Rabbit has chronic digestive problem

Question
I have two indoor rabbits which are litter box trained.  The older of the two is a neutered male (unsure of exact age).  I've owned him for about 2 years now having adopted him as an adult.  When I first brought him home his stool was normal.  Unfortunately I didn't know much about rabbit nutrition and put him on a very bad diet which included lots of treats (dried bread, wheat thins, etc).  It wasn't until he had a couple bad incidences of constipation that I was taught the errors of my ways.  Since then I've put him on high fiber pellets, timothy and oat hay, and the occasional veggies (parsley and carrots with tops).  I even cut the veggies out for a long time thinking that would help.  However, his droppings never normalized and its been a year!  They are irregular in shape and can be anything from a tiny drop to a HUGE egg shape.  I can't stress the size enough.  They are sometimes larger than what you'd expect from a Flemish Giant and my rabbit is just a 5 lb mini rex.  My vet ran all the tests and determined that it wasn't parasites, disease, etc and approved his diet.  The rabbit's stool smells really bad but its not full-fledged diarrhea.  Also, it doesn't stick to his bottom.  I just don't know what to do.  I'll never be able to sell my house with it smelling like this.

Answer
Dear Rita,

The droppings you're seeing sound like abnormal cecotropes, and the information here might help:

www.bio.miami.edu/hare/poop.html

though it sounds as if this isn't really a true case of cecal dysbiosis.

I have what might sound like an odd question, though.  What color is the bunny?  If he's mostly white but has dark eyes, he may suffer from a congenital condition in which the cecotrops do not always separate from the regular fecal pellets, and combine to make what we not-so-affectionately call "cowpoops."  You'll see these marshmallowy, big, weird poops only intermittently, with normal fecal poops found at other times.

If you think this might be the case, please let me know (dana@miami.edu), and I'll send you more information on how to handle this problem.  It might never resolve, but there are things you can try.

Dana