Seizures In Dogs And Cats
One of the most terrifying maladies a pet owner can face with his four-legged friend is a seizure. Even the mildest forms, in which a pet simply stares off into space disconnected from the world, can be terrifying. When seizures reach the most dramatic stage, the grand mal seizure, the helpless onlooker is terrified.
Let’s define seizure: it is an abnormal electrical discharge in the brain. A normal brain uses electricity to send information to its various parts, for example, the left hemisphere communicating with the right hemisphere.
The brain also uses electricity to send information out to other body parts, such as the limbs and diaphragm.
When this electricity is going to the right place at the right time, the body works normally. When things go wrong in the brain, and electrical discharges shoot around uncontrolled, seizures happen.
What causes seizures?
- Common causes are infections, such as Toxoplasmosis, and other diseases which have the ability to cause encephalitis, or inflammation of the brain.
- Physical abnormalities can cause seizures by causing excessive fluid pressure in and around the brain. For example, hydrocephalus is a condition in which the cerebrospinal fluid (CSF) is produced at a rate higher than the fluid can be removed from the cranium. The resulting pressure can cause seizures and mental retardation in pets, even death. As in people, a shunt can be installed in the brain to drain off the excess fluid.
- Trauma is another common cause of physical abnormalities that result in seizure activity.
- Brain tumors can also cause seizures by pressing against critical adjacent structures. Again, just as in people, they come in two basic varieties: malignant and benign. And, as in people, some are operable, some are not. My alma mater, Auburn University College of Veterinary Medicine, is a pioneer in brain tumor removal. The advent of magnetic resonance imaging (MRI) has greatly enhanced the predictability of the outcome of such surgery.
The Chemistry Profile is essential for determining the presence of metabolic diseases, such as Diabetes Mellitus.
Just as in people, the spinal tap is fundamental to diagnosing the cause of seizures. To perform it, a special needle is ever-so-carefully introduced into the space around the spinal cord and a small amount of CSF is removed and analyzed. Its physical properties are recorded. Then, a sample is submitted for culture and sensitivity to check for infection, and a portion is analyzed under a microscope for tumor cells and infectious organisms. Sometimes the cause can be determined by the CSF analysis and no further tests need to be done.
Sometimes we take radiographs (X-rays) of the skull to look for tumors, sinus cavity infections or foreign bodies, but, in general, radiographs are not much help with seizure diagnosis.
Electroencephalogram (EEG) is an excellent test that can not only pinpoint the source of the seizure activity, but can also help with diagnosis and prognosis for recovery. EEG is a test that measures and records the electrical activity of the brain. EEG is available only at universities and the largest specialty referral centers.
By far the most common diagnosis in veterinary medicine for seizure cause is “idiopathic.” Essentially, idiopathic means “we don’t know.” Sometimes we come to this diagnosis because all of the tests are negative, but more commonly we reach this point because the expense of exhaustive testing is beyond the capability of pet owners with no pet health insurance. Partial testing, however, is well within the reach of most including (CBC), Chemistry Profile, U/A, FF and heartworm serology as well as blood serology for parasites/infection of the CSF when indicated. Most general practitioners own X-ray machines.
Some general practitioners may perform CSF taps, but it is generally a procedure left to specialists.
When a specific diagnosis is made, treatment can be aimed at the inciting cause. For example, Toxoplasmosis is treated with antibiotic therapy.
When the diagnosis is Idiopathic Epilepsy, a decision is made between the doctor and the pet owner about when and whether to begin anticonvulsant therapy. Generally, the decision is made based on the frequency and severity of the seizures. Several anticonvulsant medications are available.
Your pet’s doctor can help you in determining which medication is best for your pet and his unique situation.