Overview
The equine caecum is huge compared with that of ruminants or carnivores. Together with the ascending colon it is where microorganisms ferment plant fibre and produce volatile fatty acids, the horse's main energy source. It has four taeniae (dorsal, ventral, medial and lateral) that gather the wall into four rows of sacculations (haustra).
Parts
- Base (basis caeci): the dorsal, widest, curved part, in the right paralumbar fossa; it is attached to the abdominal roof, next to the right kidney and the pancreas. Its lesser curvature carries, close together, the ileal orifice and the caecocolic orifice, through which ingesta passes into the right ventral colon.
- Body (corpus caeci): runs cranially down the right side and then along the abdominal floor.
- Apex (apex caeci): free, on the abdominal floor near the xiphoid cartilage.
- Folds: the ileocaecal fold joins the ileum to the dorsal taenia and the caecocolic fold joins the lateral taenia to the right ventral colon.
Clinical relevance
- Caecal impaction: may cause only mild pain and end in rupture with little warning; it has been described in horses hospitalised for other problems, after anaesthesia or on anti-inflammatory drugs. The taut ventral taenia and the full caecum are felt in the right caudal quadrant on rectal palpation.
- Caecal tympany: decompressed with a cannula or trocar through the right paralumbar fossa, at the point of greatest resonance on percussion.
- Caecocaecal and caecocolic intussusception: associated with Anoplocephala perfoliata at the ileocaecal junction; it requires surgery.
- Auscultation: caecal borborygmi are heard in the right paralumbar fossa; their absence is an important finding in a horse with colic.