There is a difference between a dog who shakes his head here and there on occasion and one who shakes his head frequently. An occasional shake of the head is normal, but if you notice your dog shaking his head more than occasionally, contact your veterinarian. The most common reason dogs shake their heads is that their ears are bothering them due to an ear infection. Additional reasons include allergies, parasites, trauma and foreign objects in the ear canal.
Canine ears provide a dark, damp environment in which bacteria and yeast thrive. Dogs with floppy ears are especially prone to ear infections. When a dog has an ear infection, his ear canal becomes inflamed and his ears appear red and swollen. Other symptoms of ear infections include excessive wax, pus and a foul smell emanating from the ear. A veterinarian will need to examine a dog's ears to determine the extent of the infection and prescribe the proper medications.
Allergies and Parasites
Allergic skin reactions to food and pollen, as well as parasite infestation by fleas, ticks and ear mites, will cause a dog's ears to itch and result in a dog shaking his head. A veterinarian will diagnose allergic skin reactions with a swab, scraping or biopsy and use a microscope to look for ear mites. Fleas and ticks can be seen with the bare eye.
Trauma and Ear Growths
Any type of trauma to a dog's ears, whether it be from an injury, frostbite, a bug bite or some other problem, can cause inflammation, pain and discomfort. If the problem is not visible, head shaking can be the first sign of trauma. Inflammation and discomfort is also felt if a dog has any type of growth on his ears, such as polyps, tumors and other ear masses.
Foreign objects, including plant matter, dirt and plugs of wax, lodged in a dog's ear are likely to cause itching, pain and irritation. Because objects can work their way deep into a dog's ear drum, a veterinarian may need to use an otoscope to locate them.
The majority of problems that cause a dog to shake his head do not improve without medical intervention. Contact your veterinarian for a physical examination if your dog is shaking his head more than usual. Many of these problems require medication.