My dog keeps taking my valve stem caps

[grandsport]

It's just one of the dogs,and he only bothers my car for some reason. Some are chewed,sometimes they are gone all together. I've sprayed them with bitter apple,covered them with small rags but he takes the rags off and chews them up in the back yard.I just think he is afraid of The Black Car,as he leaves the wife's alone. Anyone else have this problem? The techs here at work are starting to get wise to me because all the new valve stems are missing caps.