The RSPCA is releasing images and reports of the worst animal cruelty cases in South Australia in a bid to highlight the extent of neglect in the state.

RSPCA chief inspector Andrea Lewis said difficulty in tracking down owners means only a fraction of cruelty cases are prosecuted, the worst involving severe emaciation.

The RSPCA says nearly 600 animals were abandoned across the state in the last year, a few cases more than the previous year.