Archives of The Cold Blooded News

The Newsletter of the Colorado Herpetological Society

Volume 29, Number 1;   January, 2002

Ask the Vet

by Dr. Linda Randall

I have never been able to overdose a reptile with just calcium, nor have I spoken to a veterinarian who has. Reptiles are able to regulate the amount of calcium their body absorbs, and the rest is excreted in the feces. The problem begins when Vitamin D is added to the calcium mixture. This vitamin encourages the reptiles system to absorb excessive calcium, which eventually leads to hypercalcemia, a serious condition. The calcium to phosphorus ratio is also very important when looking at calcium levels in the food offered to reptiles, and when reading blood chemistry results. If you have a herp that requires calcium supplementation, make sure it is only calcium that you are using. (At our hospital we use calcium carbonate, which is inexpensive and comes in a fine powder.) For anything else, consult with your veterinarian first to ensure you are feeding your particular pet correctly. When you read labels, you will find that many of the products sold as calcium supplements have Vitamin D3 added. This is not necessarily a bonus!

There really aren't any new theories about why snakes retain eggs, just more evidence pointing to the correctness of previously held theories. Egg binding, or dystocia, in snakes (and lizards) is divided into two categories: preovulatory egg retention (more commonly seen in lizards), which refers to cessation of egg development before the shell is laid down. This creates a mass of yolks in the abdomen. These non-shelled eggs may be reabsorbed after a time, or may create problems for the snake such as "egg peritonitis." This is inflammation or infection in the abdomen that may occur due to the rupture of one of the eggs. The other form is postovulatory egg retention. In this form, which is more common in snakes, the shelled egg is retained in the reproductive tract for a variety of reasons. There appears to be a greater incidence of dystocia from infertile eggs than fertile ones, and yes, evidence also indicates perhaps a higher incidence in sub-adult and geriatric snakes. The practice of "power feeding" for rapid growth in youngsters may foster the breeding of snakes that are not as sexually mature as they appear. The same desire for as many clutches from one female as possible may also lead to breeding an older female that is past her safe reproductive years. Some breeders also double-clutch their snakes, which may also create problems with egg retention, especially with the colubrid snakes. Pythons and boas may have problems if bred annually.

In the captive snake population, most egg retention problems are related to an unsuitable environment. This includes improper temperature and humidity, incorrect lighting type and duration, an inappropriate nesting place with undesirable nesting material, overcrowding, and inadequate cage size. Additionally, the snake must be provided with a sense of security and seclusion. Too much handling, or too much activity around the housing, may also make a difference. Metabolic disturbances (especially involving calcium), infections of the shell glands, oviducts, or cloaca, systemic infections, or obstructions (by egg abnormalities, tumors, torsions or prolapses, for instance) have all been implicated in the retention of eggs. Importantly, it is thought that poor muscle condition, from lack of exercise and overfeeding, is also a critical and often overlooked factor in reproductive problems of captive snakes. This may be especially true for the snakes that oviposit most of their clutch, but retain the last few eggs.

Your experience may be related to the age and size of your older, larger breeders. In addition to the above, snakes usually produce more eggs with each cycle as they age and grow. This requires more exact attention to the details of their environment and feeding, as their body competes with an ever-increasing demand for nutrients from the increased number of eggs. More eggs also take up more abdominal room, impinging on the space usually occupied by the gastrointestinal tract. The eggs may even compress the intestinal tract to such an extent as to cause bloat and obstruction, leading to GI stasis and secondary constriction of blood flow. This can have devastating consequences, and can also lead to egg retention.

Thank you for your questions. Talk to you next month!

Linda Randall, DVM, ABVP