Epilepsy is a brain disorder that causes recurrent seizures. It is relatively common in dogs. Epilepsy generally starts between the ages of 6 months to 5 years, with a typical age of onset of 2-3 years. Epilepsy is not curable, but it can usually be managed with medications so that seizures are kept to a minimum and quality of life is good.
Seizures are a sign of abnormal electrical activity in the brain. There are many causes of seizures other than epilepsy. In fact, epilepsy is only diagnosed when other causes of seizures can be safely ruled out. Causes of seizures include:
- Congenital brain defects
- Brain tumors
- Brain injury such as head trauma or stroke
- Abnormally low or high blood sugar
- Heatstroke or high fever
- Kidney disorders
- Liver disorders
- Low thyroid level
- Medication side effects
There are 3 main types of seizure: grand mal, partial, and complex. Characterizing the seizure can help narrow down the cause.
Grand Mal seizures in dogs are dramatic and hard to miss. a dog will typically lose consciousness, fall down on one side and have uncontrollable muscle movements of the whole body, resulting in kicking or paddling. The animal may salivate profusely and sometimes urinate or defecate involuntarily. Epileptics most commonly have Grand Mal seizures.
Partial seizures, as the name implies, only affect part of the body. The dog does not fall down or lose consciousness, but may seem to be in a trance. There are odd repetitive movements such as facial twitching or jaw chattering, or pawing or biting at a body part.
Complex seizurescause bizarre behaviors such as howling, fly-biting, circling, or sudden unprovoked aggression. Psychomotor seizures can be the hardest to identify, as they can overlap with common behavioral disorders. Partial and complex seizures are more likely to be associated with focal brain disease (e.g. trauma, stroke, infection or tumor) than grand mal seizures.
Seizures, regardless of type, are often preceded by an “aura,” or a telltale sensation associated with a coming seizure. Humans describe this phenomenon as a peculiar sensory experience–a feeling, smell, taste or sight–that indicates a seizure is coming. Dogs can’t verbalize such sensations, but may act restless, disoriented or clingy right before the seizure starts. Seizures are followed by a post-ictal period in which the animal is no longer twitching, but appears confused, uncoordinated and unable to see.
A typical seizure lasts 1-2 minutes – although it can seem much longer to the worried observer! See the box, below, for how to help a seizuring dog. A single seizure is usually not harmless. One exception is when seizures last greater than 5 minutes or come in rapid succession with little pause in between. This condition is called status epilepticus. A dog in status epilepticus can dangerously overheat due to repetitive muscle movement. If your dog has been seizuring continuously for 5 minutes or more, seek emergency veterinary care immediately.
The underlying cause of epilepsy in dogs is not well understood. Epilepsy may have a heritable link, and certain breeds are thought to be more susceptible. These include: Schnauzers, Basset Hounds, Collies and Cocker Spaniels.
Epilepsy is diagnosed when all other causes of seizures are excluded. Your veterinarian will ask several questions to determine if the event truly was a seizure–a video recording of the event, if available, is invaluable–and to pinpoint any possible inciting causes such as an injury or toxic exposure. He or she will then do a full physical and neurological examination. Workup for a seizuring dog typically includes complete blood count and chemistry analysis, thyroid level, urinalysis and possibly X-rays. From here, a complete workup may include referral to a neurologist for advanced imaging (CT scan or MRI) and spinal fluid analysis. That said, most vets feel comfortable diagnosing epilepsy without advanced tests when the presentation is classic (a young, otherwise healthy dog having grand mal seizures) and basic tests are normal.
Treatment for epilepsy is rarely indicated after just one seizure. After running tests to rule out other causes, your veterinarian will most likely recommend watchful waiting. The following criteria usually indicate that treatment is necessary:
- seizures are severe
- seizures are increasing in frequency, i.e. more than once a month
- seizures occur in clusters
- the patient is from a seizure-prone breed
Treatment for epilepsy is never curative, and must be continued lifelong. The goal of treatment is to reduce the severity and frequency of seizures. A variety of anticonvulsant drugs are available. Phenobarbital or potassium bromide are two common choices. Side effects can include increased appetite and thirst, stomach upset, and sedation but the sedation usually wears off after several weeks. Blood levels must be monitored regularly and dosages adjusted to be sure the medication is working properly. Pet parents are often asked to maintain a seizure log to help guide therapy. When one drug no longer controls seizures, one or two additional drugs may be added.
Newer anticonvulsants borrowed from human medicine are gaining in popularity for dogs because of their improved safety and efficacy; however the cost can be much higher. Examples include levetiracetam (Keppra®), zonisamide and gabapentin. Note: Never give your dog a human medication that has not been specifically prescribed by your veterinarian. The newer anticonvulsants can be used as add-on drugs when seizures become refractory, or may be prescribed from the outset. Every dog reacts differently, and determining the proper treatment can require time and patience. Your veterinarian will help determine the best medication or combination of medications for your epileptic dog.
21 Apr, 2016
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