Abigail was the first born and Alpha/Dominant female in her Litter, she was the largest one too......she terrorized her Mother and littermates, her Breeder
gave me a deal @ $1,000.00 to take her @ 7 weeks she kept the rest for 12 weeks. She is now the most calm relaxed Female, but let her hear a noise or the doorbell ring.....she will bark and growl fiercely! At the Dog Park she will not hesitate to defend her personal private parts against forceful males by snapping at them, I do of course pick her up if she needs it. My male will let you take him anywhere, a perfect candidate to be stolen, he will "Kiss" you to death. Did you mean "Aggressive" towards other Dogs or Humans?
They are never aggressive towards humans, she will just shy away if they don't like them or back away and bark. Artie will only snap at a bigger dog if he's trying to hump him or he feels backed into a corner and sometimes will even lay on his back in submission. IMO. it depends on what you perceive as aggression or level of tolerance? I don't think it's aggression if they are defending themselves?