Cyd came in the other evening with a black mark on the back of his neck. The smell makes me think that it's oil. I tried to remove it with a new J cloth and warm water, but this had no effect (Cyd liked the fuss, though, he's getting really affectionate). It spread the mark about a bit, but didn't get any off.
I considered using washing up liquid, but remembered reading that it was toxic to cats, so I left it and he still has a black mark on his fur.
Is there anything safe for cats which I can use. Something easy to obtain would be great. Thanks.