Dogs typically stay in heat for about 2 to 4 weeks (14 to 28 days), with the average duration being around 16 to 21 days. During this time, the heat cycle is divided into phases:
- Proestrus: Lasts about 7 to 10 days, characterized by swelling of the vulva and bloody discharge. The female is not receptive to males during this phase.
- Estrus: The actual "heat" phase when the female is fertile and receptive to mating, lasting about 3 to 21 days, averaging around 9 days. The bleeding usually lessens or stops during this phase.
- Diestrus: Follows estrus and lasts about 60 to 90 days, during which the body either supports pregnancy or returns to normal.
- Anestrus: A resting phase lasting about 3 to 5 months before the next cycle begins
Bleeding typically lasts about 7 to 10 days but can vary between dogs
. Most female dogs have their first heat around 6 months of age, though this varies by breed and size, with smaller breeds maturing earlier and larger breeds later. After the first heat, dogs usually go into heat approximately every 6 to 7 months, or about twice a year
. In summary, the heat period itself lasts roughly 2 to 4 weeks, with bleeding for about 1 to 1.5 weeks, and cycles occurring about twice annually.
