Dog Heat Cycle Calculator
Predict your dog's next season and likely fertile days.
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How this is calculated
Female dogs usually cycle about every 7 months (range 4–13). Proestrus bleeding lasts about 9 days; estrus follows for about 9 days (3–21), with ovulation 1–3 days after it starts. Individual dogs vary a lot, so this is a calendar guide, not contraception.
Source-based educational tool; not independently reviewed by a veterinarian. Cited guidance does not imply endorsement by its authors.
Formula
Next heat = last start + interval Fertile ≈ days 11–15 · heat ends ≈ day 18
Assumptions
- •Regular cycles; first heats are often irregular
- •Average proestrus 9 days, estrus 9 days (3–21)
- •Not reliable as contraception