MBD & Gout
Two different conditions that could mimic each other.
MBD is actually the name given to a group of metabolic disorders that affect Calcium storage in bones. The most common of these diseases is one known scientifically as "Nutritional Secondary Hyperparathyroidism" but we'll use it here as a synonym to MBD. MBD is caused mostly by a deficiency in blood calcium which makes the body remove calcium from the bones. In the long run these causes weak bones that are prone to fractures and bend easily. The chameleons will take a bow legged appearance and are not able to fully lift the body from the branches. Lack of calcium is mostly due to improper diet being by improper gut loading of insects or by improper supplementation.
MBD can also occur even in the presence of adequate calcium levels if the body can't absorb the calcium. The body uses Vitamin D3 to absorb calcium from the intestines. Vit D3 is produced in the body by exposure to UV light but mostly UVB. That's why calcium supplement come without D3 for "outdoors" or with D3 for "indoors". The recent Mercury vapor bulbs seem to produce adequate levels of UVB and are a good addition to any cage setup if it is destined to be indoors. However nothing beats the good old Sun.
Treatment is not 100% successful and the animal always retain the bone deformities caused by the condition. The target is to increase availability and absorption of calcium into the chameleons body to promote storing the calcium back into the bones. In successful recoveries, the chameleons can live a somewhat normal life provided that the nutritional requirements are met.
Moving on to gout. Gout is a condition caused by excessive levels of protein in the diet. Most precisely it is excessive levels of uric acid in the blood which is a byproduct of protein metabolism). Uric acid will find its way into organs and joints mainly, and forms crystals that impede their normal functioning. It is most easily diagnosed in the joints, where the condition is called "articular gout", than it is in organs ("visceral gout"). In joints it will cause mild to severe swellings and reduced mobility of the joint. The chameleons may appear painful when walking and might even react overly aggressive when the affected joint is touched. Chameleons are usually noticed refusing food or eating very little while at the same time drinking a lot of water. If left unattended, the condition progresses to an almost arthritic stage where the animal is unable to move and then death. Gout is not uncommon in chameleons that are fed pinky mice on a constant basis or crickets that have been gut loaded solely with high protein foods like cat or dog food.
Treatment is successful when action is taken quickly. Advanced cases require surgery to remove the crystals from the joint and be able to provide mobility. Mild cases might still require surgery but some have been able to be managed medically by providing adequate amounts of water and medications that help dissolve the crystals.
These 2 conditions should not be taken lightly and should be treated as soon as possible since both are life threatening. MBD seems to be more common in young, growing animals because they need more calcium while Gout appears to affect mostly adult animals that get too much protein (although it can affect any age group).
Ivan Alfonso, DVM