Laparoscopic Surgery
Laparoscopy is a type of 'keyhole' surgery where special cameras (scopes) are used through small incisions (~1.5 cm) in the body wall to evaluate and treat certain conditions. The most common form of laparoscopic surgery is for cryptorchid horses and ovariectomies (see below). Sometimes, we even use laparoscopy to evaluate the intestines for abnormalities. The scope used for laparoscopy can also be used in the chest cavity to evaluate the lungs and chest cavity (thorax) which is referred to as thoracoscopy.
Cryptorchid Castrations
Testicle viewed via laparascopy
Cryptorchidism means "hidden testes" (crypt = hidden, orchid = testes), and is used to describe the condition in which one or both testicles do not descend normally into the scrotum. Common terms for animals with this condition include rig, ridgling, or high flanker. The condition is considered to be genetically heritable, however the exact mechanism of inheritance is still unknown and several genes seem to be involved.
In normal horses, the testicle forms within the body during fetal gestation (pregnancy) and descends into the inguinal canal (pathway from abdomen to scrotum) shortly before birth. Within three weeks after birth, the testicle descends fully into the scrotum. At the same time, the inguinal canal regresses so that the testicle is 'stuck' in the scrotum.
In a cryptorchid horse, the testicle forms normally within the body, but fails to migrate into the scrotum. It may be retained anywhere from the abdomen to the inguinal canal. Many people believe that if you wait for 1-2 years, the undescended testicle will eventually come out. This is actually an urban legend since the testicle is stuck in the position it was at around 3 weeks of age! Frequently though, we will wait until the colt is 1-2 years old to perform the surgery in order to reduce the risks of anesthetizing a foal.
Although the testicle of a cryptorchid is undescended, it still produces male hormones and these horses will have characteristic stallion behavior. Since unilateral cryptorchids are usually fertile, it is important to keep them separate from any female admirers.
In normal horses, the testicle forms within the body during fetal gestation (pregnancy) and descends into the inguinal canal (pathway from abdomen to scrotum) shortly before birth. Within three weeks after birth, the testicle descends fully into the scrotum. At the same time, the inguinal canal regresses so that the testicle is 'stuck' in the scrotum.
In a cryptorchid horse, the testicle forms normally within the body, but fails to migrate into the scrotum. It may be retained anywhere from the abdomen to the inguinal canal. Many people believe that if you wait for 1-2 years, the undescended testicle will eventually come out. This is actually an urban legend since the testicle is stuck in the position it was at around 3 weeks of age! Frequently though, we will wait until the colt is 1-2 years old to perform the surgery in order to reduce the risks of anesthetizing a foal.
Although the testicle of a cryptorchid is undescended, it still produces male hormones and these horses will have characteristic stallion behavior. Since unilateral cryptorchids are usually fertile, it is important to keep them separate from any female admirers.
Ovariectomy
Ovary viewed via laparascopy
Ovariectomy is a procedure that is performed to remove an abnormal ovary. Laparoscopy is the best way to visualize the ovary and the large vessels which provide the blood supply to the ovary. Occasionally, an ovariectomy is performed in mares which have unmanageable behavior during their heat cycle. Ovarian conditions that might lead to an ovariectomy include ovarian tumors, hematomas, and abscesses.
Ovarian tumors are the most common reason for an ovariectomy. The most frequent ovarian tumor in the horse is a granulosa cell tumor (GCT) or granulosa-thecal cell tumor (pictured above). These tumors are benign in the sense that they do not metastasize (spread to other parts of the body), but they can exert some severe physiological effects from hormones that they secrete (mostly testosterone and estrogen). These tumors can become quite large, although most start out the size of a typical ovary (~3-4" in diameter). The excess production of testosterone by the tumor causes mare to exhibit stallion-like behavior such as squealing, striking or mounting other horses. Mares can also show intermittent or continuous estrus, which is also related to excessive production of sex hormones by the abnormal ovary.
The second benign tumor is called a teratoma. Teratomas are benign and they arise from "germ" cells within the ovary. Germ cells are genetically programmed to become oocytes (the egg produced by females) and therefore contain the genetic material for all the components of the body. This leads to the bizarre nature of these tumors -- teratomas sometimes contain cartilage, skin, bone, hair, nerves, and even teeth!
The diagnosis of an ovarian abnormality is generally made by rectal palpation, ultrasound and abnormal levels of hormones found on bloodwork.
Ovarian tumors are the most common reason for an ovariectomy. The most frequent ovarian tumor in the horse is a granulosa cell tumor (GCT) or granulosa-thecal cell tumor (pictured above). These tumors are benign in the sense that they do not metastasize (spread to other parts of the body), but they can exert some severe physiological effects from hormones that they secrete (mostly testosterone and estrogen). These tumors can become quite large, although most start out the size of a typical ovary (~3-4" in diameter). The excess production of testosterone by the tumor causes mare to exhibit stallion-like behavior such as squealing, striking or mounting other horses. Mares can also show intermittent or continuous estrus, which is also related to excessive production of sex hormones by the abnormal ovary.
The second benign tumor is called a teratoma. Teratomas are benign and they arise from "germ" cells within the ovary. Germ cells are genetically programmed to become oocytes (the egg produced by females) and therefore contain the genetic material for all the components of the body. This leads to the bizarre nature of these tumors -- teratomas sometimes contain cartilage, skin, bone, hair, nerves, and even teeth!
The diagnosis of an ovarian abnormality is generally made by rectal palpation, ultrasound and abnormal levels of hormones found on bloodwork.
