| Epilepsy is a non progressive brain disorder | | | | insulinoma, an insulin secreting pancreatic |
| that induces recurrent seizures. It is very | | | | tumor. If liver enzymes are raised, a further |
| important to understand that there are | | | | liver function test (bile acid stimulation) |
| numerous disorders that can cause seizures, | | | | may be done. Blood lead levels should be |
| and in order to make a diagnosis of true | | | | measured in animals that may have had access |
| epilepsy, many of these other causes must be | | | | to lead containing materials. |
| ruled out. | | | | |
| | | | Xrays of the chest and abdomen are sometimes |
| What is a Seizure? | | | | performed to check for any other significant |
| | | | disease, and fecal analysis is recommended in |
| A seizure is the clinical manifestation of a | | | | puppies with seizures as heavy parasite |
| cerebral disorder that can appear suddenly | | | | burdens have been implicated. |
| out of a background of normality, and then | | | | |
| disappear with equal abruptness. The term fit | | | | If all of the above tests are normal, and no |
| is often used colloquially when referring to | | | | disease outside the brain has been detected, |
| a seizure. | | | | many animals will be diagnosed with epilepsy |
| | | | as further tests are of the expensive |
| In humans, an epileptic seizure is a | | | | variety. If further tests for intracranial |
| definable event that can be classified | | | | (within the brain) disease are to be |
| according to categories set by the | | | | performed, cerebrospinal fluid (CSF) analysis |
| International League Against Epilepsy. A | | | | is the first step. CSF is tested for the |
| formal classification system specifically for | | | | presence of viral (e.g. Canine Distemper, |
| dogs and cats does not exist, but seizures | | | | Rabies), bacterial, fungal (e.g. |
| can nevertheless be classified as either | | | | Cryptococcus) and protozoal (e.g. |
| partial or generalized episodes. | | | | Toxoplasmosis) infections. |
| | | | Electroencephalography (EEG) is useful for |
| Partial Seizures | | | | diagnosing malformations present since birth, |
| | | | such as hydrocephalus. Brain tumors are often |
| These are seizures in which a localized onset | | | | only able to be diagnosed by advanced imaging |
| may be determined. They usually have a | | | | techniques such as Computed Tomography (CT) |
| congenital (present at birth) or an acquired | | | | Scanning or Magnetic Resonance Imaging (MRI). |
| (cancer, encephalitis) cause, and can | | | | These must be done under general anesthesia |
| sometimes evolve into a secondary generalized | | | | as the animal must be completely motionless |
| seizure. | | | | during the scan. |
| | | | |
| Generalized Seizures | | | | Treatment of Epilepsy |
| | | | |
| Generalized seizures are the most common type | | | | Once a tentative diagnosis of epilepsy has |
| of seizures in dogs and cats. There are | | | | been made (by excluding all the other known |
| several variations of these seizures: | | | | causes of seizures), the animal can be |
| | | | prescribed anticonvulsant drugs. These drugs |
| 1. Absence seizures (petit mal): sudden brief | | | | are not appropriate for animals with seizures |
| loss of consciousness, rare in animals | | | | caused by a problem outside the brain. The |
| | | | overall goal of anticonvulsant therapy is to |
| 2. Myoclonic seizures: muscle jerk of one or | | | | eradicate all seizure activity, but this is |
| more muscles | | | | rarely achieved. Most pets benefit from |
| | | | anticonvulsant drugs by reducing the |
| 3. Clonic seizures: rhythmic muscle | | | | frequency, severity and duration of their |
| contractions | | | | seizures. A more realistic goal is to reduce |
| | | | the frequency of the seizures to a level that |
| 4. Tonic seizures: increase in muscle tone in | | | | is acceptable for the owner, without having |
| all skeletal muscles | | | | negative side effects for the animal. A |
| | | | minority of animals require such high doses |
| 5. Tonic Clonic seizures (grand mal): the | | | | of anticonvulsant drugs to suppress their |
| most common form of seizure in pets | | | | seizures that the adverse effects caused by |
| | | | it outweigh the benefits. |
| Tonic Clonic Seizures | | | | |
| | | | Since epilepsy is not curable, the owner must |
| Tonic Clonic (grand mal) seizures account for | | | | be prepared to give the medication for the |
| 60% of seizures in cats and 80% of seizures | | | | rest of the animals life. However, if after |
| in dogs. They are usually accompanied by a | | | | being on anticonvulsant medication for over a |
| loss of consciousness, and consist of a tonic | | | | year no seizures have occurred, a cautious |
