gaining weight

Question
My lab is 12 years old and his health is slowly deteriorating. At this time the vet wants him to gain more weight.  I fed him "science diet" dry food for seniors with advance protein which is what the vet recommended.  He is also taking glycosomin chews twice daily. The vet said to add noodle or rice to his dry food to encourage him to eat more. Not working! I started adding "Nutro", Natural Choice canned food for seniors, which he does eat very well, but I'm not a big fan of canned dog food! I read the article on "satin ball" to feed poodles? Any homemade receipes to help an old lab gain and maintain weight or other suggestions?

Answer
Most older dogs are too fat.  The purpose of the senior formulas is mainly to pump in enough protein, vitamins and minerals without more calories than the dog will burn.  I would go the opposite route for a dog that isn't eating enough.  If you have confidence in Nutro, I would try their small breed puppy chow.  Nothing packs in more calories.  I don't feel Nutro offers anything for the premium over such chows as Pro Plan or Iams.  

My 13 year old lab is doing very well on Pro Plan adult.