✂️ Vet’s 2025 Guide to Castration in Horses

By Dr Duncan Houston BVSc

1. Why We Geld Horses 🐴

Castration (gelding) is the surgical removal of both testicles to reduce stallion behaviour—like aggression, marking, and libido—and to prevent unwanted breeding. Geldings are typically calmer, easier to train, and safer for everyday use :contentReference[oaicite:3]{index=3}.

2. When to Castrate

• Common timing: between 6–18 months old—before full sexual maturity and optimal growth of conformational traits like cresty neck :contentReference[oaicite:4]{index=4}.
• Season: spring or autumn are best—avoiding flies and mud that can lead to infection :contentReference[oaicite:5]{index=5}.
• Late castration: after maturity may be chosen to assess breeding potential, though stallion behaviour may persist for weeks post-op :contentReference[oaicite:6]{index=6}.

3. Pre‑Op Prep & Sedation

• Full clinical exam, tetanus vaccination status, and palpation of both testicles (or ultrasound if one is undescended) :contentReference[oaicite:7]{index=7}.
• Use NSAIDs before surgery (e.g., phenylbutazone 4.4 mg/kg or flunixin 1.1 mg/kg) and consider a single dose of penicillin in higher-risk environments :contentReference[oaicite:8]{index=8}.
• Choose sedation: alpha‑2 agonists ± opioid (standing), or general anesthesia (recumbent) for mature or fractious horses :contentReference[oaicite:9]{index=9}.
• Local analgesia: lidocaine block around testicles and incision sites :contentReference[oaicite:10]{index=10}.

4. Techniques: Standing vs Recumbent

Standing castration involves sedation, local blocks, and testicle removal while standing—ideal for calm, younger horses, but carries a risk of kicking :contentReference[oaicite:11]{index=11}.

Recumbent (field GA) offers better control, exposure, and haemostasis—favoured for mature horses or cryptorchids or when sterility and precision are priorities :contentReference[oaicite:12]{index=12}.

5. Surgical Industries: Open, Closed & Semi‑Closed

• Open castration: incision through vaginal tunic, left open for drainage—common and low infection risk :contentReference[oaicite:13]{index=13}.
• Closed: tunic remains intact, incision sutured—less swelling but potentially increased hematoma risk :contentReference[oaicite:14]{index=14}.
• Semi‑closed: tunic opened and then sealed—balance between drainage and hemostasis.

6. Handling Cryptorchids

Retained testicles (rigs) require cryptorchidectomy—via inguinal, flank laparotomy, or laparoscopy—often under GA :contentReference[oaicite:15]{index=15}.

7. Intraoperative Tips & Tools

• Use emasculators “nut‑against‑nut” and hold for 2‑5 min for hemostasis :contentReference[oaicite:16]{index=16}.
• Make incision along dependent part of scrotum to promote drainage :contentReference[oaicite:17]{index=17}.
• Stretch scrotal incisions post‑removal to prevent premature healing and hematoma formation :contentReference[oaicite:18]{index=18}.

8. Post‑Op Care & Complication Management

• Allow box rest ~24 hrs, then daily hand‑walking to encourage drainage :contentReference[oaicite:19]{index=19}.
• Continue NSAIDs for pain and swelling; antibiotics only if complications occur :contentReference[oaicite:20]{index=20}.
• Monitor for edema, scrotal hematoma (common: 7% cases), colic, fever, evisceration, infection, or scirrhous cord formation :contentReference[oaicite:21]{index=21}.

9. Outcomes & Risks

Mortality is low (~1 %), though complication rates vary: ~22% standing vs ~6% recumbent cases :contentReference[oaicite:22]{index=22}. Most complications are minor and resolve with prompt intervention.

10. Welfare Considerations

The Canadian Veterinary Medical Association emphasizes castration as a surgical procedure that must include anesthesia, analgesia, and postoperative monitoring to prevent unnecessary pain and complications :contentReference[oaicite:23]{index=23}.

11. Breeding & Behavior

• Testosterone-related behaviors may persist for up to 6 weeks post‑op—training and management should continue :contentReference[oaicite:24]{index=24}.
• Cryptorchids should not be bred due to heritability and health risks :contentReference[oaicite:25]{index=25}.

12. Ask A Vet Support 🩺

With Ask A Vet, you’ll get:

• Pre‑op planning—age timing, tetanus, sedation vs GA guidance.
• On‑site photo/video for incision monitoring and swelling checks.
• Post‑op care protocols—walking schedules, NSAID dosing, when to call vet.
• Behavior monitoring and training guidance during recovery.

Download the Ask A Vet app today to support your horse through castration and recovery with confidence in 2025! ❤️

13. Quick Reference Table

14. Final Thoughts

Castration is routine yet requires meticulous preparation, surgical precision, and attentive aftercare to support horse welfare and client confidence. By integrating evidence-based practices, welfare standards, and Ask A Vet telehealth follow-up, you ensure optimal outcomes and smoother recovery. Here’s to healthy, safe geldings in 2025 and beyond. ❤️