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Lizard Rear Legs Appear Paralyzed

Our iguana has stopped walking and his back legs seem useless. What is wrong with him?

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Our iguana Gator, has stopped walking. His back legs seem useless. Gator is 7 years old and has always lived inside. His diet is fresh vegetables. Nothing different has happened to him that we know of.

I will venture a guess to try and help you with the very limited information that you have provided me with. I am assuming you don’t have a full-spectrum light for your iguana, one that provides UVB light, and that is changed out every 6 months, or as recommended by the lighting manufacturer. Is your iguana kept at room temperature, or do you have a method of heating its enclosure, with a temperature gradient of 85 to 95 degrees Fahrenheit during the day? Does the enclosure have a basking area with a focal hot-spot? What is the ambient humidity in the enclosure? Do you provide your pet with a vitamin/mineral supplement, containing calcium and vitamin D3? Do you provide a swimming area, and allow your iguana to swim at least twice a week? Has it ever seen a veterinarian for routine checkups? This is all very important information that my readers should try and provide me with whenever possible, in order that I can best answer your questions.


Iguanas are one of the more difficult lizards to maintain, and they require preventative healthy care on a routine basis, as well as a specialized habitat and lighting. Problems with calcium metabolism and kidney disease are two major problems often seen in iguanas. It is important for kidney health that they are allowed to swim in warm water for 20 to 30 minutes at least twice a week so that they drink water, exercise and defecate regularly, as well as remain well-hydrated.

If your iguana has not been provided with natural sunlight (not filtered through glass or plastic) or a full-spectrum light that emits UVB light, and if it has not been consuming a calcium/vitamin D3 supplement, I suspect that your iguana has developed an adult form of metabolic bone disease. Ultraviolet light is necessary for many herps to manufacture vitamin D3, which is necessary for proper calcium uptake and utilization. I have discussed this syndrome in detail in archived questions, so please feel free to check back to some questions relating to metabolic bone disease.

Without the necessary lighting, vitamins and minerals, your iguana’s bony skeleton may weaken over time. Because of the weight being supported by the vertebral column, the spine may buckle, resulting in the spinal cord being compressed and damaged, resulting in paralysis of the hind legs and tail. This is, of course, a very serious condition; one requiring immediate veterinary care.

If the pelvis or spine is injured, the sooner the lizard receives medical attention, the better the chance for some sort of recovery, although paralysis is a grave condition and may be irreversible. Often, a spinal cord injury will result in the inability to perform such bodily functions are urination and defecation, in addition to not being able to ambulate. Aggressive treatment with anti-inflammatories, injectable calcium, vitamin D3, a hormone called calcitonin-salmon and support care, combined with physical therapy, may result in a partial return to function. Once a qualified herp veterinarian has examined and tested your lizard, you will have a better idea about its chances.

There are, of course, other things that can cause weakness or paralysis of the hind legs in an iguana. These would include a tumor involving the spine or spinal cord, a traumatic spinal injury or an infectious lesion involving the spine. Your herp vet should be able to accurately diagnose these conditions. Please seek veterinary care as soon as possible so that a diagnosis can be made and treatment instituted, or a decision can be made about its future, based on the prognosis. It might be best to have it humanely euthanized if the damage is too severe.


Margaret A. Wissman, DVM, DABVP has been an avian/exotic/herp animal veterinarian since 1981. She is a regular contributor to REPTILES magazine.

Need a Herp Vet?
If you are looking for a herp-knowledgeable veterinarian in your area, a good place to start is by checking the list of members on the Association of Reptilian and Amphibian Veterinarian (ARAV) web site at www.arav.com. Look for DVMs who appear to maintain actual veterinary offices that you could contact.