What is Cryptorchidism ?
Cryptorchidism, also known as rig or ridgling, is an abnormality which is developmental in both animals and humans. In the stallion, it can be a unilateral condition in which only one testicle has dropped or bilateral in which neither testes has dropped. If the cryptorchid is unilateral, then the horse has an opportunity to be virile while bilateral conditions will make the animal sterile and unable to reproduce. This condition causes the hidden testes to be unable to produce sperm that is fertile but will not necessary affect the horse’s ability to produce testosterone. This means that your stallion may not be able to sire offspring but he will still act like a stallion if the condition is bilateral.
Basically, the term cryptorchidism refers to testes (testicles) which have not descended into the scrotum. This condition can be unilateral or bilateral and has the potential to render the horse sterile.
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Symptoms of Cryptorchidism in Horses
The most obvious symptom that you’ll notice is quite simply the lack of one or both testicles upon visual observation. This may also be found during a routine examination by your veterinarian, such as that performed before the planned castration of an immature horse. These are some things you might find upon examination:
- Bilateral cryptorchid - both testicles or testes have not dropped
- Unilateral cryptorchid - only one testicle has descended
- Previously bred stallions who are now gelded - having both testicles removed after a breeding history
Your horse may still behave like a stallion even if one or both of the testicles have been removed or have not dropped.
- Bilateral involving both testes
- Unilateral - involving only one of the testes
These two types of cryptorchid are found to be located in three different areas. They are:
- Under the skin in the inguinal (groin) area - referred to as a high-flanker
- In the inguinal canal - also called spermatic canal
- In the abdomen
Causes of Cryptorchidism in Horses
The veterinary medical community doesn’t have a complete understanding about the condition of cryptorchidism in horses nor do they have a solitary causative factor it. Since it is very complex, it is noted to have multiple contributors:
- Genetic - Inherited from DNA
- Hormonal - Such as inadequate stimulation of androgen or testosterone
- Mechanical - For example castration of one or both testicles for purposes of sterilization, or as a result of hidden testicles which have become tumorous
While all horse breeds have the potential to show cryptorchid, the breeds which have been reported to display it most often are:
Diagnosis of Cryptorchidism in Horses
If symptoms of cryptorchid are noted in your stallion, your veterinarian will need to do some diagnostic things to confirm the diagnosis:
- He will want to do an external exam combined with a rectal palpation (feeling the rectal area using gloves) to determine if abnormalities exist
- An ultrasound examination will enable him to view possible abnormalities in the abdomen and inguinal canal
- Blood tests will likely be needed to ascertain the levels of testosterone and conjugated estrogen - this is especially helpful when there are no testicles externally that can be felt for abnormalities as well as when there is no or little surgical history available - these blood tests are about 95% accurate and should be utilized if either of the individual tests are not conclusive
- Sedation may be required to perform some of these diagnostic tests and examinations for will be better accuracy and comfort for your horse
- Some conjugated estrogen testing may not be as accurate and reliable in horses under three years of age and on donkeys
Hidden testicles have been shown to be more susceptible to tumor development and will increase the costs and risks for castration. If your stallion has cryptorchidism, your veterinarian may recommend castration to lower the risk of testicular tumors and to prevent the trait being passed on in the breeding process.
Treatment of Cryptorchidism in Horses
If your stallion suffers from either unilateral or bilateral cryptorchid,the equine surgeon will likely recommend surgical removal of the hidden or retained testicle. This can be achieved by:
- A surgical procedure done under general anesthesia with the horse laying on its back, making an incision and manually locating and removing the testicle, closing the wound with sutures
- Laparoscopic approach that allows for standing sedation instead of general anesthesia, using a laparoscope to view the inside of the abdominal cavity to locate the testicles; the testicles are then removed laparoscopically, using small instruments inserted through small incisions and closed with sutures
During both surgical procedures, extreme care is taken to remove all testicular tissue and assure bleeding is securely shut off to the testicle removal site. The laparoscopic procedure utilizes smaller incisions that require fewer sutures and less recuperation time for your horse.
There are some procedures available through some veterinary facilities which address medical hormonal stimulation to the hidden testicle to attempt to get it to drop. This is a controversial procedure as well as largely unsuccessful according to many breeders and, accordingly, many veterinarians and owners do not recommend it.
Recovery of Cryptorchidism in Horses
There are some possible complications from surgical intervention in cryptorchidism in horses. Castration done routinely will cause various levels of post-operative swelling, though hemorrhage is usually minor at the surgical site. If the swelling or hemorrhage is not minimal and appears excessive, notify your veterinarian as soon as possible. Other more rare complications are:
- Intestinal prolapse - intestines slip from their normal positions
- Spermatic cord infection
- Abdominal infection
- Hydrocele - described as fluid build-up surrounding the testes
- Damage to the penis
- Unchanged stallion-like behavior
The veterinary surgeon will likely remove the stitches in 10 to 14 days following surgery. During the postoperative period, rest will be recommended ranging from 72 hours to two weeks, depending upon the type of surgery performed. Exercise restrictions will also be recommended and will be dependent upon the type of surgery. The laparoscopic procedure will allow the horse to return to more normal activities sooner than the open surgical procedure. There may be some recommendations given by the veterinary team for re-introducing your horse to the local society in which he lives. The hormone levels that cause the typical stallion behavior don’t stop immediately but should diminish over time.