Patience is the key. 11 years is a long time to be top dog/animal in the house before having to share attention. Something that's worked for me is to make sure that you always acknowledge and give attention to your dog first when coming home, coming into a room, getting up in the morning and greeting the animals, when feeding, etc., to let him know that he's still, and always will be, first. When I feed my dogs, I feed them in the order that they came into the pack. They do keep track, believe me!
The advice given by others to offer a treat to the dog before giving the cat an attention (after you've first given him attention, of course), is good too, IMO.
Beth and Joe
Camping Buddies: Maddie (maltese/westie?), Kramer (chi/terrier?), and Lido (yellow lab)
2017 Keystone Bullet 248RKS
2014 Aliner Expedition Off Road
2013 Ram 1500 HEMI