How can I stop my horse from chasing my goats?

We just adopted two boer wethers --they are only four months old but are big already- 75 lbs each--and although my 11 year old Belgian gelding thinks they are mildly interesting pasture ornaments, my two year old Fjord filly chases them all over the place..and since they were bottlefed babies the goats think they are people and run to me for protection which means the filly is running towards me as well. Is she just playing or is she trying to kill them? Is there any way to stop her (maybe electrified goat decoys...) Thanks for any advice!