We have tried just about everything to stop the neighbourhood cats from eating the hogs dinner. Shallow troughs of water positioned at right angles across the entrance, leaving just enough room for the hogs to get through, can be effective but a bit unsightly. We eventually went the whole ‘hog’ (pardon the pun!) and made a custom feeding station with small entrance holes (10.5cm Wide x 9.5cm high) and a baffle at either end. It was very easy to make with ready cut lengths of timber and marine ply. The hogs love it and there have been no feline insurgents as of yet.
Good luck. 🙂