Nephrosplenic Entrapment in Horses as a Cause of Colic

My gelding recently had a nephrosplenic entrapment. Treated successfully with rolling. What can be done to prevent this? Are there any early warning signs that I may have missed? How often does this recur?
-DG, Pennsylvania

Dear DG,

This question caught my eye because my own horse was diagnosed with this several years ago. Fortunately his resolved with another form of conservative treatment—administration of phenylephrine and lunging exercise. It sounds like your horse recovered with rolling under general anesthesia. Horses that don’t respond to either of these medical methods require surgery to correct the condition. Before we get into success rates, prognosis and recurrence though, let’s start at the beginning.

What is a nephrosplenic entrapment? The prefix nephro means kidney (don’t worry if you thought “reno” meant kidney – it does, too. Isn’t science fun?!), while splenic refers to the spleen. Since the spleen is on the left side of the body, we’re talking about the left kidney and the left colon. In fact, the other name for this condition is left dorsal displacement of the colon.

The Merck Veterinary Manual explains the situation well, saying:

“There is a natural space between the dorsal [top] aspect of the spleen and left kidney. This space is bounded by the renosplenic ligament, a strong band of tissue that connects the spleen with the fibrous capsule of the left kidney. This ligament provides a ‘shelf’ over which the large colon can be displaced.”

In order to be displaced however, the colon needs to have another problem such as have more gas than usual, have less motility than usual . . . something that would cause it to move into this natural space. Therefore, anything you can do to ensure the normal health and function of the hindgut may help reduce your horse’s risk for developing this condition. That could mean making sure his diet consists primarily of forage, not grain, then meeting his nutrient requirements with a multi-vitamin/mineral supplement or ration balancer. It could also mean adding digestive support that includes probiotics, prebiotics, yeast or other ingredients proven to assist in proper digestion.

As far as prognosis goes, I found an article that provided these recovery numbers:

• Up to 90% success following phenylephrine and lunging exercise
• Up to 74% success following rolling (under general anesthesia)
• Up to 93% short-term survival (survival to discharge home) following surgical correction

Recurrence may occur in approximately 8% of cases, making these horse candidates for obliteration of the nephrosplenic space.

Unfortunately, there are no early warning signs for nephrosplenic ligament entrapment, just the “usual” colic signs: abdominal pain, reduced fecal output, elevated heart rate, etc. While every horse owner should observe their horse closely for colic and contact their veterinarian at the first sign of a problem, horses with a history of a previous serious condition like this need extra close attention paid to them since the outcome is better the sooner treatment is begun.