We just heard that our [precious Mercury's brother died unexpectedly. He was almost 3, and had been very healthy and happy until a few days ago when he got lethargic, stopped eating, and died. Just before he died, his owner noticed that half his tongue was black. Sounds like poison, but he didn't go outside and lived in a very clean, safe home. The owner should have taken him to the vet, of course, but didn't. Does anyone know what might have happened?