I have no idea why some religions seem to have obsessions with avoiding certain kinds of animals. Perhaps it originates with a basic knowledge of the fact that some may damage food and spread disease.
Steve Wells from Dwindling in Unbelief did some digging, and found that although not mentioned in the Koran, mice are permitted to be killed in the Hadith. The Old Testament god also seems to have had some issues with them, despite (as it happens) the fact that he surely created them?
Copyright Ed Baker