Vitamin D question: Pellet-less diet


Post   » Thu Jan 18, 2018 1:39 pm

I am going pellet-less in my guinea pig's diet. What Vitamin D supplements are recommended during the winter months?

For the spring/ summer/ fall months I've heard outside for just 15 minutes a day will suffice. Are we talking *direct* sunlight? Or just indirect sunlight outside in shade?

Thanks so much!

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Post   » Thu Jan 18, 2018 3:48 pm

If you are aiming at vitamin D via the sun, direct sunlight is best. I would sit with your pig in the sun so you ensure your guinea pig does not overheat.


Post   » Thu Jan 18, 2018 5:30 pm

thank you for your reply. Ok. that sounds good. During the winter months though will she need a supplement of some kind if no pellets given?

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I dissent.

Post   » Fri Jan 19, 2018 10:56 pm

Just curious why you are eliminating pellets altogether. Although not vital if you're feeding a good variety of other foods, it can be hard to get the right nutritional balance.

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Post   » Tue Jan 23, 2018 12:35 am

Is Vitamin D as important for Piggies as Vitamin C is?


Post   » Fri Jan 26, 2018 12:30 pm

Yes I heard vitamin d is important for them as according to research guinea pigs need some vitamin D so calcium goes into their bones, not soft tissues. But how much I do not know.

I found this liquid vitamin D online.
Does anyone know if these ingredients in this look ok? I of course would give a much lower dose.

Nordic Naturals - Vitamin D3 Vegan, Healthy Bones, Mood, and Immune System Function, 1 Ounce (FFP

Does anyone know approximately how much vitamin D a day is recommended? I’m assuming quite a low dose.

Thank you!


Post   » Fri Jan 26, 2018 1:00 pm

This one as it is a low-dose maybe better


Post   » Fri Jan 26, 2018 4:55 pm

I'd like to know WHERE you heard this. No guinea pig that I know has ever had a lack of calcium due to low vitamin D intake.

The foods that contain vitamin D (mackerel, etc.) are not eaten by guinea pigs so the only place they get it is from sunshine but an average exposure to sunshine is sufficient. That means that they are in a room that gets sunshine through a window.

Now, with that said, there are guinea pigs with a satin coat that develop a problem with calcium. The problem shows up on an X-ray with the animal's bones becoming brittle. However, giving additional vitamin D does not treat the problem. It's treated by exposing the animal to a full-spectrum light and giving extra calcium. So unless you have a pig with the satin coat, you don't need to worry about it. In fact, vitamin D is fat soluable (sp.?), you can overdose your pig by giving it extra vitamin D. In other words, the pig cannot rid it's body of excess and it will get sick from too much.

So don't give vitamin D to your guinea pig. And to answer your question, JaneDoe, no it is not as important as vitamin C. Whoever told this poster that they need to worry about it is completely wrong.

You do need to make sure your pig gets it's vitamin C! And providing a decent pellet is a way to do that. Daily fresh veggies do help toward that end, but if you have access to a decent pellet like Oxbow, there is no reason why you should go pelletless.
Last edited by WICharlie on Fri Jan 26, 2018 5:03 pm, edited 1 time in total.

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Post   » Fri Jan 26, 2018 5:00 pm

Unfortunately, windows block vitamin D. The special lights might help.

Lizards are particularly vulnerable to problems with not enough vitamin D and need those special lights.

I believe vitamin D is added to standard pellets.


Post   » Fri Jan 26, 2018 5:16 pm

Lynx, you are right that windows do block vitamin D, but you are also right that most pellets have the appropriate amount of vitamin D needed by a guinea pig. I believe my point is that a guinea pig on a proper diet (that includes a good quality pellet) will not have any need of extra vitamin D. I don't know the reason why this poster wants to go pelletless, but I think it would be very dangerous for someone to just guess at how much vitamin D the pig should have. I certainly don't know how much they require and I would guess that most vets do not either. I'm sure the actual amount is very, very small. Considering that an overdose can cause confusion, marked thirst and dehydration, constipation, nausea, poor appetite, weakness, weight loss and heart rhythm abnormalities, it is best not something to be fooling around with.

