# Questions and thinking about oxalic acid



## Madkins007 (Aug 17, 2009)

OK, oxalic acid is a huge debate right now. Some keepers avoid anything that has oxalic acid, others don't worry about it. I am wondering what we really KNOW about it as it applies to tortoises.

Like many of us, I have seen scary facts, secondhand facts, conflicting facts, and more. Hopefully, we can clear up some of it. Here are some of the things I have read (I do not know that they are all absolutely TRUE, however)...

1. Oxalic acid binds with the available calcium in a foodstuff. The more oxalic acid, the less available calcium. This is the foundational fact- we know this to be true.

1a. Vitamin A and good hydration offsets the effects of the acid. See also point 3. 

2. Oxalic acid does not seem to interfere with calcium intake from other foods, which suggests that a dash of calcium can offset the effect.

3. Oxalic acid is one element in the formation of bladder stones. Other elements include too little vitamin A and D, too much calcium, too little water/humidity/hydration, or too much calcium. Many experts think that dehydration is the key element- concentrating the minerals in the blood and urine.

3a. Bladder stones are often found in wild tortoises. Wild torts also are known to eat plants that are considered dangerously high in oxalic acid (to the point of being considered toxic to humans). Is the oxalic acid responsible for the stones, or is dehydration? A lot of wild torts are also known to skirting the edge of dehydration for quite a bit of the year.

4. Lists of oxalic acid tend to be based on an old USDA report, other newer studies have found different results- but they sometimes disagree with each other. 

4a. One issue is that the soil a plant is raised in makes a difference, the age and exact part of the plant makes a difference, and how the plant is treated, cooked, or processed makes a difference. To claim, for example, that spinach has 0.95mg per 100 g of food is an oversimplification- are we talking baby leaves, freshly picked stuff, 'older' leaves in a grocery store? 

5. Some sites report that oxalic acid is not a problem unless it is 'activated' by cooking. 


So....

There are two main things we blame oxalic acid for- stealing calcium and contributing to soft shell, and for bladder stones. Are there other concerns I am missing?

I have seen no reports for tortoises or humans that links oxalic acid to calcium deficiencies. I doubt this is a concern in a varied diet with a little calcium supplementation.

That mostly leaves the issue of stones. Dr. Mader ("Reptile Medicine and Surgery") thinks that hydration is the key factor here, and admits that we do not know exactly how stones are formed in tortoises. Oxalic acid and stone formation in humans seems tricky as well- some sites blaming it, other sites saying there are other issues that are more important. Our dietitian at work does not think it is a big enough deal to worry about for our clients.

My gut feeling is that we are making this a bigger deal than we need to. If we can eat it, the torts can eat it. If we don't eat much of it (as in parsley, watercress or rhubarb), they should not get much of it. A small pinch of calcium powder acts as insurance with most meals.

I think the bigger, more important issues are the basics (in no order):
- good hydration (water, water content in food, humidity, etc. depending on the species)
- vitamins A and D
- overall Ca: P ratio of about 2 or 3:1 over time
- right temps
- good diet with variety


Thoughts, corrections, clarifications, discussion?????


----------



## Maggie Cummings (Aug 18, 2009)

I agree with your gut feeling that we make too much of it. Hydration is the key and it's not as easy to keep a tortoise hydrated as we think. I had a 3 year old Gopherus agassizii who got a slight URTI so I took her off to the Vet and my Vet looked at her and said, "she is dehydrated"! Yet I soaked her daily. So just because we soak them does not mean they drink and I disagree with the thinking that they soak any liquid in thru there cloaca. I recently was involved in a discussion concerning spinach and not feeding it...I do feed spinach and other foods that have a high oxalic content, but I also make sure my animals are well hydrated and I give them sub qfluids if I think they look dehydrated...


----------



## Crazy1 (Aug 18, 2009)

I also agree with Madkins in that it is a variety of things. I think not only is it possibly what he listed but whether an animal is predisposed to getting bladder stones or having a decrease in essential vitamins and mineral. But I think the age and size of the tort comes into play. In the wild they eat and walk and eat. They eat what is available green, dry you name it. A bite here a bite there. But in captivity most of the keepers set down food for the torts. So they eat what is given too them. Even the torts that are allowed to graze have foods planted for them and kept green most of the time they are grazing. Some plants have nutrients at one level at their peak and another when they are dry. Some intensify others dissipate. This is one I donÃ¢â‚¬â„¢t think there is truly ever going to be an answer on. But I do think Hydration is one big key. Though for my hatchlings I give foods lower in the toxic ingredients I have found such as oxalic acid, tannins, purines, etc. Hopefully this will give them a leg up. I am now adding TNT to their diet especially in the winter. I am also grinding hibiscus flowers, grape leaves and mulberry leaves for winter use


----------



## stells (Aug 18, 2009)

NOBODY has said don't hydrate your tortoise because Oxalic acid is the only factor in the production of stone...

