EPILEPSY. Perhaps the top cause of seizures in dogs is a condition called epilepsy, however it is important to note that epilepsy is not the cause for all seizures. The definition of epilepsy was discovered by some people who were on a walk in the woods and happened upon a wolf that was throwing fits, looking as if he were doing some odd dance on a path in the woods. This group told the rangers and since the group was considered a group of idiots, the term used to describe this type of seizure is idiopathic epilepsy. Well, that's not exactly true, but the scientific reason is a bit more boring and doesn't make any more sense. In short, the term "idiopathic epilepsy" is a catch-all for when the experts just don't know what is causing a dog to have seizures.
BRAIN TUMORS. Obviously, one of the easiest things to rule out, as a cause of dog seizures, is whether there is an abnormal growth in the dog's brain. A tumor can put pressure on the brain which can lead to seizures and other symptoms that the brain is not working properly. There are tests, like an MRI or CAT scan, that can detect tumors, but it is important to know that most dogs do not get seizures due to tumors, so it is just a possibility. A tumor or a head injury that causes seizures cannot be treated with medications, so that is why it is important to rule these causes out.
TICK INDUCED DISEASES. Aside from inflicting a painful bite on your dog, ticks can cause a dog or human to contract Rocky Mountain Spotted Fever or Lyme disease, both of which can cause a dog to have seizures. If the tick is discovered within the first 24 hours after it has attached itself to the dog, the chance of infection is greatly reduced. There are antibiotics that can kill Lyme Disease, and most dogs respond quite well in general to antibiotics.
DISTEMPER. This condition is generally marked by symptoms such as a fever, diarrhea and dehydration, all of which can lead to seizures in dogs, and is seen most commonly in puppies once they reach the age of 3 months and lose the antibodies they received from their mother. This is why it is vital to get your dog vaccinations as soon as possible, because vaccinations are the only way to prevent this disease - unfortunately once a dog gets it, it is in many cases fatal.