Many Muslim jurists consider dogs to be ritually unclean. (najis)[29] However, "jurists from the Sunni Maliki School disagree with the idea that dogs are unclean."[30] Individual fatāwā ("rulings") have indicated that dogs be treated kindly or otherwise released[31] and earlier Islamic literature often portrayed dogs as symbols of highly esteemed virtues such as self-sacrifice and loyalty, which, in the hands of despotic and unjust rulers, become oppressive instruments.[29]
Abou El Fadl "found it hard to believe that the same God who created such companionable creatures would have his prophet declare them 'unclean', stating that animosity towards dogs "reflected views far more consistent with pre-Islamic Arab customs and attitudes".[32] Furthermore, "he found that a hadith from one of the most trustworthy sources tells how the Prophet himself had prayed in the presence of his playfully cavorting dogs.
(from wiki: http://en.wikipedia.org/wiki/Animals_in_Islam_