The Canine Estrus Cycle

I Love Veterinary blog is reader-supported, and we may earn a commission from products purchased through links on this page, at no additional cost to you. Learn more About Us and our Product Review Process >

The canine estrus cycle is the time of a female dog’s heat cycle, which can last up to three weeks. This period may be accompanied by mating with males and an increase in urination.

Female dogs go into estrus about twice a year, but some breeds have shorter cycles while others may go into estrus every six months or more often. During this time many pet owners are unaware that their dog is cycling regularly, as they do not witness any vaginal bleeding or other symptoms that would indicate it.

The canine estrus cycle, like all other mammal ontogenies, varies in duration and frequency depending on the canine species. The canine estrus cycle begins around puberty and may continue until death.

How Long is a Female Dog in Heat?

Proestrus: During this stage, females show no outward signs. However, their vaginas swell and secrete bloody fluid. This bloody discharge can last anywhere from three to 10 days.

Ovulation occurs anywhere from two to five (on average) days after proestrus starts; it will last approximately one day. After mating or artificial insemination, females experience diestrus for about 58 to 68 days (the normal canine gestation period ranges from 58 to 72 days).

During diestrus, females do not come into estrus (i.e., they cannot conceive), and their uterine endometrial lining remains intact. Females give no outward signs of this stage, although some may lose their appetite or become more vocal than normal.

Diestrus is commonly divided into three to four days of early diestrus; the canine gestation period (from fertilization to birth) lasts about 58 to 72 days.

If females are not mated successfully during estrus, they remain in diestrus for twice as long (about 116 to 120 days). This condition is known as silent heat or anestrus.

5-10% of females that enter puberty will have an irregular estrual cycle – meaning that they do not have four consecutive weeks of bleeding and swollen vulva before coming into heat again. These dogs may also have reduced fertility, as the canine estrus cycle may be too short for fertilization to occur.

This stage is very important in canine reproduction because it is when females are receptive to mating. Females show intense interest in males and can stand to be mounted by them for an extended period of time.

If a male attempts to mount her during this stage, she will let him. If no successful mating takes place, then the female will remain in proestrus for another estrus cycle until she can become pregnant or experience estrus once more.

Below you can find an infographic explaining the stages of the estrus cycle in female dogs. Get this as a poster for your clinic or classroom! Order HERE!

canine estrus cycle infographic

What are the Signs of the Canine Estrus Cycle?

Canine estrus is the mating period when a female canine will allow a male canine to procreate with her. Unlike humans, canine estrus typically only lasts for four days, and it causes many changes in behavior and physical appearance.

The signs of canine estrus include heavy vaginal bleeding and swollen nipples, as well as restlessness and increased affection toward males.

When Does Canine Estrus Occur?

Dog estrus occurs halfway through any given canine pregnancy, shortly after the fetus has developed into a litter of puppies.

Depending on many factors such as nutrition and health, dog estrus usually occurs between 50 and 70 days after conception. she becomes pregnant, canine gestation lasts for nine weeks or 63 days.

How Does Canine Reproduction Work?

The canine gestation period lasts for 63 days on average. After fertilization, cells begin rapidly dividing into two groups: one destined to become the fetus and another group called the trophoblast which is responsible for producing the placenta. At day 8 post-fertilization, canine embryonic development is about 30 cells.

By day 10, the embryo attaches to the uterine lining and canine heart valves begin to form. The canine species has one of the longest gestation periods compared with other mammals. Most specimens are not fully developed until at least 63 days have passed.