Double-Masked, Placebo-Controlled Study of Intravenous Levetiracetam for the Treatment of Status Epilepticus and Acute Repetitive Seizures in Dogs

Mammalian models of status epilepticus - Their value and limitations

Status epilepticus (SE) is a medical and neurologic emergency that may lead to permanent brain damage, morbidity, or death. Animal models of SE are particularly important to study the pathophysiology of SE and mechanisms of SE resistance to antiseizure medications with the aim to develop new, more effective treatments. In addition to rodents (rats or mice), larger mammalian species such as dogs, pigs, and nonhuman primates are used. This short review describes and discusses the value and limitations of the most frequently used mammalian models of SE. Issues that are discussed include (1) differences between chemical and electrical SE models; (2) the role of genetic background and environment on SE in rodents; (3) the use of rodent models (a) to study the pathophysiology of SE and mechanisms of SE resistance; (b) to study developmental aspects of SE; (c) to study the efficacy of new treatments, including drug combinations, for refractory SE; (d) to study the long-term consequences of SE and identify biomarkers; (e) to develop treatments that prevent or modify epilepsy; (e) to study the pharmacology of spontaneous seizures; (4) the limitations of animal models of induced SE; and (5) the advantages (and limitations) of naturally (spontaneously) occurring SE in epileptic dogs and nonhuman primates. Overall, mammalian models of SE have significantly increased our understanding of the pathophysiology and drug resistance of SE and identified potential targets for new, more effective treatments. This paper was presented at the 9th London-Innsbruck Colloquium on Status Epilepticus and Acute Seizures held in April 2024.

Emergency Approach to Acute Seizures in Dogs and Cats

Seizures are a common presentation seen in small animal practices. Seizures require prompt management including initial interventions for triage, stabilization, and treatment with first-line anticonvulsant (AC) drugs like benzodiazepines. Concurrently, ruling out metabolic or extracranial causes with point-of-care diagnostics can help guide further diagnostics and treatments. Analysis of the history and a physical exam are also necessary to rule out common "look-alikes" that require specific diagnostic workup and treatments. Typically, causes of seizures can be grouped into intracranial and extracranial causes, with the latter being easier to diagnose with commonly available tests. This review presents a systematic approach to the diagnosis and treatment of single seizures, cluster seizures, and status epilepticus in dogs and cats.

ACVIM Consensus Statement on the management of status epilepticus and cluster seizures in dogs and cats

BACKGROUND

Seizure emergencies (ie, status epilepticus [SE] and cluster seizures [CS]), are common challenging disorders with complex pathophysiology, rapidly progressive drug-resistant and self-sustaining character, and high morbidity and mortality. Current treatment approaches are characterized by considerable variations, but official guidelines are lacking.

OBJECTIVES

To establish evidence-based guidelines and an agreement among board-certified specialists for the appropriate management of SE and CS in dogs and cats.

ANIMALS

None.

MATERIALS AND METHODS

A panel of 5 specialists was formed to assess and summarize evidence in the peer-reviewed literature with the aim to establish consensus clinical recommendations. Evidence from veterinary pharmacokinetic studies, basic research, and human medicine also was used to support the panel's recommendations, especially for the interventions where veterinary clinical evidence was lacking.

RESULTS

The majority of the evidence was on the first-line management (ie, benzodiazepines and their various administration routes) in both species. Overall, there was less evidence available on the management of emergency seizure disorders in cats in contrast to dogs. Most recommendations made by the panel were supported by a combination of a moderate level of veterinary clinical evidence and pharmacokinetic data as well as studies in humans and basic research studies.

CONCLUSIONS AND CLINICAL RELEVANCE

Successful management of seizure emergencies should include an early, rapid, and stage-based treatment approach consisting of interventions with moderate to preferably high ACVIM recommendations; management of complications and underlying causes related to seizure emergencies should accompany antiseizure medications.

A review of the pharmacology and clinical applications of levetiracetam in dogs and cats

OBJECTIVE

To review and summarize the pharmacology of the antiepileptic drug (AED), levetiracetam (LEV), and to discuss its clinical utility in dogs and cats.

DATA SOURCES

Veterinary and human peer-reviewed medical literature and the authors' clinical experience.

SUMMARY

LEV is an AED with mechanisms of action distinct from those of other AEDs. In people and small animals, LEV exhibits linear kinetics, excellent oral bioavailability, and minimal drug-drug interactions. Serious side effects are rarely reported in any species. LEV use is gaining favor for treating epilepsy in small animals and may have wider clinical applications in patients with portosystemic shunts, neuroglycopenia, and traumatic brain injury. In people, LEV may improve cognitive function in patients with dementia.

CONCLUSION

LEV is a well-tolerated AED with well-documented efficacy in human patients. Although its use is becoming more common in veterinary medicine, its role as a first-line monotherapy in small animal epileptics remains to be determined. This review of the human and animal literature regarding LEV describes its role in epileptic people and animals as well as in other disease states and provides recommendations for clinical usage.

Duration of constant rate infusion with diazepam or propofol for canine cluster seizures and status epilepticus

Introduction

Constant rate infusion (CRI) of benzodiazepines or propofol (PPF) is a therapeutic option for cluster seizures (CS) and status epilepticus (SE) in canine patients non-responding to first-line benzodiazepines or non-anesthetics. However, specific indications for optimal duration of CRI are lacking. The aim of this study was to determine the effect of duration of anesthetic CRI on outcome and length of hospital stay in dogs with refractory seizure activity of different etiology.

Study design

Open-label non-randomized clinical trial.

Materials and methods

Seventy-three client-owned dogs were enrolled. Two groups [experimental (EXP) vs. control (CTRL)] were compared. The EXP group received diazepam (DZP) or PPF CRI for 12 h (±1 h) and the CTRL group received DZP or PPF CRI for 24 h (±1 h) in addition to a standardized emergency treatment protocol identical for both study groups. The historical control group was made up of a population of dogs already reported in a previously published paper by the same authors. Favorable outcome was defined as seizure cessation after CRI, no seizure recurrence, and clinical recovery. Poor outcome was defined as seizure recurrence, death in hospital or no return to acceptable clinical baseline. Univariate statistical analysis was performed.

Results

The study sample was 73 dogs: 45 (62%) received DZP CRI and 28 (38%) received PPF CRI. The EXP group was 39 dogs (25 DZP CRI and 14 PPF CRI) and the CTRL group 34 dogs (20 DZP CRI and 14 PPF CRI). We found no statistically significant difference in outcomes between the groups. The median length of stay was 56 h (IQR, 40-78) for the ALL EXP group and 58.5 h (IQR, 48-74.5) for the ALL CTRL group (p = 0.8).

