The following questions were asked in relation to egg binding in chelonians. The answers reflect opinions based on current veterinary medical literature and personal experience in clinical practice. Please keep in mind that the causes of egg binding may be multifactorial, and that each individual case should be evaluated as an isolated condition. This is best left to individuals experienced with chelonian reproduction.
What is egg binding and why should it be treated?
Egg binding refers to the condition where a female oviparous animal is due to lay eggs, but because of some complication, is unable to do so. The result is that the eggs are retained within the body. This can be brought about by a number of factors.
One of the more common causes is where the egg is too large to pass through the pelvic canal. This can happen due to the internal development of an abnormally large egg, or in a condition where the pelvis has been damaged and because of this damage even normal sized eggs are unable to pass.
A second common cause of egg retention is related to behavioral stress. Many chelonians will not deposit their eggs if their habitat is not correct for oviposition (egg laying). Quite often incorrect housing, substrates and temperatures will inhibit animals from building nests and subsequently prevent egg laying. Many times, once these deficits are corrected the animal will readily build a nest and deposit the eggs without further problems.
Other factors involved with egg retention include improper nutrition, disease of the reproductive tract (e.g.. cancer, infection), prior damage to the reproductive tract (e.g.. scar tissue from previous surgery), imbalances of various reproductive hormones and general poor health of the animal.
Retained eggs must be removed because if left they can cause serious disease, and ultimately death to the affected female. Retained eggs put excessive pressure on the internal organs of the body such as the liver and stomach. This can make it difficult for the animal to eat thus adding nutritional stress to an already compromised animal.
The retained eggs may cut or otherwise injure the internal structures of the animal, and the free egg material within the body cavity can potentially cause a lethal condition called egg peritonitis.
If eggs are left inside the female too long before removal there may be irreversible damage done to the reproductive tract which will affect future reproduction by that animal.
These are just a few of the concerns regarding egg retention. The important point is that egg binding is a serious medical condition and should be attended to immediately.
Editor's note (MJC): From my experiences of using oxytocin on tortoises and turtles, the time at which successful egg laying commences following the administration of the hormone can vary from 15 minutes to 2-4 hours. If you take an animal to a veterinarian who recommends oxytocin administration remember that the time to onset of egg laying can be quite rapid. Discuss this with the veterinarian. Take the oxytocin home and administer it yourself or leave the animal with the veterinarian. Either way avoids the risk of your animal laying her eggs in the back seat of your car on the way home!