Metabolic Bone Disease
Metabolic bone disease (MBD) is a blanket term for a collection of medical maladies that include fibrous osteodystrophy, osteomalacia, osteoporosis, secondary nutritional hyperparathyroidism, and rickets.
Metabolic Bone Disease
Metabolic bone disease (MBD) is a blanket term for a collection of medical maladies that include fibrous osteodystrophy, hypocalcemia, osteomalacia, osteoporosis, secondary nutritional hyperparathyroidism, and rickets. It is caused by a disruption of calcium metabolism. This disease is normally preventable and is typically the result of poor husbandry. Animals that require special diets and lighting, such as iguanas and bearded dragons, are often the most susceptible to this condition though it can affect any reptile in which calcium metabolism is an issue.
Osteitis Fibrosis Cystica
Metabolic Bone Disease Causes
Metabolic bone disease is caused by a number of different issues. In captivity it is often caused by inadequate diets and the unavailability of UVB. UVB is the natural ingredient in the creation of Vitamin D in a reptiles body. Vitamin D is required in order to metabolize dietary calcium. A lack or deficiency of vitamin D is a common cause of metabolic bone disease as is inadequate calcium levels in the blood. (This is often the result of a poor diet.) A diet high in oxalates, which inhibits calcium absorption, is a leading cause as well. Other pre-existing conditions, such as kidney or liver disease, disease of the thyroid or parathyroid glands, and small intestinal disease are also contributors. Improper heating can cause issues with the digestive system, which in turn hinders the absorption of calcium.
Vitamin D3 Importance
Wild reptiles manufacture their own vitamin D3 by basking in unfiltered sunlight. The ultraviolet radiation from the sun acts like a catalyst which converts a substance known as pro-vitamin D3 into pre-vitamin D3. In turn, this pre-vitamin D3 is converted into vitamin D3, which binds to a blood protein and then can be transferred to the liver via the bloodstream. This "activated" form of D3, then can be utilized to influence the metabolism of dietary calcium and phosphorus. This is why access to UVB is so important.
Signs Of Metabolic Bone Disease
Metabolic Bone Disease presents itself in varying forms, each dependant on which stage the disease was caught at. Mild cases will exhibit fewer symptoms than advanced cases. Below is a list of different ailments to watch for.
Bowed Or Swollen Limbs
Softening Or/And Swelling Of The Jaw (Bilateral) - Aka: Rubber Jaw
receded lower jaw
Jerky Movements - Twitching In The Muscles (Spasms)
Bumps On The Long Bones Of The Legs
Arched Spine Or Bumps Along Bones Of Spine
Tortoises With MBD Sometimes Develop Pyramid-Shaped Scutes.
Turtles Experience Softening Of The Carapace Or Shell.
How Is Metabolic Bone Disease Diagnosed
In addition to observing the physical symptoms brought on by metabolic bone disease, blood work and x-rays may be required for a positive diagnosis.
Metabolic Bone Disease Treatment
The severity of the metabolic bone disease will dictate how aggressive the treatment will need to be. In mild cases MBD can be rectified by simply providing the animal with the proper diet, lighting and husbandry. More progressed MBD may require hospitalization, calcium and vitamin injections.
Medicinal Treatment Protocol
Option I: Boyer T. Common Problems and Treatment of Green Iguanas (Iguana iguana). AARV Premier Issue, 1991:8-11.
Option II: Boyer T. Metabolic Bone Disease. In Reptile Medicine and Surgery. Mader, D WB Saunders, Phil, PA 1996:385-392
1. 10% calcium gluconate, (100mg/mL), 500mg/kg intracoelomically weekly for 4-6 weeks; or Calphosan 0.5-1.0mL.kg (23mg/kg) b.i.d PO for 2-3 months while diet is corrected.
2. B-complex vitamin injection: 0.25-0.50 mL/kg, once.
3. Injacom-100: Dose at 100IU vitamin D3/kg SQ, two doses 1 week apart.
1. Startcalcium glubionate (Neo-Calglucon syrup, USP) at 1mL/kg (23mg/kg) PO q12h on the first visit. Calcium gluconate (100 mg/kg IM or ICe q6h prn for up to 24 hours) can be given if hypocalcemic tetany is present. After stabilization (usually 2-3 months), you may switch to an s.i.d regimen.
2. Injacom-100 (dose at 1000IU vitamin D3/kg) IM once weekly for two treatments at week 1 and week 2 visits.
3. Calcitonin (Calcimar, 200IU/mL) at 50IU/kg IM once weekly at the week 2 and 3 visits.
Metabolic Bone Disease Prevention
This disease can be easily prevented in most cases by simply researching and supplying your reptile with all of its required needs. Supplying the proper diet, lighting (UVB Access), heat gradients, photoperiod, and adequate enclosure size/exercise room are required to avoid this disease.
Most instances of this disease are from people who simply didn't know better or who couldn't afford the proper equipment to care for the animal.
Author: Richard Brooks
Ackerman, Lowell. Biology Husbandry and Health Care of Reptiles. TFH, 1997.
Zhang, Rubin. GNU Free Documentation License, Osteitis Fibrosis Cystica Image 2009
Mader, Douglas. Reptile Medicine and Surgery SE. Saunders, 2005.
Boyer T. Common Problems and Treatment of Green Iguanas (Iguana iguana). AARV Premier Issue, 1991:8-11.
Boyer T. Metabolic Bone Disease. In Reptile Medicine and Surgery. Mader, D WB Saunders, Phil, PA 1996:385-392