I already have a female 9 yr old Yorkie which I adopted a year ago. A few days ago the adoption agency asked us to look after a Yorkie boy. He was abandoned so we are not sure how old he is, vet thinks 10 or older. He's housebroken but insists on scent marking in the house. He has not been castrated but my female has. We are hoping to keep him permanently as they are getting on so well and he's a lovely little boy. Can anyone help?