My dog, Summer, is still not herself after over 3 months. I have a feeling this is her "new normal" but I have seen her age more in the three months then her whole 13 years since her "canine sister" died on the first of the year.
Unfortunately even though we tried to keep her routines the same she adamently refused this. She loved her back yard and would beg to go out first thing in the morning and stay out as long as we'd let her. She hated the back yard for quite a while after and even still just doesn't like being back there. She likes to spend time in the garage, under "her desk" and that is basically it. We try to spend as much time with her as she'll allow it and encourage her to be active and spend time with the family and she loves to go for walks now more then ever.
We did end up trying a natural remedy called Rescue Remedy that was suggested from a holistic vet asst that I know that I think did help her. I had to call around to the health food stores to find it in my area.
Perhaps in your case a new friend would be good for your dog. But not a puppy or even too young a dog - if she's 13 it may be too much for her and make things worse.
I'm sad to hear about that, poor girl. Yes, dogs do grieve, and I think we need to treat them the way we would our human friends. Love, support, affection, treats, company. But definitely routine and normalcy in life too. We can't let them wallow in it.
It's so sad though. Dogs have a family, pack mentality that is so profound and that I don't believe we can even begin to understand. I cannot imagine the sense of loss that they would go through with losing a member of their pack. It must be utterly bewildering, because you can't explain to them what has happened, so the shock and confusion involved must just make things that much worse