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?

[murrindindi]

Hi Joshua, with respect to everyone on this and other websites, the majority of members have limited knowledge when it comes to the more technical aspects of Varanid physiology, maybe if you simplified what you`re asking it might get a few more responses and hopefullly a decent discusion will take place.
They haven`t got "extremely high" metabolisms as such, just higher than most other reptiles.
What effects if any, have you seen in your monitor, which I think you`ve been keeping for 2 years or so?

[KORBIN5895]

I am thrilled to see a thread that I will actually be able to learn something new from! This is me subscribing.

[infernalis]

What a thought provoking post..

I believe that to obtain a viable answer, one would have to install an accurate C02 meter, find a way to feed the lizard without opening the front door, as each time the door opens the air exchange would alter the results, and collecting blood samples would also be a challenge without opening the door.

[blindfireak40]

Well, but wouldn't such an air exchange be allowable, given that the application would be for general husbandry? Unless we are searching for a purely theoretical answer to the question "Does a sealed habitat contribute to physiological distress", I feel as though it would perhaps be more useful to monitor (pun intended) the CO2 levels and blood chemistry with typical amounts of door opening (i.e. spot cleaning, feeding, etc.).

Certainly, it would be advantageous to examine the sealed habitat if only to provide a factor of safety in husbandry over everyday life, but at some point the added difficulty of the method (to say nothing of the potential added danger) may cease to be worth the more accurate results achieved.

As to the physiological aspects of your question, I'm definitely not qualified to discuss those, but in terms of how one would conduct an experiment to verify said physiological responses, that's my two cents.

[murrindindi]

Originally Posted by infernalis

What a thought provoking post..

I believe that to obtain a viable answer, one would have to install an accurate C02 meter, find a way to feed the lizard without opening the front door, as each time the door opens the air exchange would alter the results, and collecting blood samples would also be a challenge without opening the door.

Now that is what I call a sensible response, it would indeed be a challenge!!
And Wayne, collecting blood samples would be a challenge even if you did open the door. Not recommended unless the keeper has extensive experience taking blood from the medium to large Varanid species (or the small ones either).

[jarich]

Originally Posted by murrindindi

Hi Joshua, with respect to everyone on this and other websites, the majority of members have limited knowledge when it comes to the more technical aspects of Varanid physiology, maybe if you simplified what you`re asking it might get a few more responses and hopefullly a decent discusion will take place.
They haven`t got "extremely high" metabolisms as such, just higher than most other reptiles.
What effects if any, have you seen in your monitor, which I think you`ve been keeping for 2 years or so?

I was hoping to engage a few of the people from the zoo thread, (wink wink, nudge nudge Dave, Sam, Robert, Daniel, Frank etc) and thereby have information that would stimulate others to learn more too. Its not that I meant to exclude anyone from commenting, but there is a fair bit of technical information necessary, and I had hoped that the information in a thread like this might spawn further research in myself and others.

As for the use of the phrase 'extremely high metabolisms', sorry I thought I had made it clear I was speaking in reference to other reptiles. Of course you are right in that their metabolisms are lower when compared to warm blooded animals.

Regarding my own monitor, I cant say I have noticed a difference, or realistically am qualified to say I would be able to reliably notice a difference on these criteria alone anyway. I only have one animal, so my experience is negligible in any comparative sense. I know that Dave has said he often leaves his monitors for days while he is away, without opening the enclosure, as have I, and his animals are perfectly healthy and breeding like always. The obvious fact here is that since we are away, we would not be privy to any changes that might occur in that time. However, Im not sure that simple observation would really be enough, aside from the possibility of reduced activity as CO2 increased. That was the only theory I could think of that could be measured in an observational sense; that as the length of time increased since ventilation, activity might decrease to compensate for more limited O2 and decreasing blood pH levels.

[Zoo Nanny]

When taking this in to consideration have you thought about the impact of sealants used in the enclosures. These gas emissions are known respiratory irritants. Whether it is oil based or water based it continues to emitt gases over the course of months and in some instances up to a year. This is in a dry environment. How much of an increase to the gasses does the uv lighting and high humidty cause is at best a quess. None of the reports that I have read have gone into any serious research other than light, heat and humidity causes an increase in the emissions. I am only just learning about varanids so I pose this as a question for my own curiosity.

[dinosaurdammit]

Originally Posted by infernalis

What a thought provoking post..

I believe that to obtain a viable answer, one would have to install an accurate C02 meter, find a way to feed the lizard without opening the front door, as each time the door opens the air exchange would alter the results, and collecting blood samples would also be a challenge without opening the door.

You know I have a CO2 meter, I think I will start the experiment tomorrow. Tonight when I go to bed I will place the monitor in and at the same time that night take it out and in between monitor the flux in the co2 levels.


You are probably asking yourself, DD, why do you have a CO2 monitor? Because my husband got one for his car because it was leaking co2 but we didnt know where from.

[murrindindi]

Originally Posted by dinosaurdammit

You know I have a CO2 meter, I think I will start the experiment tomorrow. Tonight when I go to bed I will place the monitor in and at the same time that night take it out and in between monitor the flux in the co2 levels.


You are probably asking yourself, DD, why do you have a CO2 monitor? Because my husband got one for his car because it was leaking co2 but we didnt know where from.

Hi, I was asking myself why on earth would you have a CO2 meter, thanks for the answer!!
When you have the results don`t forget to give the measurements of the enclosure...

