we had the problem as kids- our neighbor's dog had barrier frustration and was so agro at the fence!
My dad asked if we could feed their dog caramels through the fence (today I wouldn't use caramels!) and after a few days it got better, 3 weeks later doggy was all wags and happy.
ETA: It helped that our Old English Sheep Dog (Daisy! with a brown and a blue eye) was sweet as pie. If a dog was threatening to her, she used to roll onto her back. When a dog mounted her, she would just lay down. What a sweetie.
My dad asked if we could feed their dog caramels through the fence (today I wouldn't use caramels!) and after a few days it got better, 3 weeks later doggy was all wags and happy.
ETA: It helped that our Old English Sheep Dog (Daisy! with a brown and a blue eye) was sweet as pie. If a dog was threatening to her, she used to roll onto her back. When a dog mounted her, she would just lay down. What a sweetie.