First things first- we are dealing with core biology. Biological function cannot be overwritten, influenced to change or be taken for granted. We cannot for one second pretend that we know more than nature or seek to second guess her. 'All of the secrets of great animal care are hidden in the wild animal". It is this dedication to and the ongoing implementations of wild recreation that we will find all of the longterm answers to the frustrations we currently encounter including Metabolic Bone Disease, shedding issues, reproductive issues, short lifespan, skin/mouth rot, fatty liver disease, obesity, lethargy, stomatitis and anorexia. Many of these old issues are simply owing to a poor understanding of reptilian biology and a slow implementation of positive changes. Our job is to continue to learn and be proactive in our change by providing the very best level of care and support and sharing both the positives and negatives that we will undoubtedly encounter as we continue to grow and expand our own personal knowledge base.
As beautiful as this hobby is, we must be open and honest with ourselves. We are, as a hobby, coming out of the stark "sterile" days and running full steam ahead into this huge change towards wild recreation through bioactivity. To every positive, there always will be a level of realistic limitation; most of these can be safely worked around, but some simply cannot. It is by realizing these limitations and finding suitable and safe workrounds that we can step forward with eyes wide open into the next generation of ethical reptile keeping.
There are five main aspects that we need to pay close attention to:
Over breeding
Mites and Parasites
Risk of respiratory infections
Animals with weakened immunity
Impaction
Impaction
The risk of Impaction is relevant in the reptile hobby whether you are using a bioactive system or not; however, the risks can be greater in a terrarium with substrates and improper husbandry. Animals in the wild ingest and pass substrates and inorganic matter rather effortsly when their environmental parameters are within normal limits. The same concept applies to captive bred animals. If the humidity, heat, light, and/or UVB requirements are out of range - animals in captivity have a much harder time passing any foreign substances through their metabolism. (UVB plays a huge role in the metabolism and we will get into that later.) Impaction is when an animal is not able to pass any foreign objects and it becomes stuck. Impaction can be fatal and also completely avoided with the correct husbandry.
Overbreeding
We must remember that animals will seek to reproduce. This in a sense is its only goal in life and with many females laying eggs, or giving birth almost continuously (unless vet care is given) can result in the depletion of any stored fats and minerals in her body. Yes, females can literally be bred to death. Young come into the world weak, and in some cases, go on into less than perfect systems from where they are bred and the cycle of ever decreasing health and well being continues. As dedicated keepers we strive to produce fit, strong, genetically diverse, and mineral rich animals that will propose strength into as many generations as possible. The goal is to see continued improvements in size, color, and organ functions as we "breed" strength back into our captive stocks and energize them in an effective way. One way to help eliminate overbreeding is by honoring brumation.
Mites and Parasites
As always, there will be a flip side or limitation to every potential positive move. An appropriate period of thinking and advice seeking is crucial for informed choices to be made and maintained. Animals that are suffering from an increased or problematic parasitical load, as an example, would do nothing more than spread the infection throughout the enclosure through their faecal matter and, as such, keep re-infecting itself and any other enclosure mates, even after a period of treatment. That's why it is ALWAYS important to quarantine any new animals I'm a separate tank for at least two weeks before introducing them into their habitats. Snakes with problematic mites also may be harder to treat in lice systems (however, there is now anecdotal evidence to suggest that springtails and other custodians deal with this issue in-situ by consuming mite eggs - yet to be proven but well worth continued debate), and of course we now have access to predatory mites that can be introduced into the environment in which they will hunt and consume the offending blood-sucking snake mites whilst they remain and then simply die off when no more are left to eat. Parasitical load can no be treated quite easily either by chemical or herbal remedy. A product such as Verm-X can be used foe just 3 days each month to ensure effective gut health and to help eliminate the risk of Parasites recurring.
Risk of Respiratory Infections
Animals that are prone to or have suffered a weakening of the respiratory tract through persistent infection, genetic weakness or exposure to (VOC) volatile organic compounds produced from heated plastics have an increased risk of developing complications in a hot and humid environment. Poor air circulation (and the lack of terrarium fans In the hobby) is viewed as a factor in humidity stagnation and prolific bacterial build up. There is also a risk of subordinate Animals not being allowed accede to basking and/or food and water sources from a more dominant animal. Social hierarchy and it's ongoing maintenance in captive reptiles is both a profound and complex set of actions and communications and should not be underestimated. In fact it should play a pivotal role in enclosure design, decoration, group size and sex ratio.
Animals With Weakened Immunity
With Animals that may have a weakened respiratory system or are historically prone to chronic infections may be best kept in sterile and easy to clean surroundings. Similarly, Animals that may have a level of disease or have come from rescues in a poor state or have been born with a genetic defect that would limit good self regulation may not benefit from bioactivity unless proven safe by a vet for that particular animal. (Again, there is anecdotal evidence here of some snakes with breathing issues being almost miracously cured when placed into a bioactive system; however, this is yet to be proven and may simply be an outworking of a higher level of ambient humidity and/or it's release from any potential VOC exposure when not tubbed, again not proven but worth debating.) We must view this implementation case by case and seek to overcome as many negatives as possible. As above every animal must be permitted a period of safe and well maintained quarantine before being introduced into a bioactive system regardless of whether or not it has live animals in it or not. When the animal is settled and feeding and has been proven healthy to not pose a parasitic risk, it can then be introduced into the system where it will surely go on to thrive.
Conclusion
Double check everything! At all times. If you have any uneasy feelings about your animal, seek veterinary advice without delay. Ask other keepers, of course, and read books. Try to back up any at home research with medical proof. Early intervention is far more effective on finding a lasting cure/repair and will save you lots of money in vets fees. Animal welfare must be at the top of our list at all times. Good record-keeping will help in this. Bioactivity is a beautiful and sustainable way of animal keeping when done properly and can add a whole new level of enrichment and strength to future generations of captive bred reptiles.
Source: Bio-Activity and the Theory of Wild Re-Creation by John Courteney-Smith MRS