I have a 2 year old great pyrenees dog, he is huge, about 150 lbs and up until today has been a great guard dog for the chickens, and has never touched any of them. In fact they all sleep with him under the house. yesterday he killed all of my magpie ducklings, in one frenzied chase, then today my daughter accidentally let go a guinea keet she was holding and he killed that too. he didnt bite into any of them, they all looked perfect, he must have shaken them to death. We are just so sad, I loved their little ducky faces and their flappy feet... Anyway, I was wondering should I worry about him now he has the taste for killing, was he defending the chickens maybe?, also he growled at me when I tried to take the keet off him, which he has never done before, he has been a very gentle dog up until yesterday.