Are we overexposing our dragons to UV?

Claudiusx

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This thread was originally posted in a section of this site for advance discussion. However I think it's only appropriate that it be posted here now so that more discussion can be brought to the table.

After reading this thread, please feel free to make comments about any of the points brought up. Debate any of the points brought up, and discuss any of the points. The goal here is to get a discussion going where we can all learn, and bring up our opinions and thoughts and share them as a group.

____________________________________

Disclaimer: I am not stating anything that I say in this thread to be fact, simply my opinions, and others, and a place to discuss

With stronger and stronger bulbs being produced as the years go by, owners need to be weary of the fact that more isn't always better.

Realistically speaking, for years we all kept our puny 10.0s on top of our mesh screens. Were our dragons developing MBD? Not anymore often than it seems they are now. Were they living long healthy lives? Arguably longer than they are living now. However that can be attributed to the morph market and not necessarily changes in husbandry.

I've been having a bit of back and fourth with Frances in regards to us working on some research to scientifically answer this question. Unfortunately, she is not in a position to do this and I am not in a position monetarily to do this as I have no strong ties to any universities. But, I will lay down facts and opinions from the both of us, and everything is up for debate/discussion.

-Brandon
 

Claudiusx

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Do we really need to be offering UVI ranges at the basking spot that are even close to noontime levels in the wild?
In my opinion, no. Usually basking creatures retreat from the sun at noontime, and get most of their basking done in the early to mid morning, when the solar angle is at such a point where the ozone layer greatly diminishes the uvi level.

If we are going to be giving them close to noon-level UVI, it should only be done for a short while IMO. I do not believe it is necessary for us to be hitting them with this much uvi for 12-14 hours a day.

My statement will be in blue, Frances in red:

But that doesn't involve giving them noon-level UVI exposure 14 hours a day, as many are starting to suggest it seems..>>
I totally, TOTALLY agree with you regarding the utterly stupid suggestions that “more UV is better” and that “people should offer the animals levels equivalent to mid-day maximums quoted on weather reports from the places where these animals live”.
All my talks and writings emphasise that these suggestions are completely wrong. Climate does NOT equal microclimate! Animals should never be offered more than they would be expected to receive in good weather in their native microhabitat at the time of day that would be when they would be most likely to be out in full sunlight (for baskers) or exposed to daylight (non-baskers). For baskers, this time of day is almost always early to mid-morning. When UVI levels are low to moderate, typically somewhere between zero at dawn to around 4 or 5 at the time they start to retreat into shade. I usually say that I believe a UVI of 3.0 is good for almost all species; I have no evidence, except for the understanding that some vitD3 researchers say that human skin responds well to UVI 3.0 for vitamin D3 synthesis, without causing rapid sunburning, and that it corresponds to a typical solar level at around 8.30am in the tropics.. a time when animals are often seen basking.

Some discussion points from her response:

I do believe it's interesting that she suggests a UVI level of 3.0 being suitable for almost all species based off of how human skin responds. We do know that lizard skin (scales) are different. But as we are breeding more and more leatherbacks and trans dragons, how much more different does it become?

Another point she makes is that for most basking creatures, they do there basking usually early to mid-morning.

-Brandon
 

Claudiusx

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One of my hopes was that we would be able to look at a large sample of blood results and hopefully find an invisible ceiling in regards to 25(OH) levels. If this was the case we could assume we are already providing enough UVB to our dragons based off a couple theories:

1. the fact that in humans, the skin will only produce so much D3 from the sun before the sun actually starts destroying more from being made. If this was the case with reptiles, we could lead ourselves to that conclusion, that if we hit the invisible ceiling in regards to their bloodwork, that we are providing enough UV.

2. If we found this to be true, we could then measure 25(OH) levels in dragons under less than commonly recommended UVI levels (EG a reptisun 10.0 ontop of a mesh top)

Few issues with this, but Frances explains it better. The main being that, we aren't providing anything close to the sun, therefor it is unreasonable to assume that the UVB we provide will also destroy extra Vit D that it produces.

