Kidney Disease - Renal Failure
Improper husbandry and diet are the most common causes of chronic renal failure.
Kidney Disease - Renal Failure
Kidney disease in snakes and lizards is unfortunately not that uncommon. There are many causes of kidney disease with gout, dehydration, infectious agents and toxicity being very common. Kidney disease is common in iguanas and is a frequent cause of death in these captive lizards, typically as a result of dehydration, diet, medication or a combination of these factors.
Terms associated with kidney disease include renal failure, renal osteodystrophy, paradoxial metastatic calcification, metastatic mineralisation syndrome in green iguanas, and tubulonephrosis of iguanas.
What Is Kidney Disease
Renal failure occurs when the kidneys are no longer able to sustain the processes of flushing out toxins from the blood stream.
Kidney Disease Causes
Kidney disease (renal failure) can be caused by a number of factors, with inadequate hydration being a leading cause in captive animals, leading to other issues, such as the build-up of uric acids, leading to toxicity. Hydration is crucial to the proper function of the kidneys in order for them to work properly. Dehydrated animals become incapable of flushing their systems adequately and toxins build up.
T actual he main causes of renal include gout, infectious agents and toxins. Metastatic soft tissue calcification can occur where calcium is deposited in tissues throughout the body, leading to a renal osteodystrophy.
The exact causes of renal disease in lizards is unknown (not enough clinical trials have been done) but is typically been associated with diets too high in protein (often the case with iguanas), dehydration, hypervitaminosis D (vitamin D toxicity), gout or uric acid crystal (tophi) deposits in tissues, which may occur as a result of the dehydration.
 "Other factors may play a role, too, such as acidogenic diets, which increase precipitation of urate crystals and cause renal failure in other animals. Low-quality protein leads to excessive nitrogen excretion, and excretion of absorbed *NPN from chitin (invertebrate exoskeletons) is via the kidneys, too. Excessive potassium excretion can also cause precipitation of urates."
It goes on to say that these factors, coupled with inadequate water intake, is what shut the kidneys down. There are secondary components that play a factor as well, which proves that overall husbandry needs to be supported on all levels, as cold temperatures and stress are contributing factors. Inadequate temperatures are known to be an issue with digestion but they also play a significant role in the proper function of the organs.
Animals who are fed a constant diet of poor or low quality protein or high phosphorus foods are prone to renal failure when hydration and improper husbandry are an issue. In iguanas, dehydration and animal protein are the leading cause of renal failure. Iguanas are not designed to properly digest animal protein and a massive strain is placed on the kidneys when their diet consists of it. Couple the strain of digesting protein with inadequate hydration and improper temperatures, and you are setting your iguana up for failure, literally.
Medications that are administered for other issues can also strain the kidneys. Most medications can be properly flushed but this is not always the case, specifically with animals who have endured improper husbandry and dehydration for any extended time.
Reptiles with gout may also experience renal failure as a result of the kidneys not being able to process the build-up of uric acid in their systems. Gout is also an illness that can be avoided in most cases by proper hydration. (Notice the pattern of hydration being a massive issue here!)
Reptiles create uric acid, which is filtered from the blood via the kidneys. When the kidneys can't process the uric acid because of chronic dehydration or improper temperatures, there is a buld-up of uric acid, which leads to hyperuricemia. Hyperuricemia is a level of uric acid in the blood that is abnormally high and typically leads to gout and arthritis issues.
Kidney Disease Signs
Kidney disease presents itself when it is already progressing. Your animal may show signs of lethargy, anorexia, may appear weak, have inadequate urates expelled, lack of appetite or may just appear "off" to you. If your husbandry is spot on, as it should be, and you notice a difference in your animals behavior, get it to a vet. Early detection is the key to survival. If you know your care is sub-par and your animal is acting off, get to a vet and get your act together! Your animal deserves the best and if you know you aren't providing it, try finding someone who can.
Diagnosing Kidney Disease
You won't be able to self-diagnose this disease. Your vet will need to know the animals history, which you should be 100% honest about. If you were feeding animal protein to your iguana, your vet needs to know this. If you weren't supplying adequate heating and lighting, your vet needs to know this. The history of the animal is as important as everything else because it all plays a role in what could be wrong with your pet.
Blood work is guaranteed to be done. The blood work results will show any abnormalities, extreme uric acid build-up (not always reliable since food items alter the levels as well), etc. A biopsy may be required based on the blood work or they may choose to do an ultrasound to see if the kidney is enlarged. There are a number of tests that can be run and they are all going to cost you money. Opposed to being placed where you need to pay to have the animal diagnosed with this illness, invest those funds into properly supporting the animal that so this doesn't become an issue. Most cases of kidney disease in reptiles were preventable with proper husbandry.
Kidney Disease Treatment
The first course of treatment will be to correct what is wrong with the animals husbandry. Your vet may change the animals diet or even use a uric acid inhibitor if needed. Fluids will likely be administered and you may require further treatment and medications. renal failure is something that needs to be cared for under a doctors supervision and many cases are fatal.
Kidney Disease Prevention
Proper husbandry goes a long ways into preventing this from happening. Adequate hydration, diet, heating and lighting all need to meet the needs of your pet. You need to strive toward keeping your animals in the best possible housing you can provide. You need to care for the animal and your husbandry should reflect this.
Author: Richard Brooks
 Mader, Reptile Medicine and Surgery, Second Edition 2006 pgs. 280-281
* NPN refers to Non-Protein Nitrogen - nitrogen in the non-protein form.
Divers, SJ. (1997). Clinician's Approach to Renal Disease in Lizards. Proc. 4th ARAV Conference. Houston, TX.