I know how on top of things you are regarding Callie's general health issues, and how often she is looked at by your vet. Unless you have a reason to suspect that there is a specific physical issue to be concerned about, I would allow her to have some "quiet time" to herself if that is what she wishes. Beau will be 13 in a few weeks, and he still participates in play with his two younger brothers a few days a week. Many days, however, he chooses to lie in one of his fuzzy dog beds and sleep the day away in the sun. That has been our experience, over the years, when our past dogs have been in their final years. They have all been content to be out of the general action of a multi-member household... but free to re-join at will. Trust your instincts if you see it as a problem, but nothing sounds alarming to me. BTW, as a near 70-year-old, I appreciate an occasional "down day" myself!