Conclusion

Even though a shorter DZP or PPF CRI duration was not associated with a worse outcome, the study failed to identify a clear superiority of shorter CRI duration on outcome or length of hospital stay in dogs with refractory seizure activity of different etiology.

Perspectives on pharmacologic strategies in the management of meningoencephalomyelitis of unknown origin in dogs

There are many non-infectious inflammatory diseases, assumed to be immune-mediated in origin, recognized to affect the nervous system in canine patients. Concentrating on meningoencephalomyelitis of unknown origin, we will discuss the medications used to treat the underlying disease process, focusing on their adverse effects, therapeutic monitoring when necessary and effectiveness. The literature overwhelmingly supports the use of a steroid/ Cytosar® or steroid/ cyclosporine treatment protocol with the steroid tapered after the acute phase of the disease, leaving the secondary medication to control the disease long term. The decision on when and how quickly to taper the steroid is clinician dependent as a best practices has not been established in the literature. Also discussed will be the supportive care treatments often needed in the acute phase of these patients' diagnosis and treatment such as anti-edema and anti-epileptic agents.

Propofol versus sodium thiopentone for the treatment of status epilepticus and refractory status epilepticus in dogs

AIMS

To compare the effect on mortality and length of hospital stay of propofol with that of sodium thiopentone for the management of dogs with status epilepticus (SE) and refractory status epilepticus (RSE).

METHODS

In this cohort study, medical records of a veterinary referral clinic in Argentina were retrospectively searched for dogs that were hospitalised and required induction of therapeutic coma (TC) with either propofol or sodium thiopentone for the management of SE or RSE of any cause. A logistic regression model was performed to evaluate the association between the type of anaesthetic used and in-hospital mortality adjusting for the type of epilepsy (idiopathic, structural, or reactive). Kaplan-Meier estimated survival curves for the length of hospital stay by the type of anaesthetic drug were compared using the log-rank test (deaths were considered censored events). Cox proportional hazards regression was used to estimate hazard ratios for time to hospital discharge, unadjusted and adjusted for type of epilepsy.

RESULTS

A total of 24 dogs with SE were included in the study: eight treated with propofol and 16 treated with sodium thiopentone. Four dogs treated with propofol (proportion = 0.50; 95% CI = 0.15-0.84), and eight treated with sodium thiopentone (proportion = 0.50; 95% CI = 0.50-0.74) died during hospitalisation. The median hospitalisation time was 43 (IQR 24-56) hours for dogs that were treated with propofol and 72 (IQR 64-96) hours for dogs that were treated with sodium thiopentone. There was no evidence of a difference in the median duration of TC in dogs treated with propofol (12 (IQR 8-24) hours) or with sodium thiopentone (12 (IQR 7.5-20) hours; p = 0.946). In the logistic regression model, no evidence of association between the anaesthetic protocol for the management of RSE and in-hospital mortality, adjusted for the type of epilepsy, was found (OR 1.09 (95% CI = 0.17-6.87); p = 0.925). Cox regression analysis revealed a difference in the time to hospital discharge, adjusted by the type of epilepsy, between treatment groups (HR = 0.05 (95% CI = 0.01-0.54); p = 0.013).

CONCLUSIONS AND CLINICAL RELEVANCE

The time spent in hospital before discharge was longer in dogs with RSE treated with sodium thiopentone compared to those treated with propofol. However, as the sample size was very small, the results obtained in the present study should be analysed with caution. Further studies including a greater number of dogs are required.

Constant rate infusion of diazepam or propofol for the management of canine cluster seizures or status epilepticus

INTRODUCTION

Cluster seizures (CS) and status epilepticus (SE) in dogs are severe neurological emergencies that require immediate treatment. Practical guidelines call for constant rate infusion (CRI) of benzodiazepines or propofol (PPF) in patients with seizures not responding to first-line treatment, but to date only few studies have investigated the use of CRI in dogs with epilepsy.

STUDY DESIGN

Retrospective clinical study.

METHODS

Dogs that received CRI of diazepam (DZP) or PPF for antiepileptic treatment during hospitalization at the Veterinary Teaching Hospital of the University of Turin for CS or SE between September 2016 and December 2019 were eligible for inclusion. Favorable outcome was defined as cessation of clinically visible seizure activity within few minutes from the initiation of the CRI, no seizure recurrence within 24 h after discontinuation of CRI through to hospital discharge, and clinical recovery. Poor outcome was defined as recurrence of seizure activity despite treatment or death in hospital because of recurrent seizures, catastrophic consequences of prolonged seizures or no return to an acceptable neurological and clinical baseline, despite apparent control of seizure activity. Comparisons between the number of patients with favorable outcome and those with poor outcome in relation to type of CRI, seizure etiology, reason for presentation (CS or SE), sex, previous AED therapy and dose of PPF CRI were carried out.

RESULTS

A total of 37 dogs, with 50 instances of hospitalization and CRI administered for CS or SE were included in the study. CRI of diazepam (DZP) or PPF was administered in 29/50 (58%) and in 21/50 (42%) instances of hospitalization, respectively. Idiopathic epilepsy was diagnosed in 21/37 (57%), (13/21 tier I and 8/21 tier II); structural epilepsy was diagnosed in 6/37 (16%) of which 4/6 confirmed and 2/6 suspected. A metabolic or toxic cause of seizure activity was recorded in 7/37 (19%). A total of 38/50 (76%) hospitalizations were noted for CS and 12/50 (24%) for SE. In 30/50 (60%) instances of hospitalization, the patient responded well to CRI with cessation of seizure activity, no recurrence in the 24 h after discontinuation of CRI through to hospital discharge, whereas a poor outcome was recorded for 20/50 (40%) cases (DZP CRI in 12/50 and PPF CRI in 8/50). Comparison between the number of patients with favorable outcome and those with poor outcome in relation to type of CRI, seizure etiology, reason for presentation (CS or SE), sex and previous AED therapy was carried out but no statistically significant differences were found.

CONCLUSIONS

The present study is the first to document administration of CRI of DZP or PPF in a large sample of dogs with epilepsy. The medications appeared to be tolerated without major side effects and helped control seizure activity in most patients regardless of seizure etiology. Further studies are needed to evaluate the effects of CRI duration on outcome and complications.

