Metabolic Bone Disease
The term “Metabolic Bone Disease” (or “Disorder”) is not an actual disease, but a catch-all term for a wide variety of conditions that can soften or deform a tortoise’s shell and skeleton. Some MBD’s are due to disease processes, like “Fibrous osteodystrophy”, “Hypertropic osteopathy”, or “Paget’s Disease”. Most MBD’s are due to problems with diet and basic care. The most common is “Nutritional Secondary Hyperparathyroidism” or NSHP. Common names for this condition are “rubber jaw” in lizards, or “soft shell” in turtles and tortoises. The root cause is usually a combination of too little calcium, too much phosphorous, or too little vitamin D, but can also be aggravated by poor temps, poor hydration, etc. Pyramiding is usually a form or symptom of NSHP as well. [Mader]
Since NSHP is almost entirely due to problems in basic husbandry (mostly diet, but also care, housing, etc.), it can be prevented by providing the tortoise with the right diet and husbandry, appropriate to the species. We may need to supplement key elements, especially calcium, vitamin D, fiber, and iron, or work to augment the temps, lighting, and humidity.Tortoises are very flexible when hatched, and need a diet and care designed to promote shell and skeleton development from the very beginning. If the shell does not “firm up” in a timely fashion, various forms of NSHP and pyramiding (see right) will develop.
NSHP shows up in tortoises as a softened, leathery, or rubbery shell*, but by the time the shell shows obvious problems, there may be problems in the bones. Problems such as pyramided or raised scutes, deformed jaws, weak and/or deformed limbs, splayed walking, dragging limbs, paralysis, and cloacal prolapses are signs
IMPORTANT: Very young tortoises are a bit soft or flexible so they can fit in the egg and so the shell can move as they grow. This often worries keepers, but there is a difference between a young shell and a soft shell. Young tortoise shells are springy, like they are made of a stiff plastic; the plastron may feel a bit springy for some time. Soft shells, however, feel more “leathery” and do not resist being compressed as much. If the shell
As long as the tortoise is still eating, the shell is not too soft, and there are no other worrisome symptoms, the tortoise can probably be treated at home. Do not, however, suddenly start dumping lots of calcium in the poor animal or flooding it with UVB lighting. Try the following:
If the shell is very soft, the tortoise is not eating, is showing other symptoms, or is not responding to your care, you should see a vet. The vet should do blood and other tests, an x-ray, and take a complete history to try to determine if the problem is NSHP or another bone problem. The vet would then determine a course of treatment based on the findings. NSHP is usually treated with vitamin D3 injections and supplemental calcium orally, then follow-ups over two weeks. More severe cases may also need dietary support and other treatment. It is important to follow the vet’s suggestions as carefully as possible for the best chance at recovery.
Treated properly, the tortoise should recover fully, although some shell or skeletal deformity will remain, and there may be residual muscle or nerve problems. The earlier it is caught, the better the chances for a complete recovery.
When scutes grow in a conical or piled-up fashion with the bone deforming behind the scutes, we call it “pyramiding”. Some tortoises, such as Star Tortoises, pyramid naturally, and some tortoises, such as some Testudo
Edited 8-15-2012 (C) Mark Adkins