definitely under one was the hardest... she never listened, always ran away from me, chewed on things like pencils, peed everywhere..etc.. and now at 3.5 years old shes matured a lot.. she also was very very aggressive and bit ppl as a puppy.. now she still is a bit aggressive and although she hardly had any training.. shes really matured and hasnt bit anyone... she just barks like crazy around them
