In reply to Eric the Red:
My condolensces to your girlfriend.
I've experienced both sides of the dog war. I've had to put up with other people's dogs barking add nauseam in closely packed housing while trying to study for exams. I've been bitten by a dog while the owner walked past with it on a lead (and I needed stitches).
I also own a dog and currently have neighbours who are entirely unreasonable and unfriendly towards dogs, even when immaculately behaved. I own two and a half acres of woodland and my neighbours are a long way away through the woods, but if my dog barks at something for more than a few moments, they call the police without even talking to us. We don't have any fences, and if my dog puts a single paw on their land, over the imagined boundary which is a long way from their house, they call the police. That's unreasonable behaviour.
We live in the wilderness (Canadian Rockies), and when out walking in the middle of nowhere, I refuse to keep my dog on a lead. She's a very friendly, relatively small mongrel, and doesn't act in an aggressive manner. And yet, a few weeks back while walking to a crag, I came round the corner to find a bloke standing in a highly defensive manner, brandishing a stick, between his almost apoplectic girlfriend and my dog, who was not acting in a problematic manner whatseoever, and was just stood on the path sniffing the air at this guy thinking 'what on earth is he doing'. The girlfriend was a gibbering mess of tears and distress.
Now that's ridiculous, and the girl in this instance clearly has a phobia that needs addressing, in my opinion. At that level it becomes her problem, not mine. If you found someone collapsed next to you by the cheese counter in a supermarket because they had a phobia of the colour shirt you were wearing, would that make you the bad guy? Let's be reasonable here.
I would also suggest your girlfriend, while not at this level, might benefit from some professional help with regards to dogs, if a barking dog behind a fence is sending her close to a panic attack. That's a bit extreme. But yes, if owners can see their dog behaving ike this close to a footpath, they should, out of courtesy, do something about it. Even if it doesn't scare you, it's just a pain in the arse.
You've probably heard this before, but dog psychology is such that they bark and go mental behind fences because they're 'showing off' how tough they are and actually feel quite safe behind their fence. Remove the fence and they shut up.