Cats vs Gizmo.

I don't expect Gizmo to love and adore all felines that cross his path, but the crazed lunging has got to stop. If a cat is in his sights, he goes nuts and tries to get at it. Up on his back legs, stiff, waving tail and absurd squeaky yowling or non-stop barking. Frantic leaping at the fence, climbing on the hen coop so he's got a better vantage point, throwing himself at trees. It's going to end badly.

I don't know how to stop this, it's not like I can snag a neighbour's cat in order to get him used to an individual.

To be honest, I would settle for indifference.

he's 18 months and has pretty much always reacted to cats like this.

Some staffs have an intolerance to cats its the terrier in them can't be helped just managed bit like a human taking a dislike to someone .

I really don't want him killing a cat just becuse it's got into our garden though.

Hmmm can see the issue. I would use the "Look at me" command when out walking so as to distract attention away from said cat, however, the cats that come into the garden are going to be a little more difficult.

Most cats are pretty clued up as to where dog gardens are, we used to have a few in our garden but since Flo has owned it, it has been pretty much clear of them. I really don't know what to suggest with the garden issue