The side effects of castration in horses

Horse owners know that most horses need to go through the castration process. The most common reason for castrating your animal is down to their behaviour, as its the testicles that produce the testosterone hormone responsible for their stallion-like behaviour.

Removing a part of the body unfortunately but expectedly has some side effects. We are going to explain and explore the anatomy of the testicles and the process of castration which will help us to understand what side effects can occur. Thankfully we have some great osteopathic techniques that will help recovery.

Anatomy and castrations techniques

As you can see on the below diagram, the testes are surrounded by many other structures, some of them are directly linked to the rest of the body as they derive from the abdominal muscles or fascia. To access the testes, the vet will have to break through each of these layers, and each of them will have to heal thereafter.

Castration involves the removal of one or both testicles and their associated structures (such as the epididymis), and part of the spermatic cord. The spermatic cord contains the Vas deferens, the blood and nerve supply to the testis and also the Vaginal tunic.

Castration can be performed with the horse standing or recumbent, and under anaesthesia. For practical reasons, most horses are castrated standing up.
In most of the cases, the vet will leave the wound open so it can heal itself.

Effects of the castration of the soft tissues and osteopathic techniques

We have seen previously how many layers are around the testes. Those layers are all designed to glide between each other so they can work individually, as well as together.

When a trauma happens such as surgery, the body worked to heal the wound and to protect the rest of the body. This is why the healing process has to be as fast as possible, therefore, the body doesn’t take the time to reattach all the layers in the testes separately, instead they are all reassembled together as one which creates adhesions (abnormal deposits of connective tissue in-between two layers). These adhesions are what we call “gelding scars”.

Soft tissues manipulation can really help in that case, we have different techniques with different purposes. Some of them, such as compression, will help with the restoration of blood flow and the removal of waste products. Others, such as stretching, will allow the realignments of the tissue fibres. The forces and loading patterns applied to the tissues will bring the fibres to the correct length and direction.

The scarring process can also create compensations elsewhere, for example the horse will usually keep his back arched (tensed abdominal muscles), to avoid extending or moving the painful area. This will create a different weight bearing posture, and potentially cause pain and stiffness within the limbs or the back.

The nerves and arteries feeding the testicles originate from the lumbar region, having them removed will force some changes within the nervous input/blood supply, and therefore within the lumbar region.

We have also seen that the layers around the testes are greatly linked to the rest of the body, having a trauma there will definitely create compensations within the abdominal cage.


Even if castration is very common and sometimes necessary, it is still very traumatic for the horse’s body. Osteopathic techniques can greatly help with the soft tissues, but also with the compensations and the hormonal balance (which we haven’t talked about here as it is a whole other subject)/
This article is specific to castration, but what has been said is valid for any type of healing wound. We need to wait at least 10 days (depending on the wound), before applying these techniques. Even if they are always efficient, the earlier the techniques are applied, the better the result will be.
Hopefully this has helped to understand a bit more about the effects of castration, please don’t hesitate to contact us if you have any questions, or if you would like to know more.