bigtoad

I didn't want to ruin the nice day at the doggy park.

He was dehydrated. For whatever reason, he stopped drinking water. We didn't notice because he was still hopping around like normal, and since both bunnies were in the same cage, the water level was still going down. Looks like Buttons was eating and drinking Zipper's share of food and water.
Well anyway, he stopped eating, and drinking, but didn't show anything wrong until it was too late.
When I got home from work Thursday, he was still moving around, but later that night, he wasn't moving around much at all.
It turns out that there aren't many vets in the area that deal with bunnies, so it took us a moment to find one that was open and available, and Friday early afternoon was the soonest we could get short of the ER, and we didn't think it was that bad since he was only showing signs of being sick for about 12 to 20 hours.

That's the thing with bunnies though... when they finally start acting sick, it's usually too late. They are REALLY good at hiding it.

We don't know what made him stop drinking. Buttons was in the same cage, eating the same food and drinking the same water, and she's still hopping around and munching on hay, so it wasn't something external that we (or the vet) can think of...

I feel sorry for Buttons because they used to snuggle together so much. But getting another bunny is not the answer because introducing bunnies isn't as easy as introducing dogs or cats. We thought they were going to kill each other that first couple of weeks, but they finally became buddies.