I'm not normally, but cannot stand West Ham, and the thought of them going 4 points clear with a game in hand, when they are not all that, just makes me feel sick.
Seriously get yourself along to the Shirley walk in centre, and up to you if you report the dog. I love dogs, but next time it could be a child that gets attacked by it.
You should have confronted the dog at the time, or reported it to the nearest steward, not asking for advice two days after the event. Dog biting is not saintly!