Sadly the members of the pack you now have will not have the longevity we humans do. Orson Scott Card commented on it in one of the books in the Ender series about how we have so much trouble so often opening our hearts to our own kind in order that we might avoid any potential pain they could cause us. He then wondered at how we can give ourselves so utterly and completely to creatures whose lives are so much shorter than ours that the very shortness of their lives (and how completely we give ourselves to them) guarantees that they WILL bring us pain in their passing. So, my thoughts would be love and care for the ones you have as you have been. Give them the best life, the best home, the best of yourself that you are able. Then when that sad day comes that one must leave you, then you will have the room, and at that time (more so than now) your heart will have the need.