Feel no evil: do Animals feel pain?

It's fair to say, we care more about the welfare of the animals we rely on for food and fibre more than we used to - and so we should. But in doing so - we have to deal with the ongoing problem - we don't speak their language. So, how do we work out what - and how they are feeling? Which is where my first guest comes in, Dr Preet Singh, a lecturer in Veterinary Anatomy and Histology at Massey University.