In dogs they can also cause vomiting and nausea, and effect the nervous system and cause comas. Since foxes aren't tooooo far off the track from dogs, I imagine they have similar risk factors.
As a side note, this is a series of pictures it seems, and there's also a magpie involved for some reason (you can see another shot here):
https://m.imgur.com/gallery/UnV4n
https://m.imgur.com/gallery/UnV4n