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WE would like to alert colleagues to the fact that in the past month we have examined four cats with a particular form of epilepsy.
All four cats lived in a radius of 80 miles from our hospital and presented with complex partial seizures characterised by arrest in a sitting position, profuse salivation, facial twitches, vocalisation (most often howling and hissing) and mydriasis. The complex partial seizures progressed within a few days with an increase in frequency and duration, and in two cats the progression led to generalised seizures with loss of consciousness and involuntary urination. One cat had general hyperaesthesia and urinary retention in the interictal period. Brain MRI revealed bilaterally symmetrical hippocampal oedema in one case (Fig 1), and focal oedema within the piriform lobe in another cat. Treatment with phenobarbitone alone was successful in one case. The cat with the most severe clinical signs was euthanased due to the severity of the seizures.
Similar complex partial seizures with orofacial involvement were first described by Fatzer and others (2000) in 38 cats from Switzerland with necrosis of the hippocampus and piriform lobe. Most of the cases described were sporadic, but two small clusters of cases were identified (one in a village and one on a farm); the authors also noticed a slightly increased frequency of cases during the warmer months. The authors suggested a possible environmental or toxic cause for this form of epilepsy.
Hippocampal necrosis was also reported in two Italian cats (Brini and others 2004) and four more Swiss cats (Schmied and others 2008). Most recently, Pakozdy and others (2011) published a retrospective study of 17 domestic shorthair cats from Austria with complex partial seizures with orofacial involvement. These cats had a clinical presentation similar to our cases and the same pathological localisation; the authors hypothesised that this type of seizure may originate from the limbic region. This group of cats was also part of a larger retrospective study of seizures in 125 cats (Pakozdy and others 2010); none of the cats with different types of seizures had necrosis of the hippocampus and piriform lobe.
In the first three publications, the authors reported a poor prognosis for recovery; Pakozdy and others (2011) reported that four cats survived and two of those cats were seizure-free, despite an initial resistance to antiepileptic therapy.
In summary, necrosis of the hippocampus and piriform lobe may be a consequence of prolonged complex partial and generalised seizures in cats rather than representing a disease entity and, based on the recent literature and our personal experience, cats treated aggressively earlier on have a better prognosis. We have identified a cluster of affected cats in the Midlands and we want to alert colleagues to this clinical presentation and the need to recognise and control the seizures as soon as possible.
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