Dogs as a Natural Animal Model of Epilepsy

Epilepsy is a common neurological disease in both humans and domestic dogs, making dogs an ideal translational model of epilepsy. In both species, epilepsy is a complex brain disease characterized by an enduring predisposition to generate spontaneous recurrent epileptic seizures. Furthermore, as in humans, status epilepticus is one of the more common neurological emergencies in dogs with epilepsy. In both species, epilepsy is not a single disease but a group of disorders characterized by a broad array of clinical signs, age of onset, and underlying causes. Brain imaging suggests that the limbic system, including the hippocampus and cingulate gyrus, is often affected in canine epilepsy, which could explain the high incidence of comorbid behavioral problems such as anxiety and cognitive alterations. Resistance to antiseizure medications is a significant problem in both canine and human epilepsy, so dogs can be used to study mechanisms of drug resistance and develop novel therapeutic strategies to benefit both species. Importantly, dogs are large enough to accommodate intracranial EEG and responsive neurostimulation devices designed for humans. Studies in epileptic dogs with such devices have reported ictal and interictal events that are remarkably similar to those occurring in human epilepsy. Continuous (24/7) EEG recordings in a select group of epileptic dogs for >1 year have provided a rich dataset of unprecedented length for studying seizure periodicities and developing new methods for seizure forecasting. The data presented in this review substantiate that canine epilepsy is an excellent translational model for several facets of epilepsy research. Furthermore, several techniques of inducing seizures in laboratory dogs are discussed as related to therapeutic advances. Importantly, the development of vagus nerve stimulation as a novel therapy for drug-resistant epilepsy in people was based on a series of studies in dogs with induced seizures. Dogs with naturally occurring or induced seizures provide excellent large-animal models to bridge the translational gap between rodents and humans in the development of novel therapies. Furthermore, because the dog is not only a preclinical species for human medicine but also a potential patient and pet, research on this species serves both veterinary and human medicine.

Transient chemotherapy-induced alopecia after successful reversal of 5-fluorouracil myelosuppression and neurotoxicosis in a 9-month-old dog

BACKGROUND

5-Fluorouracil (5-FU) cream is a common human topical chemotherapy agent with potentially fatal neurotoxic effects on dogs if accidentally ingested. There are seldom reports in veterinary literature describing the successful outcome of intervention after accidental ingestion of 5-FU cream.

CASE SUMMARY

A 9-month-old spayed female labradoodle presented 14 h after ingesting an unknown amount of 40 g tube of Efudex cream (5% 5-FU). The dog presented in status epilepticus, which was managed with benzodiazepines and levetiracetam in conjunction with induced coma and mechanical ventilation. No further seizure activity occurred throughout the ensuing 5 days of hospitalisation; however, myelosuppression was featured. The dog was discharged home after 5 days of hospitalisation. Three days post discharge, the dog was noted to develop focal alopecia around the eyes and temporal region. 14 days after discharge, the alopecia progressed to a majority of the head and body.

CONCLUSION

To the authors' knowledge, this is the first report that documents the enduring adverse effects of 5-FU cream after survival of the initial episode, including an earlier onset of myelosuppression and diffuse alopecia. Successful treatment of accidental 5-FU ingestion is possible several hours after the initial event with minimal long-term consequences.

Response to Levetiracetam Treatment and Long-Term Follow-Up in Dogs With Reactive Seizures Due to Probable Exogenous Toxicity

Limited information is available on the long-term follow-up and seizure recurrence in dogs with reactive seizures due to suspected exogenous toxicity. The purpose of this study was to report the long-term follow-up of 13 dogs referred to a single referral hospital, diagnosed with reactive seizures and treated with a standardized levetiracetam protocol. All dogs received a loading levetiracetam dose of 60 mg/kg/IV once, followed by a maintenance dose of 20 mg/kg every 8 h as part of an open-label clinical study. Levetiracetam was withdrawn after a 6-months seizure-free period by reducing levetiracetam to 20 mg/kg every 12 h for a 4-week seizure-free period, followed by levetiracetam 20 mg/kg every 24 h for a 4-week seizure-free period, before levetiracetam treatment was stopped. No adverse effects of the treatment were reported. No dogs experienced any seizures after discharge or after levetiracetam withdrawal. Median follow-up time from time of discharge was of 78 months (=6 years 6 months). The result of this study supports the use of levetiracetam for treatment of reactive seizures due to exogenous substance intoxication. Moreover, our results do not support the need for long-term antiepileptic treatment in cases of reactive seizures due to exogenous intoxication.

Intravenous Ketamine Bolus(es) for the Treatment of Status Epilepticus, Refractory Status Epilepticus, and Cluster Seizures: A Retrospective Study of 15 Dogs

Status epilepticus (SE) and cluster seizures (CS) are common occurrences in veterinary neurology and frequent reasons of admission to veterinary hospitals. With prolonged seizure activity, gamma amino-butyric acid (GABA) receptors (GABAa receptors) become inactive, leading to a state of pharmacoresistance to benzodiazepines and other GABAergic medications, which is called refractory status epilepticus (RSE). Prolonged seizure activity is also associated with overexpression of N-methyl-D-aspartic (NMDA) receptors. Rodent models have shown the efficacy of ketamine (KET) in treating RSE, and its use has been reported in one canine case of RSE. Boluses of KET 5 mg/kg IV have become the preferred treatment for RSE in our hospital. A retrospective study was performed to evaluate and report our experience with KET IV bolus to treat prolonged and/or repeated seizure activity in cases of canine CS, SE, and RSE. A total of 15 dogs were retrieved, for 20 hospitalizations and 28 KET IV injections over 3 years. KET IV boluses were used 12 times for RSE (9 generalized seizures, 3 focal seizures) and KET terminated the episode of RSE 12/12 times (100%); however, seizures recurred 4/12 times (33%) within ≤6 h of KET IV bolus. When used for CS apart from episodes of RSE, KET IV bolus was associated with termination of the CS episode only 4/14 times (29%). Only 4/28 (14%) KET IV boluses were associated with adverse effects imputable only to the use of KET. One dog experienced a short, self-limited seizure activity during administration of KET IV, which was most likely related to a pre-mature use of KET IV (i.e., before GABAergic resistance and NMDA receptor overexpression had taken place). This study indicates that KET 5 mg/kg IV bolus may be successful for the treatment of RSE in dogs.

Continuous rate infusion of midazolam as emergent treatment for seizures in dogs

Background

Midazolam delivered by continuous rate infusion (CRI) might be effective in dogs with cluster seizures (CS) or status epilepticus (SE).

Objective

To describe the use and safety of midazolam CRI in dogs with CS or SE.

Animals

One‐hundred six client‐owned dogs presenting to a veterinary teaching hospital with CS or SE.

Methods

Retrospective review of medical records for dogs with CS or SE treated with a midazolam CRI.

