Police are investigating following the release of photos which shows two calves trapped in the back of a car in Wales.
The viral photographs, posted on Facebook, shows a light blue 2004 Volkswagen Passat transporting two calves in the back.
The incident happened on Friday (6 July), and the RSPCA and South Wales police are now investigating.
One image shows the car going past junction 42 of the eastbound carriageway.
The animal welfare charity said it was "extremely concerned" about the photos.
An RSPCA spokeswoman said: "This is a completely unacceptable way to transport a large, farm animal.
"This represents an animal welfare concern but also a risk to the safety of the driver and other road users.
"We would strongly urge people never to transport an animal like this."
South Wales police are pursuing possible road traffic or animal welfare offences.
