Staffordshire bull terrier
He said this breed love people but show no mercy to intruders. A previous client of his didn’t even realise there was an intruder in her house until she saw the reflection in the mirror of her dog removing the man’s throat, soundlessly.
Purchased to keep my grandmother company, the Staffordshire bull terrier would take her hand in its mouth. She would follow it around the house until it let go.