🐴 Cryptorchid Testicle Descent in Horses: Hormonal Therapy & Breeding Decisions in 2025 🧬💉

By Dr Duncan Houston BVSc

Cryptorchidism—the failure of one or both testicles to descend into the scrotum—is one of the most common developmental issues in male foals. While some cases require surgery, certain colts may respond to hormonal therapy if the testicle is retained in the inguinal canal. In 2025, research and reproductive medicine have refined both diagnostic and therapeutic approaches. 🧠🐎

🧪 What Is Cryptorchidism?

Cryptorchidism occurs when one or both testicles remain in the:

• 📍 Inguinal canal (just above the scrotum)
• 📍 Abdominal cavity (near the kidneys)

Normally, testicular descent occurs between 30 days before birth and 10 days after birth. If it fails, the horse is classified as a cryptorchid or “rig.” 🚫

🔬 Diagnosing Retained Testicles

If a colt has only one or no testicles visible in the scrotum by a few months of age, a veterinarian may perform:

• 📸 Palpation and ultrasound to locate testicular tissue
• 🧬 Blood testing for testosterone or AMH levels
• 🩻 Imaging for older horses or in complex cases

Knowing the exact location—inguinal or abdominal—is key to choosing the best treatment path. 🧠

💉 Hormonal Treatment for Inguinal Retention

If the testicle is found in the inguinal canal, there is a chance that hormone therapy can stimulate descent into the scrotum. 📉

🔹 hCG (Human Chorionic Gonadotropin)

• 💉 Given twice weekly for 4–6 weeks
• 🧬 Mimics luteinizing hormone to stimulate testosterone and testicular descent

Dr. Steven Conboy from Kentucky reports that on a Standardbred farm, this protocol resulted in 58% success for testicular descent—compared to 6% in untreated colts. 📈

🔹 GnRH (Gonadotropin-Releasing Hormone)

• 💉 Stimulates the release of natural LH and FSH
• ✅ May have a similar effect to hCG in encouraging descent

🔪 When Surgery Is Required

If the testicle is located in the abdomen, it will not descend—regardless of hormonal therapy. These cases require surgical removal:

• 🛏️ Often under general anesthesia
• 🔍 May involve laparoscopic or inguinal exploration

Cryptorchid surgery is more invasive than standard castration and should be performed in a sterile hospital setting. 🏥

❓ Should Cryptorchid Horses Be Bred?

This remains a controversial topic. Many veterinarians believe that cryptorchidism is hereditary, though a specific genetic mutation has not been definitively identified. 🧬

📋 Breeding Considerations:

• ⚠️ If the colt required hormone therapy to descend a testicle, he may pass this trait on
• 📈 Some breed registries may disqualify cryptorchid horses from breeding approval

In 2025, gene-mapping research is ongoing, but the decision to breed a cryptorchid is still a judgment call for owners—with guidance from their veterinarian. ⚖️

📋 Summary: Treatment Path Based on Testicle Location

📲 Ask A Vet for Cryptorchid Consultation

If your colt has an undescended testicle or you're considering breeding a previously cryptorchid stallion, visit AskAVet.com or use the Ask A Vet App for personalized guidance. 📱🐴

Dr Duncan Houston and the team can help interpret hormone test results, plan hormone protocols, or refer your horse for surgical evaluation. 💬🧠

🏁 Final Thoughts

Cryptorchidism doesn’t always require surgery—especially when diagnosed early and the testicle is still in the inguinal canal. In 2025, hormonal therapy may help some colts avoid invasive surgery, but breeding considerations and responsible management are still key. 🧬🐎

Need a cryptorchid workup or descent plan? Visit AskAVet.com and take control of your colt’s future ✂️🧠