Along with his obvious body growth, your colt’s reproductive organs go through a steady process of development from the moment he’s born.  This is due primarily to the release of gonadotropin releasing hormone (GnRH) from the hypothalamus, which is located in the brain.  GnRH in turn sparks activity from the pituitary gland.   Hormones produced by the pituitary gland subsequently motivate the testes to produce and secrete androgens or sex hormones.  These hormones promote the gradual growth of your colt’s genitals. 
As puberty approaches anywhere from 12 to 24 months, but generally around 18 months of age – gonadotropin production, most importantly the male hormone, testosterone, increases dramatically.  At this time your colt’s physical masculine traits, as well as his sex drive, will become much more apparent.  The presence of these male hormones will also influence your colt’s personality thus determining how he will react in various equine social situations.

Effects of Castration

So, what effect will castration have on your colt?  The foremost reason to castrate a colt is to alter his behavior.   In general, castration will result in a much calmer, easier to manage horse, says Dr. Robert Peters DVM of Mckinlay and Peters Equine Veterinary Services in Colbert, Washington.   In the vast majority of horses, castration will eliminate sexual behavior such as herding, mounting, fighting, and excessive vocalizing.

Castration, to a degree, will also affect your colt’s physical appearance.  The only real difference in physical characteristics will be in the head and neck.  Kept a stallion until the forth or fifth year will result in a thicker neck and more prominent jowls, says Dr. Peters.

His height may also be affected.   There is evidence that suggests that early castration will result in a taller horse.  This is due to a decelerated closure of long bone growth in the gelding compared to early closure in colts that are kept as stallions.  In other words, colts with similar genes for size will be taller as geldings than those that are retained as stallions.

When to Castrate

During the last trimester of pregnancy or soon after birth, your colt’s testes migrated from the abdominal cavity into the scrotal sac.   Castration can be performed on your colt at anytime, once both testes have entered the scrotum.  However, this does not mean that right after birth is the most favorable time to castrate your colt.

In some instances the inguinal rings may not yet be fully developed in the foal.  These are the openings that restrict the size of the canal in which the testes drop through as they travel from the abdomen to the scrotum.  Should the rings not be fully developed when the colt is gelded, there is a slight possibility that the intestines could drop out through the incisions.

I prefer to castrate colts between six and eighteen months of age, particularly anywhere between six and ten months, states Peters.  At that time the colt is obviously smaller than he will be later.  This makes general anesthesia safer for him and reduces the risk of postoperative bleeding.

Making the cut

For a colt with both testicles descended into the scrotal sac, surgery is a rather simple procedure.  Depending on the veterinarian’s preferences, surgery can be performed with the colt standing, or with the colt on the ground lying on its side.

First the vet will administer a tranquilizer to relax your colt.  Next he’ll either choose to use a local anesthetic and execute the castration with the colt standing, or will administer a general anesthetic to perform the procedure with the colt on the ground.  Since not all horses react the same to the anesthesia, restraint ropes are usually applied to colts that are castrated while on the ground.  This simply safeguards the vet as well as the colt should he begin to come out from under the anesthesia prematurely.

Once your colt is fully sedated the scrotal area is cleaned with an anti-bacterial surgical wash.  The vet will then make one of two incisions in the scrotal sac, one for each testicle.  Each testicle in turn is then pulled out of the scrotum, along with a portion of the spermatic cord that is to be removed.

Nerves and blood vessels make up the spermatic cord, as well as the vas deferens, which is the duct responsible for carrying the sperm away from the testes.  An emasculator is then used to effectively crush and sever the spermatic cord.

Emasculators are used in all castrations today, as they are the safest way to prevent bleeding post-operatively, says Dr. Christina Cable DVM of Early Winter Equine Medicine and Surgery in Lansing, New York.   But the biggest improvement in equine castration is the drugs involved.

The procedure has dramatically been made easier for the horse and the practitioner with the newer drugs we have, adds Dr. Peters.  Over the past ten years there has been a much higher priority placed on pain management.  In the past, the horse just had to tough it out for five to seven days following surgery.  Now most vets use some type of post operative pain management.

Cut Proud?

A gelding that continues to act like a stallion is often said to be proud cut.  This is a layman’s term that is used to denote a horse that, when gelded, some of the tissue responsible for producing testosterone was inadvertently left in the horse, explains Cable.   In reality, the probability of a horse actually being ëproud cut’ is quite small.  Yet, many geldings are still too quickly labeled as such.

In some cases, excessive stallion like behavior may actually be due to hyperactivity of the adrenal gland, a testosterone-producing gland located close to the kidneys.

It certainly is a true condition from a behavioral standpoint, says Peters.  It is often blamed on horses with bad manners, when in fact it has nothing to do with that.  I’ve done many testosterone assays that came back negative on geldings with behavioral problems.   Proper training and handling will go a long way in correcting these horses.  There are some horses that always retain their natural herding instinct even if they are correctly trained and castrated.  In those cases the best alternative is to just separate them.

It takes time for hormone levels in the newly gelded horse to drop.  Depending on what age your colt was gelded it may take as long as six months for him to forget that he was a stallion.  In order to gain the utmost in behavior modification through castration you will need to have a veterinarian geld your colt before he reaches sexual maturity.

Contributed By: Mirror KB Ranch