Our kittens are 4 1/2 mths old and have started to wee in 2 of the corners of our living room. Im not sure if it is because they might need to be neutred or if its another reason.

The smell is very very strong of ammonia. I have cleaned it 3 times and it still stinks!

Is there a way to stop them doing this, the problem is once they start you cant stop them, if you pick them up they carry on peein......Are they marking or are they peein, if that makes sense.....