Egg binding is a serious reproductive tract emergency where a laying hen's egg fails to pass through the oviduct to be laid within a normal period of time. It occurs more commonly in hens on a poor diet, laying eggs for the first time, or prolific layers. Other reasons for egg binding include vitamin E and selenium deficiencies, inadequate exercise, poor muscle strength, oviduct infections, trauma, systemic disease, genetic predisposition, and malformed eggs.
Egg-bound hens may frequently show straining, ruffled feathers, paralysis of one or both legs, wide-based stance, loss of appetite, blood in feces or matted around the vent, dyspnea, or on occasion, sudden death. In most cases, the presence of an egg can be verified through palpation , however if it is a soft-shelled egg or has no shell then it might not be as easy to recognize through palpation, and a radiograph or ultrasound might be needed.
Usually, although it may take 12 hours or longer, supportive care alone is often adequate to result in expulsion of an egg. However, egg binding needs to be taken seriously and quickly addressed as resulting complications can include prolapse of the oviduct or death if the egg is not passed or surgically removed. Other treatment options that can be used to encourage egg expulsion include prostaglandin and hormone therapies.