[FlorayG]

I've tried everything that's pet friendly and nothing works even half as well as a pressure washer. I resisted for ages too but in the end borrowed one ( you can buy one for £30 if nobody has one to lend)
The only pet friendly 'chemical' I know of is Algon, which does a fair job. You only have to keep your pets off until it's dry then it's safe. But once it has worked (takes about a week) you still have to scrub the gunk off