According to petMD, localized involuntary muscle tremors can cause a dog's head to shake slightly. Involuntary muscle tremors can also cause a dog's entire body to shake. Localized tremors that affect only the hind legs are also common.
Genetics is one major cause of localized tremors, notes petMD. Certain dog breeds, which include English Bulldogs, Weimaraners, Dalmatians and Labrador Retrievers, are more likely to have involuntary muscle tremors. This condition is also more typical in younger and middle-aged dogs.
Idiopathic head tremors are common in English Bulldogs, Doberman Pinschers, Beagles and Boxers, according to the Veterinary Information Network. Up and down movement of the head often occurs in these breeds, but side-to-side shaking can also happen. Veterinarians do not know why this type of head shaking occurs, but it is unresponsive to epilepsy medication or other treatments. This type of head tremor can improve as the dog ages. To curb tremors and lessen attacks, owners should encourage the dog to focus on a favorite treat or toy.
Tremors are also sometimes a sign of a larger health issue, according to petMD. Canine injuries, severe pain, kidney failure, hypoglycemia, poisoning and certain diseases of the nervous symptom cause involuntary muscle tremors. Dogs also develop these tremors as a side effect of prescribed medication. It is unusual that tremors caused by these conditions are localized, but the sudden appearance of head tremors still merits a visit to a veterinarian.