A clever canine
Dogs can have a wide range of hidden talents that become apparent over time. Some can leap great distances, others can run through endurance tracks without breaking a sweat, but the OP’s dog is even more special. According to the OP, their dog is a codebreaker.
Any dog would get excited after hearing the word “walk” or the phrase “go out.” This dog would go absolutely bonkers when hearing these magical words. And the OP’s family can’t even spell these words in front of the dog. It came to the point that they’d have to use code words, but it wouldn’t take very long for the dog to crack the code.