Dave,
Many good points, and I have to agree completely with the idea of some format that would mimic "control groups", "test groups", etc. This incident reminds me of the rumor that "ficus cause eye problems in chameleons", where someone once associated "eye problems" in chameleons, a common symptom of most chameleon maladies, to ficus trees, a common plant used in the hobby. The sap of many plants are irritants, and I am not downplaying that, but the likelihood of chameleons getting it into their eyes is minimal. There are also over 50 varieties of ficus found in Madagascar. If the experience of the hobby was that there was a noticeable increase in eye problems with ficus, that was then reduced using other plants, then there might be a link. But no such correlation exists, based on thousands of observations.
In this prolapse case, the volume of food has been listed as possible, and inferred as almost likely in other posts. Perhaps you cite it only as an example of a procedure to follow:
If you had control over the situation, you could reduce the food levels a substantial amount (50% or more) and maybe try to break them up into 2 or 3 groups and feed those groups at different rates and see if you can get correlation between food levels and prolapses.
.... but I would insist to the reader that there is a wealth of experience raising veileds in captivity, where free-ranging and readly available food was always present, and no such prolapse syndrome occured. If this were a cause, it would have been seen many times already. While I would encourage any hobbyist to make a list of possible causitive agents when a problem is observed in a group of chameleons, I would then implore them to use an elimination process based on the experience available, and in this case would say that the volume of available food is easily dismissed. I believe the vet gave a fair evaluation of the possibilities.
I also want to elaborate on an observation:
.....
many experienced veiled breeder/keepers suggest that veileds are wired a bit differently than many other species of chameleons in that they do often eat to excess, meaning that they will eat so much, so often that they are prone out-grow their skeletal growth rate and are suseceptable to supplementation related health problems like MBD because of it.
There is no doubt that rapid growth in captivity can lead to MBD related problems, and this is not limited to veileds. In that respect, I have to disagree that they are "wired differently". We would likely agree that rapid growth is possible in the wild, especially if it is a good "bug" season. We would also agree that MBD is rare in the wild, if not unknown. Mother Nature gets it right. What happens too often in captivity is that the chameleon is getting 100% of some of its nutritional needs, while coming up short in others. This could be what you alluded to as "supplementation related health problems", which would exist for all captive chameleons. Could be artificial light, poor calcium supplementation, etc. As one example, I know from observation that animals grow faster, all other things being equal, if exposed to real sunlight. Take two sibling chameleons, and offer both all things equal except one is indoors under artificial light, the other outdoors. The indoor one would be where I would expect a slower growth rate, or possibly more of a disjunct between skeletal growth rate vs all other tissues, showing MBD symptoms. Put another way, Mother Nature has it in balance, and the hobbyist does not. As a matter of logic and experience, I would suggest that it is always better to fix what is deficient, rather than try to seek a balance by reducing other things. If not, then it too easily becomes a situation of fixing one problem while creating two more. As you mention, the key is to always try to "optimize", as once we put an animal in captivity, the equation is out-of-balance, and it is not easy to figure out where, much less decide what the solution is to find the balance again. I could write pages about the possible influences here, ranging from poultry growth hormones in chicken feed fed to crickets, to UVB light in the wrong part of the UVB spectrum, to just plain lousy gutload.
In the end, at least for now, with these animals seeming to be so inconsistent, my own experience is to strive for optimal (Mother Nature in a good year), expect much trial and error for each hobbyist situation, and seek the anecdotal experience of others ! And watch out for "wive's tales".
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