One of the most common questions breeders ask when a female dog comes into season is when progesterone testing should begin. Proper timing of progesterone testing is essential for accurately identifying ovulation and determining the optimal breeding window.
While many breeders rely on traditional breeding days such as day 10 or day 12 of the cycle, the truth is that every female dog is different. Ovulation can occur much earlier or much later depending on the individual dog and even from one cycle to the next.
Understanding the Beginning of the Heat Cycle
The first day of visible vaginal bleeding is generally considered day one of the heat cycle. During the early part of the cycle, progesterone levels remain very low.
As the cycle progresses and ovulation approaches, progesterone levels begin to rise. Monitoring these changes through regular testing allows breeders to determine when ovulation is likely to occur.
When Testing Should Begin
For most dogs, progesterone testing should begin around day 5 or day 6 of the heat cycle.
Starting testing at this time allows hormone levels to be tracked as they begin to rise. Early testing helps establish a baseline progesterone level and makes it easier to identify the rapid increase that occurs just before ovulation.
Depending on the results, testing may be repeated every 24 to 48 hours until ovulation is confirmed.
Why Timing Matters
Accurate progesterone testing helps breeders:
• determine the correct breeding window
• avoid missed breedings
• improve conception rates
• coordinate artificial insemination or shipped semen breedings
Without hormone testing, breeding timing often becomes guesswork.
In-House Progesterone Testing
Many veterinary clinics must send progesterone samples to outside laboratories, which can delay results by 12 to 24 hours. During a breeding cycle, those delays can make it difficult to identify the ideal breeding window.
In-house testing allows breeders to receive results quickly and monitor hormone changes closely.
At TerraSassa, progesterone testing is performed in-house with results available in approximately 35 minutes, allowing breeders to make timely breeding decisions during the cycle.
Final Thoughts
Each female dog is unique, and cycles can vary significantly from one breeding to the next. Beginning progesterone testing early in the heat cycle allows breeders to track hormone changes accurately and determine the best time for breeding.
Careful reproductive management plays an important role in responsible breeding programs and helps increase the likelihood of successful litters.
Breeders interested in progesterone testing or reproductive services can learn more here:
TerraSassa French Bulldogs 