Results

Seventy‐nine dogs presented with CS and 27 dogs had SE. Seizure control was achieved in 82/106 dogs (77.4%) receiving a midazolam CRI. The median dose associated with seizure control was 0.3 mg/kg/h (range, 0.1‐2.5 mg/kg/h). The median duration of CRI was 25 hours (range, 2‐96 hours). Seizures were controlled in 34/40 dogs (85%) with idiopathic epilepsy, 32/43 dogs (74%) with structural epilepsy, 12/16 dogs (75%) with unknown epilepsy, and 4/7 dogs (57%) with reactive seizures (P = .20). Seizure control was achieved in 81% of dogs with CS and 67% in dogs with SE (P = .18). Dogs with idiopathic/unknown epilepsy were more likely to survive than those with structural epilepsy (87% vs 63%, P = .009). Adverse effects were reported in 24 dogs (22.6%) and were mild in all cases.

Conclusions and Clinical Importance

Midazolam CRI is apparently safe and might be an effective treatment in dogs with CS or SE.

Analysis of Early Assessable Risk Factors for Poor Outcome in Dogs With Cluster Seizures and Status Epilepticus

Status epileptics (SE) and cluster seizures (CS) are serious neurological emergencies associated with poor outcome in epileptic patients. Data on risk factors associated with outcome in epileptic patients affected by CS and SE have not been studied extensively to date. In the present retrospective study potential risk factors predictive of negative outcome in a population of dogs affected by CS and SE were analyzed. Ninety-three dogs were included in the study: 21/93 patients (23%) presented with SE and 72/93 (77%) with CS. Based on multivariate statistical analysis, factors statistically associated with a poor outcome were the occurrence of the first epileptic seizure outside the defined idiopathic interval (6 months-6 years), a condition of hyperthermia at presentation and the absence of previous antiepileptic drugs (AEDs) in case of previous history of seizures. The results of the present study implement data on risk factors associated with poor outcome in dogs affected by CS or SE and can aid in the creation of an ad hoc scoring system, similar to systems currently applied in human medicine upon hospital admission to benchmark performances and establish protocols for triage and therapeutic management.

Update on Anticonvulsant Therapy in the Emergent Small Animal Patient

Seizures are common in veterinary patients and control is critical to the overall patient health. The benzodiazepine class of drugs (diazepam, midazolam, and lorazepam) often are the drug class of choice; however, levetiracetam and propofol also have been gaining favor as anticonvulsant drugs for acute seizure management. After cessation of seizures, practitioners then can discuss long-term seizure control on a case-by-case basis with clients.

Medical honey for canine nasal intertrigo: A randomized, blinded, placebo-controlled, adaptive clinical trial to support antimicrobial stewardship in veterinary dermatology

Intertrigo is a skin fold dermatitis often requiring recurrent treatment with topical antiseptics or antibiotics, which can select antimicrobial resistance. To minimize this risk, we tested the effectiveness of medical-grade Manuka honey at treating intertrigo as compared to a placebo hydrogel. We additionally characterized the culturable microbial flora of intertrigo and recorded any adverse effect with either treatment. During this randomized, placebo-controlled, double-blinded, adaptive group-sequential trial, the owners washed the affected sites on their dog with water, dried and applied a thin film of either the honey or the placebo product once daily for 21 days. Cytological and lesional composite scores, owner-assessed pruritus, and microbial cultures were assessed prior to treatment and on Day-22. The fixed effects of time, treatment, and animal-related variables on the pruritus and on each composite score, accounting for random dog effect, were estimated separately with generalized linear mixed models for repeated count outcomes (α = 0.05). The null hypothesis of equal treatment effects was rejected at the first interim analysis. The placebo (n = 16 dogs) outperformed the medical honey (n = 13 dogs) at improving both the cytological score (Treatment×Time = -0.35±0.17; P = 0.04) and clinical score (Treatment×Time = -0.28±0.13; P = 0.04). A microbial burden score higher than 4 increased the severity of the cytological score (dichotomous score: 0.29±0.11; P = 0.01), which in turn increased the severity of the clinical score and pruritus score. For every unit increase in cytological score, the linear predictor of clinical score increased by 0.042±0.019 (P = 0.03), and the one of pruritus score increased by 0.12±0.05 (P = 0.01). However, medical honey outperformed the placebo at alleviating the dog's owner-assessed pruritus after statistically controlling for masking effects (Time = -0.94±0.24; P = 0.002; and Treatment×Time = 0.80±0.36; P = 0.04). Unilateral tests of the least-square mean estimates revealed that honey only significantly improved the pruritus (Hommel-adjusted P = 0.003), while the placebo only improved the cytological and clinical scores (Hommel-adjusted P = 0.01 and 0.002, respectively). Taken together, these results question the value of Manuka honey at treating nasal intertrigo in dogs.

Placebo in epilepsy

Placebos impact epilepsy in a number of ways. Through randomized clinical trials, explicit clinical use, and also through implicit clinical use, placebos play a role in epilepsy. This chapter will discuss the reasons placebo is used, the determinants of placebo response in epilepsy, observations about placebo specific to epilepsy, and ways in which clinical trial design is impacted by placebo.

Investigating the potential for seizure prediction in dogs with idiopathic epilepsy: owner-reported prodromal changes and seizure triggers

BACKGROUND

Canine idiopathic epilepsy (IE) is characterised by recurrent seizure activity, which can appear unpredictable and uncontrollable. The purpose of this study was to investigate the potential for seizure prediction in dogs by exploring owner-perceived seizure prediction abilities and identifying owner-reported prodromal changes (long-term changes in disposition that indicate forthcoming seizures) and seizure triggers (stimuli that precipitate seizures) in dogs with IE.

METHODS

This is an online, international, cross-sectional survey of 229 owners of dogs diagnosed with IE, meeting the International Veterinary Epilepsy Task Force tier I diagnostic criteria.

RESULTS

Over half (59.6 per cent) of owners believed they were able to predict an upcoming seizure in their dog, of whom nearly half (45.5 per cent) were able to do so at least 30 minutes before the seizure commenced. The most common 'seizure predictors' were preseizure behavioural changes including increased clinginess (25.4 per cent), restlessness (23.1 per cent) and fearful behaviour (19.4 per cent). Nearly two-thirds of owners reported prodromal changes (64.9 per cent), most commonly restlessness (29.2 per cent), and nearly half (43.1 per cent) reported seizure triggers, most commonly stress (39.1 per cent).

CONCLUSIONS

The relatively high prevalence of owner-reported prodromal changes and seizure triggers shows promise for utilising these methods to aid seizure prediction in dogs, which could open a window of time for pre-emptive, individualised drug interventions to abort impending seizure activity.