Frances Baines":2z4gfy5y said:
This is known to be true in human skin under a normal SOLAR spectrum, with naturally balanced levels of UVB across the UVB spectrum.
However it is NOT true when the spectrum is UNLIKE that of the sun. Back in 1982 they discovered that the exact proportions of different parts of the UVB spectrum determine the percentages of the different photoproducts produced, only one of which is vitamin D3. If a spectrum very different from sunlight is used, the photoproducts are produced in different amounts. And since it is the production of photoproducts other than D3, which limit D3 production, you can see that some spectra might hinder D3 formation, others might enhance it... and in theory, allow more to be made than would be possible under sunlight. This might even allow too much to be produced!
Some lamps have indeed seemed to cause very high vitamin D3 levels in some animals. They have not shown any toxic effects, but there seems to be no other obvious explanation for the blood test results ... unless the assays are not actually measuring vitamin D3, instead cross-reacting with one of the other photoproducts. No-one seems to know...

-Brandon
 

Claudiusx

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All and all, we aren't going to get a scientific answer to this question until someone with enough time, money, and resources are willing to do it.

I might have one or two of those, but you need all three lol.

So, the topic is up for discussion.
As it stands now, I agree with Frances that we don't need to provide higher UVI's than 3 to our dragons. It would be different if they were only being exposed to UVB for a few hours a day, but 12-14 hours of a constant exposure (no matter the gradient) is too much IMO.

I do realize the dragon can pick the spot it wants to bask in, and it could pick a spot further from the bulb to be exposed to less, but how we setup our tanks and how we recommend tanks to be setup, the basking spot is usually the highest UVI exposure spot too. Forcing the dragon to choose the proper temperature it desires, or the UVI it would like.

-Brandon
 

Taterbug

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It's gunna be a long time.comming to get the data and studies, unfortunately. In the mean time I think we can make improvments and sort of side step the nuances of blood-data and such if husbandry becomes a more holistic discussion. With dragons, there is a lot of focus on UVB. This makes sense, next to calcium supplementation there is little in captivity that can be so deviating to the animals health. Is the answer to find out exact dosages of UV or is it better to provide the best replication of a natural environment as we can?

UV has been a limiting factor for a long time for husbandry and healthy animals, it's becoming less so. Unfortunately alot.of "best practices" were developed around the tech of the time, and are sticking around. The attitude of more UV being the end all be all goal is misplaced. Lamps are a tool, and we are fortunate to have better tools now than we did before, the rest of husbandry can catch up now.

UVI of 3 is reasonable, I 100% agree. The question then becomes how to best and most comfortably supply this? In the past, T8 lamps were the strongest available. A T8 lamp in a reflector will have an effective range of (for UVI~3) about 6-10" away from the bulb depending on fixtures, screen and so forth. That's pretty close. Alternatively, a T5 in a reflector can be more like 12-18" away. This means that not only does the light move further away (less glare, the gradient is more even with less margin between too low and too high) you are opening up more possibility for your gradient.

Unfortunately now you are most likely limited by the size of your enclosure or by heat lights. It's not possible to have a nice big (lizard sized) thermo-photogradient in a 40g tank. It's just not. Fortunately, these are much easier to remedy (space and budget allowing) than underpowered UV lights.

A small enclosure, or one that doesn't have much furnishings/enrichment has to be kept at more of and "ideal/average". Once you move to a bigger habitat, that nice strong UV light really offers new possibilities. The more space you have the more environmental enrichmenty you can offer and thats good for the mind and body.

Because I have a pretty large cage I am more comfortable with offer a wider range of options - having more space and options means the lizard gets to choose not me. I offer a basking site of about UVI 5-6 and 130F basking temp as my "too hot"; it does get used in sort bursts, as does the cool areas and hides. I also have all my lights on timers so the lights dim on/off and the UV is on only when the basking lights are 100%.
 

Claudiusx

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Thank you for your insight, you bring up some very valid points.

I can see how my post might make me sound anti T5, or anti stronger bulbs, but I am not. I am anti more is always better mentality.

