Do dogs grieve the loss of another dog?

I certainly believe they do. 4 years ago I lost my much loved galgo Polar to lymphoma. Galgo Bracken became very clingy, as did little Podenca Bebe. 3 months after losing Polar we lost Bracken to a tumour in his lungs. Bebe couldn't cope with the loss of yet another housemate and just gave up on life. She would not eat, drink, get off her bed - she was just wasting away, no matter how much we cuddled her, so we had to make the kindest decision to send her over the bridge to join the others.

Do dogs grieve?