4-year old mini lop with litterbox accidents and hind limb weakness

Question
Hi, my bunny has had 3 lots of surgery for his teeth. He is now doing fine in that area. At one stage for some reason his back leg was limp and he was dragging it. Now he is fine. But when he is on the carpet he purposely drags his hind legs and pulls himself forward into this huge stretch. This winter was the first time we have seen him run and sit next to the heater. I am wondering if he has arthritis; an after effect from some of the medication he was given.  
He was beautifully kitty litter trained but for some reason he wee's next to it or runs around us and does a circle of wee??? We have laid newspaper when he was unable to jump in his kitty litter..he is quite okay now. When he sees us he gets very excited and either sprays or wee's circling around us at the same time. Sometimes his excitment is really crazy. It is horrible having wee all over the place especially since he has never been caged at home. We don't know what is going on but we suspect he is behaving like a young teen. I am afraid to take him back to work with the school children in case he wees on the carpet. He was working with children 4 days and sleeps in a cage over night while he is there.
Can you advise us please?

Answer
Dear Sahar,

I'm glad you're not going to take him back to the classroom, because that's no place for a rabbit.  Please see:

http://www.rabbit.org/faq/sections/classroom.html

Your bunny's behavior and his age make me suspect that he could be starting to show signs of a parasite known as Encephalitozoon cuniculi.  This can be treated with Panacur (fenbendazole; do NOT use albendazole, as it has high toxicity) and/or ponazuril from your vet, and the sooner this is started the better.  Once neurological and renal damage have been done, they cannot be repaired, so prevention is essential.

Please read:

http://www.rabbit.org/journal/3-2/e-cuniculi.html

and find a good rabbit vet here who can help you:

www.rabbit.org/vets

Arthritis is a possibility, but he's pretty young for that.  If the vet suspects arthritis, this can be treated with a good NSAID, such as metacam.  But I would not rule out the possibility of E. cuniculi, especially since treating him now could prevent paralysis and other serious complications later.

I hope this helps.

Dana