Right Dorsal Displacement of Large Colon - Horse
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Description
Right dorsal displacement of the large colon is a cause of colic in horses. It is much less common than left dorsal displacements and although clinical signs can be variable, it is usually more acute and serious in presentation. In all cases the left dorsal and ventral large colon displace to sit between the caecum and the right body wall. The pelvic flexure is usually displaced cranially towards the diaphragm; the caecum is shifted towards the midline and may become secondarily distended. In some cases the displacement is accompanied by a volvulus which is responsible for more acute presentation. The exact cause of the condition is not known.
Signalment
Wide bodied horses are predisposed to the condition and horses are usually housed indoors when affected.
Diagnosis
Clinical Signs
Presentation is variable, although some cases are mild and protracted, the majority are acute and violent.
- Moderate to severe abdominal pain and signs of colic
- Right flank distension
- Tachycardia
- Signs of shock
On rectal examination a gas distended colon is palpable in the right caudal abdomen, the caecum is displaced towards the midline and the pelvic flexure cannot be palpated as it has moved cranially towards the diaphragm. If the displacement is accompanied by a 270° volvulus then the colonic walls will be thickened and oedematous.
Ultrasound
Abdominal ultrasound provides confirmation of the diagnosis.
Treatment
Prompt surgical treatment is necessary for correction. The displaced colon can be relocated after decompression of the colon and the caecum. In cases where significant impaction has developed, the colon should be evacuated via a pelvic flexure enterotomy. If a concurrent volvulus occurred, causing ischemic damage to the colon then resection of the affected portion must be performed.
Medical treatment with IV fluids and analgesia is also indicated, as described in the section Medical Treatment of Colic in Horses.
Prognosis
If the condition is identified early and surgical correction is carried out without delay then the prognosis is very good. In cases where the vascular supply to the colon has been compromised the progonsis is much worse.
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