Here is a link to a great interview with veterinarian Nancy Kay. She wrote the book Speaking for Spot. She discusses the difficulty associated with making difficult decision associated with expensive medical treatments and euthanasia. While this is not a pleasant topic to talk or think about, it is something that most pet owners will be faced with at some point. Simply listening to the interview that is posted on the linked web site will give you resources and perspective to make difficult decisions without regret.