I just saw this phrase "XX hound" which means someone is really enthusiastic about something, usually a discipline. In Chinese we have a similar phrase, XX 狗 (e.g 工科狗，化工狗，etc.), but it always comes in a sarcastic tone. I am wondering if people use the phrase in the same sarcastic way in English? Or it can also be used in a non-sarcastic way too?