There are lots of natural remedies such as
- Citrus fruits - oranges and lemon peels.
-A mixture of eucalyptus oil in water sprayed on the ground once or twice a week

There are lots of sprays on the market, but they will be costly if you need to use all the time.

Motion detector sprinkers! lol.

Just becareful what you use...as you dont want to hurt the little piggy.