will red fox urine scare away gray fox if used in a post set?

no

Nope. It will attract them......

I read a argument on here about takin a dog with u on your trapline an it seemed ppl used their dogs to find spots where fox urinated and then put sets there an put sets where the dog urinated so as for ur question I imagine that if a dogs urine doesn't bother them then one fox to another wouldn't but that also rasies the question instead of buyin fox urine should I just start bottlin my dogs and save money that way from what I've herd if its a canine it's just as good?

that would be an interesting observation you made, plus it would save money .now i'm thinking! as for pee any pee including your own will attract fox

I've heard that for years and last season tried it. Without getting my trapping log out for the exact figure, I can say I caught at least 3 or 4 fox on human urine alone, no bait or other attractant.

I think almost any urine will attract a wide variety of species.

So there is no recorded results to prove this? Sounds like it would be an experiment worth trying out.

Yeah, especially them!

I don't know of any published experiments.

I simply made two new dirt-hole sets on a farm I was already trapping. I peed down the hole and on the backing. No bait or lure or any attractant other than my pee. I caught fox...

I keep all my set info in a trapping log...so my results are recorded