I want to say there was a story about a crematorium lying about these things recently. In general, I think you just have to trust that your vet has chosen a trustworthy company.
When my animals pass, they will be cremated and/or I will harvest their bones and keep the skeleton and/or I will keep certain parts depending on my feelings at the time. But then my undergrad degree will be in anatomy, so I'm....a unique individual.
