My terrier is 11 years old and has an old spinal injury and nerve damage which limits the amount of physical exercise she can have. She also shouldn't play tug games because of her fragile discs. She is somewhat grumpy and aggressive (unsurprisingly) and mostly just wants to play rough games where she savages you on the ground and you submit. She's a bit deaf so all her games involve a cacophony of 100db barking.
She's on permanent pain and anxiety medication. She's a clever dog with great scent tracking abilities, but over-anxious and easily frustrated. We've tried various things and even deployed professional trainers over the years - she is very wary of anything new and is reluctant to try, then she simply walks away (especially if you try to target a prop, like a box or a mat). She stops engaging after only a few repetitions, so you can't really progress to the next step.
Any ideas? She's about half a kilo overweight (quite a lot for a 6 kg dog) so need to go easy on the treats....