Category:Intestines - Developmental Pathology

Developmental Anomalies

Segmental

Segmental anomalies of the intestines are common and range from incomplete occlusion (stenosis) to complete occlusion (atresia) of the lumen.

Atresia ani

Pig - atresia ani (Courtesy of Elspeth Milne)

• A common congenital defect of the lower gastrointestinal tract.
• Both the anus and rectum can be affected.
• Occurs in all species but is most often seen in calves and pigs.

Atresia coli

• Considered the most common segmental anomaly of the intestine in domestic animals.
• Can affect in particular the spiral colon of Holstein calves and the small colon of foals.

Atresia ilei

• It is less common to see atresia in the small intestine.
• Mostly seen in calves.

Persistent Meckel's diverticulum

• Meckel's diverticulum is a remnant of the omphalomesenteric duct of the yolk sac.
• Is usually an incidental finding though it can be associated with impaction and/or intussusception.

Megacolon

• Occurs in cats, dogs, and pigs.
• May be due to a lack of myenteric plexuses that occurs when neuroblasts fail to migrate from the nerual crest to the colorectal myenteric plexuses.
• Congenital colonic agangliosis, a condition occurring in white foals, can lead to megacolon. It is thought to be an autosomal recessive condition.

http://w3.vet.cornell.edu/nst/nst.asp?Fun=Display&imgID=632 megacolon

References

Brown CC, Baker DC, Barker IK: Alimentary System. In: Jubb, Kennedy and Palmer's Pathology of Domestic Animals, ed. Maxie MG, 5th ed., pp. 1-296. Elsevier, Philadelphia, PA, 2007.

McGavin DM & Zachary, JF: Pathologic Basis of Veterinary Disease, 4th ed, pp. 301-393.Elsevier, St. Louis, Missouri, 2007.