While they are unable to generate the bite force of some other animals, such as crocodiles and sharks, dogs generate significant bite forces, which greatly exceed those of humans. While it is difficult to obtain concrete results, mastiffs, Rottweilers, pit bulls and German shepherds possess some of the strongest jaws among domestic dogs. Several factors influence the strength of a dog’s bite, including the size of the jaw muscles and the shape of the skull and mandible.
Tests and Theories
Scientists determine the bite force of animals in two basic ways: direct measurement and computer modeled predictions. While both methods provide instructive results, neither method is perfect. Scientists take direct measurements by inserting a pressure-sensitive device into the animals’ mouth to stimulate the animal to bite the device. To model the theoretical bite force an animal can generate, scientists take precise measurements of the animal’s skull, mandible and musculature. They input these measurements into a computer program that analyzes the figures and predicts the maximum bite force possible for the animal.
Unfortunately, both methods of determining bite force have flaws. Direct measurements only test a small sample, meaning that individual variation may skew the results, and the tested dog may not bite as hard as he can. A team of researchers, led by Dr. Jennifer Lynn Ellis, of Guelph University, Canada, sidestepped this problem by placing the pressure sensor in an anesthetized dog’s mouth, and stimulating the jaw muscles with a weak electric current. Computer-based predictions may accurately reveal the maximum bite force possible, but living animals may not apply such force.
In 2009, Doctor Ellis investigated the bite strength of dogs, publishing her results in the Journal of Anatomy. She found that a dog’s head shape and mass largely determined the amount of pressure a dog’s jaws can impart. Accordingly, mastiffs – the breed with the largest head and widest jaws – generate the highest amount of bite force. During the tests, mastiffs generated 552 pounds of force.
Relying solely on direct tests, Dr. Brady Barr investigated the bite force of a wide variety of animals for a National Geographic television program. In addition to crocodiles and lions, which generated bite forces of 2,500 pounds and 600 pounds respectively, Dr. Barr tested three dog breeds – Rottweilers, German shepherds and pit bulls. The tests revealed that Rottweilers had the strongest bite of the three, as they were able to generate 328 pounds of pressure with their jaws. The average bite pressure produced by the three breeds was 269 pounds of pressure.
Because they have been used in a variety of military and police applications throughout history, many suspect that German shepherds have particularly strong jaws. However, while the breed does have a strong bite, it is not as strong as that of Rottweilers or mastiffs. German shepherds generate approximately 235 pounds of pressure with their bite.
Pit bulls are the subject of countless myths regarding their jaws and bite pressure, but most are unfounded. For example, a frequently parroted myth mistakenly claims that pit bulls have locking jaws, but in truth, their jaws are not unique when compared to similarly sized breeds. In the tests conducted by Dr. Barr, pit bulls generated a maximum of 235 pounds of force.