Equine Castrations
What, Why, When, Where, How?
By Dr. Julie Bryngelson

Within the equine industry, castrations are a very common procedure.  Although the procedure is common, there is a lot of information that may be helpful before owners make the decision to have the procedure performed. Being informed about the procedure helps alleviate any stress for horse owners and avoid potential complications for the patients.

What is a castration?
To “castrate” means, “To deprive of the gonads (testis in the male), rendering the animal incapable of reproduction.”  Other common terms used to describe the procedure include, “Geld,” “Cut,” “Emasculation,” “Orchidectomy,” and “Alter.”  Basically, castration involves removing testicles from a male horse (colt/stallion).

Why should you castrate a horse?
Castrations are usually performed to decrease the masculine behavior if there are no future plans for utilizing the horse for breeding purposes.  A male horse usually becomes more docile and manageable once the gonads, the primary source of androgens (testosterone), are removed.  Another reason to castrate may be to avoid the inconvenience of maintaining appropriate facilities for safely containing a stallion. 

When should you castrate a horse?
Stallions can be castrated at any age.  However, older horses are at a higher risk for complications than younger horses.  Most castrations are performed between 1-2 years of age. 

Where should a castration be performed?
The ideal location for a castration is a clean surgical suite.  However, many castrations are successfully performed out in the field.  The best location out in the field is a dry, open area of grass-covered pasture.  The area should be free of any trees or fences in order to prevent injury during the induction and recovery.  Less sand and dirt is best since it can easily enter the surgical site during the recovery process. 

How is a castration performed?  
Before the surgery, a general physical examination should be performed.  The examination ensures the patient will be stable during anesthesia and confirms the presence of both testes.  If the horse is cryptorchid (an animal with undescended testes) or has an inguinal hernia present, the surgical approach and choice of anesthesia may change.  Also, the horse's tetanus immunization should be determined and the horse should be immunized for tetanus if not current.

Castration may be performed in a standing or in a recumbent position.  A standing castration is typically faster and avoids the need for anesthesia.  However, the candidates for a standing castration must be carefully selected since the procedure can be dangerous for the surgeon to perform on a fractious colt/stallion.  With recumbent castrations, the horse is either positioned in on its back or side.  An incision is made and the testes are removed.  In most situations, the incisions are left open, not sutured closed.  This allows adequate drainage from the surgical site as the tissue heals.

Aftercare includes stall rest for the first 24 hours.  Then, the horse should be exercised to avoid the formation of excessive edema (abnormal accumulation of fluid in the cavities and intercellular spaces of the body).  The site should be monitored for bleeding, tissue hanging out of the surgical site, cloudy  discharge, or colic symptoms.  In some situations, the horse may need to receive antimicrobial treatment post-operatively.  Also, if the horse's tail hair is not long enough to reach the surgical site, fly spray around the site may be necessary.  For at least 2 days (preferably 7 days) after the surgery, the horse should be isolated from mares.