Varanexan

V. exanthematicus is a highly seasonal species, and neonates are only hatched in the spring. The hatchlings are then caught from their nests and imported en masse annually from the coastal plain of West Africa. The problem is that you will not find fairly young (or healthy) V. exanthematicus this time of year. All there is left is either adults from the previous years, or the "left overs" from this last season that did not sell and are now lingering in barren, screen-topped aquaria for months; thus taking a heavy toll on them physiologically. A common by-product of poor "temporary" enclosures is that the animals face is chronic dehydration and underheating. This is stressful to internal organs and the animals suffer years later (if they survive that long.)

It is important to note that, despite what you'll hear often on the internet, the savannah monitor isn't a very good varanid for captivity. There are a lot of monitor lizards that perform very well in captivity, and multi-generational reproduction has been established for those species; but the savannah monitor isn't one of them. Its a species that is very common in the trade and easy to buy, but no one has had long-term success keeping or breeding the savannah monitor. It lives a short life and is temporary entertainment for the thousands of people that buy them every year. The specimens that do manage to survive a few years are usually massively obese, under-heated and non-reproductive males. Your enclosure sounds better than most. If I were you, I'd save for a species that is far less of a challenge to keep and is much more rewarding. Take it from a person that currently keeps seven of them....

http://savmon.org is the only website worth reading in my humble opinion. It is authored by a biologist that has studied the species in-situ since the early 90's.