Help/advise needed quickly. We have just taking in a very small dog(1yr) but my german shepherd has it tortured. He's gentle enough with him but follows him constantly smelling his bum. He dosen't give the new arrival a seconds peace.
(Also this so called house trained dog isn't so house trained as we had been told,any suggestions how to quickly remedy this(he may have been trained at one point but had been living outside for the last 4 months and may just of forgotten:any time we try to take him outside the big dog is up his back side so he dosen't get a chance to go to the toilet)

Tell your GSD to stop it and make sure he does stop. Some sniffing is acceptable, but when it becomes a nuisance, then you step in and put a holt to it. That goes for any behaviour that you do not wish to see. With reference to housetraining: go back at basics. Treat your new dog as if he is a very young puppy and let him out on a regular basis, praising him when he goes where you require him to go. I am sure he will get the message very quickly. Especially if he has been taught not to mess in the house at some point. If your GSD is hounding him to the point where he can't even pee in peace, then keep your GSD in the house. If you have not wormed your new dog, it would be wise to do so. Good luck.