Hippocampal necrosis and sclerosis in cats: A retrospective study of 35 cases

Hippocampal necrosis and hippocampal sclerosis in cats is a neuropathological entity which is a major concern in feline epilepsy. The aim of our study was to identify associated pathologic brain lesions possibly serving as aetiological triggers in this condition. Therefore, the formalin-fixed and paraffin waxembedded brain tissue of 35 cats diagnosed with hippocampal necrosis or sclerosis was examined retrospectively. In 26 cats inflammatory infiltrates could be found in the hippocampus or adjacent brain regions. Fifteen out of these animals demonstrated mild to moderate infiltrations by lymphocytes and complement deposition in the hippocampus similar to human limbic encephalitis, seven showed unspecific, predominantly non-suppurative inflammation, and two demonstrated suppurative inflammation of the hippocampus or adjacent brain regions. Additionally, one cat was diagnosed with central nervous manifestation of feline infectious peritonitis virus and another one with cerebral Toxoplasma gondii infection. Intracranial neoplasia was present in five cases altogether. Three of them comprised meningioma which was present additionally to lesions resembling limbic encephalitis in two cases, and a dentate gyrus alteration in one case. The other two tumour-associated cases comprised oligodendroglioma. Structural alterations of the dentate gyrus together with hippocampal sclerosis were encountered in three cases in total. Besides the case associated with a meningioma, one case demonstrated lesions resembling limbic encephalitis. A vascular infarct in the temporal lobe was encountered in one cat. In four cases no lesions other than hippocampal necrosis or sclerosis were found. The involvement of feline immunodeficiency virus infections, which may be able to produce hippocampal lesions, was not encountered in the cats examined

International Veterinary Epilepsy Task Force Consensus Proposal: Diagnostic approach to epilepsy in dogs

This article outlines the consensus proposal on diagnosis of epilepsy in dogs by the International Veterinary Epilepsy Task Force. The aim of this consensus proposal is to improve consistency in the diagnosis of epilepsy in the clinical and research settings. The diagnostic approach to the patient presenting with a history of suspected epileptic seizures incorporates two fundamental steps: to establish if the events the animal is demonstrating truly represent epileptic seizures and if so, to identify their underlying cause. Differentiation of epileptic seizures from other non-epileptic episodic paroxysmal events can be challenging. Criteria that can be used to make this differentiation are presented in detail and discussed. Criteria for the diagnosis of idiopathic epilepsy (IE) are described in a three-tier system. Tier I confidence level for the diagnosis of IE is based on a history of two or more unprovoked epileptic seizures occurring at least 24 h apart, age at epileptic seizure onset of between six months and six years, unremarkable inter-ictal physical and neurological examination, and no significant abnormalities on minimum data base blood tests and urinalysis. Tier II confidence level for the diagnosis of IE is based on the factors listed in tier I and unremarkable fasting and post-prandial bile acids, magnetic resonance imaging (MRI) of the brain (based on an epilepsy-specific brain MRI protocol) and cerebrospinal fluid (CSF) analysis. Tier III confidence level for the diagnosis of IE is based on the factors listed in tier I and II and identification of electroencephalographic abnormalities characteristic for seizure disorders. The authors recommend performing MRI of the brain and routine CSF analysis, after exclusion of reactive seizures, in dogs with age at epileptic seizure onset 6 years, inter-ictal neurological abnormalities consistent with intracranial neurolocalisation, status epilepticus or cluster seizure at epileptic seizure onset, or a previous presumptive diagnosis of IE and drug-resistance with a single antiepileptic drug titrated to the highest tolerable dose

International Veterinary Epilepsy Task Force consensus report on epilepsy definition, classification and terminology in companion animals

Dogs with epilepsy are among the commonest neurological patients in veterinary practice and therefore have historically attracted much attention with regard to definitions, clinical approach and management. A number of classification proposals for canine epilepsy have been published during the years reflecting always in parts the current proposals coming from the human epilepsy organisation the International League Against Epilepsy (ILAE). It has however not been possible to gain agreed consensus, “a common language”, for the classification and terminology used between veterinary and human neurologists and neuroscientists, practitioners, neuropharmacologists and neuropathologists. This has led to an unfortunate situation where different veterinary publications and textbook chapters on epilepsy merely reflect individual author preferences with respect to terminology, which can be confusing to the readers and influence the definition and diagnosis of epilepsy in first line practice and research studies. In this document the International Veterinary Epilepsy Task Force (IVETF) discusses current understanding of canine epilepsy and presents our 2015 proposal for terminology and classification of epilepsy and epileptic seizures. We propose a classification system which reflects new thoughts from the human ILAE but also roots in former well accepted terminology. We think that this classification system can be used by all stakeholders

