excessive urination

Question
I have a three year old (adorable) mini rex bunny.  It is a male and has not been fixed. Rocky lives in an indoor single rabbit habitat.  His diet is plain rabbit pellets and timothy hay.  Recently, over the past two weeks he has been drinking more than usual and urinating excessively.   His litter box develops a puddle over the yesterday's news pellets in just two to three days where as he could go for at least a week or more before the box needed to be changed.  He is acting just fine and he looks fine, but I am concerned.  The only thing that has changed in his diet is that the plain rabbit food pellets that I had been giving him weren't available and I purchased a bag of timothy hay enriched pellets.  I have no idea what the problem may be and I would love any input you may have.  I am really hoping that this does not mean diabeties!  Greatful, Denise in Waterford, CT.

Answer
Dear Denise,

Excessive urination and excessive drinking can be a sign of diabetes, but this is very uncommon in rabbits.  Unfortunately, it can also be a sign of renal disease.

The only way to diagnose this is via bloodwork, preferably coupled with measurement of the urine's specific gravity, to see if your bunny is properly concentrating his urine.  If he's not, but is still acting normal, the vet may tell you that he's able to maintain his own osmotic balance by drinking as he sees fit.

In late stages of renal failure, subcutaneous fluid therapy may be necessary to help your bunny maintain comfort and function, but your vet will best be able to guide you there.  You can find a good rabbit vet here:

www.rabbit.org/vets

It also could be that since the weather is very warm, your bunny is drinking more to keep cool.  We do see this in the summer.  But it's best to be sure there's not an underlying health problem that needs to be addressed.  Normal water intake for a mammal is about 90-100ml/kg per day, including the liquid taken in via foods containing water.

I hope this helps.

Dana