Abnormally Bent Jaw and Front Leg of Chameleon with NSHP

Nutritional Secondary Hyperparathyroidism (Metabolic Bone Disease, Calcium Deficiency)

Nutritional secondary hyperparathyroidism (NSHP), a form of metabolic bone disease, results in abnormal skeleton development, particularly evident in the shape of the bones in a chameleon's legs or the shape of its lower jaw.  NSHP is due to one or a combination of factors: 1) lack of calcium in the diet; 2) lack of vitamin D3 in the diet;  or, 3) lack of ultraviolet-B light in the cage.  Proper temperature and adequate hydration are important for calcium uptake and distribution so it is important to look at the whole care of the chameleon to figure out what inadequacies have led to this condition.  NSHP is a disease of growth as young chameleons are lengthening their skeleton and have a higher need for calcium than they will later in life.  It also afflicts female chameleons that are gravid as the production of eggs or, in the case of viviparous chameleons, babies also creates a high calcium demand.  It may be detected at a very early stage when the jaw is just starting to slightly bow outward or where a long leg bone may be slightly rotated or curved abnormally.  Often, a clue is that the chameleon is much smaller than it should be.  As the disease progresses, the chameleon may stop moving around its cage as its legs hurt from their odd shapes and from undetected broken bones that may or may not have healed.  It may or may not be able to feed itself--if the hyoid bones which control its tongue are damaged it may not be able to accurately target, shoot, and withdraw prey insects.  The earlier NSHP is detected, the better the chances that the chameleon can be treated and return to a good quality of life.  Treatment consists of providing adequate husbandry with a UVB-emitting light (e.g., Reptisun or Powersun), calcium, and often D3.  Supportive care such as assist-feeding and fluids may be needed.  Pain management drugs such as Metacam may be prescribed.  Unfortunately, many chameleons come in with such deformed legs and other bones that euthanasia is the only humane option.

Kidney Failure

Chameleons that stop eating and become weak are often found to be suffering from kidney failure.  This disorder should be suspected in any chameleon that has two or more of the following signs: a lump just in front of its pelvis, inability to defecate (or pass eggs), fluid beneath the skin under its jaw or neck, dehydration even with plenty of water offered, a foul odor to its breath, swollen joints, bloodshot eyes, or white shiny deposits in the lining of its mouth.

Constipation and dystocia are due to the malfunctioning kidneys becoming so large that they physically obstruct the pelvic canal and prevent anything passing from the intestine or oviduct to the cloaca.  All the other signs are due to the kidneys not filtering the blood as they should.  Swollen joints, bloodshot eyes, and white deposits in the lining of the mouth are the result of crystals forming in the tissues and are signs of a very ill chameleon.

The green arrows point to the front and back of the right kidney (the head would be to the right).  The kidneys are about ten times the normal size and are yellow instead of dark red due to the build-up of uric acid crystals as a result of kidney failure. The blue arrows point to active ovaries which were blocked from normal ovulation due to the kidney disease. 

So why do chameleons seem so prone to kidney failure? It is associated with two common husbandry errors, insufficient intake water and a lack of vitamin A in the diet.

Most chameleons will only drinking moving water.  Captive specimens require water to be dripped or gently sprayed on them throughout the day to insure that they are drinking enough.  It is not good enough to assume that a chameleon is drinking just because you have provided a drip system--you need to see that the chameleon is actually drinking!  A wild chameleon’s water also comes in the form of moisture in the air, either through high relative humidity or by events such as fog, rain, or dew.  In captivity, particularly in central Arizona, it is quite challenging to reach a sufficiently high relative humidity (85-95% RH) for any length of time without completely saturating a cage with water many times a day.  An ultrasonic humidifier placed in the same room as a chameleon’s cage may only bring that room up to 45-50% RH, too low for a chameleon stay healthy if it endures that low humidity 24 hours a day.  Unless a lot of effort goes into creating a humid environment that is well ventilated, the chameleon will live in a much drier realm than its wild habitat.  Even the veiled chameleon, a more arid-adapted species than many others in the pet trade, requires a few hours of high humidity every 24 hrs to do well.  You need to assess your chameleon’s water intake daily and adjust the cage environment as needed to keep the air moist but fresh.  A well-hydrated chameleon has bulging eyes and skin that doesn’t wrinkle.  It also sheds easily and doesn’t have old skin cling to its toes, tail tip, or around the eyes.  If your chameleon shows any of these signs, it is likely under-hydrated and under enough water stress to put it at risk of kidney failure.