[dinosaurdammit]

Originally Posted by murrindindi

Hi, I was asking myself why on earth would you have a CO2 meter, thanks for the answer!!
When you have the results don`t forget to give the measurements of the enclosure...

okies will do! this thing also measures CO as well, so it should be interesting as to what it tells me tomorrow! I decided i would do it tomorrow as I have opened and closed it a number of times today doing spot cleaning and such so i think it would be best to start when it wont be bothered.

[MDT]

the measurement of CO2 in a small "unit" such as a monitor would be interesting to say the least. In humans (specifically in the critical care sector), diffused gases are measured typically by arterial blood (blood gases). End tidal CO2 (exhaled CO2) is measured by capnography which samples the actual exhaled breath of the patient, we see this displayed as a numerical value on the vital sign display monitor and is usually used in conjunction with the pulse oxymetry reading. I'm not sure how relevant ambient CO2 readings would be, prob fairly accurate or at least a ballpark. The blood gas will also give the pH, HCO3 pO2 and pCO2 level. All of these will give the data for the acid/base/metabolic status.

I really don't know the *clinical* relevance in these instances, if the animal in question is thriving, you are probably "doing it right". We learned something in med school which was "treat the patient and not the monitor"....I applaud the seeking of knowledge and since precious little is known about varanid physiology, any bit of gained knowledge is a good thing. However, let's say you pull some blood from the lizard, and it happens to be arterial, and you happen to have a blood gas analyzer right there to accept the iced sample, and it happen to indicate a metabolic acidosis or alkalosis....then what? Do you open the cage to let more air in (room air is approx 21% O2), do you have a respiratory acidosis or a metabolic alkalosis? who do you call? I would venture that most of you guys on this board are better versed in varanid husbandry than a vast majority of veterinarians. I am continually impressed with the fund of knowledge you guys have and the dedication you have in caring for your animals. i hope there is a way to evaluate the questions you are asking, but if not, I don't think you guys need to worry....

[MDT]

Originally Posted by dinosaurdammit

You know I have a CO2 meter, I think I will start the experiment tomorrow. Tonight when I go to bed I will place the monitor in and at the same time that night take it out and in between monitor the flux in the co2 levels.


You are probably asking yourself, DD, why do you have a CO2 monitor? Because my husband got one for his car because it was leaking co2 but we didnt know where from.

is it a CO meter or CO2 meter?

[dinosaurdammit]

Originally Posted by MDT

the measurement of CO2 in a small "unit" such as a monitor would be interesting to say the least. In humans (specifically in the critical care sector), diffused gases are measured typically by arterial blood (blood gases). End tidal CO2 (exhaled CO2) is measured by capnography which samples the actual exhaled breath of the patient, we see this displayed as a numerical value on the vital sign display monitor and is usually used in conjunction with the pulse oxymetry reading. I'm not sure how relevant ambient CO2 readings would be, prob fairly accurate or at least a ballpark. The blood gas will also give the pH, HCO3 pO2 and pCO2 level. All of these will give the data for the acid/base/metabolic status.

I really don't know the *clinical* relevance in these instances, if the animal in question is thriving, you are probably "doing it right". We learned something in med school which was "treat the patient and not the monitor"....I applaud the seeking of knowledge and since precious little is known about varanid physiology, any bit of gained knowledge is a good thing. However, let's say you pull some blood from the lizard, and it happens to be arterial, and you happen to have a blood gas analyzer right there to accept the iced sample, and it happen to indicate a metabolic acidosis or alkalosis....then what? Do you open the cage to let more air in (room air is approx 21% O2), do you have a respiratory acidosis or a metabolic alkalosis? who do you call? I would venture that most of you guys on this board are better versed in varanid husbandry than a vast majority of veterinarians. I am continually impressed with the fund of knowledge you guys have and the dedication you have in caring for your animals. i hope there is a way to evaluate the questions you are asking, but if not, I don't think you guys need to worry....

my guess would be to gradually introduce Ox into the set up, I imagine that letting a crap ton of Ox into the set up can actually make them hyper ox saturated all at once and that can cause problems as well. When I open mine, since the pressure of the house is different than the pressure of the enclosure, I let the vent open and that lets a slow imput of house air into the enclosure. Because the lights super heat it and my house is around 70 or so, give or take a degree depending on time of day- and the enclosure ambient temps are anywhere from 95 to 80 depending on where (not counting burrows- they sustain a pretty constant 70).

I do this because I actually have the plexiglass bow in because of the pressure change. To keep from breaking the glass I vent some air to even out the pressure. Doing this gradually lets Ox in and doesnt seem to spook him as if I just BAM open door. I imagine they get used to a specific level of air quality and when you disturb it by just BAM opening a door it can mess with them. I often wondered if the change in air quality could give them problems like this and that maybe pajaaamas had this happen when I removed the air from the enclosure and replaced it with "garage air".

Before I vented I would notice a slight change in pajaaamas, he seemed to get disoriented and almost drunk. I think their bodies adapt to what environment they are in and you are bound to have some CO2 in there though I dont know if a blood test would give any insight in how to regulate it other than let them gradually be introduced to more ppm of Ox rather than all at once. It would be the same as if you lived at sea level with low levels of Ox and then were placed in a higher altitude with a rain forrest. Odds are for a while it would bother you until you adapted. My guess is that there is more CO2 in their burrows than in the surrounding air. CO2 being heaver will sink and probably pool into the burrows- a measurement of it will need to be made as well as ambient CO2 will be different than the lower areas.

[dinosaurdammit]

Originally Posted by MDT

is it a CO meter or CO2 meter?

it does both actually