To me, the beauty of the t5's is the fact that they make having a larger tank much easier. Having t5's and t8s as an option now is a tool that hobbyist should take advantage of in my opinion.

A stronger uvb bulb isn't always better and I think you touched on it a bit with your post.

You wouldn't want to use a t5 mounted inside your 10 gallon or 20 gallon tank when it can only be 4 or so inches away from your basking surface. The beauty is, you have options now. Do you mount a t8 inside the tank? Do you mount a t5 on top of the mesh?

T5's aren't better than t8 in the sense of "whats best". They both offer pros and cons and both can be used very effectively depending on your setup.

My whole issue is with everyone recommending a t5 and saying it needs to have a reflector and it needs to be mounted inside the tank, without taking into any consideration the distance it will be, the rest of the setup, or even the type of dragon.

Taterbug":38r7eobb said:
Because I have a pretty large cage I am more comfortable with offer a wider range of options - having more space and options means the lizard gets to choose not me. I offer a basking site of about UVI 5-6 and 130F basking temp as my "too hot"; it does get used in sort bursts, as does the cool areas and hides. I also have all my lights on timers so the lights dim on/off and the UV is on only when the basking lights are 100%.

Very interesting. How long would you say then that your uvb bulb is on during the day?

Goes to show, there are multiple ways to care for dragons, just like babies. My only problem is when someone only accepts their own way of thinking and pushes it on others.

-Brandon
 

Taterbug

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I think new information and old information/"best practices" get conflated alot, it's unfortunate. People want to help and maybe don't quite understand the details so well. So the telephone game gets played and there ends up some questionable advice going around.

I have to disagree on the point of "what's best" though, but it's purely from an idealized vantage point. T8 lamps are loosing their relivance when it comes to best husbandry practices for beardies. They are adequate and they do broaden the options available, they are neccisary for some situations due to space or budget etc. Sometimes, you have to work with what you've got. However, I think they also reinforce inferior standards as being good ones. I'd much rather see a T5 without a reflector on the ceiling than a T8 mounted on the wall. At the same time, i'd rather see a lizard in a big (floor space) enclosure with T8 lamps, than a small enclosure (or tall skinny one) with a T5. Again, it's a personal mindset on my part. I do.agree that perfectly healthy animals can be raised under T8 lamps, but I'd consider it lower in a good better best scale becuase it does limit the rest of the environment.


As for my setup, my basking lights are synced to the local day/night and the ramp up is about 60-90mins. So in the summer everything is on longer. UV about 2-3hr less than the basking lights (I forget the exact times).
 

Claudiusx

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Taterbug":yfgbg1tw said:
I have to disagree on the point of "what's best" though, but it's purely from an idealized vantage point. T8 lamps are loosing their relivance when it comes to best husbandry practices for beardies.

Fair enough, I will disagree on that, but thats the beauty of discussion. :)
IMO, T5's add some risk that T8's might not. Although I suppose you could considers T8's to provide the risk of potentially under providing UV, T5's have the opposite problem.

I do want to get your opinion on the fact that we used t8's for decades, even on top of our screens. Since we weren't really seeing much MBD if the rest of the husbandry was up to par, would this not imply that the levels of UV we were providing back then were suitable?

I guess I'm assuming that everyone will answer this question the same as me so I will ask you just to get your thought.
Is it not better to provide just enough UV, as opposed to more than enough. Considering the damaging effects of UV exposure?

I guess depending on how you feel about that question, will determine how you feel about your uvb setups.

For what it's worth, I use t5's without reflectors, mounted to the tops of my custom enclosures.
I'm really not as anti T5 as I seem. I'm anti my way or the highway. :mrgreen:

-Brandon
 

Taterbug

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We do have to make some judgement to choose to err on the side or too much or too little. My research has led me to choose the too much side, and to mitigate that risk with environmental enrichment as best as I can. It's definitely not the only way and I wouldn't even say it's "the right way", it's just the way I choose to do it.

