Your post proves I'm never too old to learn something new!! I would have never thought about a limit or to even check on one. I, too, live in the country where we don't even have a leash law
Lots of dogs roaming loose in the neighborhood - that's why we keep our gate closed once we are all home in the evening and mine never go out without one of us with them. Doubt I have anything to worry about, though, with only 2 and no plans to add another any time soon (despite my desire to do otherwise) except for hubby's lab that we'll be getting in another 6 weeks or so.
Good question, I'll have to check into it here where I live.