Even with forensic and digital evidence, convictions remain difficult to secure because animal cruelty cases are not always treated with the same urgency as other criminal offences, the NSPCA said.

Two recent NSPCA investigations into alleged sexual abuse of animals in KwaZulu-Natal and Mpumalanga have exposed one of South Africa's least visible forms of animal cruelty, as investigators warn the 30 complaints relating to bestiality received over the past three years represent only a fraction of cases.

The investigations have renewed calls for stronger prosecutions, improved investigations, and greater public awareness of a crime experts say is far more common than reported.

Investigators believe the figure represents only a fraction of cases because the abuse is notoriously difficult to detect and prosecute.

Recent investigations began months ago after the NSPCA's Special Projects Unit received information about the alleged sexual abuse of animals.