I was involved in the spinach discussion... i choose not to feed it.... that does not make me wrong... and makes nobody else wrong for feeding it... but it is what i do with my tortoises... remember no two tortoise keepers... keep them the same

Oxalic acid is a FACTOR in stones... as is hydration... and i will keep on giving MY advice based on My experience... as will others with theirs... 

I don't think that making people aware of all factors is a bad thing... 

I tell people not to feed Dandelion more than once or twice a week... due to the fact they contain moderate amounts of Oxalic acid and are also a Diurectic.. so you get both factors with the one plant... maybe i am over cautious but if i can keep my tortoises hydrated and watch there Oxalic intake then that is what i will do... i have experienced a stone with a tortoise that was soaked daily had access to water 24/7 and that i regularly saw drink...

I have changed my diet since that... and kept up my soaking regime... with no more problems... that says enough for me

Wild tortoises... they are going to come across Oxalic acid with some of their food items... and they are going to not have the soakings we provide... so yes they are going to produce stones... 

Humans... we are built slightly differently to tortoises... it doesn't take days for my food to pass through me... and i certainly don't have a shell on my back


----------



## Yvonne G (Aug 18, 2009)

Kelly: I think you're being too sensitive here. I don't think anyone was pointing fingers at you personally. When I read what he had to say, your stone experience didn't even enter my mind. Madkins has opened the discussion, giving points that he has read about. I think the object was to open a discussion and hear what others have to say on the subject. I think it would be a good idea for your to repeat your stone experience here in this thread for others to read...that way we have it all in one place.

This is a really good subject for everyone to become familiar with. Thanks for starting it.

Yvonne


----------



## Maggie Cummings (Aug 18, 2009)

I just reread all the posts here and I don't anything was pointed at her. I agree with Yvonne, Kelly you are being too sensitive. 
I too am glad this subject came up as it is always great to get all the different views from other keepers.
Because of where I live dandelions grow in profusion here and I feed my bigger Sulcata them daily along with the graze he's on, and I also collect grape leafs and mulberry leafs for him and feed that daily. I have 2 Rose of Sharon bushes for him and I harvest the flowers and feed him those daily as a treat. The people in the produce dept save their trimmings for me so my grazers get the aforementioned food and also get grocery store greens daily. 
But soon the dandelions will stop growing and obviously I will stop feeding him them. Everything I have read has dandelions on the good side.
I have been feeding this way for the 3.5 years that I have lived here and Bob and the other tortoises that I feed dandelions to seem outwardly healthy. None have had to go to the Dr for anything.
I don't understand why they shouldn't be fed daily. Maybe Kelly would explain that to us?


----------



## stells (Aug 18, 2009)

I wasn't being sensitive... i was just merely stated my view on it 

Dandelions... i used to feed these daily... after one of mine produced a stone... knowing i had regularly seen her drink... i watched what she ate out of a variety of weeds at every feeding... daily she was picking out the Dandelion... so i stopped feeding them so often for reasons in my first post on this thread... and have since had no problems with any of my tortoises... again my own experience... which is what these forums are about... sharing experiences


----------



## Maggie Cummings (Aug 18, 2009)

stells said:


> I wasn't being sensitive... i was just merely stated my view on it
> 
> Dandelions... i used to feed these daily... after one of mine produced a stone... knowing i had regularly seen her drink... i watched what she ate out of a variety of weeds at every feeding... daily she was picking out the Dandelion... so i stopped feeding them so often for reasons in my first post on this thread... and have since had no problems with any of my tortoises... again my own experience... which is what these forums are about... sharing experiences



Ok thanks for the come back...


----------



## Madkins007 (Aug 18, 2009)

My intention for this discussion was not based on any one thread, but rather on the MANY threads where the phrase 'but it is high in oxalic acid' pops up.

Stells: According to my sources (elook.org), dandelion has 0.02mg of oxalic acid per 100grams of food- that is a pretty low value. Do you have a source that lists it as higher?

