# Vitamins through skin



## Blort (Feb 5, 2005)

Hi,

I was reading about Xenopus tads and morphs absorbing calcium through the skin/gills and how common frog medicines for darts are given by either eyedroppers to the skin or soaks. Also, I recall seeing something about darts having seizures attributed to calcium deficiency being treated by dusting the frog (with Tums if I remember correctly :shock. So, I was just wondering does anybody apply vitamin solutions to the frogs instead of dusting the food? Is this feasible, are there vitamins that need to be metabolized through the digestive tract first, or are too large to make it through the frog's skin. If anybody is doing this, what dosage do you use and how do you apply the solution?

Thanks in advance,

Marcos


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## bbrock (May 20, 2004)

One of the herp product makers were making a spray-on vitamin supplement for herps but I read really bad reviews on it. My personal opinion is that the ability of frogs to absorb nutrients through their skin is a blessing that we can take advantage of to treat when things are not goin well but not something we should rely on as a standard husbandry practice. There are several reasons. 1) Not enough is known about proper supplement dosing for amphibians but what we do know is based on dosing for oral consumption. We know even less about skin absorption. 2) It is likely that the skin absorbs different nutrients at different rates which could lead to overdosing some vitamins while underdosing others. 3) frogs appear to be adapted to obtain the majority of their nutrients through food consumption. Who knows what damage chronic absorption of vitamins and minerals through the skin might do. No doubt some species of amphibians have adapted to take advantage of their natural environments so amphibians living in waters with high levels of calcium carbonate may obtain significant amounts of calcium simply by absorbing it from their environment. I just feel like it is best to try to simulate a fairly natural environment and let the frog's physiology do what it would do naturally.


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## Blort (Feb 5, 2005)

Thanks. That all makes a lot of sense. It would be interesting if somebody with the resources and equipment could do some studies about this. So, any ideas as to what is providing calcium in the wild? That has puzzled me about most reptiles in captivity and the need for calcium supplementation. What about some of the other vitamins that seems hard to replicate in captivity what are the best theories about that? Is it insects that we can't provide in captivity or "gut loading" in the wild by some insects eating different things in the wild. I'm guessing that you are right about the primary intake being oral, but couldn't there also be some things in the wild that transmit nutrients through the frogs skin in the leaf litter, etc? Given what I understand about how frogs hydrate, it seems like this should be a possibility. Maybe providing more dermatropic nutrients in the substrate or leaf litter is a good way to simulate a natural environment as you suggested. How you would go about this, I haven't a clue. I find it fascinating though.


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## bbrock (May 20, 2004)

My personal theory is that the greatly increased variety of foods a wild frog eats has everything to do with getting adequate nutrition. They eat a lot of soil arhthropods (little mites, springtails, and such) that no doubt have particles of soil sticking to them. Also, just feeding in a "real" soil probably means they ingest soil particles directly. The soils are largely mineral and probably provide all of the calcium the frogs need. In addition, many of the wild insects are gut loaded as you suggested and the varied diets of the insects are just as varied as the insects themselves.

It is hard to see a substantial amount of nutrients coming through the skin of terrestrial frogs as they hop around the environment. Nutrients need to be in solution to pass through the skin and into the body. So even standing on a solid block of calcium probably doesn't bring the frog much in the way of calcium supplementation. I could see where possibly some trace elements might be obtained just through contact with things in the environment as the moisture from the skin might put a tiny amount of nutrient into solution and some of that might get absorbed. But I don't think they could get nearly as many nutrients from their environment as something that lives a substantial part of its life in water might. Water creates a nutrient soup that may provide a number of nutrient supplements that could pass through skin. Basically, I think you need to consider how easily a nutrient could pass through the skin (is it in solution?) and then you have to consider how long the animal would be in contact with those nutrients to absorb them.

So one simple thing we could do in our setups to address this is to use real soils. That has its drawbacks but I think overall it is something people wanting to replicate a naturalistic environment should revisit.


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