Join Date: Jul 2010
Location: Cobourg, Ontario, Canada
If the bond is as close as you say, the cat will likely grieve the loss. He may look for him throughout the house, want doors opened, may seem depressed, eat less and sleep more. It may take him a few weeks or months to return to normal.
On the other hand if the dog bugged the cat when he didn't want it, hogged more attention, was jealous if you pet the cat and tried to push him away from you, the cat may be happy he's gone and has all your attention. You will know how strong the bond is by how the cat reacts when the dog is gone.