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September 2014

Calf, Small intestinal (jejunal) atresia (type I, membrane atresia)

09_14

History: Calf, 4 days, male

Diagnosis: Small intestinal (jejunal) atresia (type I, membrane atresia)

Description: The calf presented clinically with marked abdominal distention. Defecation was never observed. Blood analysis showed severe leukocytosis and acidosis.

175 cm orally to the ileocecal junction, the duodenum and jejunum were distended a focally extending, acute, moderate, fibrinous serositis. There was an abrupt reduction of the jejunal lumen and further preparation of the connecting area between the distended and narrowed jejunum yielded a thin membrane that obstructed the lumen (see inlay). Aboral, the jejunum, ileum, colon, caecum and rectum contained only minimal amounts of yellow-brown mucus.
Comments: Segmental anomalies of the bovine intestine include stenosis (partial narrowing of the intestinal lumen) and atresia (complete lack of the intestinal lumen).

The most common segmental anomaly in the bovine intestine is atresia coli, followed in decreasing incidence by jejunal and ileal atresia.
Atresia can be subdivided into types I through IV. In membrane atresia (type I), the intestinal lumen is obstructed by a thin membrane or diaphragm. In cord atresia (type II), the blind ends of the gut are joined by a cord of connective tissue. An intestinal section is completely missing in blind-end atresia (type IIIa), leaving 2 blind ends and a V-shaped mesenteric defect, whereas in “Christmas tree” or “apple peel” atresia (type IIIb), the distal end of the intestine is wrapped around a single perfusing vessel. Several of the aforementioned defects are combined in type IV atresia (multiple atresias).

Colonic atresia may be inherited by an autosomal recessive trait in Holstein Friesian cattle. A predisposition for male calfs has been described, but this is not consistent among studies.

Clinically, dilation of the oral segment with progressive abdominal distension is commonly observed. Aborally to the atresia the intestine is notably reduced in diameter and contains only mucus and exfoliated epithelial cells.

Figure and authored by: Angele Breithaupt, Department of Veterinary Pathology, Freie Universität Berlin, Germany