The D3 cycle and the role of it's components in the body is complicated, and I worry that it's not a clear delineation between thriving and surviving sometimes. For me, the lack of MBD is not a good baseline. MBD that we can easily identify on on sight is a devistaiting level of defficency. Not having MBD does not mean the animal has adequate D3 levels for all their systems, or that we have found the level of "just enough" UVB, (or that we haven't for that matter.)

To draw a parallel, one form of MBD in humans is osteomalacia (rickets in children), it's crippling and painful and it is the far end of the spectrum of low-D3 related maladies. Maybe a person's defficency not bad enough to cause disfigurement or broken bones, but still cause lots of pain. D3 also plays a role in other systems. Yhis is all poorly understood in humans; there aren't really good limits for deficiency vs adequate vs optimal. So of course, it's even harder to assertain where on that spectrum our pets end up. Fatigue and weakness and other other subclinical symptoms may exist... How can we tell the difference between our pets being lazy because they are living the good life or if they don't move because they are tired or their muscles are too weak or they are in pain?

From how I understand the D3 cycle too much (from photosynthesis) is less harmful than too little, within reason. I limit my UVI to 6 max with plenty of options, and only use lamps that are vetted by the community for having "safe" spectrums. I also provide UVB lights for my snakes. even though they are capable of surviving without it they can utilize it. So again I choose to effectively over provide with the setup designed for self regulation.
 

Claudiusx

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Taterbug":39h584sc said:
The D3 cycle and the role of it's components in the body is complicated, and I worry that it's not a clear delineation between thriving and surviving sometimes. For me, the lack of MBD is not a good baseline. MBD that we can easily identify on on sight is a devistaiting level of defficency. Not having MBD does not mean the animal has adequate D3 levels for all their systems, or that we have found the level of "just enough" UVB, (or that we haven't for that matter.)
Agreed, and a valid point in regards to the MBD we can actually see.

Taterbug":39h584sc said:
From how I understand the D3 cycle too much (from photosynthesis) is less harmful than too little, within reason.
Not too sure I agree with you on this one, although I'm admittedly on the fence on it just because I haven't done as much research into it as other aspects of this. In natural sunlight, the sun will start destroying more d3 from being produced in the skin once a certain threshold is reached. This is not true for artificial lighting, and in theory could lead to over production of D3, which of course like everything, has it's own issues.
I don't believe we've actually seen any clinical cases of hypervitaminosis D simply from over exposure to artificial UVB bulbs in dragons, so I might be reaching a bit there, but it's in the realm of possibilities I'd imagine.

EDIT: not to mention, too high of a dose can lead to other issues such as cell damage.
Once again though, we don't know what that level is. I personally like to err on the side of less, but in the range that Francis mentions also. Especially with the ability to supplement vit D3 in a calcium powder, I think any slight deficiency in the uvb bulbs power can be made up for in supplement. I BELIEVE it takes less UVI to get the other benefits of uv exposure (such as the feel good endorphins, immune system benefits, etc.) than it takes to synthesis D3.

It's a complicated subject, but an interesting one to discuss at least. And I appreciate different viewpoints being discussed here.

-Brandon
 

Taterbug

BD.org Addict
I'll be the first to admit my biochemistry understanding is fuzzy at best. Hah.

Out of curiosity; your quote from Fran...

However it is NOT true when the spectrum is UNLIKE that of the sun. Back in 1982 they discovered that the exact proportions of different parts of the UVB spectrum determine the percentages of the different photoproducts produced, only one of which is vitamin D3. If a spectrum very different from sunlight is used, the photoproducts are produced in different amounts. And since it is the production of photoproducts other than D3, which limit D3 production, you can see that some spectra might hinder D3 formation, others might enhance it... and in theory, allow more to be made than would be possible under sunlight. This might even allow too much to be produced!
Some lamps have indeed seemed to cause very high vitamin D3 levels in some animals. They have not shown any toxic effects, but there seems to be no other obvious explanation for the blood test results ... unless the assays are not actually measuring vitamin D3, instead cross-reacting with one of the other photoproducts. No-one seems to know...

