First have a will made out and leave money to those who take her so they can take care of her, then decide if you want to bury her or have her cremated. When my 16 year old Delsi was on a decline, friends of ours bought her a nice casket that doesn't deteriorate in the ground.
Small Eternal Rest Pet Casket - Cat, Dog or Other Pet I knew I wasn't going to have her cremated due to the expense of it. (To make sure your pet is the only one cremated, you can be there to see the empty crematorium and wait till they are cremated, but it's terribly expensive).
I'm happy to see your thinking ahead like this. It's such a comfort knowing your babies will be taken care of in your passing, or while your alive.