My bunny was diagnosed with renal issues last night. In part he has an elevated BUN. The vet suggested adding beet greens, beet pulp or dandelion greens to his diet to help absorb some of the nitrogen. What is the science behind this chemical reaction? Are there other sources of what ever the good stuff is in battling the high nitrogen?
While I can't find any reputable Veterinary source that states or explains this, I can tell you that Farmers use Calcium Carbonate (Agricultural Lime) to treat acidic soil. The idea is that the Calcium replaces the acidic factor, in your bunny's case, Nitrogen, and that the Nitrogen reacts with the Carbonate to create Carbon dioxide and Water. This causes the soil to be more alkaline
This principle is explained at length here: Correcting soil acidity
As for battling the high BUN:
While I am nowhere near being a Vet yet, I would suggest you assess what you are feeding your rabbit.
Any food high in protein, such as Alfalfa hay, will cause it's BUN to rise, because BUN is a byproduct of the body breaking down and using proteins.
Rabbits can't process dairy products very well. It would be best to avoid GI upset if there are renal problems present.
Long stem fiber will help to keep bunny's gut from going into stasis (not moving).
Overall, the best way to combat Renal problems or failure is through dietary management. Should the beet tops and dandelion green prove ineffective, you can ask your Vet about Nitrogen binding medication, as it may be available for rabbits.
Disclaimer: I do not know that this answer is correct. I have linked the sources of information where i have found them. This answer is based on my experience and research, but beet greens and pulp and not a food source I have experience with.
The most common nitrogens in the blood (particularly ammonia) are alkaline. In fact they commonly have a PH in the range of 10-11 which is fairly basic and can react with many tissues in ways that cause damage. Most of the time the body handles this by filtering out the ammonia in the kidneys. But if the kidneys are compromised(renal issues) they can not filter out these compounds as fast as they are created. So the intent is to counter them with substances that will naturally react to neutralize the reactivity.
I found this except from a book which i read to basically say that the beet pulp reacts with the ammonia to neutralize the effects. In this case we are not looking to cancel out the beneficial effects as was seen in the article but to neutralize the ammonia in the blood stream so that it does not cause damage.
I have always used parsley to help with kidney function, and have seen it recommended in other places. It helps the rabbits kidneys clean out and function properly. In season there is nothing my rabbits enjoy more that dandelions. They are purported to have the following benefits:
DANDELION – Blood purifying, respiratory ailments, anti-inflammatory, bladder infections, diarrhea, milk flow of nursing does, good treat for does after having a litter. Some rabbit respiratory problems, such as pasteurellosis, can eventually cause serious problems including head tilt, loss of balance and death. There have been tests on rabbits that were treated with dandelion’s showing that it is effective against pneumonia, bronchitis and upper respiratory infections. Use fresh leaves, flowers and dig up root, the root can be dried to make a weak tea to add to the rabbits water. Well known for its curative powers. The bitter milky sap stimulates the working of all glands, including the milk glands of lactating does. The plant has both laxative and astringent qualities and regulates constipation and diarrhea.
You may also want to consider lavender. I use it quite often with my expectant mothers and its claimed calming effects I believe in:
LAVENDER – Circulation problems, nervous stress, exhaustion, induces labor. To bring on labour or expel placental material etc. in problem kindling’s. Use with caution. sparingly. in extreme cases only. The flowers are actually a mild tranquilizer, acting upon the heart in easing blood pressure rather than acting upon the brain as an anti-stimulant. Great for stressed out rabbits.
The other thing i found was Milk Thistle. I have no experience with this but it appears that it is a common supplement in health food stores. I do not know how it works but so far my experience with the this medicinal herb site has been completely positive.
MILK THISTLE – Helps take ammonia from the blood and protects both the liver and the kidneys, increases milk flow in nursing does
I have not spoken to the vet again to ask for clarification (next appointment in 2 weeks), but this is what I have learned.
There is a class of food described as 'fermentable carbohydrates' these include sugars and starches. Some sugars are absorbed by the bunnies digestion and some travel through to the cecum where they encourage bacteria to create protein. There are lots of different 'fermentable carbohydrates' and beets are a good source. Beet pulp which has had all or most of it's sugar removed is another source.
Bacteria are important in the 'Nitrogen cycle' resulting in the conversion to proteins. When 'fermentable carbohydrates' have traveled through to the cecum, they pull nitrogen from available sources. Not all 'fermentable carbohydrates' are equal in this process, as described in this study 'Transfer of blood urea nitrogen to cecal microbial nitrogen is increased by mannitol feeding in growing rabbits fed timothy hay diet' which compared glucose to D-mannitol. The rabbits in this study who consumed D-mannitol had about 50% less nitrogen in their blood as those feed glucose.
In all cases balance must be maintained, and diet changes should be slow (see Do I need to do anything special when I change what I feed my rabbit?).
In the end it seems that encouraging gut bacteria will help strip access nitrogen. In the rabbit with renal issues like elevated BUN this can help lower the high values and make your bunny feel better and be healthier.