Oh my goodness. I would have been a wreck too! I agree, you would have had no idea what a potential problem you could have on your hands had you not been home.
I know they are in our area too, my husband and neighbor have both seen one on our dirt road. I know they are pack animals, so if you see 1, there are others lurking somewhere close. It may be that it's a female looking to feed it's pups in a nearby den.
I also let my girls out during the day. I was surprised to see 2 black dogs up at my garage one day last week, I went flying out there hollering at them, and they did leave. My dog is great with my chickens, so they may not even know to be afraid of dogs.
We've also got guns, but with small kids, they are unloaded, in a safe with the ammo in a different safe. By the time I figure the combinations to both safes, figure out how in the world to load the gun, I'd be way late. Guess I'm better off hollerin for now, LOL! Oh, but I do always have a shovel or rake out by the coop, I could grab it in a pinch....