I set a complaint to preloved and have received this reply.
Hello Angie,
Many thanks for your comments.
In general, I do want to say that we do share your concerns. We do put a lot of work to ensure the advertising of animals is handled as responsibly as possible.
For example, we screen all animal adverts to ensure they are not being sold at too young an age, check that they are not controlled under dangerous dogs legislation, check they are not listed as a dangerous wild animals, check they are not an endangered species, check they have not been illegally docked, check it is not one of the many scams coming from Africa, prevent people swapping animals and more. We believe that we go further than any other similar sites in enforcing such requirements.
However, I'm sure you will understand that there is a limit to what we are able to enforce and control and unfortunately I believe the issue you raise falls outside of these limits.
That said, I would be very happy to forward on to this member any constructive advice that you have. Our experience is that given the right knowledge the vast majority of owners are keen to do the best for their animals.