I would say that if someone was worried about it and wanted to get one of those special lights and offer a bit of short exposure it wouldn't hurt anything, as long as the pigs were allowed to move out of the light if they wanted to. But it seems overkill in my book.

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Post   » Fri Jan 26, 2018 10:03 pm

I agree with you on the risks of going pelletless if you don't really know what you are doing.


Post   » Sat Jan 27, 2018 12:08 am

So I am going pelletless as according to research “Recent studies have shown that the composition of the majority (90%>) of urinary stones in guinea pigs is 100% calcium carbonate. A certain percentage also contain traces of calcium phosphate, oxalate or struvite (1). Pure calcium phosphate or struvite stones are extremely rare”

This means their main source of stones is NOT by food but from an artificial source of calcium. Calcium carbonate . This type never occurs in vegetation to my knowledge but is found in many pellet brands. There are some good brands out there that don’t use this, but they also use molasses etc, that should be in guinea pig food. Most of the nutritional information we use to make pellets came from keeping guinea pigs as a food source or lab animals (i.e how to fatten them or barely keep them alive enough to experiment on them).

Vitamin D is in all pellets so it seems it could be important for them. But I agree, the number must be very small that’s needed as their body mass is small and they wouldn’t have spent much time in the sun naturally as wild cavies. But nonetheless vitamin D is needed in all animals for calcium to be properly synthesized into the body. I was hoping someone had some info on what dose is being put into pellets and I could go from there. But yes, overdosing on them is a very real danger.

Your right. Making sure she gets enough nutrients is challenging. She is eating her veggies and I have lots of herbs and forages with naturally courting vitamins and minerals. Last week she ate all her veggies I gave. This week she is getting picky about them which is making it hard but we will get there.

And of course limitless hay and I recently bought readigrass as well which she loves.

Wild cavies actually do not eat vegetables oddly enough. They only eat grass, leaves, flowers, roots, sticks, herbs. Occasionally nuts and seeds it says which I know has been stated is not advised to be offered to domestic guinea pigs though as it could be a choking hazard. But really I think it’s probably not advisable for most cavies as most do not run around anywhere near the amount that would warrant that level of protein and fat in their diet.

If all else fails for the vitamin d, I will just try and put her outside a couple times a week when weather is nice.
Thanks so much


Post   » Sat Jan 27, 2018 12:30 am

Also, regarding the pellets, research states “if insufficient water is consumed this leads to more concentrated urine sitting in the bladder and, therefore this, contributes to the formation of stones. Conversely more diluted urine dilutes the calcium carbonate making larger stones less likely to form, as has been suggested in rabbits [62]. is demonstrates the importance of the need for guinea pigs to drink a su cient amount therefore it is clearly a husbandry issue if the water isn’t provided in the manner that guinea pigs nd best suits them.”

It has been shown that when guinea pigs consome pellets they do not drink enough water proportional to how much dry food they have eaten. Therefore the problem of calcium carbonate may be compounded by dry pellets further encouraging stone production.

And got the T-shirt

Post   » Sat Jan 27, 2018 12:37 am

This means their main source of stones is NOT by food but from an artificial source of calcium.
You're making an awfully big leap here that's not supported by the evidence. There's enough calcium in hay and vegetables for a pig to form stones if it is prone to do so. And even high-calcium diets may not cause stones if the pig is not so prone.

Bladder stones (uroliths) in guinea pigs are not well understood, and may or may not have any relation at all to diet. I had a guinea pig that developed stones in spite of a pelletless diet for three years. I also pig-sat for a pig that ate high calcium foods, including high calcium pellets, all his life. He lived to be over seven years old, and never had a stone at all.

Some pigs will have one episode of stones, and never another. Some pigs we've known have developed stones within two weeks of surgery to remove them.