How does the spectrum of Arcadia/reptisun bulbs compare in those photobiology active wavelengths. She mentions "when the spectrum is different" and "some bulbs". Are these bulbs very far off on those key wavelengths, or are they actually relatively close?

If it was shown that the wavelengths responsible for the photo regulation are intact... Would it effect your opinion?
 

Claudiusx

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Taterbug":f697542z said:
How does the spectrum of Arcadia/reptisun bulbs compare in those photobiology active wavelengths. She mentions "when the spectrum is different" and "some bulbs". Are these bulbs very far off on those key wavelengths, or are they actually relatively close?
Hmm, interesting I didn't even think to ask when we were discussing this. I went back through our e mails just now and she doesn't really elaborate on that at all.

Taterbug":f697542z said:
If it was shown that the wavelengths responsible for the photo regulation are intact... Would it effect your opinion?
I had to think of that for a minute before feeling comfortable with giving an answer. My answer is, it would change my opinion to a degree. I would feel more comfortable with slightly higher UVI's than I feel comfortable with right now, but it wouldn't in complete essence change my thoughts. Only because their are other potential harms from higher UVI levels than just excess vit. D production.

Since I went back through our past conversations, I did find another interesting comment she made that I think adds to my thoughts too that noon time UVI levels are not a good basis for what we do in our enclosures.

I'm blue, she is red.

At what point is mimicking their natural environment going to start being more detrimental than simply knowing what they need and providing that.
I would say that “mimicking their natural environment” is the very best we can do, and if done properly, is exactly what we DO need to aim for... but the key is in the words “natural microhabitat” not “natural climate” which is what so many people imagine they need to provide. Quite the opposite! I have a series of slides of UVI readings on a sunny June day here. At human height, in the sun, UVI 5.6. In an only moderately-leafy grass meadow: UVI 0.9, the meter (or animal) shaded just by the blades of grass.

I worded my question kind of weird I suppose, and her response kind of reiterated the fact to me that recreating natural habitat is what we should aim for as a basis (and then make adjustments based on any data we can get on different morph skin types such as hypos and trans and leathers).
But she makes a good example of the simple difference in UVI a slight change in scenery can make, and the importance of realizing that micro-habitat, is the important part here, not natural climate.
Which is why I never bought into the whole basing general uvi levels of the outback to what we do with our enclosures.

-Brandon
 

kingofnobbys

BD.org Sicko
I aim for about 180 to 200 microW UVB / sq.cm and 1 mW UVA / sq.cm at my centrals' basking spots I wont repeat (ad nauseum) why these are good UV irradiation levels for a bearded dragon .

I suggest people take the time to actually do their own literature research targeting aspects such as :

>> the actual UV irradiation in summer in TROPICAL & SUBTROPICAL regions of AUSTRALIA and take note of the UV-Index and UVB flux (which is DIRECTLY linked to and relevant to vitD3 photosynthesis in wild bearded dragons' skin) between mid morning and mid afternoon (which happens to be period of the day when while bearded dragons are most active).
Available from scientific organisations such the Australia BOM.
This is what pogona (all species) have evolved to flourish in all their natural ranges inside mainland Australia. Yes these are significantly higher than even in mid summer in places like FL and other southern states.

>> observations of herpetogists who have actually visited the natural range of bearded dragons and had the opportunity to see their behavior in the wild.

>> the studies and scientific papers by professional herpetogists in the field in the native range of bearded dragons ( refer to peer reviewed scholarly articles , papers , journals and books written by expert reptile vets and research scientists) , if the advice is not supported by REAL science and provided with citations , it's an UNINFORMED OPINION and should be regarded as dubious.

>> careful of claims made that are not supported by publically accessible evidence.
Sorry secret message boards don't cut the mustard , nor does dropping "names" . If someone makes a claim they had better be prepared to back it up with good unrefuteable substantive proof and evidence. Heresay wont cut the mustard in a court house , nor is it considered acceptable in science.
 

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