Jamie
There cousins hyenas etc attack lions on an empty stomach so I would say yes
bluebonnetgranny
Depends on how many are in the pack of coyotes. The dog doesn't have any experience in killing or fighting & would end up being torn to pieces by the coyotes. I would be very afraid for the dog. It has no experience doesn't know how to protect itself from many coyotes. Coyotes are very coy & could easily take down the dog if there were enough of them, they hunt in packs.
The First Dragon
As somebody mentioned, coyotes rarely go in packs. They also mate freely with dogs, when they get a chance. So they regard dogs as the same species, though the mastiff may be a stranger. They might behave aggressively toward the mastiff to make it go away, especially if they have pups. And if they are defending pups, and they think the mastiff is getting too close, they might bite. You could call this an attack, but really it is a defense and is not intended to kill but to scare the intruder away. Animal control would not consider this as a case of coyote aggression.
Swear
Probably not unless the leader of the coyote pack had rabies and had no sense in its head. And then the rest of the pack would tend to follow the leader
Anonymous
They're not going to go randomly attacking things for no reason, but if they had a reason, then yes