Although equine castration is a common procedure, it is not without complications in some cases.  Equine veterinarians castrate hundreds of horses over their careers and most do very well.  However, complications can occur and the first one is bleeding.  In most cases, the castration incision is left open to drain and most of the incisions will bleed a small amount at the time of surgery and may have some blood dripping for 1-2 days.  However, the vessels to the testicles are large and if these vessels are not treated correctly, significant hemorrhage can occur and can even lead to the horse’s death.  The vessels are either crimped, twisted, or ligated (tied) with suture to prevent bleeding and some horses — and especially donkeys — tend to bleed more than others.  Ligating the vessels with suture is the best option but can result in chronic infection called a scirrhous cord, which will require more surgery so most vets do not like using suture.  If bleeding does occur, it can be a real problem as the vessels retract up into the abdominal cavity and cannot be ligated if bleeding continues unless the horse can be taken to a referral center for major abdominal surgery.

The next concern is an inguinal hernia in which case the intestines can come out of the abdominal cavity through the castration incision.  Some horses have a large inguinal ring and through no fault of the vet, part of the intestine can enter the inguinal canal and exit the skin.  This can be a deadly complication unless treated aggressively and immediately.  Lastly, an infection at the incision can occur and this is usually due to flies contaminating the open wound so I do not like castrating horses in the summer and recommend doing this procedure in colder weather when there are less fly problems.