This was a real problem for my outdoor pets. Before I discovered how to deal with ants I would
hover over the pets at mealtime and immediately remove their dish when they were done. Normally they like to slowly graze their food, so they didn't much like it being snatched away so soon.
But now I have created a water mote around the dish (by placing the feeding dish inside a slightly larger dish filled with water and elevating the feeding dish out of the water by placing it on top of a clay pot's drip saucer turned upside down in the middle of the larger dish). It works okay,
but the water gets mucked up and full of food, leaves, etc. pretty quickly.
Anyway, I ran across this wonderful solution and thought I'd share. It also works to keep ants away from other items (garbage cans, food, etc.).
http://theantser.com/antserinformatio.html