Excerpt from Ask the Vet About Dogs: Easy Answers to Commonly Asked Questions
There are many specific causes for seizures, including poisons, head trauma, brain cancer, heatstroke, liver disease, low blood sugar (hypoglycemia), meningitis or encephalitis (inflammation around the spinal cord or of the brain), and canine distemper virus infection. Seizures caused by these disorders are diagnosed by examination of the dog, blood tests, and X-rays. Modern veterinary technology even allows for a dog to have a magnetic resonance imaging (MRI) test, which provides images of the brain. The dog’s history often provides important clues to the cause of seizures. For example, did the dog have access to slug bait (could be poison)? Is she an older dog (possible brain tumor)? Does she have diabetes (seizure could be due to hypoglycemia)?
More often, however, the cause of seizures in dogs cannot be determined, and the presumed diagnosis is idiopathic epilepsy, or epilepsy due to unknown cause. Epileptic seizures usually occur early in a dog’s life; a first seizure in a dog more than five years old suggests that epilepsy is not the cause of the problem. There are many forms of seizures, ranging from mild stiffness or twitching, to the stereotypical seizure during which the dog becomes stiff, chomps her jaws, drools profusely, urinates, defecates, howls, and paddles with all four legs. Some dogs recover immediately after the seizure, but most appear confused, disoriented, and lost for a few minutes to several hours afterward (and sometimes before). Some dogs have one or two short seizures a year, while others have three or more in a day, an event known as a cluster seizure. Most seizures are short-lived, lasting only a few minutes (although they seem longer to the dog’s scared owner), but sometimes a dog has a seizure that does not end, a condition called status epilepticus, which demands emergency veterinary care.
Single-episode seizures are not usually life threatening. Prevent the dog from hurting herself on surrounding objects or from falling down stairs and wait for the seizure to end. Do not put your hand in her mouth. A dog cannot swallow her tongue during a seizure, but she can bite you badly.
Dogs who suffer significantly from epilepsy (those who have frequent and/or severe seizures) can be treated with antiseizure medication, although most dogs need to remain on the medication for life. The medication can be expensive, and frequent blood tests are necessary to monitor the level of medication in the dog’s bloodstream. Phenobarbital and potassium bromide are most commonly used, and they are sometimes both given at the same time. Phenobarbital is somewhat toxic to the liver and most dogs taking it eventually develop some degree of liver disease. New drugs that are less toxic and more effective are available for humans, and should become widely available for dogs in the near future.