Types of Seizures
It is important to be able to recognize a seizure. Events that can look like seizures include syncopal episodes, vestibular disease, and behavioral disorders. The most commonly recognized seizure type is a generalized tonic-clonic seizure. Another term for this is a grand mal seizure. The typical signs of a generalized tonic-clonic seizure include neck extension with stiff, rigid limbs followed by rhythmic movement of the limbs and head. Commonly these animals will salivate, urinate, and defecate during a seizure. A partial seizure describes a focal seizure that can cause tonic/clonic signs in one limb or side of the face. Partial seizures are divided into simple partial seizures, complex partial seizures and psychomotor seizures. Patients with simple partial seizures maintain consciousness but exhibit focal motor activity. Patients with complex partial seizures exhibit focal motor activity but also have a loss of consciousness. Psychomotor seizures are displayed as abnormal behavioral activity such as fly-biting, aggression or hysteria.
When Is a Seizure an Emergency?
Most seizures are isolated events that stop spontaneously. A seizure becomes an emergency when two or more seizures happen in a 24-hour period (cluster seizures), a single seizure lasts more than 5 minutes, or the patient has three or more seizures without returning to normal between seizures (status epilepticus). In these cases, the patient may eventually stop having convulsions despite continued electrical seizure activity in the brain. Cluster seizures and status epilepticus are emergency situations, as irreversible neuronal damage or death of the patient can occur.
Emergency Therapy for Seizures
Gain Venous Access
Venous access is important, and most drugs are going to have the fastest onset of action when given intravenously. An IV catheter should be placed to allow for rapid administration of medications. If an IV catheter cannot be placed, then several drugs can be administered intranasal or per rectum.
Administer a Benzodiazepine
0.5 mg/kg of diazepam is given IV. If IV access is not established then 1.0 mg/kg of diazepam can be administered per rectum. Midazolam 0.06–0.22 mg/kg can be given IV or IM instead of diazepam. These drugs can be redosed, but if the animal continues to seize after three doses, a diazepam constant rate infusion (CRI) at 0.5–1.0 mg/kg/h should be considered.
Consider Anesthetizing the Patient if Diazepam Does Not Stop Seizure
Propofol or pentobarbital can be used if benzodiazepines fail to stop the seizure. Administer propofol 1–6 mg/kg to effect, then a 0.1–0.6 mg/kg/min CRI should be started. Pentobarbital 2–15 mg/kg IV can also be used. When using propofol or pentobarbital, be prepared to intubate the patient.
Pull Blood
A blood glucose should be checked immediately. Treat the hypoglycemia, if indicated. Also, blood should be saved for a serum biochemistry profile, complete blood count, and possible bile acids or resting ammonia. If a patient is on antiepileptic drugs, blood can be saved from serum concentration testing.
Provide Supportive Care
A facemask can be used to provide oxygen therapy to the patient.
Additional Considerations
If the patient worsens neurologically, mannitol 0.5–1 g/kg IV can be given. Steroids should be avoided prior to a neurological work-up.
Administer a Maintenance Drug
A loading dose of the maintenance antiepileptic drug should be considered. The loading dose of phenobarbital for dogs is 12–16 mg/kg. Many neurologists like to split this into two to four doses to minimize the sedating side effects. In cats the loading dose of phenobarbital is 4 mg/kg. It important to administer a maintenance drug following the administration of diazepam, to have a longer acting antiepileptic medication in effect. Diazepam only lasts about 30 minutes, so a longer acting drug is needed.
Maintenance drug therapy
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Dog dose
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Cat dose
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Side effects
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Phenobarbital
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2–3 mg/kg PO q 12 h
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1–4 mg/kg PO q 12 h
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Polyphagia, sedation, liver damage
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Potassium bromide (for oral use only)
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20–40 mg/kg PO q 24 h (sodium bromide can be used for IV loading at 400–500 mg/kg IV over 24 hours)
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Do not use
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Polyphagia, ataxia, skin eruptions
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Levetiracetam
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20–30 mg/kg PO q 8 h
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20–30 mg/kg PO q 8 h
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Minimal
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Zonisamide
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5 mg/kg PO q 12 h (if receiving phenobarbital increase to 10 mg/kg)
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Not known in cats
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Anorexia, blood dyscrasias, sedation
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Felbamate
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15 mg/kg PO q 8–12 h
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Nervousness, hyperexcitability and anorexia
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Pregabalin
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2–4 mg/kg PO q 8 h
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Minimal
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Nursing Care of Epileptics
The patient's temperature should be checked, and if the patient is hyperthermic it should be cooled. Care should be taken not to overcool the patient and create hypothermia. Once the patient reaches 103–104°F (39.4–40°C), active cooling should be discontinued.
Some dogs will be very sedate following a seizure or with the addition of a new antiepileptic drug. Rotation of the patient should be done every 4 hours to prevent lung atelectasis, and the bedding should be kept clean and dry. Sedate patients might require eye lubrication to prevent corneal ulceration.
Following a seizure, patients may appear to be agitated and be pacing, and they may be blind. Care should be taken to place these patients in a confined, padded space to avoid self-trauma. For dogs who are acutely blind following a seizure, be sure to walk them on a short leash to prevent them from running in to walls, doors, or other obstacles.
References
References are available upon request.