Mich. Comp. Laws § 287.388

Sec. 8. A dealer, a county, city, village, or township operating a dog pound or animal shelter shall not sell or otherwise dispose of a dog or cat within 4 days after its acquisition. If the dog or cat has a collar, license, or other evidence of ownership, the operator of the pound or shelter shall notify the owner in writing and disposition of the animal shall not be made within 7 days from the date of mailing the notice. Each operator of a pound or shelter shall be required to maintain a record on each identifiable dog or cat acquired, indicating a basic description of the animal, the date it was acquired and under what circumstances. The record shall also indicate the date of notice sent to the owner of an animal and subsequent disposition. This section does not apply to animals which are sick or injured to the extent that the holding period would cause undue suffering, or to animals whose owners request immediate disposal.