Oh how sad!

If they really want to know, their vet can do a necropsy. I had one done on Bill last year when he died suddenly; I needed to know if it was something contagious, with so many pets in the house. I only had the organs reviewed. They "could" have sent out samples and blood work to a lab, I didn't request that. As it turned out, the organ reivew showed his liver was fully involved in disease, and that is not contagious, so I had the info I needed.