Intussusception - Horse

See Colic Diagnosis in Horses

Medical Treatment of Colic in Horses

Description

An intussusception is an invagination of a length of intestine (the intussusceptum) into an adjacent more distal segment (the intussuscipiens). The small intestine is the most common site for this to occur. The length of intestine affected may range from a few centimeters up to a metre. Intussuception in the horse most commonly involves the ileum (ileo-caecal or ileo-ileal). Jejuno-jejunal intussusceptions also occur in the horse but they are considerably less common.

The aetiology of the condition is not fully understood, but is thought to be due to underlying disorders of gut motility. This may be due to one of several conditions including parastitism, enteritis, use of anthelmintics and surgical trauma.

Signalment

Small intestinal intussusceptions can occur in horses of all ages but those aged between six months to three years are most commonly affected. There is no breed or sex predilection.

Clinical signs

Clinical signs are dependent on whether the obstruction caused by the intussusception is partial or complete. Complete obstructions are characterised by acute onset, severe abdominal pain. Vascular impairment is a feature of complete obstructions and strangulation usually occurs, leading to clinical signs of tachycardia, tachypnoea, prolonged capillary refill time and congested mucous membranes. Borborygmi are often absent or significantly reduced. Large volumes of gastric reflux may be obtained and loops of distended small intestine may be palpated on rectal examination.

Partial obstructions are associated with more chronic clinical signs. Abdominal pain may be mild and intermittent, often co-inciding with feeding. Other clinical signs may include weight loss and reduced faecal output. Signs may occur over a period of weeks, during which time muscular hypertrophy of the intestine proximal to the partial obstruction occurs.

Diagnosis

Abdominal ultrasonography may reveal a characteristic target or 'bulls eye' lesion on cross section. Peristalsis in the affected region is reduced or absent. Oedema and thickening (>3mm) of the intestinal wall are often seen with a distended, fluid filled region proximal to the intussusception. In the case of jejuno-jeunal intussusceptions, rectal examination may reveal a sausage-shaped, tubular structure in the mid-abdomen of the horse.

Abdominocentesis rarely reveals any abnormalities due to the strangulated portion of gut being contained within the intussuscipiens.

Treatment

References

• McIlwraith, C. W., Turner, Robertson, J. T. (1998) McIlwraith & Turner's Equine Surgery: advanced techniques Wiley-Blackwell

• Orsini, J. A., Divers, T. (2007) Equine Emergencies: Treatment and Procedures Elsevier Health Sciences

• Radostits, O. M., Arundel, J. H., Gay, C. C. (2000) Veterinary Medicine: A textbook of the diseases of cattle, sheep, pigs, goats and horses Elsevier Health Sciences

• White, N. A., Edwards, B (1999) Handbook of Equine Colic Butterworth Heinemann

This is a condition in which one part of the intestine "telescopes" inside another. Usually this obstructs the blood flow to the inner part, and so forms a strangulating obstruction. Intussusception can occur within the small intestine, and also between small intestine and caecum (ileo-caecal intussusception). The latter is predisposed by Anoplocephala perfoliata tapeworm infection. When working up an acute abdominal case, it must be borne in mind that this form of colic is serious and necessitates surgery, however, peritoneal fluid changes will not usually be seen, as will often be found in a surgical colic. This is because the strangulated portion of gut (the inside of the "telescope"), is contained within an intact piece of intestine, so leaking fluid and protein is contained from the peritoneal cavity.