fox or coyote?

so just this morning i am sitting at the computer reading about how captain phil(deadliest catch) died and out of the corner of my eye i see this beautifully colored tail walk by the on the wall in the backyard. just as it passes by chewy starts growling.  i hurried out to see what it was (i thought it was a house cat)the old guys on the street have told me to be careful with the kids and the dog in the backyard because of coyotes/foxes/mountain lions(seriously the coyote thing doesn't bother me much we heard wild dogs/coyotes all the time in tucson).  well when i realized it was bigger than a cat i ran back to get my camera(just as you walk in the backdoor on a shelf) because i new jeremy would never believe me.  that sucker was fast because by the time i was out to take the picture he was 4 houses down .  i started taking pictures and he stopped and turned around and headed back a bit and then turned around and went on his way.  i wish that the pictures would have turned out better but he was in the shade and i had the sun on my back so i couldn't see the screen on my camera. 

now i wonder should i be more careful with the kids and dog?  they go in and out all the time when i am in the shower etc.  so should i check first then let them out?  does chewy sound fierce enough to scare away anything?