396 First Street

Los Altos, California 94022

Veterinarian Always on Duty

Metabolic Bone Disease

Metabolic Bone Disease (MBD), also known as Rubber Jaw, or Nutritional Secondary Hyperparathyroidism, is a very common disease in captive reptiles. It is a condition caused by a lack of adequate calcium. Calcium is essential for muscle contraction (from general locomotion to making the heart beat), skeletal strength, some enzyme functions, and neuromuscular communication. Hense, the body strictly regulates calcium blood levels to maintain life. Calcium is absorbed from the diet in the intestinal tract and any excess is stored in the bones of the body. If dietary calcium intake is insufficient and the blood levels become low, the hyperparathyroid gland detects this and signals special cells to reabsorb calcium from the bones. This condition is similar to osteoporosis in humans. As calcium is removed from the bones, it is replaced by fibrous connective tissue which makes the bones appear swollen. Unfortunately, the loss of calcification also causes these bones to be very weak and pliable (thus the name rubber jaw). These bones can easily be fractured. Eventually even the calcium in the bones is depleted and the body becomes severely hypocalcemic. At that time, the reptile demonstrates signs of tremoring, twitching, seizures, and even death.

How do you prevent this problem from happening? The obvious solution is to ensure that your reptile's diet is calcium enriched. If your reptile is herbivorous (consumes mainly vegetable matter) or insectivorous (consumes mainly insects), there are many calcium supplements which can be sprinkled on the food with each meal. Ideally you would supplement with calcium daily or with every meal (especially important in young growing reptiles) and with a multivitamin once to twice a week. It is possible to over supplement with the multivitamin. Vitamins such as A, D, and E can reach toxic levels if given too frequently, so give with caution. Carnivorous reptiles are not as prone to metabolic bone disease because they consume whole prey which provides adequate calcium.

Now that the calcium is available, your reptile has to be able to absorb the calcium from its intestinal tract. This is where the UV light and Vitamin D are important. In order for the intestinal tract to absorb the calcium, it requires activated Vitamin D3 to be present. Vitamin D, which reptiles absorb in their diet, needs to be exposed to UV radiation (light) in order to become activated. This is why it is so important to have a full spectrum UV light in your reptile's environment. In order to be effective, it should be within twelve inches from your reptile and should be on for ten to fourteen hours a day. UV light is filtered out when it hits the glass, so it is not enough to have your reptile's enclosure near a window. Nothing is as effective as natural sunlight as a UV light source. If possible, have your reptile exposed to direct sunlight (careful not to overheat your reptile) for twenty to thirty minutes daily or several times a week.

How do you know if your reptile has metabolic bone disease? One way to get an idea would be to have your reptile examined by a veterinarian. Your veterinarian would perform a routine physical exam (look for signs of swollen limbs, soft/pliable mandible and limbs, soft shells), test the levels of blood calcium and phosphorous, and/or take a radiograph (x-ray) to see what the bone density is like. Metabolic bone disease takes a long time to occur and even longer to correct, so it is important to diagnose it early.

We Are Moving!
 

Veterinarians in San Francisco/San Jose   What is the AAHA? Employment Frequently Asked Questions   Summer Hazard - Foxtails Los Altos Planning Commission approves our move! Adobe Animal Hospital voted best veterinary hospital - 2009