A couple of lads I know (Mackems and Mags) were out on Sat and saw some of the bother - they said that it was evidently the hooly brigade out, and that the 'Mackems' (not Mackem football fans I'd suggest) who were acting the cunts, one of them kicked fuck out the copper's dog, and the copper lost his rag and twatted him over the head leaving him bloody as fuck.
They said both sides were well out of order, but I suppose in a small bit of defence to the copper, if you worked with an animal like that every day and someone attacked it, you'd be tempted to lash out. Problem is, as a copper, you need to justify that and I don't think he could.