Overview
The bovine large intestine (intestinum crassum) is only slightly wider than the small intestine and, unlike that of the horse, has no taeniae or sacculations. Microbial fermentation of what escaped the rumen continues here, and water and electrolytes are absorbed. It lies in the right half of the abdomen, together with the small intestine.
Parts
- Caecum (caecum): the blind continuation of the ascending colon beyond the ileal orifice. Its free apex points towards the pelvic inlet in the dorsal part of the right flank.
- Ascending colon: begins with the proximal loop (ansa proximalis), continues as the spiral loop (ansa spiralis) and ends with the distal loop (ansa distalis). The spiral loop forms a flat disc in the sagittal plane, on the left face of the mesentery, so that it lies between the mesentery and the rumen. Its centripetal turns (gyri centripetales) converge on a central flexure and the centrifugal turns (gyri centrifugales) run back out to the periphery, interleaved with them.
- Transverse and descending colon: the transverse colon passes from right to left cranial to the root of the mesentery; the descending colon runs caudally, near the midline and the roof of the abdomen, to the rectum.
- Rectum: in the pelvic cavity; through its wall the genital organs, bladder, left kidney and other structures of the caudal abdomen are palpated.
Clinical relevance
- Caecal dilatation and volvulus: in adult dairy cows, often after calving and on concentrate-rich diets. It causes a ping on percussion of the right paralumbar fossa; the dilated caecum is felt per rectum as a cylinder whose apex points towards the pelvis. Volvulus requires surgery.
- Rectal palpation: it is the basis of the reproductive examination; rough handling can cause rectal tears.
- Atresia coli: a congenital anomaly of calves, more common in Holsteins, with no faeces and progressive abdominal distension. It has been linked to transrectal palpation of the amniotic vesicle in the first weeks of pregnancy.
- Winter dysentery: an epidemic disease of adult cows associated with bovine coronavirus, with diarrhoea, sometimes haemorrhagic, and a drop in milk yield.