It is true that we generally recommend a low-calcium diet for a pig that has stones, and that a high calcium diet be avoided in the hope of preventing stones. We also know that won't work for all pigs -- it's just giving them the best odds we can that they won't have stone problems.

You can tie yourself in knots over feeding your pigs calcium,vitamin D, phosphorus ratios, and whatever other issue you choose. But the fact remains that no one, not here or anywhere else, can tell you exactly how those things interact to cause or to prevent problems. What works very well for one pig may not work at all for another, and there's no way to predict which is which.

My recommendation to you is that you feed your pig a reasonable diet and don't stress yourself, or your pig, with contortions about dietary elements that are not supported by firm research. Unfortunately, for you and for guinea pigs, that's most things about their diets.


Post   » Sat Jan 27, 2018 1:30 am

Yes. Is true. Just like some people can smoke packs of cigarettes a day to know ill affect and live well into their 90s. :D and I agree, some pigs, no matter the best diet, will get stones.

I think the problem is the TYPE of calcium often found in pellets (not all though). It is an entirely different calcium than occurs in the vegetation. calcium carbonate *is* a huge problem in cheap pellets if that is what is being found when they dissect stones. It states stones from calcium phosphate (i.e what they eat) are “extremely rare”.

Pellets are a processed food. Like a fortified cereal. I think with plenty of hay, leafy veggies, herbs that should be enough. They are basically tiny little cows. And like cows and horses they just need hay/ grass and forages with proper 2:1 calcium phosphorous ratio.

I think the bottom line is more research needs to be done into this issue. And sadly they don’t get the attention and funding of more common pets which is a shame.

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Post   » Sat Jan 27, 2018 8:36 am

It sounds like you have been doing a lot of reading here. Stones are not well-understood. I make the point that dietary guidelines for guinea pigs are actually poor (based on lab animals).

You can find out how much vitamin D is added to processed food by pound/kilo of food and perhaps project the daily amount.
Nutrition links here:

The one you want is:
Nutrient Requirements of Laboratory Animals, Fourth Revised Edition, 1995.
The National Academy of Sciences lists the Nutrient Requirements of the Guinea Pig .

Pros: a reference bringing together what is known about the nutritional requirements of guinea pigs.
Cons: some data is over 50 years old, other data is extrapolated from rat studies (the authors of this article encourage more research). Some of the specific diets recommended are only suitable for laboratory animals. The authors note the high protein, low fiber diet typical of a laboratory animal and mention that a guinea pig's diet in the wild consists of much more fiber and green vegetation.
A complete list of requirements is printed on page 104. Keep in mind, these are not daily requirements but instead the amounts of vitamins and minerals they recommend adding to a kilogram of food to provide proper nutrition. Your pig will only eat a fraction of a kilo per day.


Post   » Sat Jan 27, 2018 9:47 am

Thank you so much for that link. I'll look it over more thoroughly this weekend. The vitamin D3 seems very high to me even after I consider the amount in grams my guinea pig eats in a day. I think natural sunlight, sparing the winter, might be the only where forward here. I'd be too worried about toxicity at these upper levels. I teenager can take such a dose lol

I have been reading a lot (still a lot more I'm sure), but I agree too. These guidelines, while the best we have, are not very good. I think the guinea pigs nutritional requirements are not well understood, and I think they may be slightly thrown on their head meaning, that possibly restricting calcium in their diets could be deleterious. In the wild it's possible there diet is full of calcium, just the right kind, and in the right balance. I'm not keen on these pellets as i think they are giving these large/ imbalanced doses of vitamins that more than likely are skewing this internal hormonal and mineral balance as the nutritional research to arrive at these numbers in probably abysmal. Also, any diet high in sugars, processed foods, chemicals (like BHA in some of them) is going to wreak havoc on their small systems as well. When I first got my pig she was on the cheapest pellets imaginable from the store. Her first pee at home (on my wood floor lol) was thick cream sludge. I actually called the vet thinking something was wrong. Turns out that's considered a "normal" color and consistency for them. That is not normal. Her kidneys were working overtime for sure. Now her urine is clear.


