I live in Ontario, Canada and we have a healthy population of coyotes here. I have come across them twice so far with my dog which was a 3 year old rottweiler at the time, he is now 4
First Time
We were on a school soccer field simply walking around, the field is was fenced off with the other side of the fence being a small trench then there being a second fence with a large field being there with tall grass. As I was walking around the field with my dog off leash I noticed he stopped right at the fence and was staring across both fences. I walked over looking towards where he was looking and saw nothing, it was only after I nearly reached him that I saw the coyotes eyes then the rest of it staring back at him. Once I said hi to it the thing took off.
Second Time
Was walking my dog on leash and through the neighborhood. Along the main road are houses with no neighbors behind them, only to the sides. As we are walking both of us stopped because between two houses was an empty lot and we saw a coyote about 15 meters away from us. It looked at both of us and we looked at it for a few seconds before it ran towards the field a bit, stopped, looked at us again, then faded into the grass. It looked creepy due to how the light from the light post was shining in its eyes. Like a yellow eyed demon.
Never had an attack but apparently in other areas they have gotten bold to the point of walking on main roads during the day and jumping into yards. I have read that a lady was walking her dog and the coyote tried to get her dog because it was small, only when she picked it up did it go away.
Honestly, unless you have a good strong dog that can defend itself like a rottweiler, pit bull, dobermen, german shepherd, mastiff, or something like those keep a close eye on your pets at all times. Keep them indoors or if you are outdoors with them try to be in a secure place like a fenced off baseball field. I'm personally not worried about one or two when I'm walking my dog, but at night we can hear packs of them howling sometimes and that is the only thing that would worry me.