Thank you so much @Michael A Brooks! We’ll definitely try the noise sensitivity training and see how it goes. From what I’m reading it is a long way to go but hopefully it’ll be a successful one! I’m sure I’ll be posting if there is a progress! Or crying for more help if there isn’t. What surprises me that the vet didn’t really seemed bothered (from what my husband was saying) and didn’t even mention any training, just the plug as according to him that should be enough to get him back to his old self.
I think I understood what you meant the first time too. I’ll start recording Roger to see if I can notice things in his behaviour I haven’t before. As perhaps I thought he had been ok in a particular situation when there might have been signs of him getting stressed already!
Good luck. And happy to hear about your training. It is my understanding that Vets learn about classical conditioning. But beyond an introduction to the concept they don't do any dog training nor do they study dog behaviour theory as part of their course. They are experts on physiological issues. Not behavioural issues. By reading books written by dog behaviourists, threads on this site and training your own dog you are going to understand more about dog behaviour training than the typical vet!