Post   » Sat Jan 27, 2018 10:31 am

Can you please give us the sources of your quotes? You can't quote research to us and not tell us where you are reading it.

There is nothing wrong with trying to provide a good diet for your guinea pigs. But I'm with bpatters that you are overthinking this. Also, you cannot assume that feral guinea pigs living in their natural habitat are eating a well-balanced diet. They are prey animals and they only need to stay alive until they become food for another animal. They eat what is available to eat and have a very short lifespan due to disease, injury or predators, so there is no way to determine if their diet would have taken them into old age. If anything, we are trying to make an animal live a long life that is, by design, meant to live a very short life in the wild.


Post   » Sat Jan 27, 2018 11:34 am

Journal of the American Veterinary Medical Association regarding stone composition.

Calcium Minerals section

Talks about ca : p balance and it’s importance in stone formation.

Among a bunch of others. These are the only two studies I have saved on my phone at the moment. But I can see if I can find the others later.

I’m not sure I agree they would be eating unhealthy or incomplete diets in the wild. And I don’t mean this in argumentative way. I just don’t know if I have enough info to agree with that claim. On one end, maybe a diet of more calcium would be higher because females are must constantly be ready for calcium requirements of motherhood but this wouldn’t account for males on the same diet. I’m not sure either nature would design a creature that is constantly in physical crisis from some deficiency. Usually animals are designed to have no deficiencies If in the ecosystem with which they were designed for, regardless of their life span of place in the food chain. For example in captivity cavies often have vit c deficiency but in the wild this never occurs as all grass has vitamin C when fresh and at the high level they ingest. I am going to assume (but I could be wrong) that the ca : P level they consume is the perfect amount to maintain their health in the wild. Life usually is designed to live and be suited for where it evolves.

I’m very science- oriented by nature and enjoy studying biology so I often get really curious about nutrition of animals etc :)

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I dissent.

Post   » Sat Jan 27, 2018 2:41 pm

There are dozens if not hundreds of threads on GL about calcium carbonate and a possible link to urinary stones *in some pigs.* I have long been of the opinion that there is a correlation, and tried to plead my case to Oxbow many times in the past--after seeing incident after incident personally and on here with guinea pigs developing stones while on Oxbow pellets (interestingly, Oxbow adult pellets no longer contain calcium carbonate). You can do a search on "Zachary" and read some of my struggles and research, or search for my user name and "calcium carbonate" to see what I have written here over the years. I have been in contact with numerous exotics vets over the past decade; hit the wall with most of them, and especially Oxbow vets who were not willing to even consider the possibility that calcium carbonate could be at least part of the problem. I still boycott most Oxbow products, just as a matter of principle. As a caring pet owner who was looking for answers after losing 5 guinea pigs to bladder stones while on their product, I would have hoped to have my concerns taken seriously. I believe it was Michah Kohles who once wrote to me, 'You're just looking for a scapegoat." Nice.

All of that said...I agree with the others that stone formation is still very poorly understood. After I switched to a pellet that did not contain calcium carbonate a few years ago, we went without a single case of bladder stone whereas we had seen case after case for 5-7 years previously. Then one of our guys developed multiple, recurring stones. Nothing could explain it. We had another case shortly after that -- again, on pellets without calcium carbonate (KMS Hayloft, Zupreem and now Oxbow adult are three that don't have it). Genetics may play a role; there's also no way to know if a guinea pig has a bladder stone when you adopt him or her, and it might not present until much later. Recurring UTI's may also be a factor.

I still maintain that pellets can play an important role in a well-balanced guinea pig diet, though, because there are a lot of important nutrients in the better formulas that can help ensure good overall guinea pig health. These days, I do feed fewer pellets and focus mainly on a good variety of fresh veggies and unlimited hay.

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