Open-label clinical trial of rectally administered levetiracetam as supplemental treatment in dogs with cluster seizures

Background

Treatment options for at‐home management of cluster seizures (CS) and status epilepticus (SE) are limited. The pharmacokinetics of levetiracetam (LEV) after rectal administration in both healthy and epileptic dogs has been investigated recently.

Hypothesis/Objectives

To investigate the clinical efficacy of rectally administered LEV in preventing additional seizures in dogs presented for CS and SE. We hypothesized that rectal administration of LEV in addition to a standard treatment protocol would provide better control of seizure activity as compared with the standard treatment protocol alone.

Animals

Fifty‐seven client‐owned dogs with CS or SE.

Methods

Prospective open‐label clinical trial. Patients included in the study were assigned to receive either a standard treatment protocol comprising IV/rectal diazepam and IV phenobarbital q8h (control group) or a standard treatment protocol in association with a single dose of 40 mg/kg LEV rectally (rectal LEV group). Dogs that experienced no additional seizures were defined as responders, whereas those that showed additional seizure activity were classified as nonresponders.

Results

Twenty‐one dogs were assigned to the rectal LEV group, and 36 to control group. Given the small number of cases of SE, statistical analysis was performed only on patients with CS. The response rate was 94% in the rectal LEV group and 48% in the control group (P < .001).

Conclusions and Clinical Importance

Rectally administered LEV combined with a standard treatment protocol provided good control of seizure activity in patients with CS. The validity of these results should be confirmed in a double‐blinded, placebo‐controlled clinical trial.

Antiepileptic Drug Use Patterns in Suspect Epileptic Dogs Among Neurology and Emergency Specialists

This study used a cross-sectional survey designed to inquire about antiepileptic drug (AED) use in newly diagnosed idiopathic epileptic dogs among board-certified emergency and neurology specialists. Results were obtained from 300 completed surveys by 128 board-certified neurologists and 172 board-certified emergency and critical care (ECC) specialists. Case volume was slightly different between groups, with 36% of neurologists and 18% of ECC specialists managing >50 cases of first-time canine seizure patients yearly. The initial AED of choice was similar between the groups, with 66% of neurologists and 64% of ECC specialists using phenobarbital and 16% of neurologists and 26% of ECC specialists using levetiracetam. Although most respondents gave a loading dose of phenobarbital, roughly one-fourth of neurologists did not load the drug versus 6% of ECC specialists. The total loading dose was similar between respondents (16 mg/kg) but varied in administration protocol. Approximately half of neurologists and nearly two-thirds of ECC specialists gave a higher initial dose of levetiracetam than recommended. Almost all the respondents who gave a higher initial dose of levetiracetam used 60 mg/kg IV once. Understanding the common practices in AED use may promote future discussions regarding best practices in the management of canine idiopathic epilepsy.

Recurrent seizures in cats: Treatment - which antiepileptic drugs are recommended?

Practical relevance: Seizures are one of the most common neurological problems recognized in cats, affecting approximately 1-3% of the general population. Treatment options and prognosis are closely related to the underlying cause, so it is important that veterinarians are familiar with the diagnostic approach to cats with seizures and options for medical management. Series outline: This is the second of a two-part article series that reviews the diagnosis and treatment of seizures in cats. Part 2 describes chronic medical treatment options and prognosis for cats with recurrent seizures, and acute treatment of status epilepticus.

AUDIENCE

This review of recurrent seizures in cats is intended for all veterinarians who are facing the challenges of seizure diagnosis and management in the feline patient. Evidence base: Recommendations for diagnosis and management of feline seizure disorders have historically been extrapolated from the canine and human literature. The information and guidance provided in this two-part series is based on a review of the recent published literature addressing seizure disorders and antiepileptic treatment in cats, as well as the authors' clinical experience.

Pharmacokinetic and Pharmacodynamic Evaluation of Intravenous Levetiracetam in Children With Epilepsy

This study aimed to evaluate the safety and tolerability of intravenous (IV) levetiracetam (LEV) as a monotherapy in children aged 1 month-16 years and to explore the pharmacokinetics (PK) of IV LEV and the time to seizure after IV then oral administration of LEV in pediatric children with epilepsy. Children diagnosed with acute unprovoked seizures requiring in-hospital IV LEV administration were included. After administration, the clinical seizure outcomes, side effects, and the Korean-Child Behavior Checklist were monitored and the PK and repeated time to seizure were analyzed via modeling using NONMEM software. Overall, 37 children with epilepsy were enrolled and underwent a PK analysis (median age, 4.6 years; median weight, 18.0 kg). Nine children (24.3%) had seizure recurrence during the follow-up period (median, 3.8 months) and 5 children (13.5%) experienced LEV-associated adverse events such as irritability (n = 2; 5.4%) and somnolence (n = 3; 8.1%). The plasma LEV concentrations after IV LEV were best described by a one-compartment linear PK model. Only body weight was associated with both the clearance and volume of distribution of LEV. The Weibull distribution model described the time to seizure recurrence well; no statistically significant predictor for the time to seizure was identified. Therefore, IV LEV was a well-tolerated and effective alternative in children with acute unprovoked seizures, and models for the PK and time to repeated seizure recurrence after LEV were successfully developed. In particular, the current use of a weight-based IV LEV dosing regimen in pediatric children is practical.

A Review: Emergency Management of Dogs With Suspected Epileptic Seizures

Dogs with seizure disorders are commonly presented to the general practitioner for initial evaluation. The most common diagnosis provided is idiopathic epilepsy. As witnessing seizures is often traumatic for owners, it is important for the practitioner to understand seizure classification, know when to initiate antiepileptic drug therapy and be comfortable with client education regarding seizures. This review briefly discusses the most up-to-date classification of seizures, the necessity to obtain accurate histories and complete examinations, base-line diagnostics to perform, the importance of owner education, and when to start medications. This is not intended to discuss detailed differential lists, in-depth information on antiepileptic drug therapy, long-term management of epileptics or those refractory to their current treatment.

A serious adverse event secondary to rapid intravenous levetiracetam injection in a dog

OBJECTIVE

To describe a serious adverse event as a result of rapid intravenous injection of undiluted levetiracetam in a dog.

CASE SUMMARY

An 8-year-old female spayed Chihuahua was evaluated for cluster seizures and tachypnea. The patient was administered an intravenous dose of undiluted levetiracetam (60 mg/kg) and immediately developed tachycardia, hyperglycemia, hypotension, and a dull mentation. The patient's blood pressure and mentation did not respond to intravenous fluid boluses but improved immediately after administration of epinephrine intravenously. The patient subsequently developed respiratory failure necessitating mechanical ventilation, prior to cardiac arrest. Necropsy examination noted a pulmonary inflammatory cell infiltrate, pulmonary edema, and interstitial pneumonia.

