How do I know when it is best to put my dog down?

How do I know when it is best to put my dog down?

Shelby Marlo, CPDT (Animal Behavioral Specialist, Professional Dog trainer) gives expert video advice on: How long do dogs usually live?; How can I prepare my kids and myself emotionally before putting our dog down?; How long should I wait to get a new dog after my dog's death? and more...