Can service dogs be kept indoors?

Dogs are "haram" to be kept (except as hearding or guard dogs) and are not allowed in one's home. But what about dogs trained to help disabled people(blind,hearing impairment,seizures......)? They need to be close to their owner and living with them in order to be of help. Could those dogs be kept indoors? Sunni point of view please but would like to know about others as well.