Our 2 1/2-year-old rescue cat, Mouse, passed away unexpectedly Saturday evening. We aren't sure what happened. He had been acting a bit "off" for a few weeks. He stopped using his litter box and seemed to spend a lot of his time hiding from us. But, when we took him to the vet three weeks ago, he was perfectly healthy (other than having a few fleas) and, when he came out of hiding at night, he didn't act sick. He wasn't losing weight, would still eat his food and drink water and would let us pet him and play with him. Friday evening, he was growling a bit and seemed somewhat lethargic. But, Saturday morning, he seemed perfectly fine again. Then, suddenly, Saturday evening, I heard him making a strange noise from under our recliner and, by the time my wife and I were able to get him out from under it, he was gone. We were all devastated by this loss, especially my youngest daughter, who would carry him around the house like a rag doll and would have him ha...