Dog Heat Cycle Calculator
Tracks the four phases of the canine estrous cycle from the start date of your dog's last heat, and projects the next expected cycle.
Last heat - start date
Size category
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For trained veterinary professionals. Check every result against current drug labels, your formulary, and the patient before acting on it. This tool is not veterinary advice. Clinical disclaimer
How to use this tool
The phases
- Proestrus (~9 days) - swelling and bloody discharge, not yet fertile.
- Estrus (~9 days) - the fertile window, straw-colored discharge.
- Diestrus (~2 months) - reproductive rest, whether or not pregnant.
- Anestrus (~4 months) - full reproductive rest before the cycle repeats.
Cycle frequency varies by size
The full cycle (heat to heat) averages around 6 months but ranges roughly 4-12 months depending on breed and individual - larger breeds commonly cycle less frequently than smaller ones.
This isn't a breeding tool
This gives a rough planning window, not ovulation timing. For breeding, progesterone testing (tracking the LH surge and ovulation directly) is the accepted standard and far more precise than calendar estimates alone.
Frequently asked questions
How long is a dog's heat cycle?
The full cycle (one heat to the next) averages around 6 months but ranges roughly 4-12 months depending on breed and individual - larger breeds often cycle less frequently. Each heat itself (proestrus + estrus) typically lasts about 2-3 weeks.
What are the phases of the canine estrous cycle?
Proestrus (~9 days, swelling and bloody discharge, not yet fertile), estrus (~9 days, fertile window, straw-colored discharge), diestrus (~2 months, whether or not pregnant), and anestrus (~4 months of reproductive rest) before the cycle repeats.
Can I use this to time breeding?
No - this gives a rough planning window, not ovulation timing. For breeding, progesterone testing (tracking the LH surge and ovulation directly) is the accepted standard and far more precise than calendar estimates alone.