My aunt got a boxer recently and it has a tattoo of a snake on its hip wat does it mean?

its a rescue dog and it has attacked a 4year old and a 12 year old already and has killed and mauled many other animals so im wondering if the tattoo has to do anything with the dog being pitted and what not i mean i would hate for the dog to kill someone or if the dog was affiliated with the mafia or if it was gang related