It sounds as iff he is bored,wouldnt you be if you had to eat the same boring dry bickies day in day out??And then getting them as a treat as well,it's not really a treat in your dogs eyes if he gets it for his main meal aswell,why not try liver bits or you could make a liver or sardine cake to use as training treats.
Why dont you introduce a bit of "variety" you can mix extra's in with his dry food such as,cottage cheese,yoghurt,sardines,pilchards,chicken broth,chicken,beef,lamb,rabbit.The list goes on and on!
It truly breaks my heart when i hear of dogs having to eat the same food for breakfast,lunch and dinner for ever.Eating is what dogs look forward to the most imo(and walks)why not try and make it as interesting as we can for them??I have shih-tzu's and they never get the same meals 2 days in a row,lettalone the 2 same meals in a row on the same day

Variety is the spice of life :D I also alternate my dogs dry food each month when the last bag runs out,they only get dry in the morning with added extra's and homecooked for dinner.
As for changing to Burns,well there really is no comparison with euk., one is a super premium food the other is a so so brand,i would definately change to Burns,have you tried naturediet?alot of people mix burns with naturediet with great success.
christine