Seizures in dogs - first assessment and status epilepticus

When a dog is presented for what the owner calls a fit, three questions need answering in order: was it actually a seizure, is the cause inside the brain or outside it, and should treatment start today?

Taking them out of order is the commonest mistake in practice. Starting an antiepileptic before investigating the cause masks the underlying disease.

Was it actually a seizure?

What the owner describes is not always a seizure. The things to separate out:

• Syncope — loss of consciousness of cardiac origin. Usually briefer, with no aura and no postictal phase, and often related to exertion. In an older dog with heart disease this is the first consideration.
• Vestibular episodes — loss of balance, head tilt, nystagmus; consciousness is preserved.
• Narcolepsy, sleep disorders, behavioural episodes

The most valuable diagnostic tool is a video recording. Thirty seconds filmed on the owner's phone says more than half an hour of history. Ask for it in every suspected case.

The typical shape of a seizure: a brief prodrome, loss of consciousness, tonic-clonic activity, urination or defecation, salivation, and then a postictal phase — disorientation, blindness, ravenous hunger and restlessness lasting minutes to hours. The presence of a postictal phase is among the strongest features separating a seizure from syncope.

Where the cause lies: inside or outside the brain

Seizures fall into three groups:

Reactive seizures — The brain is structurally normal and the cause is metabolic or toxic. Hypoglycaemia, hepatic failure and portosystemic shunt, electrolyte disturbance, toxins. These are excluded first, because their treatment is entirely different and they are correctable.

Structural epilepsy — There is a lesion: neoplasia, inflammatory disease, infarct, malformation, the sequel of trauma.

Idiopathic epilepsy — No structural or metabolic cause is found. It is a diagnosis of exclusion, but not an arbitrary one; it has a recognisable profile.