Hi there, my 7 month old male Border Terrier is house trained and learning to ask to go out in our own house.  Whenever he goes to another house which has a dog he cocks his leg and marks territory (at least that's what we think  he's doing as it's only a splash).  Obviously this isn't acceptable to the people whose houses we are guests in! He only does it where there is another dog, most recently at a neighbours house, she has a female BT and sometimes we look after each other's dogs, but we feel we can't take him there anymore. He knows how to use her dogflap so we're sure it's marking, is castration the only solution?
He also takes a fancy to some dogs in the park and relentlessly tries to hump them, obviously this is natural for teenage dogs but it gets to the point where I pull him off so many times it's embarrassing!  He does it more to male dogs and he'll mount any part of their body, often the head - any advice?
thanks

This can happen with adolecent dogs, correct the behaviour and he will grow out of it.