Idiopathic epilepsy in dogs: IVETF confidence tiers
3-year-old Border Collie with three generalised tonic-clonic seizures in 4 months, more than 24 h apart. Normal interictal neurological examination. Haematology, biochemistry, urinalysis and pre- and post-prandial bile acids are normal. MRI with an epilepsy protocol and CSF analysis are unremarkable.
According to the IVETF consensus, which diagnostic confidence tier does this dog reach?
chevron_right Show answer and explanation
A. Tier I
Tier I only requires the history (≥2 unprovoked seizures ≥24 h apart, onset between 6 months and 6 years), a normal interictal examination and a normal minimum database. This dog has already gone beyond that tier.
B. Tier II
Correct. Tier II adds normal bile acids, a normal epilepsy-protocol MRI and normal CSF to Tier I. That is exactly what this dog has.
C. Tier III
Tier III additionally requires electroencephalographic abnormalities (ictal or interictal) consistent with epilepsy. No EEG has been performed here.
D. None: idiopathic epilepsy cannot be diagnosed without a genetic test
Genetic tests exist for only a few breed-specific epilepsies. Idiopathic epilepsy is a diagnosis of exclusion, graded with the IVETF confidence tiers.
lightbulb Key takeaway
Idiopathic epilepsy is a diagnosis of exclusion. Tier I already allows treatment of a typical dog (onset at 6 months–6 years, normal interictal examination), but MRI and CSF are strongly advised if onset is atypical, there are interictal deficits or the response to treatment is poor.
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Updated: October 31, 2026 · Educational content for veterinary professionals. It does not replace current clinical guidelines or the judgement of the attending veterinarian.