Maggie: I agree that soaking is probably only a small part of the hydration issue. It reminds me of an episode of 'Good Eats' with Alton Brown (Food Network), where he addresses washing mushrooms. The tradition is that you scrub mushrooms, but do not wash them, because they soak up the water. So, he weighed a bunch, washed them, dried/drained them, and reweighed them (and the collected water)- and discovered that they absorbed virtually nothing. 

I'd be willing to bet that careful measurements of soaking tortoises would show that soaks don't change things much- but especially for grassland species that eat fairly dry foods, it may help enough.



A quick note on hard research vs. experience vs. theory... I know different people look at each of these in different ways- often emphasizing some and scoffing at others. I think it is important to know that each of these have strengths and weaknesses. 

My goal with this thread is to try to combine these elements to come up with a simple policy or philosophy or a set of guidelines.


So... any other thoughts?


----------



## tortoisenerd (Aug 18, 2009)

Interesting points; thanks! Can't wait until I get more time to come back to this.


----------



## katesgoey (Aug 18, 2009)

Great Thread/Discussion!! 

I am not as experienced as most of you but a distinguishing point is those tortoises raised outdoors with more free grazing access to a variety of plants than those more strictly enclosed and "hand" fed. My clarifying question would be whether there is a distinction to be made between the two in this topic. In other words - are you all discussing outdoor grazed tortoises? I also wonder if stones are partially a hereditary question and not solely based on diet??


----------



## BlackRose15 (Aug 18, 2009)

If we don't eat abundant of it (as in parsley, watercress or rhubarb), they should not get abundant of it. A baby compression of calcium crumb acts as allowance with a lot of meals.



________________
Dental insurance plans


----------



## Maggie Cummings (Aug 18, 2009)

I want to take this opportunity to say this quickly...I had a Gopherus agassizii who was 4 years old. I soaked her every other day, she came down with an URTI so I took her to the Vet and the first thing the Vet said was...Oh my, she is dehydrated! Yet she was soaked regularly. So, I am of a thought that we need to rethink this soaking thing...the tortoise died less then 3 weeks later BTW...
I am not sure soaking does much good.

Now...I have always fed in a way that satisfies me. I don't ever look up the vitamin ratio or the calcium ratio of anything. I try my best to feed a wide variety of food. But some stuff I feed daily grape leafs and dandelions are 2 that I am feeding daily right now. But soon both the grape leafs and the weeds will be gone and I will feed something else. When I say I feed those daily, they aren't the only things I feed...as an example...today my grazers got the trimmings from the produce dept...red leaf and green leaf lettuces, kale, collard, grape leafs, dandelions, some weed I don't know and hibiscus blooms and leafs. Rose petals and leafs and blackberry leafs, and they grazed all day.
Tomorrow they will get about the same thing, but I'm probably not going to hunt for dandelions or grape leafs. I think that variety is the key and I think that we over think our husbandry...I am not sure if this post helps anyone, but my animals look and act healthy.

I personally think that no matter what we feed variety is the key, that's the most important thing.


----------



## katesgoey (Aug 18, 2009)

maggie3fan said:


> I want to take this opportunity to say this quickly...I had a Gopherus agassizii who was 4 years old. I soaked her every other day, she came down with an URTI so I took her to the Vet and the first thing the Vet said was...Oh my, she is dehydrated! Yet she was soaked regularly. So, I am of a thought that we need to rethink this soaking thing...the tortoise died less then 3 weeks later BTW...
> I am not sure soaking does much good.
> 
> Now...I have always fed in a way that satisfies me. I don't ever look up the vitamin ratio or the calcium ratio of anything. I try my best to feed a wide variety of food. But some stuff I feed daily grape leafs and dandelions are 2 that I am feeding daily right now. But soon both the grape leafs and the weeds will be gone and I will feed something else. When I say I feed those daily, they aren't the only things I feed...as an example...today my grazers got the trimmings from the produce dept...red leaf and green leaf lettuces, kale, collard, grape leafs, dandelions, some weed I don't know and hibiscus blooms and leafs. Rose petals and leafs and blackberry leafs, and they grazed all day.
> ...




I think it helps. Common sense is always refreshing. Thanks!


----------



## stells (Aug 19, 2009)

Madkins007 said:


> My intention for this discussion was not based on any one thread, but rather on the MANY threads where the phrase 'but it is high in oxalic acid' pops up.
> 
> Stells: According to my sources (elook.org), dandelion has 0.02mg of oxalic acid per 100grams of food- that is a pretty low value. Do you have a source that lists it as higher?
> 
> ...



