I've not had a chameleon die, but my first lizard death was a bearded dragon I had owned for some years. He developed a penchant in his 5th year, for eating anything brightly colored. He was always well fed and very healthy, but one day I caught him trying to eat the rubber suction cap from a yellow analogue thermometer I had stuck to the glass.
Fortunately I caught him before he did, but some months after he began to refuse food,
stop pooping and become lethargic and dehydrated.
Having been vary careful (i thought) to eliminate impaction threatening items he might eat, the cause of his obvious impaction was a mystery. Off to the vet.
Note that since he was showing symptoms, his problem had occured some time earlier.
The investigative operation revealed a large chunk of almost totally undigested raw carrot was blocking his lower intestine. This was removed by the vet and post operative care began.
No food was offered immeadiately, overall ambient temperature was increased several degrees, fliuds were given, including a product like pedalyte to assist with increased hydration. He was given shots every two days SC, and began to recover, feeding again and looking better, more active, though basking alot.
Just as suddenly, he began to go off food again and one morning soon after, died.
A system wide infection had set in due airborn contamination during surgery. It shut down his renal system and it was all over.
I had made a habit of leaving raw carrot in the enclosures, along with greens to keep the insects gutloaded.
I never suspected a beardy was capable of biting off a peice and swallowing it, or that it would be inclined to for that matter,
but it was obviously bright colored enough to attract his fetish, silly bugger.

It was quite sad and had been this vets 'debut' reptile operation, assisted by my current vet who is a reptile specialist, by phone.
A first for the surgery, the staff were all quite upset at losing their first reptile patient, but these things happen, we can only do our best.
I have photos taken during surgery,somewhere if I can find them.