NEW OR UNIQUE INFORMATION PROVIDED

This report documents a serious adverse event associated with intravenous levetiracetam administration to a dog.

Disposition of levetiracetam in healthy adult horses

Nine horses received 20 mg/kg of intravenous (LEV_IV ); 30 mg/kg of intragastric, crushed immediate release (LEV_CIR ); and 30 mg/kg of intragastric, crushed extended release (LEV_CER ) levetiracetam, in a three-way randomized crossover design. Crushed tablets were dissolved in water and administered by nasogastric tube. Serum samples were collected over 48 hr, and levetiracetam concentrations were determined by immunoassay. Mean ± SD peak concentrations for LEV_CIR and LEV_CER were 50.72 ± 10.60 and 53.58 ± 15.94 μg/ml, respectively. The y-intercept for IV administration was 64.54 ± 24.99 μg/ml. The terminal half-life was 6.38 ± 1.97, 7.07 ± 1.93 and 6.22 ± 1.35 hr for LEV_CIR , LEV_CER, and LEV_IV , respectively. Volume of distribution at steady-state was 630 ± 73.4 ml/kg. Total body clearance after IV administration was 74.40 ± 19.20 ml kg^-1  hr^-1 . Bioavailability was 96 ± 10, and 98 ± 13% for LEV_CIR and LEV_CER , respectively. A single dose of Levetiracetam (LEV) was well tolerated. Based on this study, a recommended dosing regimen of intravenous or oral LEV of 32 mg/kg every 12 hr is likely to achieve and maintain plasma concentrations within the therapeutic range suggested for humans, with optimal kinetics throughout the dosing interval in healthy adult horses. Repeated dosing and pharmacodynamic studies are warranted.

Intravenous Topiramate: Pharmacokinetics in Dogs with Naturally Occurring Epilepsy

RATIONALE

Barriers to developing treatments for human status epilepticus include the inadequacy of experimental animal models. In contrast, naturally occurring canine epilepsy is similar to the human condition and can serve as a platform to translate research from rodents to humans. The objectives of this study were to characterize the pharmacokinetics of an intravenous (IV) dose of topiramate (TPM) in dogs with epilepsy and evaluate its effect on intracranial electroencephalographic (iEEG) features.

METHODS

Five dogs with naturally occurring epilepsy were used for this study. Three were getting at least one antiseizure drug as maintenance therapy including phenobarbital (PB). Four (ID 1-4) were used for the 10 mg/kg IV TPM + PO TPM study, and three (ID 3-5) were used for the 20 mg/kg IV TPM study. IV TPM was infused over 5 min at both doses. The animals were observed for vomiting, diarrhea, ataxia, and lethargy. Blood samples were collected at scheduled pre- and post-dose times. Plasma concentrations were measured using a validated high-performance liquid chromatography-mass spectrometry method. Non-compartmental and population compartmental modeling were performed (Phoenix WinNonLin and NLME) using plasma concentrations from all dogs in the study. iEEG was acquired in one dog. The difference between averaged iEEG energy levels at 15 min pre- and post-dose was assessed using a Kruskal-Wallis test.

RESULTS

No adverse events were noted. TPM concentration-time profiles were best fit by a two compartment model. PB co-administration was associated with a 5.6-fold greater clearance and a ~4-fold shorter elimination half-life. iEEG data showed that TPM produced a significant energy increase at frequencies >4 Hz across all 16 electrodes within 15 min of dosing. Simulations suggested that dogs on an enzyme inducer would require 25 mg/kg, while dogs on non-inducing drugs would need 20 mg/kg to attain the target concentration (20-30 μg/mL) at 30 min post-dose.

CONCLUSION

This study shows that IV TPM has a relatively rapid onset of action, loading doses appear safe, and the presence of PB necessitates a higher dose to attain targeted concentrations. Consequently, it is a good candidate for further evaluation for treatment of seizure emergencies in dogs and people.

Fit for purpose application of currently existing animal models in the discovery of novel epilepsy therapies

Animal seizure and epilepsy models continue to play an important role in the early discovery of new therapies for the symptomatic treatment of epilepsy. Since 1937, with the discovery of phenytoin, almost all anti-seizure drugs (ASDs) have been identified by their effects in animal models, and millions of patients world-wide have benefited from the successful translation of animal data into the clinic. However, several unmet clinical needs remain, including resistance to ASDs in about 30% of patients with epilepsy, adverse effects of ASDs that can reduce quality of life, and the lack of treatments that can prevent development of epilepsy in patients at risk following brain injury. The aim of this review is to critically discuss the translational value of currently used animal models of seizures and epilepsy, particularly what animal models can tell us about epilepsy therapies in patients and which limitations exist. Principles of translational medicine will be used for this discussion. An essential requirement for translational medicine to improve success in drug development is the availability of animal models with high predictive validity for a therapeutic drug response. For this requirement, the model, by definition, does not need to be a perfect replication of the clinical condition, but it is important that the validation provided for a given model is fit for purpose. The present review should guide researchers in both academia and industry what can and cannot be expected from animal models in preclinical development of epilepsy therapies, which models are best suited for which purpose, and for which aspects suitable models are as yet not available. Overall further development is needed to improve and validate animal models for the diverse areas in epilepsy research where suitable fit for purpose models are urgently needed in the search for more effective treatments.

A single-blinded phenobarbital-controlled trial of levetiracetam as mono-therapy in dogs with newly diagnosed epilepsy

Treatment of canine epilepsy is problematic. Few antiepileptic drugs have proven efficacy in dogs and undesirable adverse effects and pharmacoresistance are not uncommon. Consequently, the need for investigation of alternative treatment options is ongoing. The objective of this study was to investigate the efficacy and tolerability of levetiracetam as mono-therapy in dogs with idiopathic epilepsy. The study used a prospective single-blinded parallel group design. Twelve client-owned dogs were included and were randomised to treatment with levetiracetam (30 mg/kg/day or 60 mg/kg/day divided into three daily dosages) or phenobarbital (4 mg/kg/day divided twice daily). Control visits were at days 30, 60 and then every 3 months for up to 1 year. Two or more seizures within 3 months led to an increase in drug dosage (levetiracetam: 10 mg/kg/day, phenobarbital: 1 mg/kg/day). Five of six levetiracetam treated dogs and one of six phenobarbital treated dogs withdrew from the study within 2-5 months due to insufficient seizure control. In the levetiracetam treated dogs there was no significant difference in the monthly number of seizures before and after treatment, whereas in the phenobarbital treated dogs there were significantly (P = 0.013) fewer seizures after treatment. Five phenobarbital treated dogs were classified as true responders (≥50% reduction in seizures/month) whereas none of the levetiracetam treated dogs fulfilled this criterion. Adverse effects were reported in both groups but were more frequent in the phenobarbital group. In this study levetiracetam was well tolerated but was not effective at the given doses as mono-therapy in dogs with idiopathic epilepsy.

