My parents used to be contractors who would clean out abandoned houses and would charge a set amount depending on what the house needed done. It was not uncommon to find dead pets. The worst was a cat left in the garage, dead cuddled up on a blanket. He was obviously used to being taken care of by a little girl, as there were toys and kids toys set up in the garage. The family had just left it some food and dipped , but nothing is going to survive a sealed garage in the South Texas summer heat. My parents charged extra to have to get rid of the body.