There is an interesting story in a non-canonical text over how Muslims were forbidden from keeping dogs in Islam.
Apparrently during the Islamic conquests, Mohammed caught a dog chewing at his supply of Nolvadex. Since Mohammed (peace be upon him) only had enough to last him through the conquest of Syria, he was naturally outraged. Mohammed could not appear in front of his generals with bitch tits.
So, Muslims were banned from keeping dogs as pets.