
I use anything I can put somewhere the dogs cannot reach!
I once had a plastic dog food storage bin, with a snap on lid, that I thought was fool proof. Had 2 GSDs, a Cairn and a Yorkie at the time. The bin sat on the kitchen floor and held 40 lbs of dry dog food, so this was a really big bin. One day I came home and fed the dogs. Took the lid of the bin off as usual and scooped out the food. I thought my Cairn looked really big ... and she ate her dinner very slowly. Very odd, usually I had to restrain her for eating her own food in a second and than rushing to one of my benevolent GSD's dishes to shove her face in there for more.
A couple of days later, same thing happened. My Cairn looked like she had been pumped up with air like a balloon - ate her dinner very, very slowly. Something was clearly wrong. So this time I examined the bin very closely. I noticed teeth marks along the rim of the lid. To this day I do not know how she did it, but somehow she had managed to prise the lid up enough ... and then shove herself into the bin to eat until she nearly burst - without the lid coming off completely or the entire bin falling on its side, so to me everything looked as normal. From then on I kept the bin up on a chair and all was well!
Next time I saw my Cairn looked that big was about a week before she had 4 puppies ..... :-)