Two weeks ago we heard horrible shrieking coming from the pig area. We rushed down and found a mature sow who had only been with us a week caught by the jaw in the fence. She had put her nose through the six inch mesh and the wire had then caught behind two incisiors on the lower jaw trapping her tongue beneath. We cut through the wire and she seemed to recover quickly, eating and drinking as normal. I don't know how long she had been trapped but if we had not heard her I don't think she would have been able to release herself, the harder she pulled the more the wire cut in to her.
We put it down as a freak accident but today exactly the same thing happened again. The only solution we can think of, apart from refencing in a smaller mesh, is to put electric strands round the whole inside. It must have been very distressing for her, it certainly was for us.