The Potential of Adaptive Design in Animal Studies

Clinical trials are the backbone of medical research, and are often the last step in the development of new therapies for use in patients. Prior to human testing, however, preclinical studies using animal subjects are usually performed in order to provide initial data on the safety and effectiveness of prospective treatments. These studies can be costly and time consuming, and may also raise concerns about the ethical treatment of animals when potentially harmful procedures are involved. Adaptive design is a process by which the methods used in a study may be altered while it is being conducted in response to preliminary data or other new information. Adaptive design has been shown to be useful in reducing the time and costs associated with clinical trials, and may provide similar benefits in preclinical animal studies. The purpose of this review is to summarize various aspects of adaptive design and evaluate its potential for use in preclinical research.

Canine status epilepticus treated with fosphenytoin: A proof of principle study

OBJECTIVES

There are a limited number of marketed intravenous antiepileptic drugs (AEDs) available to treat status epilepticus (SE). All were first developed for chronic therapy of epilepsy, not specifically for SE. Epilepsy and canine SE (CSE) occur naturally in dogs, with prevalence, presentation, and percentage of refractory cases similar to human epilepsy. The objective of this study was to determine if CSE treated with fosphenytoin (FOS) results in a similar responder rate as for people.

METHODS

A randomized clinical trial was performed for dogs with CSE. Dogs who presented during a seizure or who had additional seizures after enrolling received intravenous (i.v.) benzodiazepine (BZD) followed immediately by intravenous infusion of 15 mg/kg phenytoin equivalent (PE) of fosphenytoin (FOS) or saline placebo (PBO). If seizures continued, additional AEDs were administered per the standard of care for veterinary patients. Total and unbound plasma phenytoin (PHT) concentrations were measured.

RESULTS

Consent was obtained for 50 dogs with CSE. Thirty-one had additional motor seizures and were randomized to the study intervention (22 FOS and 9 PBO). There was a statistically significant difference in the 12 h responder rate, with 63% in the FOS group versus 22% in the placebo group (p = 0.043) having no further seizures. The unbound PHT concentrations at 30 and 60 min were within the therapeutic concentrations for people (1-2 μg/ml) with the exception of one dog. There was mild vomiting in 36% of the FOS group (7/22) within 20 min of FOS administration and none of the placebo group (0/9) (p = 0.064).

SIGNIFICANCE

This proof of concept study provides the first evidence that FOS is tolerated and effective in canine SE at PHT concentrations clinically relevant for human SE. Furthermore, naturally occurring CSE can be utilized as a translational platform for future studies of novel SE compounds.

Intravenous levetiracetam in clinical practice--Results from an independent registry

PURPOSE

Most common clinical studies with antiepileptic drugs do not reflect medical everyday practice due to their strict in- and exclusion criteria and specifications of treatment regimens. Here we present a large non-interventional registry with the intention to evaluate the spectrum of applications in daily use and the efficacy and tolerability of intravenously given levetiracetam (LEV-iv).

METHODS

In a prospective approach of 17 neurological and neuropediatric centres in Germany LEV-iv treated patients of all ages were included over a period of 10 months. The observational period was 10 days with daily documentation of LEV-iv administration, type and frequency of seizures, currently used drugs and doses, and adverse events (AEs). In addition, treatment efficacy and tolerability were assessed by patients and physicians at study end as well as practicability of LEV-iv using a five-step scale.

RESULTS

In 95 patients LEV-iv was administered, 93 were included into the analysis. The median LEV-iv dose was 1500 mg (range 110-6000 mg) per day. Median age was 66 years (range 0.7-90.3 years). The majority of patients (n=70, 75%) suffered from status epilepticus (SE, n=55, 59%) and acute seizure clusters (n=15, 16%). Of those with SE, 41 patients (75%) had SE for the first time. Acute seizure clusters and SE terminated in 83% after LEV-iv administration. A total of 29 adverse events were reported in 17 of the 95 patients from the safety set. Ten of these were at least possibly related to LEV-iv treatment. Slight decrease of blood pressure during the infusion (3 patients each) was captured most frequently. No serious side effect was observed. Physicians rated the efficacy and tolerability of LEV-iv treatment as good or very good in 78% and 82% of the cases, respectively.

CONCLUSION

In this large observational study of everyday practise the use of LEV-iv exhibited a remarkable good response and tolerability in patients with acute onset seizures (mostly SE). Further randomized controlled studies, like the established status epilepticus trial (ESET) are needed to confirm these findings.

Assessment into the usage of levetiracetam in a canine epilepsy clinic

Background

Retrospective studies can complement information derived from double-blinded randomized trials. There are multiple retrospective studies reporting good efficacy and tolerability of the anti-epileptic drug levetiracetam (LEV) in human patients with epilepsy; however, reports of LEV's tolerability and efficacy in dogs with epilepsy remain limited. The purpose of this retrospective study was to describe the use of LEV in a canine epilepsy clinic and determine the long-term efficacy and tolerability of LEV in veterinary clinical practice. The electronic database of a UK based referral hospital was searched for LEV usage in dogs with seizures. Information and data necessary for the evaluation were obtained from a combination of electronic and written hospital records, the referring veterinary surgeons’ records and telephone interviews with dog owners. Only dogs that were reportedly diagnosed with idiopathic epilepsy were included in the study.

Results

Fifty-two dogs were included in this retrospective study. Two treatment protocols were recognised; 29 dogs were treated continuously with LEV and 23 dogs received interval or pulse treatment for cluster seizures. LEV treatment resulted in 69% of dogs having a 50% or greater reduction of seizure frequency whilst 15% of all the dogs were completely free from seizures. Seizure frequency reduced significantly in the whole population. No dog was reported to experience life-threatening side effects. Mild side effects were experienced by 46% of dogs and a significantly higher number of these dogs were in the pulse treatment group. The most common side-effects reported were sedation and ataxia.

Conclusions

LEV appears to be effective and well tolerated for reduction of seizures.

