Seizures are not difficult to detect. The hard part is figuring out why they are happening. Presented with a dog that is suspected of having some sort of seizure disorder, a veterinarian will go through a detailed initial evaluation in an attempt to figure out whether the dog’s spastic episodes, as described by its owner, actually are seizures. She will ask the owner questions about the dog’s health history, living environment, exposure to other animals, exposure to potential toxins, history of possible physical head trauma and vaccination status, among other things. She will be very interested in learning when the episodes started, what they look like, whether they have changed over time and whether they have become more or less frequent. If the veterinarian doesn’t ask about all this, the owner should be prepared to volunteer it. After taking a detailed history, the veterinarian will perform a thorough physical examination of the dog. This will include a neurological examination and a close assessment of the eyes. She will probably take blood and urine samples as well. The results of blood and urine tests may reveal metabolic disorders, poisoning, liver disease, kidney disease or other abnormalities. In dogs with primary epilepsy, the results of these tests usually are normal.
Based on the results of the initial evaluation, the veterinarian may recommend one or more of the following advanced diagnostic procedures:
- Electrocardiogram (ECG), to assess the health of the dog’s heart. Dogs with heart disease that involves abnormal heart rhythms (arrhythmias) can have clinical signs that mimic primary seizures.
- Thoracic (chest) and abdominal radiographs (X-rays), to look for any visible abnormalities.
- Serum bile acid assay, to check for hepatic encephalopathy and portosystemic shunts.
- Magnetic resonance imaging (MRI) or computed tomography (CT or CAT scan) of the skull and spine; these sophisticated diagnostic tools can identify tumors or other lesions in the brain or spinal cord. Typically, these tests are only available at veterinary teaching hospitals and specialty clinics. Radiographs of the skull are usually unremarkable in dogs with seizures, unless the cause of the disorder is physical trauma to the head.
- Sampling and analysis of cerebrospinal fluid (CSF); a spinal tap can help to identify certain types of neurological disease and inflammation.
- Advanced blood testing, especially if exposure to a particular toxin is suspected as a possible cause of the dog’s seizure episodes.
- Electroencephalogram (EEG), to trace the electrical impulses in the brain. This test is available in limited, highly specialized veterinary hospitals. Its usefulness in helping veterinarians diagnose the cause of canine seizures is unproven.
Dogs under 6 months or over 5 years of age that have seizures probably do not have primary epilepsy; structural brain abnormalities are a more likely cause of their symptoms. Research is underway to identify a genetic marker for true epilepsy.