Our run is 8ft high. Foxes have NEVER got in. Last year neighbours cat (a Bengal) climbed in, grabbed an Amberlink and dragged it out over the top. Fortunately, a mechanic here at time saw it happen!
Hen was ripped and died! Neighbour didn't believe us! Told her I'd shoot it if it came near birds again! They put framed mesh roof on top of run!
Haven't seen cat lately!!
I like cats. Just don't want them peeing / crapping on my hay or attacking my birds!