Horse Cryptorchidism, Rigs, or Ridglings

vet introducing stallion to mare

When discussing a who acts like a stallion but is assumed to be a gelding, you may have heard the terms 'rig' or 'ridgling.' Cryptorchidism may be to blame for this behavior. Cryptorchidism implies that, despite the fact that a is unable to breed, it nevertheless generates testosterone and, as a result, behaves like a stallion. The greatest recommendation for anybody looking to acquire their first is to avoid a ridgling since its stallion-like temperament may necessitate handling that is beyond the ability of a novice rider or owner.

What is a ridgling horse?

A ridgling horse is a male horse with one or both testicles that have not been descended. These horses are sometimes misidentified as geldings (castrated horses) until they begin to demonstrate stallion-like traits and are examined by a veterinarian.


The growing testes descend from within the abdominal cavity through the inguinal canal—a tunnel in the abdominal wall through which blood vessels, tubes, and ligaments pass—and into the scrotum during a prenatal development. Normally, both testes descend and everything is well, but this does not always happen. As the vaginal rings at the base shut, the inguinal canal narrows (usually about two weeks after birth). Although blood can reach the testes or a single testicle, one or both testes are unable to descend into the scrotum as they should. The testes might either remain high in the abdominal cavity or within the inguinal canal. While it's impossible to say why each case of cryptorchidism arises, the timing is awry for some reason during the colt's growth. There are several possibilities as to why this may occur. Cryptorchidism might be caused by genes, hormones, the mare's health, or environmental causes.


A rig or ridgling will behave like a stallion. As a result, they are unsuited for novices and might be difficult for seasoned riders. Some believe that because descending testes do not operate in the same manner as regular testes, the horse will be significantly more volatile than a stallion, alternating between gentle and aggressive behavior.


Cryptorchidism is frequently overlooked until it is time to geld a colt. Because the testes might be confused for other scrotal structures, a veterinarian may be needed to confirm any findings. Palpation of the scrotum externally and the rectum internally is usually all that is necessary. This invasive internal examination may need the horse to be sedated. When a ridgling with two undescended testes is mistaken for a gelding and the testes cannot be found by palpitation, the ridgling may be misidentified. A blood test can tell whether testosterone is present if this is the case.


Cryptorchidism causes a horse's behavior to resemble that of a stallion. Although undescended testes seldom generate viable sperm, they do create testosterone. Some ridglings have a stallion-like demeanor that makes them tough to handle. If you're searching for a pleasure horse, you should probably avoid a ridgling. Some ridglings can reproduce and are maintained as breeding animals. There is a lot of debate regarding this since some people believe that if a sickness has a hereditary component, it should not be passed on to future generations. Of course, there are exceptions to every rule, but a rig is unlikely to be a good first-time horse.


Surgery to remove or a ridgling is more expensive than gelding because it needs additional operations. The cost of gelding your horse can range from $250 to $1000, depending on where the testes are kept in the abdominal cavity. The examination and operation will be fairly pricey if the testes are concealed high up in the belly. The most prevalent form of surgery is laparoscopy. The surgical equipment and a tiny camera with fiber optics are both placed into the belly through the same small incision. While the procedure is not very intrusive, it does need the use of specific equipment and expertise. This sort of service may not be easily available at every veterinarian facility. This is why many rigs are not gelded, or are only half-gelded if just one descending testicle is present.


Cryptorchidism is a difficult condition to prevent. Many people believe that cryptorchids that can reproduce should not be utilized for breeding since they believe it is hereditary. However, the argument is that, until there is proof that cryptorchidism is actually hereditary, it is fair to utilize them as breeding material because there are a variety of reasons why it happens.

If you suspect your pet is sick, call your vet immediately. For health-related questions, always consult your veterinarian, as they have examined your pet, know the pet's health history, and can make the best recommendations for your pet.


"Cryptorchidism (Undescended Testicles) in Horses. ACVS.", "CRYPTORCHIDISM. Colorado State University Equine Reproduction Lab.", "Cryptorchidism in the Horse. Ontario Ministry of Agriculture, Food, and Rural Affairs." ;