Keep a bull pup

Mr. Conan Doyle uses a phrase in Sherlock Holmes (sorry, I don't know which): someone who "keeps a bull pup" is said to have a quick and bad temper; have you heard of this saying?

I've never heard it, but I think the meaning is fairly clear, and the allusion plain.

Oh, and on an incidental but pedantic note, it's Sir Arthur, not Mr Conan Doyle. Sorry about that.

DFG

Is now a good time for me to reveal that I am both a Kentucky colonel AND an admiral in the Kentucky navy? Please use my titles in future.

A bull pup is a pistol -- it barks or growls. U.S., mid to late 19th century. "Cassell’s Dictionary of Slang" by Jonathon Green (Wellington House, London, 1998). Page 166.