Merck Manual

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Estrous (Heat) Cycle in Female Dogs

Estrous (Heat) Cycle in Female Dogs

  • Proestrus—Start of heat. Lasts 7 to 10 days. Vulva swells and blood flows. Females attract males but will not allow mounting.

  • Estrus—Mating period. Lasts 5 to 10 days. Blood flow lessens and then stops. Females attract and accept males. Ovulation occurs during this time, usually 2 to 3 days after mating.

  • Diestrus. The period 10 to 140 days after heat, when the dog is either pregnant or in a resting phase.

  • Anestrus. The resting period between diestrus and the next heat cycle.