Breeding dogs is part science, part strategy, and part holding your breath.
If you’ve ever wondered why a breeding didn’t take—even though she was flagging, standing, and “seemed ready”—you’re not alone.
Because while timing is everything, there’s one big problem:
Most beginner dog breeders are taught to time the wrong thing.
📉 Behavioral signs aren’t useless—just incomplete
Many breeders learn to rely on signs like:
- Tail flagging
- Standing for the male
- Softening of the vulva
- Changes in discharge
And the truth is? These signs often work.
Nature is remarkably efficient at reproduction, and in many cases, behavioral cues line up beautifully with the biochemical signals.
So yes—if you’ve been breeding for decades without progesterone testing and have had consistent success, I believe you.
But here’s the thing:
When behavior and biology line up, everything goes smoothly.
But when they don’t? You’re flying blind.
Relying only on behavior can leave you guessing—especially with tricky heats, silent ovulators, split cycles, young or maiden bitches, or frozen semen timing.
If you’ve ever had a breeding that didn’t take and you’re not sure why… this might be the missing piece.
🔬 Progesterone: The Hormonal Map
To accurately determine the optimal breeding time, monitoring progesterone levels is essential. Progesterone is a hormone that rises predictably during the estrous cycle, providing key insights into ovulation timing.
Here’s a simplified overview:
- Baseline Levels: During anestrus and early proestrus, progesterone levels are low, typically below 1 ng/mL.
- LH Surge: As the cycle progresses, progesterone begins to rise. When levels reach approximately 2 ng/mL, it indicates the luteinizing hormone (LH) surge, signaling that ovulation will occur in about 48 hours.
- Ovulation: Ovulation typically occurs when progesterone levels are between 5–10 ng/mL. However, the exact number can vary; what’s crucial is the trend—a rapid rise in progesterone levels.
- Fertile Window: After ovulation, the eggs require approximately 48 hours to mature before they can be fertilized. This means the optimal breeding time is a few days post-ovulation.
By tracking these hormonal changes, breeders can more accurately determine the best time to breed, reducing the guesswork associated with behavioral signs alone.
🧭 It’s About the Trend, Not Just the Numbers
It’s important to note that while specific progesterone values provide guidance, the overall trend is more informative. A single progesterone reading can be misleading; serial measurements offer a clearer picture of the cycle’s progression.
For instance, a sudden rise from 2 ng/mL to 6 ng/mL over a short period indicates that ovulation is imminent or has occurred. This information is invaluable for timing breedings, especially when using chilled or frozen semen, where precise timing is critical.
👩⚕️ Supporting Breeders Through Science
Understanding and interpreting progesterone trends can be complex, but you don’t have to navigate it alone. As a veterinarian who loves reproductive medicine, I’m here to support breeders in making informed decisions based on science and experience.
If you’ve ever felt uncertain about breeding timing or overwhelmed by conflicting advice, know that you’re not alone. With the right tools and support, you can approach breeding with confidence and clarity.
Want to delve deeper into progesterone testing and its role in successful breeding? Stay tuned for upcoming resources and workshops designed to empower breeders like you.
👉 Join my email list to receive updates, educational content, and support tailored to your breeding journey.
You don’t have to figure it all out on your own. Let’s navigate this together!
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