Nephrosplenic Entrapment Colic in Horses

Updated October 30, 2023 | By: Andris J. Kaneps, DVM, PhD, DACVS, DACVSR

What is Nephrosplenic Entrapment Colic?

Nephrosplenic Entrapment (NSE) colic is caused by an upward displacement and entrapment of the left colon over a ligament that connects the spleen with the left kidney. The trapped part of the colon hangs like a dumbbell over the ligament, obstructing blood circulation and the flow of intestinal contents. The horse’s large colon distends or stretches with gas or fecal matter and causes abdominal pain.

Of all horses presented for colic, NSE is found in 6-9% of cases [1]. Middle-aged, deep-chested breeds, such as Warmbloods, are most commonly affected.

Breaking Down the Terminology

The prefix “nephron” means kidney, while “splenic” refers to the spleen. Since the spleen is on the left side of the horse’s body, this refers to the left kidney and the left colon.

Another name for this condition is left dorsal displacement of the colon.

Causes of Nephrosplenic Entrapment Colic in Horses

Excessive gas within the horse’s large colon can cause the intestine to move up into this space and become trapped over the nephrosplenic ligament. Causes of gas build-up may include:

• Quick changes in hay or grain, such as suddenly switching to a new source of forage.
• Being exposed to readily fermentable grasses or hay, such as grazing on lush pasture rich in clover content.
• A blockage or impaction in the colon that prevents the normal passing of gas.
• Inflammation in the hindgut, which may reduce normal motility in the colon and predispose the horse to colic.

Signs and Diagnosis

The indicators of NSE colic mirror the clinical signs for all types of colic in horses, such as abdominal pain, reduced fecal output, elevated heart rate, etc. However, horses with NSE colic may have observable distension of the abdomen, often noticed as a larger filled flank compared to normal.

A veterinarian can diagnose a case of NSE colic by rectal palpation or through an ultrasound exam. In these cases, your vet would find your horse’s colon displaced over the ligament that connects the spleen to the left kidney.

Treatment and Prognosis for NSE Cases

If your horse shows signs of colic, contact your veterinarian. Your vet is the best resource to determine the likely cause of the colic and administer the appropriate medications.

Initial treatment for NSE is similar to the treatment for gas colic as it typically includes anti-spasmodic and non-steroidal medications to reduce intestinal pain. Your veterinarian may also administer treatments via a stomach tube, such as warm water with electrolytes or mineral oil, to help reduce free gas and may treat constipation or manure impaction.

Treatment at an Equine Hospital

Horses that do not respond to initial treatment may require referral to a veterinary hospital. Once there, the vet will confirm the diagnosis and begin treatment with intravenous fluids, food fasting, and close monitoring in intensive care.

An option for medical treatment is the administration of phenylephrine, which is a drug that causes the spleen to contract [2]. With the spleen contracted and smaller in size, your horse is exercised in hand or on the lunge to encourage the colon to return to its normal position in the lower part of the abdomen.

In some situations, surgery is required to resolve NSE colic. Surgery involves emptying the affected colon of fecal material and excess gas, then repositioning the colon in its normal anatomic location.

For horses with recurring episodes of NSE colic, a standing surgical procedure with laparoscopy may be done to close the space between the spleen and left kidney [4]. This procedure involves placing sutures (or sutures and mesh) to eliminate that space where the colon may become trapped [4].

The prognosis for recovery is over 90% for horses treated with medical therapy or surgery [3, 5]. A reassuring 54-72% of horses recover without going to surgery [2, 5].

Prevention and Management Best Practices

Prevention of gas accumulation in the gut that may lead to NSE colic involves following feeding and management best practices, including:

• Ensuring your horse’s diet consists primarily of forage (not grain) and meeting nutrient requirements with a multivitamin and mineral supplement or ration balancer.
• Making hay or grain changes slowly.
• Ensuring clean, fresh water is always available.
• Introducing pasture grazing gradually, especially during the rapid growth of grasses in the spring.
• Allowing ample free exercise (turnout) whenever possible.
• Adjusting exercise (whether increasing or decreasing activity or intensity level) with a gradual approach.
• Maintaining regular preventative care, including parasite control measures.

Supplements That May Lend Digestive Support

Making efforts to ensure the normal health and function of the hindgut may help reduce your horse’s risk for developing this condition. Adding a digestive supplement that’s designed to promote the natural well-being and optimal function of the hindgut may be beneficial.

Digestive supplements typically include prebiotics which may minimize disturbances in the cecum and colon, as well as inhibit uptake of detrimental bacteria within the hindgut. Other ingredients like yeast, enzymes, and probiotics also work to support healthy functioning of the hindgut.

Evidence-Based References

1. Burba DJ, Moore RM. Renosplenic entrapment: a review of clinical presentation and treatment. Equine Vet Educ 1997;9:180-4.
2. Gillen AM, Munsterman AS, Reid Hanson R. Evaluation of phenylephrine and exercise with or without trocarization for treatment of suspected nephrosplenic entrapment in horses. J Am Vet Med Assoc. 2019 Jun 15;254(12):1448-1453. doi: 10.2460/javma.254.12.1448. PMID: 31149874.
3. Hardy J, Minton M, Robertson JT, Beard WL, Beard LA. Nephrosplenic entrapment in the horse: a retrospective study of 174 cases. Equine Vet J Suppl. 2000 Jun;(32):95-7. doi: 10.1111/j.2042-3306.2000.tb05342.x. PMID: 11202393.
4. Nelson, B.B., Ruple-Czerniak, A.A., Hendrickson, D.A. and Hackett, E.S. (2016), Laparoscopic Closure of the Nephrosplenic Space in Horses with Nephrosplenic Colonic Entrapment: Factors Associated with Survival and Colic Recurrence. Veterinary Surgery, 45: O60-O69. https://doi.org/10.1111/vsu.12549.
5. Lindegaard C, Ekstrøm CT, Wulf SB, Vendelbo JM, Andersen PH. Nephrosplenic entrapment of the large colon in 142 horses (2000-2009): analysis of factors associated with decision of treatment and short-term survival. Equine Vet J Suppl. 2011 Aug;(39):63-8. doi: 10.1111/j.2042-3306.2011.00376.x. PMID: 21790756.