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Issue One Hundred One – May 2016
standards of
C.A.R.E.
CLINICAL CASE MANAGEMENT NEWSLETTER
The Calgary Animal Referral & Emergency Centre Animal Hospital
standards of
C.A.R.E.
Issue One Hundred One – May 2016
Management of Status Epilepticus and Cluster Seizures
in Patients with Idiopathic Epilepsy
Deanna White, BSc, DVM
A common presentation in small animal veterinary practice is seizures. A large percentage
of those cases are due to idiopathic epilepsy. The goal of treating patients with idiopathic
epilepsy is to reduce the severity, frequency and duration of seizures. Ideally seizure activity
would be eradicated but generally this is not an achievable goal so we aim to reduce
seizure activity while minimizing the adverse effects and side effects of anti-epileptic drugs
(AED).
Unfortunately, our patients that are not well controlled often present on an emergency basis
and facing additional expense and heartache for the owner. Patients experiencing cluster
seizures and status epilepticus are more likely to be euthanized than patients with single
event seizure activity. The goal of this communication is to provide treatment options for
patients presenting on an emergency basis, as well as options to be used at home for cluster
seizures hoping to reduce emergency visits when possible. The options are only intended
for patients with idiopathic epilepsy. They are not intended for patients with seizures due
to other secondary epilepsy (ex: neoplasia, non-infectious encephalitis, hydrocephalus) as
these patients likely require additional therapies beyond AED.
Idiopathic epilepsy is generally defined as seizure onset from 1-6 years of age, no abnormalities
noted on blood work (this generally includes CBC, Chemistry panel, pre and post prandial
bile acids), normal neurologic exam between seizures and no abnormalities noted on MRI
and CSF analysis. Obviously in some circumstances, such as when clients have financial
constraints and can’t pursue imaging and CSF analysis, we make a presumptive diagnosis
based on signalment, clinical presentation and blood work alone. It is also very important to
have a strong veterinary-client relationship and to ensure the client is well informed on the
associated risks of status epilepticus or cluster seizures at home, such as cerebral and noncardiogenic pulmonary edema. Clients also need to be aware that if their pet continues to
seizure after initiating treatment that their pet will require veterinary care, hospitalization and
further treatments are recommended.
Firstly, it is important to define status epilepticus and cluster seizures. Status epilepticus is
defined as a “continuous seizure, or two or more discrete seizures between which there
is incomplete recovery of consciousness, lasting at least five minutes”. Cluster seizures
are defined as “two or more seizures within a twenty-four hour period”. The protocols are
formulated depending on the individual patient’s typical seizure pattern.
For patients who have cluster seizures that occur minutes to hours apart benzodiazepines
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standards of
C.A.R.E.
Issue One Hundred One – May 2016
are generally our first line therapy. The owner can administer Diazepam rectally at home. If
the patient is already on Phenobarbital then 1-2mg/kg should be utilized for each dose. If
they are not already on Phenobarbital then 0.5-1mg/kg can be used. The first dose can be
given immediately while they are having the seizure. The dose can be repeated two more
times each at 30-45 minutes apart. Rectal Diazepam is not likely to control the initial seizure
but the goal of this therapy is to prevent subsequent seizures in the 2-4 hours following the
initial event. If the patient is actively seizing for longer than 5 minutes then they should be
seen by a veterinarian.
If the patient has cluster seizures that are spread out by hours to days then one of the
following two protocols can be utilized. The first is using Clonazepam (Clorazepate). This is a
longer acting benzodiazepine and should be administered orally (0.5mg/kg) every 8 hours
for 3 days following the initial seizure activity. The second is giving Levetiracetam (Keppra)
orally (20-30mg/kg) every 8 hours for 3-5 days following the initial seizure. Oral Levetiracetam
is generally dispensed due to ease of administration but injectable Levetiracetam can also
be dispensed to owners that are comfortable performing subcutaneous injections and for
small patients that can’t be dosed by the available oral tablet formulations. For both of
the options listed it is important to inform the owner that they must wait until the seizure
activity has stopped and a swallow reflex present to administer the medications as they
are administered orally. If the above protocols fail to control the seizures then they should
be seen again by a veterinarian. It is then recommended that the owners have follow up
veterinary care to address whether additional anti-epileptic therapy needs to be instigated
or to ensure that their current anti-epileptic therapy is in the therapeutic range.
For patients presenting on emergency for status epilepticus or that have failed the above
protocols and continued to have cluster seizures there are multiple treatment options
available. First line therapy is generally benzodiazepines administered rectally or IV if a
catheter is placed on admission. A CRI can be considered if they continue to seizure but
responded to the bolus. Once a blood sample has been collected to test for therapeutic
levels of current anti-epileptic medications then they can be added to the therapy. This is
generally most significant for Phenobarbital but can be considered for Zonisamide (sample
to be taken one hour before the next dose is administered) and Potassium Bromide. If seizure
activity continues Keppra or Phenobarbital can also be used. Propofol bolus followed by a
CRI or Ketamine bolus followed by a CRI can also be tried as a next line of therapy.
References:
Hardy, B.T., Patterson, E.E., Cloyd, J.M., Hardy, R.M. and Leppik, I.E. 2012. Double-Masked, Placebo-Controlled Study of Intravenous
Levetiracetam for the Treatment of Status Epilepticus and Acute Repetitive Seizures in Dogs. Journal of Veterinary Internal Medicine. 26.
334-340.
Lowrie, M. 2013. Canine status epilepticus. Companion animal. 18(5). 198-204.
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