I have to argue against this notion that so many people have, that substrates are what are responsible for causing the impactions which cause the death of the animal. I am also talking more about natural substrates such as sands and soils, not so much as mulch, as mulch is not naturally occuring, and is a manufactured/processed item(I have never found jagged cypress mulch littering the ground in a cypress swamp before...etc). I think that people usually overlook their own husbandry, and do not even consider it to be a possibility for the cause of the situation; instead they make a rash decision on what the only "obvious" cause could be... blaming it on the substrate. "My husbandry was perfect, everything was flawless, so it must have been something else...like the substrate.."- that kind of mentality.
Through my many years involved in the herp hobby, working for pet shops in my younger years, and later on two separate zoological institutions/attractions in more recent years, I have talked to, and have seen firsthand, hundreds of other keeper's setups and conditions, as well as having experimented with my own animals that I have kept, and the ones that I responsible for taking care of at my institutions of employment.
The biggest problem that I see captive animals are faced with, is dehydration... Dehydration is THE #1 underlying cause of death in captive reptiles, whether they are captive bred, or wild caught. This is most often caused by the keeper's inability to understand or offer adequate humidity conditions, or areas that the animal can seek out to use humid conditions. Most reptiles are kept at ambient/room relative humidity levels(20%?) all the time, which are insufficient for virtually all herp species, even desert dwelling herp species.
This 'sand/dirt impaction' fear/problem is most abundant in desert/dry climated herps, such as leopard geckos, bearded dragons, uromastyx, collard lizards, etc. This is one consistency that I have been able to notice between most of these cases.
The reason why so many keepers of the aforementioned species experience such 'substrate problems', in my opinion, is due to insufficient humidities. Most people(general public), and most keepers see a desert dwelling reptile, and think, "well, since this animal comes from the desert, it must like it hot and dry all the time", and keepers in turn offer their captives just that-hot and bone dry.
In all actuality, most desert dwellers do not like the conditions of a desert, or at least not all the time, and will only spend a portion of their time up above where it is hot and sunny. In an environment which is extreme-so hot and dry, any living organism must use whatever resources are available to help conserve water... What is life without water??? Therefore, you will find that desert dwelling/arid environment dwellers spend a great deal of time below ground in burrows(whether they dug them themselves or are utilizing another animal's burrow), deep within rock crevices/fissures, beneath rocks, inside the root balls of plants, etc, etc., where temperatures are cooler, and more importantly, humidity levels are higher.
I presume everybody is familiar with the physical property that molecules move from high concentrations to low concentrations? Animals situate themselves in these damper/humid environments to decrease the rate of water loss through respiration(the #1 source of water loss in reptiles) where there is not as drastic of a difference in humidity levles. Look at it like this; what would evaporate faster? a bowl of water left out in full sun, 100F heat, and 4% humidity, or in a cool, damp cave? Animals(not just reptiles) revolve their survival strategies around conserving water... as without water, they would surely die. So they do whatever they can to escape these dry conditions, where dehydration/dessication rates are amplified. This is something that people of desert/arid dwellers do not understand when going about their husbandry, and do not offer them.
These animals are forced to constantly remain in these dry conditions ALL the time. Therefore, these animals then become dehydrated(even if it is not extreme, and apparent to you, the keeper). Externally, it is almost impossible to understand or notice what is going on physiologically, inside their bodies. Dehydration compromises organ systems hindering efficiency and effectiveness. The digestive system is no exception. A dehydrated animal will have a difficult time digesting normal prey items, let alone inorganic material, as its system is working at a decreased efficiency(perhaps only operating at 20% capacity?)- due to lack of adequate water reserves to aid in such processes. This is why dehydrated animals purposely do not feed(yet people go and force feed them anyways); they know that their bodies are not in the best physical condition to digest food, so they hold off until conditions get better.
Wild animals will be ingesting substrate particles(in one form or another) all the time, with virtually every meal, throughout their entire lives. Reptiles in the wild also live on a wide variety of substrata, of varying chemical compositions, as well as particle size and shape. Members of the same species will be exposed to vastly different substrates according to their natural ranges, and are not 'adapted' or designed to handle one particular substrate.
There are some species of lizards,(Can't remember which species/genera- I will try to find the reference to this study)and other animals such as mammals and birds, which actually INTENTIONALLY ingest clay particles, to aid in digestion of some toxic plant material, as clay acts as a natural buffer, neutralizing harmful chemical reactions which would take place during digestion. We see many other animals intentionally eat rocks and substrate to aid in mechanical digestion.
And yet, for some strange reason, only in captivity, these animals die when living upon these substrates... Something just doesn't make sensse... Something is very different between captive situations and the wild... What stands in between the conditions that captive animals are exposed to, when compared to what wild animals are exposed to... oh yeah, Us!!! It is our own husbandry(the conditions we force our animals to live under) which stands between captive and wild animals.. We are the problem, as we are not providing them with what they need to carry out healthy lives.
And as for all of those people out there, who do believe that substrates kill your herps, because your vet found in an autopsy that there was sand in its intestine... let me ask you this? Did your vet perform any analysis on the kidneys and livers? The problem that I see with most of these "autopsies", is that they look at the proximate causation(sand was lodged in the intestine), as opposed to the ultimate causation(dehydration led to a weakened digestive system, which in turn led to impaction and then death). I would be surprised to see any "substrate death" journal article or publication written by a vet, where he/she also analyzed the kidney and liver functions at the time of death..as these would be indicators of dehydration. In every report I have read on the subject matter, this has been completely overlooked.... Proximate causation is a terrible method for determining the true cause of an event or effect.
This is the problem that I see most keepers do not understand. It is their way of thinking about, and rationalizing situations and problems. To them, everything seems so simple and obvious to them(substrate killed my gecko, therefore I won't keep geckos on substrates anymore), when in all actuality, the problem is much deeper rooted, and more complex in origin.
For those of you who do not understand proximate causation, vs. ultimate causation, I will use an analogy that I used on another fora to support this same discussion..
Proximate Causation: Grandpa died because he had lung cancer
Ultimate Causation: Grandpa smoked 2 packs a day for 50 years, which led to his development of cancer, which in turn led to his death.
Now, which of these two statements gives you the most accurate and comprehensive rationale for Grandpa's death? This is a no-brainer, if you ask me.. This is no different than:
Proximate Causation: "My leopard gecko died because it ingested sand"
Ultimate Causation: "My leopard gecko became dehydrated due to improper humidity levels available to him, thus weakening the digestive system, allowing for an impaction to occur, thus leading to its death".
-----
Treemonitors.com
.
). I consider it a good deal because he was captive bred, and it's a baby, and in seemingly perfect health. I could have just as easily bought a larger WC russian tortoise for only $45, but it was likely to not do so well. Plus I am a firm believer in captive breeding.
