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EQUINE LAPAROSCOPY
Introduction
A laparoscope is a specialized camera that allows ACVS Veterinary Surgeons to examine the inside of the abdomen (belly). The laparoscope is attached to a video camera, which displays the image on a monitor. Unlike traditional abdominal surgery techniques, which require large openings to allow the surgeon's hands to enter the abdomen, laparoscopic surgery is performed through tiny incisions. Specialized long handled surgical instruments are passed through separate cannulas (tubular ports or artificial openings) into the abdomen (Figure 1). Like a video game, the surgeon uses these instruments while watching the procedure on the television screen, cutting and sewing and cauterizing.
Figure 1- A laparoscopic instrument (A) is being placed through a cannula (B) that is already in the abdomen of a horse under anesthesia. The laparoscope (C) is placed through a separate cannula to look inside the abdomen.
During most laparoscopic procedures, the abdomen is kept distended, or filled, with carbon dioxide (known as "insufflation"). Distension of the abdomen allows visual access to many of the abdominal organs.
Some procedures are performed using a combination of laparoscopy and traditional surgeries, known as "hand-assisted laparoscopy". The excellent view provided by the laparoscope allows surgeons to see up close what their hands and instruments are doing within the abdomen.
Benefits of Laparoscopy
Laparoscopy is a minimally invasive surgical technique. This means that the surgery is performed through several small incisions. Advantages include:
1. Decreased hospitalization and rehabilitation time
2. Reduced discomfort associated with incisional healing and therefore decreased need for postoperative medications
3. Excellent cosmetic outcome.
The laparoscope also provides direct magnified visualization of the surgery site. Therefore, surgeries can be performed in areas that cannot be seen with traditional surgical approaches. Also, surgical sites can be critically evaluated for control of bleeding (hemostasis) and placement of sutures or other implants. Many laparoscopic procedures are performed with the horse standing under sedation and local anesthetic, reducing the inherent risks associated with general anesthesia and recovery.
Limitations Of Laparoscopy
Specialized equipment and surgical skills are required for laparoscopy. Thus, laparoscopic procedures are generally only performed at large hospitals by board certified ACVS Veterinary Surgeons. Find a Surgeon
Not all regions of the abdomen are visible with laparoscopy. Some regions are better accessed when the horse is standing, while others are better seen while the horse is on its back under general anesthesia. Also, not all types of surgeries can be performed safely within the abdomen through small incisions. Because of the large size of some of the abdominal contents and the relatively small size of laparoscopic equipment, it may be more practical to perform some procedures through a standard open incision. For example, if a portion of the intestine is dead and requires removal, it can be performed much more quickly and safely through a large abdominal incision.
Most Common Complications of Laparoscopy
Most of the complications associated with laparoscopy occur during placement of the cannula (portals into the abdomen) and insufflation (gas distension) of the abdomen with carbon dioxide. Complications include:
1. Laceration (tears) of vessels within the body wall,
2. Laceration or puncture of abdominal organs, and
3. Insufflation within tissue planes of the body wall outside of the abdomen (retroperitoneal insufflation).
When experienced ACVS Veterinary Surgeons perform laparoscopic procedures, the risk of complications is minimal and usually does not affect the surgery or cause long-term problems.
Types of Equine Laparoscopic Procedures
Exploratory and diagnostic procedures. Laparoscopy allows the surgeon to "visualize" (at least on the television monitor) many intra-abdominal organs. Portions of the gastrointestinal tract (such as small intestines, small colon, and large colon), urinary system (such as bladder), genital tract (such as ovaries, uterus, and retained testicles), spleen, and liver are readily seen during exploratory laparoscopy. The ability to access different organs is dependant on whether the laparoscope is placed in the right or left flank or the underside of belly. The approach chosen is generally based on the area of interest.
Exploratory laparoscopy may be recommended as a diagnostic test for horses that demonstrate chronic, intermittent colic (abdominal pain) of unknown origin. It can also be used to further evaluate and potentially biopsy abnormalities in the abdomen that were detected by other diagnostic tests (i.e. ultrasound, rectal palpation, or bloodwork).
Adhesiolysis. The term "adhesion" is used to describe an abnormal fibrous band of tissue within the abdomen that is often sticking or "adhering" to intestine. Adhesions may cause colic if they prevent normal movement of food and waste products within the gastrointestinal tract. Adhesions are formed secondary to inflammation in the abdomen. This is most commonly associated with previous colic surgery, but may be related to other conditions such as peritonitis (infection and inflammation of the tissue lining the abdomen) or umbilical infection. Laparoscopy can be used to identify and break down these adhesions ("adhesiolysis"). The use of laparoscopic surgery, rather than a traditional surgical approach, decreases handling and exposure of the gastrointestinal tract during surgery and therefore reduces the chance that more adhesions will develop (Figure 2).
Figure 2- Inside the abdominal cavity, a laparoscopic scissors is being used to transect adhesions between the intestine and body wall.
Mesenteric rent repair. The mesentery is a thin, flexible tissue that carries blood and lymph vessels to the intestinal tract. Tears (known as "rents") in the mesentery can be congenital (present since birth) or acquired (developing later in life during strenuous events such as foaling). Mesenteric rents may cause colic if a portion of the intestine becomes entrapped, or stuck, through the hole. If necessary, correction of the entrapment and resection of the entrapped portion is performed using traditional surgical methods. However, if the rent cannot be reached by a traditional surgical approach, it may be closed under laparoscopic guidance.
Rectal tear. Rectal tears can occur in horses during rectal palpation (eg., for reproduction evaluation or colic) or foaling. They are life-threatening conditions that are difficult to treat because of the potential for severe contamination and subsequent infection within the abdomen. A method for laparoscopic repair or rectal tears has been developed and tested experimentally, but has not yet gained widespread use clinically because of the difficulty in accessing some tears.
