http://www.i-mockery.net/viewtopic.php?t=5606
We're 90% certain that it was a twisted gut. He was sick a few times yesterday, and he kept going outside to be on his own, but we figured that he would recover from it. He had sudden bursts of energy, and by the end of the night he seemed fine. It took less than 24 hours, and we were actually planning on taking him to the vet this morning if he still seemed unwell.
What gets me is that he was only 5 years old and that we had pretty much no time to do anything about it. He was just a big baby, I really can't get my head around it.