The importance of Proper Caging
The following information is very important to ensure a long and healthy life for your captive Monitor lizard. over one million monitor lizards have been imported, exported and bred over the years and sold into the pet trade. Of this huge number only a small handful have survived past their first birthday, and an even smaller amount have lived beyond 5 years. This page will address why so many captive Monitors suffer and die in the hands of reptile enthusiasts worldwide. Please read carefully because failure to provide these very basic requirements always results in a slow, excruciating death of these beautiful, highly intelligent animals.
Long term, low level dehydration & Gout
Since reptiles do not have pores, they do not sweat, since they pass Urates as a solid white chalky clump, they do not urinate in liquid form. So how exactly does this slow dehydration take place? By breathing dry air, that's how.
To put it in perspective, when we breath outside in the winter, we draw in dry winter air, and when we exhale, you can see your breath. This is because our lungs transfer water molecules to the dry air and we exhale moist air forming condensation, hence the "cloud" we see when we breath. This same exact principal applies to Monitor lizards. When you take an animal that has evolved over millions of years to breath damp, tropical air and place it in an enlosure that has too low humidity, each and every breath the animal takes will release precious moisture into the air.
Since monitors breath very slowly and each of those slow breaths only release minuscule amounts of body water, the process can take many months, even years, to bring the internal dehydration to critical levels. This process in turn stresses the kidneys and liver eventually causing them to fail altogether, then the uric acid levels in the blood begin to rapidly escalate leading to Gout. By the time the symptoms of gout manifest and become visible, it's entirely too late to reverse it.
This is where burrows come into play as a method of water conservation. If you have ever been in a dank basement you can feel the humidity in the air, it's thick. This is why the air in mines and deep basements is so heavy, suspended water molecules in the air add weight to it.
During the hottest parts of the day, droughts and dry seasons, Monitor lizards will retreat to burrows, shady areas, hollow logs, swamps & rock crecives and not come back out until the conditions are more favorable. When we keep them in enclosures that do not have correct humidity levels and also do not provide enough soil substrate for the animal to dig a burrow or otherwise retreat, they begin drying out slowly through breathing. (respiration)
Misting a poorly set up cage will not prevent this, soaking the lizard in a bath tub will not prevent this, big water bowls do not prevent this. Only correct humidity and offering the opportunity to burrow will prevent this. Proper caging is paramount to your lizard's heath; This cannot be stressed enough.
One of the first symptoms of dehydration will be a loss of appetite. Force feeding a moderately or a severely dehydrated animal may result in shock and death. The digestive tract requires fluids to process foods, if there is not enough, The body will try to take water from other critical systems, including the brain. When dehydrated, the accompanying loss of appetite may be one way the body tries to protect itself.
A recent research article was published describing the full necropsy reports of the 108 documented fatalities recorded at the Bronx zoo, of the remains examined, 10.8 percent of the fatalities were attributed to gout, and "Although not necessarily the cause for death, gout was present in 18.8 percent of the individuals examined"
Gout in captive varanids is attributed primarily to dehydration and chronic exposure to insufficient temperatures.
Basking spots that are not hot enough to support proper renal tubule function stress the kidneys allowing uric acid to elevate leading to gout.
Source: Robert W. Mendyk, Zoo Biology 00: 1-11 (2012)
As a general rule of thumb, basking spots should be a minimum of 130 degrees Fahrenheit.
Allowing your captive Monitor Lizard to roam about the house or keeping it in a room is not a suitable substitute for a proper enclosure.
In conclusion, this is why keeping any monitor in conditions that do not support it's basic physiology needs will ultimately lead to failure.
A short video clip of a dehydrated Savannah Monitor
The best enclosure substrate to use
The very best substrate to ensure a long and healthy life is a mixture of chemical free top soil and washed play sand at a ratio of 60% dirt 40% sand mixed together. It should be able to form a ball and be easy to dig, promoting burrowing. Soil depth should be 24 inches deep, this will be roughly equal to a pickup truck load! It will be very heavy, please make sure your floor can support the weight.