ive thought about this too, and i came up with putting your weed in a air tight bag in the middle of a bowl of jello. yes thats right, jello.

fill up a container halfway with jello mix, let it harden, put the weed bag on the middle of the jello's surface, fill the rest of the container up with jello mix, and let it harden.

Maybe you could add strong spices to the jello to overpower any other smells the dog could pick up.