Calculadora del Celo de la Perra

The Four Phases of a Heat Cycle

Dates below are estimated from your last heat start date. A full heat cycle (proestrus through diestrus) typically lasts about 2-3 weeks; anestrus is the resting phase that fills the rest of the interval until the next heat.

Fertile Window

• The fertile window typically falls around days 9-14 of the heat cycle, once discharge lightens and she becomes receptive (the estrus phase).
• Ovulation timing varies between dogs, so days 9-14 is a general guide, not a guarantee.
• Behavioral cues — standing to be mated, tail-flagging to the side — are a better real-time signal than the calendar alone.

Irregular Cycles

• Some cycle-to-cycle variation in interval and heat length is normal, especially in young dogs whose first few cycles can be irregular.
• A first heat usually arrives between 6 and 12 months of age, though large breeds can start later.
• Very irregular, unusually long, or unusually frequent cycles are worth mentioning to your veterinarian.

This calculator provides a general estimate based on average cycle timing and is informational only, not veterinary advice. Talk to your veterinarian about your dog's individual reproductive cycle, especially before breeding or if you notice irregular bleeding.