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