Sheikh Sulaymân al-`Isâ, professor at al-Imâm University in Riyadh
Al-Salâm `Alaykum wa Rahmah Allah wa Barakâtuh.
The Prophet (peace be upon him) forbade keeping dogs as well as selling and buying them.
Ibn Qudâmah said in his book al-Mughnî (volume 4 page 281): “It is unlawful to keep dogs for other purposes than hunting, herding or farming”.
Therefore, a Muslim may not keep a dog except for a dire need such as protection if one’s house in a remote place away from other people. If a blind person needs to have a dog as a guide or for protection, then that would also be permissible.
A Muslim should not play with dogs. The saliva of a dog is impure (najas). The way to remove this impurity is to wash the affected are seven times, one time with dirt. It does not matter whether the contaminated area is a dish, an article of clothing, or the skin. A person who comes in contact with the saliva of a dog must purify the affected area correctly in order for him to be able to perform prayers.
Source: Islam Today