‏البيوع : Hadeeth No:3814 Ibn Mughaffal reported: Allaah's Messenger (sallAllaahu alayhi wa sallam) ordered the killing of dogs and then said: what is the trouble with them (the people of Medina)? How dogs are nuisance to them (the citizens of Medina)? He then permitted keehing of dogs for hunting and (the protection of) her...

‏الطهارة : Hadeeth No:548 Abu Huraira reported: The Messenger of Allaah (sallAllaahu alayhi wa sallam) said: When a dog drinks out of a vessel belonging to any one of you, he must wash it seven times....