The most aggressive dog breeds named in new study Dog owners have long debated which breed is the best-behaved 4 May 2021 • 4:29pm Anyone who has had a small dog snapping at their feet will declare that the most dinky of pooches often are the most inclined to start a fight. Now, a new study has found that smaller dogs are almost always more aggressive than their larger counterparts. Miniature Poodles and Miniature Schnauzers top the list of most aggressive dogs in a new study, published in Scientific Reports. Larger dogs including Labrador Retrievers, Golden Retrievers and Lapponian Herders were found to be the most docile.