Metabolic bone disease is a very common problem in reptiles, especially chameleons, bearded dragons, lizards and tortoises. The most common form of metabolic bone disease is nutritional secondary hyperparathyroidism. This is caused when a reptile does not have enough calcium or vitamin D3 in the diet, does not receive enough exposure to ultraviolet (UVB) light or has too much phosphorus in the diet.
1. Parathyroid hormone
Due to low levels of calcium being absorbed in the body, the parathyroid gland will produce too much parathyroid hormone. This hormone causes a process in the body to release the calcium from the bones. The bones become rubbery and soft when too much calcium is removed from the bones. Especially your animals are more prone in developing this disease, while they require higher levels of calcium for growth and development of bones. Females also require higher calcium for their egg production during the breeding season.
2. Clinical symptoms
Clinical symptoms shown mostly by reptiles with metabolic bone disease are; swollen legs, especially the hind legs. The jaw becomes rubbery or swollen and the gums can become exposed when the lips start to droop. In chameleons the tongue becomes affected and will often start to hang from the mouth. If the tongue hangs out of the mouth it can dry out and even break. The reptile will not be able to eat when the jaw or tongue becomes affected and will rapidly loose weight. Other symptoms are broken bones, kinking of the tail, spinal abnormalities such as kinks, curves or bumps, difficulty walking or climbing, weakness. They can show problems with egg-laying, constipation or prolapses of the rectum or penises. In more advanced stages the reptile will show tremors, seizures, or paralysis.
It is important to immediately take your reptile to the veterinarian if you suspect a calcium deficiency. The veterinarian will immediately start treatment with calcium injections and will advise the correct calcium supplements. It is important to keep your sick reptile in a cage with low climbing branches. It is important to keep your sick reptile in a cage with the correct humidity and temperature. If the reptile is not eating on its own, your veterinarian will show you how to feed with a syringe or tube. This treatment takes often several weeks to months to correct the calcium deficiency.
Take your reptile out daily for 10 to 15 minutes to expose your pet to unfiltered sunlight to produce its own vitamin D3. A reptile should have a UVB light in its cage for 10 to 12 hours per day. The light should be changed every six months depending on the lifetime of the UVB light. Reptiles should receive calcium and vitamin D supplements, either dusted on the insects or given as food to the insects. The insects should be dusted at least three times a week. Plant eating reptiles should receive plants that have a correct calcium-to-phosphorus ratio. Especially parsley, dandelion greens, kale, spinach, collard greens, endive, rocket and hen and chickens (Chlorophytum comosum). Give less then 10 percent of the total diet in the form of fruits, while this can cause gas in the intestinal tract of your reptile. Plant eating reptiles should also receive calcium and vitamin D supplement at least three times a week.
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Written by Dr Tessa Brouwer, BVSc, MSc, BSc