Dusty's Mom,

In order; Yes dogs can grieve for a 'missed friend'.
Signs can be not eating, not being active, or just
mopeing around, or wanting to go off by themselves
alone somewhere ,and sometimes pacing or whineing.
What can you do ? Not much I think. Maybe getting
another younger dog for company after a week or two.

Is this something you are seeing with a dog now ?
They can be so pitiful looking, and it hurts the heart
to see them go through the grieving process. Dogs
can get past the sadness with time...