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Table 1 Clinical characteristics of episodic disorders

From: International veterinary epilepsy task force consensus proposal: diagnostic approach to epilepsy in dogs

Discriminator Syncope Narcolepsy/Cataplexy Neuromuscular weakness Paroxysmal behaviour changes (compulsive disorder) Vestibular attack Paroxysmal Dyskinesia Idiopathic head tremor Seizure
Clinical status between episodes Normal or arrhythmia, pulse deficits, heart murmur, cyanosis, abnormal lung auscultation Altered sleep/wake cycle, normal clinical examination Normal or generalised weakness, muscle atrophy, pain, decreased reflexes Normal Normal Normal Normal Normal or forebrain signs
Precipitating event or trigger Exercise, excitement Excitement, eating Activity, exercise Behavioural triggers (e.g., fear) None None or activity, exercise, excitement, stress None or stress, fatigue, overstimulation None or flashing lights, anxiety, stress
Pre-event changes None None None None None None None Pre-ictal signs may be observed including: anxiety, restlessness, increased affection, contact-seeking, withdrawal, hiding, aggressiveness, and vocalization
Event description Brief, sudden collapse and rapid recovery Sudden collapse Stiff, stilted gait prior to collapse Pacing, barking, licking, chasing imaginary objects or tail, chewing objects Head tilt, nystagmus, vestibular ataxia, collapse towards side of head tilt Dystonia, chorea, ballismus, athetosis, tremors, impaired posture, inability to stand or walk Vertical or horizontal rhythmic head movement Depending on seizure focus, focal or generalized, tonic-clonic movements most common
Level of consciousness Reduced to absent Normal if only cataplexy. Absent (asleep) in narcolepsy Normal Normal Normal or disorientated Normal Normal Often impaired
Autonomic signs Possible abnormalities of heart rate and rhythm None None None None None None Possible: hypersalivation, defaecation, urination
Muscle tone Flaccid (all body) Flaccid (all body) Often flaccid (can appear spastic with certain myopathies) Normal Unilateral decrease in extensor muscle tone Hypertonicity (focal or generalised) Normal Typically increased: tonic (hypertonicity) or alternating tonic-clonic movements
Lateralising signs No No No No Yes Possible No Possible
Duration Seconds Seconds to minutes Minutes to hours Minutes to hours Seconds to hours Seconds to hours Seconds to hours Seconds to minutes or > 5 min in case of status epilepticus
Post-episodic changes None None None None None None or tiredness None, tiredness, or restlessness Post-ictal signs frequently occur including: disorientation, aggressive behaviour, restlessness, pacing, lethargy, deep sleep, hunger, thirst, ataxia, proprioceptive deficits, and blindness
Further comments May be accompanied by cough, increased respiratory noise Often occurs in young purebred dogs. May be accompanied by dysphagia, dysphonia, regurgitation, dyspnoea History of anxiety disorder Subtle signs of vestibular disease might persist Interaction with the owner can alleviate or interrupt the episode. Consider breed specific disorders and age at onset. Episodes can be interrupted by the owner Facial muscles often involved during the ictus