| phase, where the increased muscle tone causes | | | | slow reduction in dose can be attempted. |
| the animal to fall on its side with its limbs | | | | |
| extended, and a clonic phase, consisting of | | | | The three most commonly used drugs in the |
| intense muscle jerking or paddling movements. | | | | treatment of epilepsy in cats and dogs are: |
| | | | |
| Causes of Seizures | | | | 1. Diazepam |
| | | | |
| In order to diagnose true epilepsy, other | | | | Known to many by its trade name Valium, |
| causes of seizures must be first ruled out. | | | | diazepam is used in emergency short term |
| The questions a veterinarian must answer are: | | | | situations to treat animals in status |
| | | | epilepticus, i.e. during a seizure. It is |
| Is the cause inside the brain or outside the | | | | best administered intravenously so that it is |
| brain? | | | | delivered to the brain quickly, though |
| | | | finding a vein or placing a catheter in a |
| If inside the brain, is the cause progressive | | | | fitting animal can be a challenge. In those |
| (e.g. cancer, infection) or non progressive | | | | situations, it is sometimes given rectally, |
| (epilepsy)? | | | | where it is fairly rapidly absorbed across |
| | | | the rectal wall. If status epilepticus |
| If outside the brain, does the cause | | | | continues despite the repeated administration |
| originate inside the body (e.g. low blood | | | | of diazepam, phenobarbitone can be given |
| glucose, kidney failure, a liver problem) or | | | | intravenously. |
| outside the body (e.g. lead poisoning, | | | | |
| organophosphate toxicity)? | | | | 2. Phenobarbitone |
| | | | |
| Making a Diagnosis | | | | Phenobarbitone is the most commonly |
| | | | prescribed anticonvulsant drug for both |
| If an animal has a solitary seizure, most | | | | canine and feline epilepsy, owing to its |
| veterinarians will advise against expensive | | | | efficacy and its low cost. Over three |
| and time consuming tests for something that | | | | quarters of epileptic dogs have their |
| may never happen again. If an animal has more | | | | seizures controlled by phenobarbitone alone. |
| than one seizure though, tests are indicated. | | | | Sometimes it can take several weeks for the |
| | | | level of phenobarbitone in the blood stream |
| A veterinarian will start by taking a | | | | to reach a high enough level to work |
| detailed case history, focusing on the | | | | properly, so many vets favor using a higher |
| description of the animals seizures, their | | | | loading dose initially, reducing it for the |
| frequency and duration, and the animals | | | | maintenance phase. However, care must be |
| behavior between seizures. Ideally the | | | | taken as high doses of phenobarbitone can |
| seizure should be videotaped by the owner, | | | | cause liver damage, and liver enzymes should |
| and then shown to the veterinarian. It is | | | | be periodically checked in animals on long |
| important to differentiate a proper seizure | | | | term therapy. Annual blood tests are also |
| from other causes of collapse such as an | | | | advised to check serum concentration levels |
| episode of syncope (where the heart misses | | | | of the drug, to calibrate the dose |
| several beats), narcolepsy or weakness due to | | | | effectively. High doses can also cause |
| another neurological problem (e.g. myasthenia | | | | sedation. |
| gravis). Features of the description which | | | | |
| indicate a seizure are: | | | | 3. Potassium Bromide |
| | | | |
| 1. Tonic (increased muscle tone) and clonic | | | | A proportion of dogs are resistant to |
| (jerky) muscle movements | | | | phenobarbitone. In such dogs, the addition of |
| | | | potassium bromide, i.e. a second drug, can be |
| 2. Loss of consciousness (though not always) | | | | tried. The potassium bromide may also be |
| | | | tried alone as an alternative to |
| 3. Increased salivation | | | | phenobarbitone, but generally only after |
| | | | phenobarbitone has been thoroughly |
| 4. Spontaneous urination or defaecation | | | | investigated at various doses and found to be |
| | | | inadequate. Phenobarbitone is also deemed |
| The veterinarian will then conduct a full | | | | unsuitable if the dog has liver dysfunction |
| clinical examination, followed by a more | | | | of any kind, in these cases potassium bromide |
| specific neurological examination. Blood will | | | | (often referred to simply as bromide as that |
| then be taken for full hematology and | | | | is the therapeutic part) can be used. |
| biochemistry profiles. A fasting blood | | | | Potassium bromide is not used in cats, only |
| glucose is useful to rule out hypoglycaemia, | | | | diazepam and phenobarbitone are recommended |
| which is a frequent cause of seizures in dogs | | | | in this species. |
| less than 6 months old and dogs with an | | | | |