Many of the reptile vitamins on the market lack vitamin A.  Their advertising and labeling suggest that the beta-carotene they provide is an adequate substitute for vitamin A with chameleons and other reptiles.  Unfortunately, there seems to be no rigorous scientific data to support this belief.  I have seen many chameleons and other insectivorous and carnivorous reptiles with overt vitamin A deficiencies that were fed supplements containing beta-carotene.  A vitamin A deficiency changes the structure of certain cells within the kidney.  As these cells become affected, the kidney is less efficient at processing wastes and moving them out of the body.  Over time, the waste products, known as urates, build up in the kidneys and cause them to enlarge.  As the kidneys get bigger, they start to interfere with other body functions and can cause constipation and dystocia.  The kidney also serves a vital role in balancing calcium and phosphorus levels in the body so once it is damaged then other organs are affected. 

Various tests may be performed to confirm kidney failure.  A blood sample will look at factors such as calcium, phosphorus, uric acid, albumin, and hematocrit (a measure of red blood cell numbers).  A radiograph or cloacoscopy (inserting a “telescope” into the chameleon’s cloaca) may help distinguish enlarged kidneys from other masses.  Once it is confirmed, the question becomes whether it is reversible or irreversible.  While it is sometimes obvious when a chameleon has irreversible kidney failure, it is not always so predictable.  Generally, a course of treatment may be tried and if the chameleon doesn’t improve within a few days, it is likely not reversible.  Whether to treat or not is an individual decision and may be based on the chameleon’s quality of life.  Sadly, most chameleons diagnosed with kidney failure are suffering and their suffering will not be relieved with treatment.  For those chameleons, euthanasia is the most humane option.

Dystocia (Egg-binding)

Dystocia, a failure to lay eggs or deliver live young, is also in the top three things that go wrong with chameleons.  The causes for dystocia vary but many females that are unable to lay eggs also have NSHP (described above).  Sometimes they do not have full blown NSHP but simply low levels of calcium in their blood which impairs the shelling of the eggs or production of skeleton in embryos.  Sometimes there is enough calcium to reach the delivery stage but not enough for successful contraction of the oviduct and expulsion of the ova or offspring.  Supplement calcium and a hormone may help in some cases but most egg-bound chameleons needs surgery to remove the eggs.  A chameleon that has become egg-bound once is more likely to do so in the future so it is often best to spay the chameleon to prevent future problems.

This squinting chameleon has a build-up of dead cells on its gums and beneath its eyelids.

Eye Problems

Many chameleons suffer eye problems due to vitamin A deficiencies.  As mentioned in the section on Kidney Problems, vitamin A deficiency can cause serious problems in chameleons.  The glands around the eye stop producing normal moist secretions which makes the eye irritated and painful.  Over time, the eye may get very large as dead cells and thick secretions build up beneath the eyelid.  It is very important to supplement their diet at least once a week with a vitamin powder that contains vitamin A.  If the labels says "Vitamin A provided by beta-carotene" DO NOT USE IT!

The green arrow points to cells that are abnormal due to lack of vitamin A in the diet.  The lining of this chameleon's eyelid is packed with dead and dying cells.

Small pieces of sand, bark, and other materials sometimes get in the eye and cause a chameleon to squint.  These may need to be gently flushed out of the eye by a veterinarian.

The cells flushed out of the chameleon's eye are keratinized instead of being soft.  There are no white blood cells so the eye is not infected, it is abnormal due to vitamin A deficiency.

There are many other eye problems such as ulcers, infections, and injuries,.  All need veterinary attention as soon as possible.

Copyright 2010
Kevin Wright DVM
Arizona Exotic Animal Hospital, LLC
744 N Center Street
Mesa, AZ 85203
info@azeah.com