To most people, the term epilepsy conjures up images of generalized convulsive seizures with salivation and loss of consciousness for several minutes. However, cats are known to show strange types of seizures in which consciousness is usually impaired although not all of the body is affected. New research by Akos Pakozdy and colleagues at the University of Veterinary Medicine, Vienna shows that cats that suffer in this way have changes in the hippocampus, the part of the brain most commonly affected in human epilepsy. Although cats with such epileptic seizures may not respond immediately to treatment, they sometimes do so within a few days and if treatment continues they may once again show normal behaviour. The findings are published in the current issue of the "Journal of Feline Medicine and Surgery".
Many cat owners are not sure how to react when their animals start behaving abnormally. The diagnosis of epilepsy and similar conditions is particularly difficult because the symptoms are so variable. In some cases the first sign has been described as “looking into space” – which is generally considered to be how most cats spend the majority of their time anyway. But when it is followed by twitching of facial muscles, chewing and swallowing and excessive salivation even the most unaware owners are probably tempted to consult a vet.
Akos Pakozdy and colleagues at the University of Veterinary Medicine, Vienna now report an investigation into a total of 17 cats that were presented to the Clinic for Internal Medicine and Infectious Diseases with specific epileptic symptoms. The condition of nine of them was unfortunately so severe that nothing more could be done. In the other cases, the researchers noticed that treatment seemed ineffectual for the first 4-11 days, which made many owners fear that their animals would never recover. But when treatment was continued beyond this period a good number of the cats responded well and in four cases the animals survived even longer than it took the scientists to prepare their results for publication.
All the affected cats were found to have changes in the hippocampus and related structures, the part of the brain most commonly affected in human epilepsy. Importantly, no structural problems could be found in other areas of the brain. The changes in the hippocampus appeared similar to those observed in a special type of human epilepsy (MTLE-HS), although the researchers report some differences.
There are several indications that the seizures directly lead to hippocampal damage. Although the evidence is not clear-cut, it is clearly preferable to treat the condition as soon as possible to minimize damage. Pakozdy notes that some cats may be particularly susceptible to hippocampal damage and thus not respond to treatment but in other cases “if the cat is treated early it may not develop severe lesions with refractory seizures and the final outcome will be better”.
The new work at the University of Veterinary Medicine, Vienna suggests that cats with hippocampal damage may have a better prognosis than indicated by previous studies and that the condition is not necessarily fatal. The owners of the surviving cats report that their pets enjoy a good quality of life, so it is clear that this type of epilepsy in cats can be treated effectively. Whether their owners will be happy to let them continue staring into space afterwards is of course another matter.
The paper Complex Partial Cluster Seizures in Cats with Orofacial Involvement by Akos Pakozdy, Andrea Gruber, Sibylle Kneissl, Michael Leschnik, Peter Halasz and Johann G Thalhammer is published in the current issue of the Journal of Feline Medicine and Surgery.
The work follows on from the group’s previous research on the aetiology of seizures in cats, also published in the Journal of Feline Medicine and Surgery (Pakozdy et al. 2010, J Feline Med Surg 12, 910-916).