It can be very hard to tell when the "right" time to say goodbye is because it's not a black and white issue. There is a window of time where euthanasia is an appropriate and loving decision to make. “The three things rule" can help decide when the right time is. So long as they are doing all three of the things that have brought them the most joy over the past few years, life is good. When they are doing 2 of the 3 things, but not finding pleasure from one- it's time to start getting yourself prepared that the end is near. When they are only doing one of their 3 formerly favorite things, I think that's when it's time to let him go- while they still have dignity and are feeling joy. I feel there are a few exceptions to when the “three things rule” doesn’t work as well. Those would be if they can’t catch their breath and if they can’t get up to get out of their own mess. The first is very scary and anxiety inducing and the other creates unsanitary conditions for your pet. Most importantly- don't let them wait until they are suffering.