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. When listing your pets in your will, it helps to be specific especially if you own more than one animal.What goes in a letter of instruction? No form should be completed or filed until thirty (30) days have elapsed since death. The first thing to do is to check whether or not there's a Will. The letter is not legally binding, and the friend or relative is not obligated to carry out the instructions of the pet owner. The best way you can make sure that your pet is taken care of after your death is to include your pet in your estate planning.