The interrelated effect of sleep and learning in dogs (Canis familiaris); an EEG and behavioural study

The active role of sleep in memory consolidation is still debated, and due to a large between-species variation, the investigation of a wide range of different animal species (besides humans and laboratory rodents) is necessary. The present study applied a fully non-invasive methodology to study sleep and memory in domestic dogs, a species proven to be a good model of human awake behaviours. Polysomnography recordings performed following a command learning task provide evidence that learning has an effect on dogs’ sleep EEG spectrum. Furthermore, spectral features of the EEG were related to post-sleep performance improvement. Testing an additional group of dogs in the command learning task revealed that sleep or awake activity during the retention interval has both short- and long-term effects. This is the first evidence to show that dogs’ human-analogue social learning skills might be related to sleep-dependent memory consolidation

Kutyák idiopathicus és szimptómás epilepsziáinak fontos szempontjai

This dissertation presents an overview of the research performed by the author in examining dogs with seizure disorders. In the first study we summarized the clinical work-up and ictal analysis of 240 dogs with recurrent seizures. The aim was to examine the underlying aetiology and to compare idiopathic epilepsy (IE) with symptomatic epilepsy (SE) regarding signalment, history, ictal patterns and findings of the clinical and neurological examination. The diagnosis of symptomatic epilepsy was based on confirmed pathological changes in haematology, serum biochemistry, cerebrospinal fluid (CSF) analysis and morphological changes in the brain by CT/MRI or histopathological examinations. The seizure aetiologies were classified as idiopathic epilepsy in 115 (48%) dogs and symptomatic epilepsy in 125 (52%). Symptomatic epilepsy was mainly caused by intracranial neoplasia (39 dogs, 16%) and encephalitis (23 dogs, 10%). The following variables showed significant differences between the IE and SE groups: age, body weight, presence of partial seizures, cluster seizures, status epilepticus, ictal vocalization and neurological deficits. Status epilepticus, cluster seizures, partial seizures, vocalization during seizure and impaired neurological status were more readily seen in symptomatic epilepsy. If the first seizure occurred between 1 and 5 years of age or the seizures occurred during the resting condition the diagnosis was more likely to be IE than SE. In the second study we investigated the clinical usefulness of EEG in dogs with seizures in a clinical setting in combination with other advanceddiagnostic tools. We found that the interictal electroencephalographic (EEG) examination of epileptic dogs suffering from IE or SE rarely showed epileptic discharges using chemical restraint with propofol (2-6mg/kg). Only 5 out of 40 (12.5%) dogs showed EEG changes, which were considered as epileptiform discharges (ED). The EEG changes identified were spikes in four cases and periodic epileptiform discharges in one case. We concluded that since epileptic discharges were infrequently detected the diagnostic value of EEG in such a work-up seemed to be rather low. Otherwise, we frequently found transient EEG phenomena (spindles, k-complexes, vertex waves, positive occipital sharp transients of sleep, cyclic alternating patterns), which were non-epileptic but their differentiation from epileptic phenomena was challenging and thus being aware of these patterns could reduce misinterpretation. In the following studies possible therapy of two particularly difficult clinical conditions were evaluated. In the third study we investigated the therapeutic effect of immunosuppressive cyclosporine on granulomatous meningoencephalomyelitis (GME), a condition that can cause seizures and which has a poor long-term prognosis. Fourteen dogs were included in this study and randomly divided into two groups. Seven dogs were treated with corticosteroids and seven dogs with corticosteroids in combination with cyclosporine. The median survival time of the seven dogs on immunosuppressive corticosteroid therapy was 28 days (range 3-63 days) while for the seven dogs with additional cyclosporine treatment it was 620 days (range 8-870). Four dogs were still alive at the time the study was completed. We concluded that cyclosporine combination therapy prolongs survival time in comparison with prednisolone therapy in dogs with granulomatous meningoencephalomyelitis. Total remission can also occur. The fourth study evaluated the effect of gabapentinin the at-home treatment of 15 dogs with idiopathic refractory epilepsy, including cluster seizures (CS). When a CS started, additional gabapentin treatment was initiated PO at a dosage of 20 mg/kg TID for at least 3 days by the owner. In four dogs, a 49-100% reduction was reported in the seizures per cluster. The severity and duration of seizures were reduced in four and two dogs, respectively. The general interictal condition during CS was considerably ameliorated by gabapentin in four dogs. Eight out of fourteen owners considered that their dog’s quality of life during a CS had been improved by the use of gabapentin. We concluded that gabapentin can be considered as an alternative at-home treatment for CS, although only a small proportion of dogs might experience considerable benefits

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