We've all heard of trainspotting, well now there's dog spotting.

The craze has swept America with dog fanatics walking the streets with notebooks and cameras sharing their days' findings with their internet fanbase.

There is now a Facebook group with rules and a points system, with extra awarded for free-range dogs spotted off the lead and action dogs jumping - but celebrity dogs are the most valuable.

One user recently caught what was said to be a 12 point dog, the Obama's Bo.