The short answer to this question is: Pit Bulls. The long answer to this question is that any dog can become dangerous if not properly cared for. Calling particular breeds of dog dangerous or violent can be very offensive to some dog owners and animal rights activists. Many canine apologists opine that no breed of dog is born with a naturally vicious tendency. Based on well documented studies and statistics, such an opinion is misguided. Different breeds of dog have different innate instincts and abilities. A lion does not react the same way to a given stimulus as a rabbit does. A Pit Bull does not react the same way to a given stimulus as a Yorkshire Terrier does. Although an owner of a Rottweiler will surely tell you that their, “dog would not hurt a fly.” The opinion of one person is rarely ever a reliable source for any information and opinions are rarely universally applicable. According to a research study at DogBite.org, during the last eight years, two breeds have combined to account for 73% of all recorded fatal dog bite attacks in the United States—Pit Bulls, and Rottweilers. Pitt Bull lovers will argue that little dogs bite just as much as Pit Bulls do and that Pit Bulls should not be characterized that way just because they are larger and their bites are more deadly. Unfortunately, that is exactly why they must be characterized in such a way. If you are bitten by a Chiwawa, it will likely hurt. You may require some medical attention and you will likely no longer be a big fan of Chiwawa’s. If you are attacked by a Pit Bull, things may never be the same.
Pit Bulls actually killed more than twice as many humans as Rottweiler’s did during that eight-year span. They are the most dangerous breed of dog for three reasons. One, they were selectively bred for dog fighting. They were abused and mistreated and the most violent ones were bred with the other violent ones in an effort to create monsters. Most Pit Bulls today are well cared for and they can be very mild mannered and loving creatures. Sadly, when an unusual situation arises, even loving Pit Bulls have trouble fighting their basic attack instincts. The second reason they are so dangerous is that they use an offensive attack style as opposed to a defensive attack style. If a Labrador feels threatened, he will back up, hunch down, bare his teeth, and growl. These are signs that something bad is about to happen. An intelligent human will back off and leave the dog alone. The attack will then be avoided entirely. When a Pit Bull Terrier feels threatened, its goal will be to protect itself and destroy its enemy. It will not take the time to give warning. It will go straight for the kill. The third reason Pitt Bulls are the most dangerous is that when they bite, they use their large powerful jaws to clamp down and shake back and forth. This process drives the teeth as deep into its victims skin as possible. If the teeth hit a vein, the damage could be catastrophic.
All breeds of dogs can be properly cared for and it is possible that they can go their entire lives without issue. Other breeds that have shown higher propensities to bite are: Dalmatians, Chow Chows, Doberman Pinschers, German Shepherds, Alaskan Huskies, and Boxers. If you get into an altercation with a dangerous dog, seek safety, then consult with a Utah Dog Bite Attorney to get educated about your rights.