Bit by dog

I was bit by a dog pretty badly today on my route. About 7 dogs loose, behind an invisible fence, was turning the van around, thought I was in the clear to walk over to the delivery tote that shouldn't have been anywhere near the dogs. 2 tried pulling me out of the van, had I been a smaller person I may not have been able to pull myself away. I got away, called the police, have a police report, and will be seeking medical attention in the morning, but I'm not sure about how to go about making sure this doesn't happen to somebody else.