Hi Leon
From the look of the poor hog on your video, it has been artificially marked. Possibly by using some sort of spray device. I don’t think that a hog would be able to get such defined patches like that accidentally.
I would say you should be concerned about this. If spray has been used it is quite possible that the substance reached the skin. When the majority of the males return and begin to be involved in biffing sessions, this marking may well come off on the faces of other hogs. I have seen hogs looking like completely different hogs because their faces have had such a lot of foreign substance on them – presumably from biffing a hog who had been artificially marked – it was the same colour. This was including around their eyes which potentially could damage their eyesight.
Hedgehogs rely a large amount on their sense of smell. It is possible that being covered in foreign substance (which it is very likely they can smell, even if we cannot) could interfere with their social interactions.
If anyone wants some tips about how to identify hogs naturally, I have included some tips within the following topic
https://www.hedgehogstreet.org/forums/topic/tolerant-hedgies/
