“Once Gabriel promised the Prophet (that he would visit him, but Gabriel did not come) and later on he said, ‘We, angels, do not enter a house which contains a picture or a dog.'” — Sahih Bukhari 4.54.50
“Abdullah (b. Umar) (Allah be pleased with them) reported: Allah’s Messenger (may peace be upon him) ordered the killing of dogs and we would send (men) in Medina and its corners and we did not spare any dog that we did not kill, so much so that we killed the dog that accompanied the wet she-camel belonging to the people of the desert.” — Sahih Muslim 10.3811
“Narrated ‘Aisha: The things which annul the prayers were mentioned before me. They said, “Prayer is annulled by a dog, a donkey and a woman (if they pass in front of the praying people).” I said, ‘You have made us (i.e. women) dogs.’ I saw the Prophet praying while I used to lie in my bed between him and the Qibla. Whenever I was in need of something, I would slip away. for I disliked to face him.” — Sahih Bukhari 1.9.490
“Tehran police’s new target: Pet dogs,” by Dudi Cohen for Ynet News, May 21 (thanks to David):
…Tehran police are beefing up enforcement of Islamic law against women improperly dressed ahead of the summer, and adding a new target: pet dogs.
Police in Tehran are conducting a new crackdown on women wearing mandatory headscarves improperly or in “vulgar” dress.
Typically, such women are fined or detained in police stations until relatives collect them hours later with more modest clothing.
As part of police operations in Tehran, officers also issue warnings to dog owners walking their pets outside. In Sharia-ruled Iran, dogs are considered “impure.” Dozens of dogs in Tehran were round up last month and placed in quarantine.
Iran’s Islamist rulers consider ownership of pet animals “un-Islamic.” Authorities distinguish between pet dogs and “work dogs” used for guarding and helping in rescue missions.
Iran’s parliament even introduced a bill according to which dogs cannot be taken out in public, with offenders facing fines of up to $1,000.