Dog Heat Cycle Calculator
Track your female dog's heat cycle, estimate the next estrus start, fertile window, and prepare for breeding or protection.
Input Parameters
Enter details for calculation.
Next Heat Start
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Expert Tip
A female dog's heat cycle lasts about 2-3 weeks. The peak fertile window is usually 9 to 14 days after bleeding begins, but sperm can survive for up to a week in the reproductive tract.
Calculation Methodology & Details
Formula
The heat cycle is calculated by converting the cycle frequency in months into days (using an average of 30.44 days per month). The fertile window (estrus) is estimated to occur 9 to 14 days after the onset of proestrus (bleeding).
Important Disclaimer
All veterinary dosage guidelines and calculations are for educational purposes only. Always consult a licensed veterinarian before administering any medication or making major changes to your dog's diet.
How to Predict Your Dog's Heat Cycle: Step-by-Step
Forecast dates for bleeding and breeding phases using this method:
Mark the Start Date
Note the exact day you first observed swelling or bleeding (Proestrus).
Determine Average Cycle Length
Most dogs cycle every 6 months, but smaller dogs can cycle every 4 months, and giant breeds only every 12 months.
Calculate Fertile Period
Add 9 days to the start of the estimated next heat to find the beginning of the fertile window, and 14 days for the end.
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