Large Colon Torsion - Horse
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Large Colon Torsion is also known as Large colon Volvulus
Description
Large Colon Torsion results from the rotation of the organ about its axis. The degree of torsion dictates the severity of clinical signs and the speed at which the condition progresses. Volvulus can occur at any point along the colon; the most common site is the junction between the caecum and the right ventral colon, and most twist in a clockwise direction, when looking at the horse from behind.
The condition can be described as strangulating if the rotation is greater than 360°, causing vascular as well as luminal obstruction to the intestine. This form of torsion is more serious and acute in presentation, resulting in endotaemia and death within hours if treatment is not prompt.
Signalment
Post parturient mares, large breed horses and those with a history of dietary change or grazing on lush pasture are predisposed to the condition.
Diagnosis
Clinical Signs
- Signs of Colic
- Tachycardia
- Poor periferal pulse quality
- tachypnoea
- Abdominal distension
On rectal examination the colon is distented and tympanic, the mesentry is palpably oedematous and the colonic bands may be felt in a transverse orientation. See Colic Diagnosis in Horses
Ultrasound
Abdominal ultrasound reveals a distended large colon with oedematous walls. Peritoneal fluid should be sampled under ultrasound guidance, typical changes include an increase in protein and cellular content.
Treatment
Strangulating torsion is a surgical emergency- the horse should go to surgery within 2-4 hours of the onset of clinical signs if the outcome is to be good. See Medical Treatment of Colic in Horses
Prognosis
Prognosis depends on the degree of volvulous and the speed of diagnosis and treatment. Torsions of less than 270° have a good prognosis, for more severe torsions, those that are stragulating, or in cases where surgery has been delayed, the prognosis is poor.
References
- Mair, T.S, Divers, T.J, Ducharme, N.G (2002) Manual of Equine Gastroenterology, WB Saunders.
- Mair, T., Love, S., Schumacher, J. and Watson, E. (1998) Equine Medicine, Surgery and Reproduction WB Saunders Company Ltd
- Merck & Co (2008) The Merck Veterinary Manual (Eighth Edition) Merial