Ventilation, acidosis and blood chemistry

[jarich]

After seeing Wayne's post about wanting to have more serious discussions on varanids here, I thought I would post a thread. I started discussing this on another forum but didnt get as much of a response as I had hoped for, so maybe some of you that saw it there will forgive me for repeating the question, (and, who knows, maybe even post a response here).

I do not post this with the idea that new keepers, or myself, will change their husbandry techniques due to this discussion. This is merely an observation and the first question in understanding further how we care for these animals. Again, no matter how this thread progresses PLEASE DO NOT change any husbandry techniques based on this discussion or suggest to others that they do so. Ok enough prelude...

We are rightfully concerned about the sealing of our varanid enclosures to ensure that humidity levels stay constantly high, as they need them to be. However, I worry that there may be some unknown effects to the monitors based on the limited ventilation that results.

Varanids are unique among reptiles not only in their extremely high metabolisms, but also in their ventilatory response and manipulations of blood chemistry. While it is often suggested that they are a good example of an intermediary stage between true ectotherms and endotherms, their thermoregulation is more than just an effort to digest food, and has further effects on disolved ions in the blood, pH levels, etc. In other words, their thermoregulation and high metabolism have more far reaching connections than just how they process food. As well, their ability to regulate their oxygen intake, and CO2 output, through breathing as a response to both metabolic increases and exercise equally is an important key to their success.

Given that we recommend they be fed daily, their metabolism is perhaps consistently increased, and any exercise after that is in addition to this metabolic increase in a demand for oxygen. As this results in a bump to CO2 levels, and therefore blood acidosis, ventilation is increased for both metabolic needs and exercise. Yet due to microhabitat constraints on humidity levels, we still continue to keep them in small, non ventilated enclosures.

My question is this; what is your opinion on their ability to optimally respond to these metabolic and excitatory increases in such contained enclosures? Even though they are not airtight, do you think the obviously increased levels of CO2 that would build up in the enclosure over time inhibit the ability of these captives to respond in normal ways to changes in blood chemistry due to metabolism and exercise? What effects could this have on them over a long term?