Ovulation Confirmed: What Lady Dyanaformer’s Ultrasound Means and What Comes Next
This week has been all about precision—and so far, everything is going according to plan for Lady Dyanaformer and the team at Horse Husband Stables.
A scheduled ultrasound today confirmed that Dyana ovulated following her live cover breeding yesterday with champion stallion Knicks Go. This is exactly the result her veterinary team was hoping for, and it officially begins the countdown to her next milestone: a 14-day pregnancy check.
Understanding the Breeding Timeline
In equine reproduction—especially with live cover, as required for Jockey Club-registered Thoroughbreds—timing is critical. A mare's egg remains viable for fertilization for only 6 to 12 hours after ovulation. To maximize the chance of conception, breeders aim to cover a mare shortly before ovulation, so viable sperm are already present in the reproductive tract when the egg is released.
Here’s how Dyana’s carefully timed breeding came together:
Monday at 3:30 PM – Ultrasound revealed a 49mm dominant follicle, strong uterine edema, and cervical relaxation—all signs pointing to imminent ovulation.
That same afternoon, Dyana received an intramuscular injection of a GnRH analog, a hormone that helps trigger ovulation within 36 to 42 hours when a mare is already close to ovulating.
Tuesday at 1:00 PM – Dyana was bred via live cover at TaylorMade Farm. Upon arrival, she was presented to a teaser stallion to confirm she was still displaying estrus behaviors.
Wednesday (today) – A follow-up ultrasound confirmed that ovulation had occurred, indicating the breeding was likely timed well for successful fertilization.
This 36–42 hour window from hormone administration to ovulation is the gold standard in live cover breeding and significantly increases the odds of a positive result.
The Role of Ultrasound in Breeding Management
Ultrasound is an essential tool in modern equine reproduction. It allows veterinarians to:
Track follicular development and predict when ovulation will occur
Monitor uterine edema and cervical changes to evaluate estrus
Confirm ovulation by visualizing the collapse or disappearance of the dominant follicle
Identify pregnancy vesicles at 14–16 days post-breeding
Detect and manage twin pregnancies
Why Early Pregnancy Scans Matter: The Risk of Twins
Unlike many other species, horses are not well-suited to carrying twins. The equine uterus is designed to support a single foal, and when two embryos are present, complications are almost inevitable. The majority of twin pregnancies result in:
Late-term abortion of both fetuses
Or the loss of one foal with significant health risks to the other
In rare cases where both foals are born, they are often underdeveloped and nonviable
Twin pregnancies also pose serious risks to the mare, including:
Uterine rupture
Infection or retained placenta
Difficult or dangerous foalings
To prevent these outcomes, veterinarians perform a procedure known as twin reduction, or “pinching”, during the 14–16 day ultrasound. If two embryonic vesicles are seen, one is manually terminated before placentation occurs. This improves the odds of a healthy pregnancy and allows the remaining embryo to grow and develop normally—bringing the success rate back in line with that of a single pregnancy.
Caslicks Procedure: Protecting the Pregnancy
After confirming ovulation, Dyana’s veterinarian also performed a Caslicks procedure, which involves suturing the upper portion of the vulva to create a physical barrier against contamination. This is especially important for mares with prior foaling history or those with conformational risks that can allow air and debris to enter the reproductive tract.
The Caslicks remains in place throughout pregnancy to help prevent infections that could jeopardize the embryo or later fetus. It is reopened near the end of gestation in preparation for foaling.
What Happens Next?
With ovulation confirmed and her Caslicks in place, Dyana now enters the waiting phase. At 14 days post-breeding, her veterinary team will perform another ultrasound to:
Confirm the presence of a pregnancy vesicle
Check for twins and perform reduction if needed
Begin tracking the embryo’s development
If pregnancy is confirmed, the next critical check happens around day 28, when the embryo’s heartbeat can usually be detected. A further check around day 45 ensures continued healthy development.
Mares typically carry their foals for about 340 days, though the range can vary between 320 and 360 days depending on the mare and her history.
Everything so far suggests a well-timed and carefully managed breeding, and The Foal Circle will continue following Dyana’s journey closely. If all goes well, a Knicks Go foal could arrive in early 2026—and we’ll be here to share each step of the way, from foal to forever.
