I really do think it depends on the dog. We have three. Jack, our Mini Aussie, is VERY curious about the chicks. I've let him sniff at them, and, so far, he's been very good. Stella, our Beagle mix, is pretty slow and laid back, so I'm not too worried about her, either.
Then there's Zoe. Zoe is a Husky mix. She will chase anything that moves. Our chicks spent their first night in the coop last night, and I literally had to drag Zoe away to put her up for the night. She's been out at the coop since we let her out this morning, sniffing around, and trying to find a way in. I tied her up to the picnic table while I fed and watered them, today.
We're going to be building our run while the chickens get used to their new home, and I'm accepting the fact that Zoe will be our predator test case. If we can keep her out of the run, I'm pretty convinced that foxes, coyotes, raccoons, etc. won't be able to get in, either!
And the good news is, I know no other daytime predators will get near the chickens, with Zoe lurking around the coop all day!
Good luck, Carlton!