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May/June 2014 Today's Veterinary Practice 31 tvpjournal.com E pilepsy is a common canine disease—thought to affect up to 1 in 20 dogs—and potentially life threatening. 1 A useful working understanding is essential for the small animal practitioner. When a patient presents for an episode of odd behavior or movement, the clinician must immediately consider 4 questions: 1. Are the events described by the owner (or recorded on video) truly a seizure? 2. Can an underlying cause be identified and treated versus treating only the seizure? 3. Should an anti-epileptic drug (AED) be administered? 4. If medical therapy is pursued, which AED should be chosen? 1 IS THE EVENT A SEIZURE? There are many behaviors, events, and diseases that mimic a true seizure (Table 1). Electroencephalography Electroencephalography (EEG) records the brain's elec- trical activity and is considered by many human physi- cians to be an essential tool for characterizing seizure ThE CaninE SEizurE PaTiEnT Four Important Questions PEEr rEviEwEd Table 1. behaviors, events, & Diseases with Seizure-like appearance • atlantoaxial subluxation • breed and drug induced dyskinesia/movement disorders • Cataplexy, narcolepsy, rapid eye movement (ReM) sleep disorder • Cervical muscle spasm • Chiari malformation/syringomyelia associated episodes • encephalitis • episodes of neuromuscular disease • exercise-induced collapse • extreme agitation • Head bobbing/tremor syndromes • Intermittent decerebrate/decerebellate rigidity • Jaw chomping/fly biting • Metabolic/toxic event • Myoclonus • Syncope • Vestibular episode PROFILE OF EPILEPSY Definition Epilepsy is defined as 2 or more seizures, at least 24 hours apart, resulting from a nontoxic, nonmetabolic cause. an epileptic seizure is defined as a transient occurrence of signs, symptoms, or both due to abnormal, excessive, or synchronous neuronal ac- tivity in the brain. 2 Seizure events can result from: • Disease localized to the brain (symptomatic/struc- tural) • a reaction of the healthy brain to a metabolic or toxic insult (reactive) • an unknown or genetic cause (idiopathic). In human medicine, the term idiopathic has been replaced by the terms genetic or seizure of unknown cause. 2 Classification by Frequency Seizures can be classified into 3 categories based on frequency. 3 1. Cluster: 2 or more seizures within 24 hours 2. Acute repetitive: 2 or more seizures within 5 to 12 hours, separate from normal seizure pattern 3. Status epilepticus: Continuous seizure for 5 or more minutes or 2 or more seizures with no recovery between seizures Classification by Breed In veterinary medicine, epilepsy is considered genetic when the frequency in a breed exceeds that of the general population (eg, Petit basset Griffon Vendeen). 4 Classifying seizures by breed is important—certain types of genetic epilepsy have different prognoses, and much interest exists with regard to using dogs as models for human epilepsy. border collies have a 2-year median survival from time of seizure onset, with 94% affected by cluster seizures, 53% status epilepticus, and 71% rate of drug resistance. 5 Conversely, the lagotto Romagnolo has seizure onset at 5 weeks, which spontaneously resolves by 13 weeks, similar to benign familial neonatal seizure in humans. 6 William Bush, VMD, Diplomate ACVIM (Neurology) Bush Veterinary Neurology Service Leesburg, Springfield, and Richmond, Virginia & Rockville, Maryland TVP_2014-0506_Seizure Patient.indd 31 5/24/2014 10:44:50 AM