Yorkies are not particularly prone to seizures or epilepsy. Usually, if a Yorkshire terrier starts having seizures this indicates an underlying medical issue. A recurring pattern of seizures will likely lead to an epilepsy diagnosis.
Toxicity
If your Yorkie ingests anything toxic, this can cause a seizure. Household chemicals, plants toxic to dogs or chocolate can all cause seizures if eaten by a dog. Certain topical tick preventatives can also cause seizures if your dog is able to lick the liquid from its fur. If your dog ingests anything toxic and experiences a seizure, call for immediate veterinary assistance.
Brain Injury or Tumor
The onset of seizures is often one of the earliest symptoms of a brain tumor. Your veterinarian may use X-ray imaging technology to detect and diagnose a brain tumor. It can be difficult to see a tumor inside a dog's skull, so some veterinarians will instead X-ray the chest. The presence of lung tumors can indicate that brain tumors have spread to the lungs. In the absence of brain tumors, a brain injury -- such as a blow to the head -- can cause seizures.
Illness or Disease
Yorkies, as a breed, are at a relatively high risk of developing the medical condition known as liver shunt. Left untreated, liver shunt can cause ongoing seizures. Other diseases can cause seizures in a Yorkie. If your dog has lyme disease or Rocky Mountain spotted fever -- both of which are carried by ticks -- she may have seizures as a symptom of these diseases.
Canine Epilepsy
Canine epilepsy is diagnosed when a dog has a recurring pattern of seizures with no known reason -- there is no tumor, disease, liver shunt or hypoglycemia to explain these seizures. Canine epilepsy is estimated to affect between 2 and 3 percent of all dogs and can run in family lines. Yorkies with epilepsy are likely to be prescribed anti-seizure medications, which must be taken regularly and correctly. These medicines do not cure epilepsy, but they can reduce the number and severity of seizures.