Why might a dog keep shaking its head?

If a dog is consistently shaking its head back and forth, then the dog most likely has a type of ear infection from bacteria, yeast or other allergens, such as ear mites, notes WebMD. If the shaking is violent, then the dog may end up breaking blood vessels in its ears, resulting in ear hematomas.

Ear hematomas will only cause additional pain for the animal and lead to additional problems. If an owner notices that his dog is shaking its ears excessively, then the dog should be brought in for a veterinarian examination, notes Vetstreet. The veterinarian can take a look at the ears, swab them or test them if necessary and then administer treatment.