An alternative is to write a letter to a friend or relative stating that upon the death of the pet owner, the animal should be euthanized. What goes in a letter of instruction?A letter of instruction is a document that lists all relevant financial information that your family members or executor need if something happens to you. Your bank account may not go directly to your heirs after you die. Learn how to set things up so that it does. A deceased person's bank account is inaccessible unless you're a joint owner, a beneficiary of the account or the estate executor. I have been a companion to several dogs. To start things off, here's a tribute I wrote for my Border Collie Pearl years ago: