New research shows that a minimally invasive surgical technique developed at New Bolton Center for horses prevents the recurrence of colic caused by entrapment of the large colon.
The technique, nephrosplenic space ablation, is performed routinely at New Bolton Center on horses suffering from entrapment of the colon in the nephrosplenic space. A new examination of cases over the past eight years shows that those horses did not have a recurrence of the condition, indicating that this laparoscopic minimally invasive approach is effective.
“The research shows us that the surgery was successful in that none of the horses have had a repeat of the entrapment, and no complications from the surgery,” said Dr. Eric Parente, Professor of Surgery at New Bolton Center.
However, he cautioned that the surgical technique does not prevent all types of colic. “Some of the horses had later colic episodes, because although the ablation prevents the entrapment, it doesn’t prevent all forms of colic,” Parente said.
What is Nephrosplenic Entrapment?
Gastrointestinal problems are the most common cause of colic, which is the number-one cause of death in horses. Colic describes the signs horses show when they are experiencing abdominal pain: pawing, flank watching, kicking at the abdomen, and rolling.
Large-colon displacements or entrapments are one cause of gastrointestinal problems leading to colic. A nephrosplenic entrapment occurs when the colon becomes entrapped over the nephrosplenic ligament that attaches the left kidney (nephron) to the spleen (splenic) in a space that is normally empty.
Because the colon is quite mobile within the abdomen, if gas accumulates in the colon, it can float up and over the nephrosplenic ligament. If more gas accumulates within the colon while it is in the nephrosplenic space, the entrapment gets tighter, and the condition becomes painful, causing colic.
Nephrosplenic entrapments can be treated medically or surgically to remove the colon from the nephrosplenic space, but the recurrence rate is significant, in about 20 percent of cases.
Research Shows Surgical Technique is Successful
Since 2006, New Bolton Center surgeons have been using the minimally invasive mesh technique, pioneered by Dr. Parente. The technique involves placing mesh in the nephrosplenic space to induce fibrosis, which leads to collapse of the space, preventing future entrapment.
According to new research performed by Dr. Megan Burke, Resident in Surgery, New Bolton Center surgeons have performed the procedure on 26 horses with a history of recurrent nephrosplenic entrapment of the large colon since 2006. No complications associated with the procedure were reported, and none of the horses treated with mesh had recurrence of nephrosplenic entrapment, she discovered.
The Surgical Procedure
The entire surgery is performed with the horse standing, through three stab incisions, using laparoscopic cameras and instruments. A piece of prosthetic mesh is inserted into the abdomen, and anchored to the spleen and fascia (connective tissue) next to the kidney.
The material that the mesh is made of causes an inflammatory reaction within the tissues that it contacts. Over three to four weeks, this reaction results in the formation of fibrous scar tissue. As this tissue forms and contracts, the edge of the spleen moves into direct contact with the kidney, and the nephrosplenic space is permanently closed. Once the space has closed, even though the colon can still move around within the abdomen, it can no longer get trapped over the nephrosplenic ligament.
“A positive aspect of the surgery is that it is done standing with sedation and local anesthetic through a few small incisions in the flank, so the horse can be back to full work within three weeks,” Dr. Parente said.
Horses undergoing the procedure are transitioned to a diet of pelleted feed two days before surgery. This decreases the bulk of the intestines, which improves visibility during surgery. After surgery, horses are reintroduced to hay over 12 hours, and are ready to go home the morning after surgery. Because the surgical incisions are so small, the cosmetic outcome is excellent.
Geldings, as well as Warmblood breeds, have been shown to suffer more from this type of colic, although the reasons for this predisposition are not fully understood.
“Preventing future episodes of colic is almost impossible, but this is a fairly simple method that can have a big, positive impact on a horse’s future,” Dr. Parente said.
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