus cycle, occurs for most dogs twice per year. Just as small dogs come into heat earlier, they also cycle more often, and may go into heat three times per year. Larger dogs may cycle only once per year. Young dogs of any breed may enter into their cycle on an irregular basis, which can make using a dog heat cycle calculator slightly unreliable.

When your dog's cycle becomes more reliable, there are some dog heat cycle calculator apps you can use. Another option is to track the stages on your calendar or dog heat cycle chart, and you should have a pretty good idea of when your dog is entering the stages of being in heat, how long they are lasting, and how long it will be before she is done.

Stages of a dog in heat

There are four phases of a canine estrus cycle. Altogether, the four phases last a total of 79 days to 111 days. The first phase is called proestrus, the second stage is called estrus, the third stage is called diestrus, and the final stage is called anestrus, according to Pet Life Today.

Proestrus

This phases lasts seven to 12 days. During this phase you will notice your dog's outer reproductive organ, the vulva, enlarging. This is the phase in the dog heat cycle during which bleeding will occur. Male dogs who have not been neutered will be attracted to her because of the chemical scents related to mating that she is giving off. However, your female dog will not be interested in mating yet.

If you notice your dog in heat bleeding heavy, try to ascertain if it is a normal amount of bleeding or if it seems excessive. Heavy bleeding or bleeding outside of a heat cycle is not normal. Hills Pet says that the amount of discharge that dogs produce can vary quite a bit. You may notice your dog leaving spots of what looks like blood on her dog bed or on the furniture.

Typically, the discharge is heavier in the beginning of the proestrus cycle and then fades to both less discharge and discharge that is lighter in color. If cleaning up the furniture is becoming a chore during this time, manufacturers do make a diaper-like product that is specifically for use during the dog heat cycle bleeding phase.

Estrus

The estrus phase lasts nine days. This is the phase in which your female dog's body will be receptive to mating. You will notice many of the same signs as in the proestrus phase, including discharge and enlarged vulva.

Diestrus

The longest phase of the estrus cycle is the diestrus phase, which lasts about 65 to 90 days. During this phase, there is no more vaginal discharge. She is no longer interested in mating. If she has been mated and the mating resulted in a successful pregnancy, the puppies within her will begin to grow.

If she is not pregnant during this time, the diestrus phase will last a little bit longer, at 75 to 90 days. If your dog is not pregnant, during this time she will look and act normal.

Anestrus

This final stage of the estrus cycle lasts from whatever the end of the diestrus phase is to the beginning of the new proestrus phase. During this time, the dog will also look and act normal.

Female dog in heat behavior

You will likely not notice any difference in your dog's behavior except during the proestrus and estrus phases. Between the beginning of proestrus and the end of estrus is 19 to 21 days, therefore the female dog in heat behavior that you will notice lasts approximately three weeks.

Breeding Business lists some of the signs of a female dog being in heat. For one, her vulva will swell. You may notice bloody spotting on furniture, the floor, or her dog bed. However, some dogs are good at keeping themselves clean, so you may not notice much or any spotting if it is light.

That said, one sign of a dog being in heat is that she may be licking her genital area a lot more than normal. This will be her attempt to keep herself clean, so if you are trying to determine if she is in heat look for some of the other signs, such as tail flagging.

Tail flagging is a behavior in which the female dog holds up her tail so her genitals are more exposed. She will move her tail from side to side. This helps ensure her scent goes out into the world and attracts males who may want to mate with her.

One other sign is she may have personality changes. For instance, she may seem more agitated than normal around other people or animals.

Male dog behavior around heat

When non-neutered males sense a female dog in heat nearby, they can be very persistent about wanting to get to the female. They can break away from you and escape, even when you think they are well-contained.

Breeding Business says that a non-neutered male dog is able to detect a female in heat up to three miles away. If you see random male dogs coming into your yard and sniffing around, this could be a sign that your dog is in heat even if you have not noticed any of the other signs.