What goes in a letter of instruction? This article chronicles the evolution of enforcing after-death gifts for the benefit of pet animals.Part II reviews the common law background. 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. You seek out a law firm that can help you set up a trust for said cat. You also have to make arrangements for SOMEONE to take care of the cat. Providing for your Pets in your Will – Sample Will provisions and Pet Trusts. Fill out your free custom Pet Trust document - guided step-by-step! A traveller comes to a fork in the road which leads to two villages. Many of the best responses are later in the list.