My source is a person not an internet page... who went to university and studied plants/weeds etc... can you tell me when this list you use was comprised... which part of the plant did they take those readings from... as different parts of the plants contain different levels of Oxalic acid... the stalks being worse... as said they are also a diurectic... and used as a natural way to relieve water retention....in that case and with others views on dehydration being the cause... shouldn't this be where common sense comes into play???

I do still feed them... just not on a daily basis and i do believe they are a good part of a varied diet.... again this is not somebody saying NEVER feed your tortoise Dandelions.... variety is the key that is something i agree with... there are foods with an Oxalic content i feed but those are fed on occassion and not all the time.... then there are the ones i never feed such as the Spinach...


----------



## Madkins007 (Aug 19, 2009)

Kelly- elook.org is based on the USDA database, and is measuring the leaves. I'd love to find a good reference for other parts, and other common non-food plants.


----------



## Madortoise (Aug 20, 2009)

Madkins or Kelly, 
How does oxalic acid content differ in dandelion leaves vs. flower? 
Is it bad to give a 4 yo DT a 3-5 flowers everyday? Mine chomps on the leaves when she feels like it but I have to vend the stems for her so she can reach the flower. It's been our routine this summer every morning when I put her outside.


----------



## stells (Aug 20, 2009)

Its a shame its only based on the content of the leaves... when the variation within the plant can be so much...

If you are feeding the flowers all i will say is take the stalk off... I still wouldn't feed everyday... but some people are going to say thats fine.... its up to you to read the info given out and decide for yourself... i would feed twice a week at most


----------



## Maggie Cummings (Aug 20, 2009)

Yes, this 'some people' feeds the dandelion flowers and leafs daily. I also feed a wide variety of other healthy stuff not just dandelions, I also keep my tortoises well hydrated. Soon the dandelions will be gone from here and I will feed something else daily.
I have to go run some errands now, but I just recently read something that showed that dandelions are low in oxalic acid. Most tortoise research calls on dandelions to be one of the good foods. 
Here again, this is one of those subjects that experienced people feel strongly about and I am sure that we won't change our minds about it either. It's like Mazuri or not, UVB or not. We are passionate in our opinions...


----------



## Madkins007 (Aug 21, 2009)

Few flowers have much oxalic acid, and considering that dandelion flowers are considered edible for humans as well, I doubt they have much.

It would be nice to have a better database of nutrients and plants, but for crying out loud- can you imagine what that would look like? Listing different parts of plants, and in many cases, even different ages or treatments? 

Just another quick note- red and white clover is considered HIGH in oxalic acid (the German name for the plant comes from the acid content), but it shows up on 'safe' lists all of the time. Makes me wonder how many other garden or yard plants are high in it but still on the lists.

Anyone got a couple hundred torts sitting around we can experiment with? (we'd need a couple of test groups and a control, so the more the merrier!) 
:shy:


----------



## Maggie Cummings (Aug 21, 2009)

Bob's pen in the Spring is thick with Crimson and New Zealand white clover, but I don't see any evidence that it is harmful to him...what would we see?


----------



## katesgoey (Aug 21, 2009)

I didn't ask my first question very clearly so I'm going to try again: Do we know if there is a loss or lessening of content of the oxalic acid if the plant has been picked for and fed to the tortoise rather than the tortoise "picking" it fresh from the ground itself? I've read where some plants lose some elements after picking if they are not fed within a period of time so I'm curious to know if this makes a difference. Thanks.


----------



## stells (Aug 21, 2009)

It would certainly be a list that would take alot of bedtime reading lol

English and American list do differ quite abit... more veggies being on the American lists than what we seem to put on over here...

Just because a plant is deemed safe to eat... i think and this is just my thought on it... that in safe it is meant they aren't toxic... they don't seem to go on from that with regards contents of other substances.. so yes safe plants are not going to be dangerous to your tortoise in a toxic way if eaten... but they just may not be suitable for daily feedings due to being to high in others things i.e Oxalic acid...





Madkins007 said:


> Few flowers have much oxalic acid, and considering that dandelion flowers are considered edible for humans as well, I doubt they have much.
> 
> It would be nice to have a better database of nutrients and plants, but for crying out loud- can you imagine what that would look like? Listing different parts of plants, and in many cases, even different ages or treatments?
> 
> ...


