try spinking spices such as chilli or cloves on the path, my brother also swears by filling bottles with water and leaving them where cats can see [no idea how this would work] citrus peel, & you can also buy lion dung from amazon and garden centres,
Do you have a pressure washer? If you have keep it powered up and handy and every time you see the enemy give it a blast it will soon get the hint, if it doesn't throw some lead at it.