He came from my sisters who had trouble with the housing association and rules with respect to keeping dogs. With the exception of food he is a lovely dog but I've seen this before and it often spreads to other objects in the house. I knew a German Shep once who had exactly the same problem, the poor thing ended up guarding everything in the house and the result was a very unhappy dog.

I've started by feeding them in different rooms and I keep adding bits of tuna to the terriers dish while he's eating just to get him used to people coming near his food. Other than this I'm stuck.

It's very sad but the terrier will have to be rehomed if the issue continues or gets worse. At the end of the day I have to consider the welfare of both of my dogs and if both become unhappy then no one wins.