THE NEPHROSPLENIC SPACE
contents cannot move, causing distention and pain seen as colic. Approximately 9 percent of colic cases seen at referral clinics are caused by nephrosplenic entrapment.
“We don’t know for sure why some horses are more prone to nephrosplenic entrapment,” says Megan Burke, DVM. “All horses have this space, yet not all are prone to this problem.” Factors such as large abdomen size, the shape of the nephrosplenic space in certain horses and abnormalities in how a particular horse’s colon might move are suspected to contribute to this problem. But no definitive causes have been proven.
Several treatments are common for nephrosplenic entrapment. In some cases, medication to shrink the spleen is administered, and then the horse is jogged to try to jostle the colon back into normal position. Another option is to put a horse under anesthesia and roll him to free the colon. Finally, surgery may be performed to manually correct the problem.
Although most horses with nephrosplenic ANATOMY: The nephrosplenic ligament connects the left kidney to the spleen.
entrapment recover, studies show that up to 21 percent of survivors will have a recurrence of the problem. That risk has led veterinarians to explore options for closing or blocking the nephrosplenic space to prevent future entrapments. One technique involves suturing the space closed, which requires an experienced surgeon.
An easier alternative, according to Burke, is mesh ablation. This involves tacking a square of surgical mesh across the top of the spleen, which causes the space to completely contract, keeping the colon from being able to slip into it. Accomplished through a laparoscopy---in which an endoscope and tiny surgical tools are inserted through a small incision--the procedure can be done in about 30 minutes.
“The mesh is inserted through a laparoscopic portal and unrolled onto the surface of the spleen,” Burke says. “Then, a tacking device is used to anchor it to the upper surface of the spleen and the ligament. The major benefit of the mesh technique is that it’s very quick and easy to perform. There is almost no learning curve. Additionally, with the mesh, there is never any tension on the closure; therefore, there is no risk of failure.”
In the University of Pennsylvania study, researchers examined the records of 26 horses with a history of nephrosplenic entrapment who had the spaces closed with mesh. They found that none had a recurrence in the follow-up period, which ranged from one to seven years.
Burke says that the ease of the procedure, combined with this success rate, make it an effective option for preventing repeat entrapments. “We don’t necessarily recommend mesh ablation for horses after the first episode of nephrosplenic entrapment,” she says. “However, we do educate owners that the procedure is available and that they may want to consider it if their horse has a recurrence. There are plenty of owners who prefer to do the mesh ablation after the first entrapment, because it is substantially less expensive and has fewer complications than having a second colic surgery to correct a second entrapment.”
Although most horses with nephrosplenic entrapment recover, studies show that up to 21 percent of survivors will have a recurrence of the problem.
Reference: “Prosthetic mesh for obliteration of the nephrosplenic space in horses: 26 clinical cases,” Veterinary Surgery, February 2016