Boy cat peeing in bath, new dog

Hello I'm desperate for some help and understanding !
We brought a new dog home (3yr old male fully intact) into our home with two cats the dog marked his territory the first day we had him in a few spots we cleaned up with the smell removing spray ! We tried to introduce the cats to the dog he's previously lived with cats and totally ignore our cats but they where scared back up hissing at him and frozen that night we shut the cats out the bedroom and the dog in with us, things are just getting worse now ! The cats have moved into the spare room where I have put a baby gate on (to stop the dog getting in but he's only intreasted in the food) but my boy cat keeps peeing in the bathroom in the bath on towels and on our dirty clothes anything he can even tho there is two cat little boxes one in the bathroom one in the cat room ! The girl cat attacked the dog scratching his eye now both cats will come nowhere nere the dog and we have to shut them upstairs out the way of the dog! Sorry for the long post but I'm at my wits end on how to reduce the stress on the cat and stop the behaviour

The cats were there and established in the home first and now the dog has full access to *their* areas and everywhere else, that's not fair to them.

The cat is peeing on clothes and rugs for two reasons:  because they are there.  And because he is major stressed because of the dog and because his access to his normal areas have been closed off - the dog should have been in a closed access so you could monitor his urinary habits, take him out on schedule, and a separate area away from the cats at bedtime in the initial introduction period.  Short time periods to introduce and supervise are the key.

Don't leave clothes piled up on a floor or where a cat has access to, same goes for rugs, these are always the first thing a stressed cat will pee on.

Introductions must be done slowly and carefully.  The cats should have been allowed to remain in your bedroom  - the dog should not have access to the cats' food and litter boxes and "safe havens"  (where they sleep, eat, etc). 

Move the cats back into your bedroom and focus on the dog.  Teach him where the cats' boundaries are (bedroom, at first - cat food dishes and litter boxes) - provide him his own feeding area and sleeping area and train him on a schedule for outside potty duty.  The cats should be allowed access throughout the house, it is after all, their house but you may need to keep the dog in a separate area for awhile and do slow and supervised introductions for a bit.

Use enzymatic cleaners to rid the areas where the dog marked - if there is still traces left, both the dog and the cats will continue marking there or elsewhere in the home.

Dogs and cats can be great friends. But there's a lot to take into consideration! How old are they? What was their situation before arriving? If you rescued either or all of them, there's no way you can know their experience before moving into your home. If it's hard on humans, who are of the same species to live together, how much more for cats and dogs? It's not a given that they'll ever become friends or that you'll have the ideal pet sanctuary in your home. I'd suggest keeping the dog outside or in the garage if this is at all possible.

Thanks for the replys I live in the U.K and would not keep the dog outside as it's winter and freezing plus I want him to be a member of the family not to just live outside the boy cat that is seeing did live with dogs before coming to live with us they got was recused she turned up on the garden pregnant and in a bad way so we took her in. The cats are not locked in the room all day they have access to all upstairs all day where they mostly stayed before the dog anyway and only closed in while the dog goes upstairs and is closed in our room they then have full run of the house all night the dog is no longer peeing and I did u the proper spray to rid the smell they boy cat is peeing upstairs It not where the dog has been the dog cannot get into where there food or litter trays are as there is a baby gate on the door to stop this thank you for your help and advice