What exactly is Oxalic Acid?
Oxalic acid is a natural compound found in many plants, including those that bunnies like to eat. Usually oxalic acid is bound to the minerals in the plants, and it forms oxalates. Yet, both words oxalic acid and oxalates are used interchangeably in the nutrition science fields.
Oxalates are completely harmless to humans and animals when consumed in small amounts. However, some plants produce more of these chemicals (called alkaloids) than others, and this can create toxicity the the bunny’s gut.
What makes them dangerous is the fact that it binds calcium in the colon, preventing the absorption, and this can lead to kidney stones.
Obvious high oxalates in the diet can have these symptoms:
- grainy looking stools
- calcium deposits on stools
- cloudy urine
- gassy stomach
- dry skin
Oxalates and Calcium
There must be a balance of calcium and oxalates in a bunny’s diet, that’s because calcium helps with the removal of the oxalates in the colon.
Oxalic Acid is found in lots of foods that you feed you rabbit. You will notice brown marks in the bottom of their litter box when your rabbit has had too many oxalates.
Oxalates are in spinach, beet greens (chard), berries, carrots and parsley. Oxalates cause bladder issues and should be fed sparingly. If rabbits are fed a high oxalate diet over a long period of time they can get liver problems.
Like with Buttons, and his tummy issues, he gets large oxalate excretions when he eats parsley. This is because his system cannot store the required oxalates and it excretes the full amount. I have to be very careful with how much parsley he eats, if any at all.
Foods low in oxalates are coriander, basil, carrot tops and dandelions.
I always feed Buttons dandelions when his tummy is being a problem. Dandelions fix all digestive issues within hours.
This is what oxalates look like.
When you put vinegar on it, it disappears within seconds. Give it a good clean with a brush and the stains will be gone. Vinegar is not a good disinfectant, so make sure you wash the litter box with lots of water and a little squirt of dishwashing liquid to make sure it is clean. Remember that vinegar kills plants.
Keeping it Simple
In your bunny’s diet keep calcium and oxalates low, or as low as you can.
I personally don’t feed vegetables to my bunny on a regular basis, only because he produces a lot of calcium deposits for a few days afterwards. I make sure to feed him a lot of grass instead. Grass is a more natural way to cleanse a bunny and gives them the right nutrition. Always give your bunny a range of different grasses, because each one has different vitamins and minerals.
Tip
Don’t feed your bunny kikuyu, buffalo or couch grass, it is high in oxalates and will bind calcium in no time.
Actually, don’t feed your bunny any grass that grows across the ground in strings – like hard-wearing lawn grasses – they aren’t healthy for bunnies. Feed them grass that grows in clumps instead.
Have a look at my Grass and Hay and the Good and Bad Foods articles to give you more insight.
This table is a list of vegetables that you can give your bunny and their rating for calcium and oxalates.
This information was collated by someone else and I just made it look pretty. They give two references, however, both of them don’t lead to the websites they think it does. So, I’m not sure what’s going on there. I didn’t include the links.
While researching oxalates…
I spend a lot of time researching quality information for you and one of our reliable companies have gone and done it again. This time Oxbow, our beloved Oxbow, is giving incorrect information.
Here I was reading about the veggies that cause oxalate build up, and I find the list of vegetables Oxbow recommended for bunnies to eat.
Initially the information is quality. But, in my typical fashion, I read it carefully.
Never feed rabbits spinach, cabbage, broccoli (or cauliflower) or Brussels Sprouts.
Feed kale sparingly – it is addictive.
Swiss chard (silverbeet) is a heath hazard.
Only feed herbs sparingly.
Feed Mustard Greens sparingly.
If you want more information about why this is the case, have a look at the Diet section in the Health Library. To start you off, have a look at Good and Bad Foods.
Back to Oxalates…
Oxalates are usually paired with goitrogens – they are the substances that disrupt the production of thyroid hormones.
So, for many of us the concept of goitrogens are probably new. So, I’ll give you a quick run down of what they are and what they do:
If you have thyriod problems, you’ve probably heard of goitrogens (goy-tro-gen). You may have even heard that foods with goitrogens in them should be avoided.
Goitrogens were first found in 1928, when a rabbit was eating fresh cabbage and the enlargement of its thyroid gland (goiter) made scientists want to poke and prod it in different places. By doing that they found that goitrogens affect the thyroid in adverse ways. Here’s the scientific information on that.
There are three types of goitrogens: goitrins, thiocyanates and flavonoids.
Goitrins and thiocyanates are produced by plants when they are chewed, sliced or damaged. While flavonoids are the healthy antioxidants and are in lots of different foods, like red wine and green tea. However, some flavonoids are converted to goitrogenic compounds in the gut and this can cause issues.
If someone has thyroid problems eating foods with goitrogens can make it worse, by blocking iodine intake, stuffing up the thyroid peroxidase (TPO) enzyme, and reducing thyroid stimulating hormone (TSH). All of these things can affect metabolism, body temperature, heart rate, protein production, calcium levels and how bodies use fats and carbs.
Goitrogens are in vegetables, fruit, starchy plants and soy-based products, and most of these are the foods we feed rabbits.
Cruciferous Vegetables
- Bok choy
- Broccoli
- Brussels sprouts
- Cabbage
- Cauliflower
- Collard greens
- Horseradish
- Kale
- Kohlrabi
- Mustard greens
- Rapeseed
- Rutabagas
- Swedes
- Turnips
Fruits and Starchy Plants
- Bamboo shoots
- Cassava
- Corn
- Lima beans
- Linseed
- Millet
- Peaches
- Peanuts
- Pears
- Pine nuts
- Strawberries
- Sweet potatoes
But, you don’t have to worry too much about goitrogens, unless of course your rabbit has been diagnosed with a thyroid issue. But let’s have a look at a rabbit goiter anyway.
Rabbit Thyroids
Studies showed that when a rabbit was given cabbage as its only food, it developed thyroid hyperplasia in 2 months. The thyroid continued to swell after three months and developed into a goiter of 45g. The goiter lowered the rabbits metabolism, but when given small amounts of iodine, its metabolic rate increased and over time the thyroid hyperplasia reduced.
Kale on the other hand, causes more significant thyriod problems in rabbits. In a disgusting study of rabbits, six castrated males were kept in separate cages and fed on dry kale, old kale, new kale or standard pellets. The study lasted eight weeks, where the rabbits were pinned to a board in a clamp through their face and forced to eat. If the rabbits struggled, they were patted along their back. You can see the device in the full article if you’re into torture devices. Through this test they learned that over 15 hours new kale causes a 70% increase in thyroid issues, old kale 60% increase, dried kale 30% increase, and pellets only 20%.
Should I be worried?
Not if you feed your bunny limited amounts of vegetables and salad foods.
Here’s a bunch of links to articles that will help you: