This afternoon when I emptied Mimzy's litter box into the trash, I was kind of blown back by the smell of ammonia from the used litter. Now I am used to this with the cat litter boxes and know that if it sits too long it tends to get worse. But in the almost year and a half that I've had bunnies, I haven't yet come across ammonia smell in a rabbit's urine even when the box sits for long periods of time. And today I had half a dozen things in my way before I could get to the cage cleaning.

Could the litter have smelled bad because it sat extra time today? The other bunnies' boxes don't smell this bad and I just finished them. Could Mimzy be passing something through that's left over from his upset tummy/mylicon episode the other night? Perhaps the red leaf lettuce made his pee a little stronger? (Which he is no longer eating, btw, I switched him to romaine and he still has italian parsley each day.)

I just want to make sure he is not ill. (Of course, I have to worry like this at the beginning of a weekend.)

I have smelled the ammonia smell b4 with buns.  Sometimes a food will make a change in smell.  Anything else I dont' know. Hopefully someone else can come tell you if it is a go to see a vet issue.  I doubt it but I am not experienced in this area. Though as I said I have smelled the ammonia smell b4 especially in HB's litterbox.  He is bigger and pees more than the other smaller buns I have.

yes, it could have smelled worse if it litter had sat longer.    I also read somewhere that bunnies may drink less in winter.   (though if it's cold, they eat more as it takes more energy to stay warm and if they eat more than they would drink more)  However, what I'm trying to say is...IF you notice yours drink less, or one is drinking less, this can lead to a more concentrated urine.  Do you notice that it is darker in color or anything?  That can also sometimes indicate less water consumption.

On another note - this reminds me of your other post about Mimz recent eye problem - IF he was in a litterbox that was soaked in strong amonia urine, this can cause eye and respitory irritation.   So this post actually may help explain your other post.  ???

Also, something else is nagging me about some relation to a strong amonia smell - that I am missing something.   GRRR!  I did a quick research to see if something would remind me, but so far nothing has hit.    I'll post again about it if I can remember. 

yuk I can relate. I have a seperate trash can just for litter box changes that is outside on my balcony. I have to change Honey's litterbox everyday in order for it not to smell like a barn in my house ~.^

Oh yes.

I'm reluctant to empty the litter box every day because I hate wasting so many plastic trash bags (biodegradable litter in non-biodegradable bags makes no sense to me), so I tend to layer litter for up to a week. What a mistake! It doesn't smell until I disturb it, but then it's awful. You'd think I'd have learned by now...