Left Dorsal Displacement of Large Colon - Horse

Also known as: Nephrosplenic Entrapment

Introduction

Left dorsal displacement, or nephrosplenic entrapment, is a frequent cause of colic, where the left dorsal and ventral colon become displaced, and then trapped by the spleen laterally, the kidney medially, and the nephrosplenic ligament ventrally. Entrapment over the nephrosplenic ligament results in simple obstruction of the colon, usually without vascular compromise. The exact cause is unknown but it is thought that changes in the ingesta, gas content and motor activity of the colon are important factors.

Signalment

Large breed and wide bodied horses are predisposed to this condition.

Diagnosis

Clinical Signs

• Moderate abdominal pain and signs of colic
• Mild tachycardia
• Decreased faecal output
• Inappetence

See Colic Diagnosis in Horses
Rectal examination is usually sufficient to make a diagnosis but in some cases abdominal ultrasound is needed for confirmation. On rectal examination the pelvic flexure or left colon can be felt in the nephrosplenic space, the spleen is often displaced towards the midline. The displaced colon becomes distended with gas due to compression over the nephrosplenic ligament.

Ultrasound

Abdominal ultrasound is a sensitive diagnostic tool; the left colon can be identified in the nephrosplenic space, it may partially or completely obscure the left kidney.

Treatment

The condition can usually be resolved with medical management, IV fluids and analgesia in the form of NSAIDs should be given to correct hydration status and make the horse comfortable.

Mild displacements may respond to the withdrawal of feed, allowing the colon to empty and return to a normal position. This can be aided by the intra-venous administration of phenylephrine which causes splenic contraction, significantly reducing its size and allowing the colon to relocate. Light exercise can also be beneficial to encourage movement of the abdominal contents. Circling on the left rein is considered particularly helpful, as it increases the potential space between the spleen and the body wall, allowing more room for the colon to return to its normal location.

In some cases a rolling technique may be used to try and correct the displacement. The procedure involves anaesthestising the horse and placing it on its right side, lifting it with a hoist and returning it onto the left side. Rectal manipulations can aid the relocation of the colon but it is not always successful.

Where conservative management has failed or in severe cases of left dorsal displacements, surgical exploration and correction is indicated.

Prognosis

Prognosis is good; in most cases the condition can be resolved without surgery.

Literature Search

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Left Dorsal Displacement of Large Colon in horses publications

References

• Mair, T.S, Divers, T.J, Ducharme, N.G (2002) Manual of Equine Gastroenterology, WB Saunders.
• Merck & Co (2008) The Merck Veterinary Manual (Eighth Edition) Merial
• Robinson, N.E., Sprayberry, K.A. (2009) Current Therapy in Equine Medicine (Sixth Edition) Saunders Elsevier
• Rose, R. J. and Hodgson, D. R. (2000) Manual of Equine Practice (Second Edition) Sauders
• White, N.A., Edwards, G.B. (1999) Handbook of Equine Colic Reed Educational and Professional Publishing Ltd