Is it permissible to own a dog for guiding the blind?

The basic principle regarding owning dogs is prohibition, except for hunting dogs, farm dogs, or livestock dogs. Scholars have differed on owning a dog for guarding, and the preponderant opinion is that it is permissible by analogy with what is mentioned in the Hadith. By analogy, this extends to a dog guiding a blind person if no other means are available, because it brings benefit and repels harm. Therefore, there is no harm in owning a dog to assist a blind person if this benefit is realized.