If you were to be walking with your family down the street, and a kerfuffle with a stranger were to break out, risking the safety of yourself or your family, in both federal and state courts for just about any state in the Union a "self defense" defense would apply for any legal action resulting from the resulting mayhem, so long as a reasonable person could reasonably fear for your safety or that of your family as a result.
But what if the stranger threatened your dog? To be specific on jurisdiction, I'll mention the United States, as well as the states of New York and California. Let's assume this stranger very specifically did nothing to suggest physical harm to any humans present, but actively threatened harm to the fluffiest member of the family.
Does the "self defense" defense apply?