It may be that the dog was a little TOO eager to please the owners... reading transient moods as though they were ways to relate to others in general. Most of the attacks are on strangers.
“From 2005 to 2017, family dogs inflicted 54% of all fatal attacks. 64% were perpetrated by pit bulls. Of the 284 fatal pit bull attacks, 52% involved killing a family or household member.
U.S. Dog Bite Fatalities: Breeds of Dogs Involved, Age Groups and Other Factors Over a 13-Year Period (2005 to 2017) by DogsBite.org, May 2018”
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Re strangers, pit buls “get out” of their enclosures and go hunting...for people and pets. That isn’t normal domesticated pet behavior. Re Family: Per the statistics above, 52% of the people pit bulls killed were family or household member.