Hello, we are not dog owners, because dogs need to be indoors and we already have two indoor cats + allergies. But we have a friend in a sudden housing transition who needs a safe place for his dog (an 18 month old retriever/dachsund mix very attached to him). Several other options have fallen through so as a last resort we have have offered our backyard as a temporary home. "Waffles" is both dog and cat aggressive but calm and friendly with people. Our problem is that of course he is anxious and lonely in the backyard and is barking. We dont't know whether it's better to ignore the barking? Respond by going out to him? Shushing him? Keep the blinds open so he sees us but can't be with us? Close the blinds so he feels all alone? Get a vibrating bark collar? This is day one of several and we are worried already. But at present the owner is running out of options. Advice and suggestions welcome!