The scariest dog I’ve ever run across was a basenji.
It wasn’t that big but boy was it fast and quiet. They don’t bark. So you don’t know they are there.
Years ago, I met and did some work for a couple who married late in life. He was a retired accountant, and she was - well - something. It appeared to be a case of “Jack Sprat and his wife”. They were both on the dog show circuit, and I believe that they were both judges at one time. He bred Papillions and Basenjis, and she and her daughter bred Old English Sheep Dogs.
They also kept cats, birds, and fish tanks. The puppy litters were kept in the kitchen, the cats and Paps had the run of the house, and the OEs were kept in 5x8 kennels in the garage and let out for relieving themselves - sometimes.
The dogs all traveled, showed and placed, but these persons were not clean. And the conditions for the OEs were appalling. I had never seen aggressive OEs before.
On the other hand, I know a bachelor electrician who has kept a Basenji for 6 years, and carries it like a baby everywhere. The dog is silent, and that can startle you, true.
Thank you for allowing a reminiscence.