Nephrosplenic space closure. One cause of colic in horses is displacement and entrapment of the large colon over a ligament that connects the spleen to the kidney (nephrosplenic ligament). This is referred to as nephrosplenic or renosplenic entrapment or left dorsal displacement of the large colon. In approximately 5-10% of horses, the condition is recurrent (i.e. it happens more than once). In order to prevent recurrence several methods for laparoscopic closure, or ablation, of the space between the spleen and the kidney have been developed. The space may be closed with suture or by placement of a synthetic mesh (Figure 3a,b).
Figure 3a- A laparoscopic view of the normal nephrosplenic space prior to surgery.
Figure 3b- The space visible in Figure 3a has been filled with a mesh and fibrous tissue to eliminate the possibility of colonic entrapment.
Colopexy. In addition to becoming displaced and entrapped between the kidney and the spleen, the large colon can become displaced on the opposite side of the belly (right dorsal displacement) or twist on itself (large colon torsion or volvulus), obstructing it and even cutting off blood supply. To prevent recurrent displacement or volvulus of the colon, a portion of the colon can be sutured down to the body wall ("colopexy"). This can be done through a traditional surgical approach at the time of colic surgery or laparoscopically after surgical recovery. Colopexy is generally reserved for non-performance horses and broodmares that have a history of multiple episodes of displacement or volvulus. It is important to discuss these options with your ACVS Veterinary Surgeon.
Bladder stones-cystic calculi. The formation of stones (calculi) within the urinary tract is dependent on a number of factors that are not fully understood. In horses, most bladder stones that require surgical removal are found in geldings. Horses with bladder stones show clinical signs such as posturing to urinate without actually producing urine, frequent urination of small amounts, and blood in the urine, especially after exercise. In horses, bladders can be difficult to reach through traditional surgical approaches. A technique for laparoscopic assisted removal of bladder stones from a ventral approach under general anesthesia has been developed. One of the portal incisions may need to be enlarged to get large bladder stones out of the abdomen.
Ruptured bladder. A ruptured bladder is most commonly seen in neonatal (newborn) foals. Colts appear to be predisposed. Affected foals do not urinate as expected within hours of birth and show clinical signs of straining to urinate. Eventually they become depressed and systemically ill because of electrolyte imbalances. Ruptured bladders can be repaired laparoscopically.
Nephrectomy. Nephrectomy, or surgical removal of a kidney, is not commonly performed in horses. Indications for nephrectomy might include urinary stones within the kidney or very severe infection of one kidney. Traditional surgical approaches to the kidney provide limited visual access and may require resection (removal) of a rib to reach the area. Recently, a technique for hand-assisted laparoscopic nephrectomy has been published.
Ovariectomy. Ovariectomy is the surgical removal of an ovary. Indications for ovariectomy include ovarian tumors and behavioral modification. Laparoscopic and hand-assisted laparoscopic ovariectomies are most commonly performed with the horse standing, and under sedation. Specialized instruments and sutures are available to provide hemostasis (i.e. stop bleeding) when the blood vessels to the ovary are cut. One of the skin incisions is often enlarged to remove the ovary from the abdomen.
Cryptorchid castration. A cryptorchid testicle is one that has not completely descended out of the abdomen. Normally during fetal development, the testicle travels out of the abdomen, through the inguinal canal (a natural gap in the abdominal wall muscles), and into the scrotum. If the testicle remains in the abdomen or inguinal canal, castration is more difficult. Cryptorchid testicles can still produce testosterone and must be removed to prevent stallion-like behavior. Laparoscopic cryptorchid castration can be performed with the horse standing or under general anesthesia (Movie 1). The decision for the type of approach is based on factors such as behavior, accurate history of which side has the retained testicle, need for removal of a "normal" testicle, and surgeon preference.
Movie1- A left flank laparoscopic view in the standing horse (the laparoscopic camera has been inserted through the left body wall). The intraabdominal testicle is grasped and a loop of suture is tightened around the blood vessels to prevent bleeding. The attachments to the testicle are then cut and the testicle is removed from the abdomen.
Inguinal hernia repair. An inguinal hernia is a condition where intestines or other abdominal contents slip through the inguinal canal, traveling along the same path where the testicle descended in the developing fetus. If the intestines are not severely compromised, it may be possible to push them back into the abdominal cavity and then close the inguinal ring with sutures, staples, or synthetic mesh. If the intestines are compromised or entrapped by the inguinal ring, a traditional surgical approach will be required to remove any damaged intestines or to widen the ring and release them. The ring can then be closed laparoscopically at a later date. Laparoscopic inguinal ring closure can be performed in a standing horse under sedation. It is important to discuss the advantages and potential disadvantages of these techniques with an ACVS Veterinary Surgeon
Abdominal wall hernia repair. An abdominal wall hernia is a defect in the musculature of the abdominal wall. It can develop secondary to trauma or abnormal healing of a traditional surgical incision. Synthetic mesh can be sutured in place laparoscopically to repair the abdominal wall.
Umbilical remnant resection. The umbilicus (belly button) is the portion of the umbilical cord that remains attached to the foal after birth. It can become infected and require removal in some foals. A laparoscopic technique can be used for resection of the umbilical remnants.
Conclusion
Laparoscopy is a specialized field of surgery that has many advantages over standard surgical techniques. It cannot replace all common procedures and requires specialized equipment and training. To determine whether your horse can undergo laparoscopic surgery for its condition, consult an ACVS Veterinary Surgeon. Find a surgeon
—Kira Epstein , DVM
Large Animal Resident
—Eric Parente, DVM
Diplomate ACVS
Posted 9/8/2006
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