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Stones and sludge in rabbits – ugh, ouch!

stones sludge rabbits

Your rabbit is sitting in the litter box, and hasn’t moved for minutes.  It looks like she is up on her back toes, and her tail is way up in the air.  When you check the area, there is no urine, or only a few drops.  These are symptoms that your rabbit has some bladder stones, and THIS IS AN EMERGENCY.  CALL YOUR VET NOW, FROM THE CAR.

Or - you look in the litter box and notice this gunky white stuff instead of the typical pale yellow urine.  While not an emergency, you do still want to do something about this.

UTI, urinary tract infection, blood in urinephoto credit: wabbitwicki

What are stones?

Bladder or kidney stones are hard pebbles made up of mostly calcium, and are called calculi.  These stones can pass through the urinary tract into the urethra, even getting lodged there and causing a partial or full blockage.  If you’ve ever had a kidney or bladder stone, you know how incredibly painful these can be.

What is sludge?

Hypercalcinuria is the fancy name for bladder sludge (sometimes called urine sludge).  It happens when there is an abnormally high amount of calcium salts going through the urinary tract.  These salts are the same nasties that cause bladder stones, but some animals form stones and some end up with this sludge.  Sludge can be as thick as toothpaste, and can feel smooth, slightly grainy, or even gritty.  Imagine that going through your urethra – OUCH!

Why do these things happen?  Nobody is quite sure yet. Why do some animals get stones, and some sludge?  Nobody knows that yet either.

In rabbits, it may have something to do with the way calcium is processed by the body.  Rabbits have much higher levels of calcium in their blood than any other pet mammal (everyone else has about 2%, rabbits have 45-60%).  Rabbits hold on to more calcium than they need at any given time.  This might be due to the irregular forage available to their wild ancestors, but there is no clear evidence yet. 

hay, timothy hay, orchard hay, orchard grass, alfalfa, alflafa, aflalaImaging of rabbit with stone.  
Photo credit Mathilda on Flickr

For a long time, the belief was that a diet too rich in calcium would contribute to both sludge and stones, but recent lab tests have shown that to be false – for several months, the test rabbits were given diets many times higher in calcium than any diet our house rabbits would get, and yet the test rabbits did not develop sludge or stones. 

Particular breeds may be prone to stones and sludge, or maybe there is something else in the environment that kicks off an imbalance.  Male animals are more likely to suffer from blockages than females, due to their longer urethras.  Animal who are overweight have a higher rate of problems than those who are fit and active.  Age seems to make no difference at all. Infection of the bladder seems to increase chances, as do polyps.  At this point, it looks like both stones and sludge are caused by a perfect storm of a variety of factors.  In other words, a few different problems are going on at the same time, and the stones or sludge can be seen as one more symptom of these other issues. 

How can you prevent stones and sludge from happening?

Can you do anything to protect your friend from having to go through all this discomfort?  There are a few things you can do to help prevent calcium from getting out of whack. 

Make sure your rabbit drinks plenty of water.  Try heavy flat bowls instead of hanging bottles, since our friends often don’t drink as much from the bottles.  Make sure the water is fresh, and that nothing is added to it that might make your friend refuse it (meds, for instance). 

Make sure your rabbit has a clean litter area, and that the placement meets the rabbit’s approval (a rabbit who doesn’t like the placement will simply avoid using that litter box).

Your rabbit may have a Vitamin B6 deficiency, or some other issues (bladder infection, kidney disease) that you don’t know about yet, so a trip to the vet to do some testing is a good idea.

We do tend to talk about litter boxes and their contents a lot, but there is a great deal of important information in there!  Never feel silly taking a good look at The Box, even poking around in there a bit.  The Box is a treasure trove of clues to your animal’s health.

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