@unhurt, "This doesn't suggest increasing numbers of dogs."
It's the existing population of dogs, especially those in urban built-up areas, that is the problem. Or rather, I should say, the behaviour of a sizeable minority of dog owners in such areas.
My anecdata tells me that, at least in the Easter Road/Hillside areas, there appear to be more dogs than when I moved to the area a couple of decades ago. There may be a correlation here with the phenomenon noted in that link - "smaller breeds of dogs have become more popular."
Live in a tiny flat? Can't keep a big dog, impractical (though some do it seems). How about a small dog? No problem, hardly any more bother than a cat. Except for the walks for "exercise". Where is fido going to do that "exercise"? On the street, among the parked cars? Maybe. In the back green? Hm, better not, the neighbours might see. Where then? The park, of course! But a sign says "NO DOGS". How unfair, the "clowncil" are waging a war against otherwise law abiding dog owners! Those busybodies really shouldn't interfere with my fido's right to roam! Oh well, just slip in after dark, nobody will notice until tomorrow when the evidence of the "exercise" sits resplendent on the grass or footpath...