Heat Cycle

Estimate your dog's next heat and fertile window.

Cycle Details

Start of Last Heat

Average Interval (Months)

Projected Dates

Jan 20, 2027Date

Next Heat Start

Based on average canine cycles

Fertile WindowJan 29, 2027 - Feb 7, 2027

* Keep supervised during this time!

Cycle Timeline

ProestrusBleeding & Swelling

Day 1-9

EstrusFertile Window

Day 10-18

DiestrusPregnancy or Rest

Day 19-60

The full cycle (including Anestrus) usually spans 6 months (180 days).

Understanding the Cycle

The canine heat cycle has four stages. Proestrus (bleeding/swelling) lasts about 9 days, followed by Estrus (fertile stage) where the female accepts mating. Most dogs cycle every 6 months.

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Pro Tips

Small dogs can have their first heat as early as 6 months.
Giant breeds may wait until 18-24 months for their first cycle.
Dogs do not go through menopause; they can cycle for life.
A 'silent heat' occurs without obvious external bleeding.

Fun Facts

"The Basenji breed typically only cycles once a year, usually in the autumn."
"During a 'tie', dogs are physically locked for 15-30 minutes; do NOT try to separate them as it causes injury."
"A female dog's pheromones during heat can be detected by an intact male from up to 3 miles away."
"If you aren't breeding, the 'Estrus' phase is the highest risk time for accidental pregnancy."
"Hormone testing (specifically progesterone levels) via a vet is the only 100% accurate way to predict the exact ovulation day."

Formula: Next = Last + Interval

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