----------



## Crazy1 (Aug 21, 2009)

So I have been reading and researching a lot regarding spring mix, spinach, dandelion etc. What I have found is most plants if not all, have some toxins in them. Tannins, glucosinolates, glycosides, oxalic acid, you name it. Heck even lettuce has an opiate like substance in it. The amount is the key. Some are low, some are high. Some plants concentrate substances when they are dry others when they are young or sprouts. Unless we are all shooting to be horticulturists or botanists this is going to be well out of our reach. All lists are not alike either some list a particular substance like calcium or vitamin A in one cup of plant matter and another list will list different amounts of the same substances in the same plant. So when the plant is harvested and the soil and area it is grown can also a factor. All we can do is educate ourselves and do the best we can by our animals.

Now I lost a little tort to a badderstone recently and I do not feed spinach to my hatchlings but I do feed it on occasion to my DTs and adult Greeks. But since this incident I look at things with oxalic acid much differently. I also realize hydration is a large key. So I do understand both sides of the coin. Kelly I understand not feeding spinach or kale etc. and Maggie I understand feeding both spinach and kale. Sound ambivilant. I'm not. You must know your torts and do what you-mind you I said YOU feel is best for them. And for me right now decreasing oxalic acid in their diet and increasing hydration is my focus for my hatchlings and juvaniles. And keeping an eye on my adults (which by the way are doing fine).


----------



## Madkins007 (Aug 21, 2009)

katesgoey said:


> I didn't ask my first question very clearly so I'm going to try again: Do we know if there is a loss or lessening of content of the oxalic acid if the plant has been picked for and fed to the tortoise rather than the tortoise "picking" it fresh from the ground itself? I've read where some plants lose some elements after picking if they are not fed within a period of time so I'm curious to know if this makes a difference. Thanks.



Oxalic acid is more of a mineral than a vitamin. As the plant dries out, the acid becomes more concentrated, but there is not 'more' of it. Because the plant is drier, it hydrates the animal less as well, which is probably the more important element.

The 'drying time' between picking and feeding in situations like local farmer's markets or backyard gardens is probably not as big a deal as the drying time involved in long-distance trucking for mega-marts.

We do know that cooking it kicks the chemical reaction into hyperdrive, however. It has been said on some sites that if the stuff is not cooked, it has much less effect. Not sure I believe that completely, but the theory makes sense.



maggie3fan said:


> Bob's pen in the Spring is thick with Crimson and New Zealand white clover, but I don't see any evidence that it is harmful to him...what would we see?



That's kinda the point- I don't think you WOULD see anything. My take on this debate is that as long as the animal is properly hydrated (as in eating live, green plants) with good levels of calcium, UVB, warmth, and vitamin A, then oxalic acid is a non-issue.


----------



## katesgoey (Aug 22, 2009)

Madkins007 said:


> katesgoey said:
> 
> 
> > I didn't ask my first question very clearly so I'm going to try again: Do we know if there is a loss or lessening of content of the oxalic acid if the plant has been picked for and fed to the tortoise rather than the tortoise "picking" it fresh from the ground itself? I've read where some plants lose some elements after picking if they are not fed within a period of time so I'm curious to know if this makes a difference. Thanks.
> ...


----------



## Tccarolina (Oct 8, 2009)

How about spurge? Spotted spurge grows like crazy here in July, August, and September. My two Greek tortoises chowed through it like little combines until I found out it was on almost every toxic list, with high oxalic acid levels. But I'm reading it exists in many of their native habitats, and they have been observed eating it in the wild.
If it is safe for Mediterranean tortoises, I don't want to waste time weeding it out of my large pen all summer. On the other hand, if it is truly dangerous, I don't want to lose my tortoises.
Those of you that lost tortoises to bladder stones; how did you find out? Are bladder stones always killers? My two greek tortoises have been inactive the last month and have lost a little weight since their summer high. They will eat, and appear bright-eyed, dry-nosed, and healthy when I dig them out, but quickly re-bury themselves as soon as they have the opportunity. They don't seem to come out on their own right now at all. 
I got them on Craigslist in May, and they stayed hidden at first, but then were active and feeding well, grew a quarter inch each, and gained weight till about the beginning of August. They reached about 525 grams at that point, but now they are both about 460 grams. I try soaking them, but so far, they always weigh slightly less after I soak them, probably due to defecating/urinating. Of course, my box turtles lose weight nearly everytime I soak them, unless I actually observe them drinking extensively during their soak.
So, is this a normal activity pattern for Syrian Greek tortoises? I live in the central valley in California, and my local climate is almost identical to Syria's.

Steve


----------

