I'm a master gardener in my county. If you call your county extension office, which is where the master gardener office usually is as well, they can give you free recommendations on types of plants for your area. If you give them a rough size estimate of the space you want to fill, whether the plants would be in sun or shade and then that you'd like something with thorns that will work as a barrier they should be able to recommend a few different things. The info is free and is provided as a service of the county you live in. I think most counties offer it.
If all else fails you could resort to scooping dog poo and using it outside the fence as a barrier. I personally don't think I'd go that route though.