Antiepileptic drug therapy and monitoring

Over the past 2 decades, the number of antiepileptic drugs (AEDs) available to veterinarians has grown exponentially. Coupled with this increase is the ability to rapidly and accurately diagnose underlying brain disease with readily accessible magnetic resonance imaging. As a result, the veterinary community is attuned to the need for early treatment intervention. As more treatment choices become available, the unrelenting questions still arise are when should treatment begin, which initial drug therapy is best for our patients, when should treatment changes be considered, and finally, what are the advantages that newer drugs provide for our patients. The purpose of this chapter is to review decision-making strategies for AED therapy, provide an overview of the applicability of current AED available, and present information on the therapeutic advances in epilepsy.

Epilepsy in cats: theory and practice

The veterinary literature on epilepsy in cats is less extensive than that for dogs. The present review summarizes the most important human definitions related to epilepsy and discusses the difficulties in applying them in daily veterinary practice. Epileptic seizures can have a wide range of clinical signs and are not necessarily typical in all cases. Whether a seizure event is epileptic can only be suspected based on clinical, laboratory, and neuroimaging findings as electroencephalography diagnostic techniques have not yet been developed to a sufficiently accurate level in veterinary medicine. In addition, the present review aims to describe other diagnoses and nonepileptic conditions that might be mistaken for epileptic seizures. Seizures associated with hippocampal lesions are described and discussed extensively, as they seem to be a special entity only recognized in the past few years. Furthermore, we focus on clinical work‐up and on treatment that can be recommended based on the literature and summarize the limited data available relating to the outcome. Critical commentary is provided as most studies are based on very weak evidence.

Levetiracetam rectal administration in healthy dogs

BACKGROUND

Levetiracetam is used to manage status epilepticus (SE) and cluster seizures (CS) in humans. The drug might be absorbed after rectal administration and could offer a practical adjunct to rectal administration of diazepam in managing SE and CS.

HYPOTHESIS

Levetiracetam is rapidly absorbed after rectal administration in dogs and maintains target serum concentrations for at least 9 hours.

ANIMALS

Six healthy privately owned dogs between 2 and 6 years of age and weighing 10-20 kg.

METHODS

Levetiracetam (40 mg/kg) was administered rectally and blood samples were obtained immediately before (time zero) and at 10, 20, 40, 60, 90, 180, 360, and 540 minutes after drug administration. Dogs were observed for signs of adverse effects over a 24-hour period after drug administration.

RESULTS

CLEV at 10 minutes was 15.3 ± 5.5 μg/mL (mean, SD) with concentrations in the target range (5-40 μg/mL) for all dogs throughout the sampling period. Cmax (36.0 ± 10.7 μg/mL) and Tmax (103 ± 31 minutes) values were calculated and 2 disparate groups were appreciated. Dogs with feces in the rectum at the time of drug administration had lower mean Cmax values (26.7 ± 3.4 μg/mL) compared with those without (45.2 ± 4.4 μg/mL). Mild sedation was observed between 60 and 90 minutes without other adverse effects noted.

CONCLUSIONS AND CLINICAL IMPORTANCE

This study supports the use of rectally administered levetiracetam in future studies of clinical effectiveness in the management of epileptic dogs.

What new modeling approaches will help us identify promising drug treatments?

Despite the development of numerous novel antiepileptic drugs (AEDs) in recent years, several unmet clinical needs remain, including resistance to AEDs in about 30 % of patients with epilepsy, adverse effects of AEDs that can reduce quality of life, and the lack of treatments that can prevent development of epilepsy in patients at risk. Animal models of seizures and epilepsy have been instrumental in the discovery and preclinical development of novel AEDs, but obviously the previously used models have failed to identify drugs that address unmet medical needs. Thus, we urgently need fresh ideas for improving preclinical AED development. In this review, a number of promising models will be described, including the use of simple vertebrates such as zebrafish (Danio rerio), large animal models such as the dog and newly characterized rodent models of pharmacoresistant epilepsy. While these strategies, like any animal model approach also have their limitations, they offer hope that new more effective AEDs will be identified in the coming years.

Status epilepticus attributed to inadvertent intrathecal injection of cefazolin during myelography

OBJECTIVE

To describe a case of status epilepticus believed to be a consequence of inadvertent intrathecal administration of cefazolin in a dog undergoing a myelogram.

CASE SUMMARY

A 4-year-old, 6.5 kg, male neutered Dachshund was referred for evaluation of an acute onset hind limb paraparesis. While performing a lumbar myelogram, cefazolin was inadvertently injected into the ventral subarachnoid space. Subsequent refractory seizure activity was attributed to the epileptogenic effects of intrathecally administered cefazolin. Supportive therapy led to eventual complete recovery.

NEW OR UNIQUE INFORMATION PROVIDED

Although epileptogenic effects of intrathecally administered cefazolin are well documented in the human and experimental animal model literature, to the authors' knowledge this has not been characterized in the veterinary literature. This case highlights the need to be diligent and mindful when one administers medications, and describes the management of a dog adversely affected as a consequence of a medical error.

Epilepsy after head injury in dogs: a natural model of posttraumatic epilepsy

PURPOSE

In humans, traumatic brain injury (TBI) is one of the most common causes of acquired (symptomatic) epilepsy, but as yet there is no treatment to prevent the development of epilepsy after TBI. Animal models of posttraumatic epilepsy (PTE) are important to characterize epileptogenic mechanisms of TBI and to identify clinically effective antiepileptogenic treatments. The prevalence and phenomenology of naturally occurring canine epilepsy are similar to those in human epilepsy. However, the risk of epilepsy after TBI has not been systemically studied in dogs. We therefore performed a large retrospective study in 1,000 dogs referred to our clinical department over a period of 11.5 years with the aim to determine the incidence of early and late seizures after head trauma in this species.

METHODS

Two strategies were used: in group I (n = 392), we evaluated whether dogs referred for the treatment of a head trauma (group Ia) or other trauma (group Ib) developed seizures after the trauma, whereas in group II (n = 608) we evaluated whether dogs referred for the treatment of recurrent epileptic seizures had a history of head trauma. Data for this study were obtained from our clinical database, questionnaires sent to the dogs' owners, and owner interviews.

KEY FINDINGS

In group Ia, 6.6% of the dogs developed PTE, which was significantly different from group Ib (1.9%), indicating that head trauma increased the risk of developing epilepsy by a factor of 3.4. The risk of PTE increased with severity of TBI; 14.3% of the dogs with skull fracture developed PTE. In group II, 15.5% of the dogs with epilepsy had a history of head injury, which was significantly higher than the incidence of PTE determined for group Ia.

SIGNIFICANCE

Our study indicates that head trauma in dogs is associated with a significant risk of developing epilepsy. Therefore, dogs with severe TBI are an interesting natural model of PTE that provides a novel translational platform for studies on human PTE.