Retained caseous yolk sac in a Burmese python (Python molurus bivittatus).

Retained yolk sacs are common in the domestic chicken and account for considerable morbidity and mortality during late embryonic development and within the first 10 days of life. What is believed to be the first recorded instance of a retained caseous yolk sac and its successful surgical removal from a Burmese python (Python molurus bivittatus) is reported. The snake experienced no post-operative complications and continues to be well 16 mo following surgery.