Undercover footage acquired by the organization shows wool workers in Scotland 'striking terrified sheep in the face with electric clippers, slamming their heads into the floor, beating and kicking them, and throwing them off shearing trailers'.
The 12-page complaint asks the SPCA to launch an investigation and, if appropriate, file criminal charges against the workers for apparent violations of laws prohibiting cruelty to animals.
"The video footage obtained by the eyewitness highlights just some of the cruelty observed at 24 sheep farms toured by shearers from a shearing contractor earlier this year," said a PETA spokesperson.
"Shearers are paid by volume, not by the hour, which encourages fast, violent handling that leads to gaping wounds on the animals' bodies, which shearers stitched up using a needle and thread but no pain relief.
"One of the sheep was suffering from mastitis and couldn't stand up, and a worker explained that she was going to be shot."
The exposé reveals horrific animal suffering
The latest exposé follows an August investigation - the first-ever video exposé of cruelty within the English wool industry - which showed similar abuse.
"After exposing cruelty within the English wool industry, we've found the same horrifying abuse of sheep at farms in Scotland," says PETA Asia Senior Vice President Jason Baker.
"Everywhere that eyewitnesses from PETA Asia and its affiliates go - from Australia and the US to South America and now the United Kingdom - they see the same disturbing behaviour.
"The production of all wool - no matter where it originated or what 'ethical' or 'responsibly sourced' claims are made on its label - spells extreme suffering and death for millions of gentle sheep and lambs."
'Shocked and saddened'
Speaking about the footage released by PETA earlier this year, British Wool issued a statement saying it was 'shocked and saddened' - and pointing out that the filming was secret.
"As a farmer-owned organisation, British Wool collects and sells the wool on behalf of British farmers. We are passionate and committed to continuously seeking to improve shearing skills and good practice in the UK," the statement added.
"Every year we train more than a thousand people in all parts of the UK on two-day training courses that are tailored to their existing level of experience and skill."