Regression of the ovary may result in leakage of free yolk into the abdomen (yolk peritonitis); this rarely causes death except when yolk material migrates through the air sacs to the lung and causes foreign body pneumonia. Free yolk occurs in many cases of acute illness, injury, or forced molt. Regression of the ovary is frequently caused by low body weight, deliberate reduction of feed, overcrowding, or lack of feeder space. Infectious diseases such as Newcastle disease, fowl cholera, pullorum disease, and avian influenza are known to cause this condition. It can also result from severe stress, which is often accompanied by feather molt, emaciation, and dehydration.

Last full review/revision March 2012 by A. Gregorio Rosales, DVM, MS, PhD, DACPV