Bovine omphalocele: errors in embryonic development, veterinarian importance, and the way forward.

Omphalocele is an embryonic developmental error presented as a neonatal visceral umbilical herniation. Epidemiological and embryological studies are reviewed that revise our understanding of midgut development and defects in cattle. Google Scholar and PubMed were searched for omphalocele, exomphalos, calves, calf, cattle, epidemiology, genetics, disease presentation, and omphalocele treatments of bovine neonates. Omphalocele contains small intestine and sometimes liver and/or pyloric abomasum. This condition may arise from inadequately expanded abdominal cavity, herniated midgut entrapment, or inappropriate umbilical ring growth. Full-term neonates are otherwise healthy but comorbidities may be present. Limited epidemiological evidence suggests neonates, commonly female, of dairy dams have much higher omphalocele prevalence than humans but with fewer co-morbidities. Genetic or environmental influences may present at low incidences, especially with co-defects, while also epigenetics operate in metabolically challenged dairy cattle. Calf survival after surgical repair was commonly good if damage to eviscerated tissue was minimal and surgery prompt. Inadequate follow-ups prevented assessment of their commercial value. We also revised understanding of embryonic midgut development. There is little useful epidemiological information on bovine omphaloceles. To address this, we suggest: (i) Observations on omphaloceles should report herd and dam histories, abdominal disposition of contents, and comorbidities. (ii) Cases of surgical restitution must report full histories and thoroughly explore post-surgical follow-ups to assess animal commercial viability. There is a need for very large-scale multi-centre prospective observational studies on cattle health and productivity that should include omphaloceles.