Comparison of phenobarbital with bromide as a first-choice antiepileptic drug for treatment of epilepsy in dogs

Bromide: the good, the bad, and the ugly of the oldest antiseizure medication

Bromide is the first effective antiseizure medication used in human medicine since the XIX century. Initially met with skepticism, bromide quickly gained enthusiasm within the medical field until being largely replaced by newer antiseizure medications with significantly fewer adverse effects in people. In veterinary medicine, bromide continues to be used in the management of epileptic patients for over 30 years, yet adverse effects can impact owners and patients alike. We sought to provide the general practitioner and veterinary neurologist with insightful information on both the positive and negative attributes of bromide, explore factors that may influence its desirability as an antiseizure medication in specific veterinary cases and elucidate its current role in modern epilepsy treatment for veterinary patients. It's also our endeavor to discuss the current use as an alternative or add-on with other known antiseizure medications and potential future studies that might enhance our understanding and use of this medication.

Feasibility of in-home electroencephalographic and actigraphy recordings in dogs

Introduction

Idiopathic epilepsy is a prevalent neurological disease in dogs. Dogs with epilepsy often present with behavioral comorbidities such as aggression, anxiety, and fear. These behaviors are consistent with pre, post, or interictal behaviors, prodromal changes, seizure-precipitating factors, or absence and focal seizures. The overlap in behavior presentations and lack of objective research methods for quantifying and classifying canine behavior makes determining the cause difficult. Behavioral comorbidities in addition to the task of caring for an epileptic animal have a significant negative impact on dog and caregiver quality of life.

Methods

This pilot study aimed to assess the feasibility of a novel technology combination for behavior classification and epileptic seizure detection for a minimum 24-h recording in the dog's home environment. It was expected that combining electroencephalography (EEG), actigraphy, and questionnaires would be feasible in the majority of trials. A convenience sample of 10 community-owned dogs was instrumented with wireless video-EEG and actigraphy for up to 48 h of recording at their caregiver's home. Three questionnaires (maximum 137 questions) were completed over the recording period by caregivers to describe their dog's everyday behavior and habits.

Results

Six of the 10 included dogs had combined EEG and actigraphy recordings for a minimum of 24 h.

Discussion

This shows that in-home EEG and actigraphy recordings are possible in community-owned dogs and provides a basis for a prospective study examining the same technology combination in a larger sample size.

Tools and techniques for classifying behaviours in canine epilepsy

Idiopathic epilepsy is the most common neurological disease in dogs. Similar to humans, dogs with epilepsy often experience behavioural comorbidities such as increased fear, anxiety, and aggression, as reported by their caregivers. Investigations of behaviour in canine epilepsy have yet to untangle interictal and pre and postictal behaviours, prodromal changes, and seizure-precipitating factors. Under-recognition of absence and focal seizures further complicates these assessments. These complex behavioural presentations in combination with caring for an epileptic animal have a significant negative impact on the dog's and caregiver's quality of life. Despite the growing recognition of behavioural comorbidities and their impact on quality of life in dogs with epilepsy, few objective research methods for classifying and quantifying canine behaviour exist. This narrative review examines the strengths, limitations, and granularity of three tools used in the investigation of canine behaviour and epilepsy; questionnaires, electroencephalography, and actigraphy. It suggests that a prospective combination of these three tools has the potential to offer improvements to the objective classification and quantification of canine behaviour in epilepsy.

Diagnostic utility of serum bile acids in dogs presenting with epileptic seizures consistent with a tier 1 confidence level diagnosis of idiopathic epilepsy

BACKGROUND

The International Veterinary Epilepsy Task Force consensus guidelines recommend performing fasting serum bile acid (SBA) and/or serum ammonia measurements as part of a tier 1 diagnosis of idiopathic epilepsy in dogs. The aim of this retrospective study was to determine the diagnostic utility of fasting SBA in this population.

METHODS

Dogs that met the tier 1 confidence level diagnosis of idiopathic epilepsy, with the additional requirement of both fasting and 2-hour postprandial SBA measurements, were included. The incidence of significant hepatopathies and usefulness of dynamic SBA testing and minimum database results were analysed.

RESULTS

A total of 233 dogs were included. All dogs diagnosed with clinically significant hepatopathy had elevations in postprandial SBA, with eight of 14 (57.14%) showing elevations in fasting SBA. The prevalence of clinically significant hepatopathies that could have been missed without using postprandial SBA measurement was 1.29%.

LIMITATIONS

The further investigations performed were not uniform and there were limitations in the ability to control sampling techniques due to the retrospective nature of this study. Investigations into hepatopathy were not standardised across this study population.

CONCLUSIONS

This study documents the importance of postprandial SBA measurements in the detection of hepatopathies and reveals that non-dynamic blood sampling has a negative predictive value of 91% for detecting elevated postprandial SBA, specific to dogs meeting the tier 1 confidence level diagnosis of idiopathic epilepsy.

Remarkable anecdotes illustrating the nature and effect of seizure-precipitating factors in Border Collies with idiopathic epilepsy

Epilepsy is one of the most common chronic neurological syndromes in dogs and has serious implications for the quality of life of both the dogs and owners. Seizure-precipitating factors (SPFs) (also termed "triggers" or "provocative factors") have been studied and reported in both humans and dogs with idiopathic epilepsy. In dogs stress, hormones, sleep deprivation, and the weather have been reported as SPFs. The Border Collie (BC) is a breed of dog that is predisposed to idiopathic epilepsy, and the outcome is often poor. BC is described as a very sensitive dog with a strong focus on their owners, and this may have an influence on their and their owners' stress level. In this article, we described six unrelated BCs with idiopathic epilepsy in which several remarkable SPFs were identified, and avoiding them improved the outcome of these dogs. The possible SPFs were different for each dog. The SPFs were, among others, the other dog in the family, the lack of intellectual challenge, the presence of an autistic child, a busy street, the relation with the owner, and throwing a ball at the beach. These cases illustrate that recognizing the SPF(s) and taking measures with regard to management can lead to a reduction in epileptic seizure frequency or even achieving seizure freedom.

Pathophysiology of drug-resistant canine epilepsy

Drug resistance continues to be a major clinical problem in the therapeutic management of canine epilepsies with substantial implications for quality of life and survival times. Experimental and clinical data from human medicine provided evidence for relevant contributions of intrinsic severity of the disease as well as alterations in pharmacokinetics and -dynamics to failure to respond to antiseizure medications. In addition, several modulatory factors have been identified that can be associated with the level of therapeutic responses. Among others, the list of potential modulatory factors comprises genetic and epigenetic factors, inflammatory mediators, and metabolites. Regarding data from dogs, there are obvious gaps in knowledge when it comes to our understanding of the clinical patterns and the mechanisms of drug-resistant canine epilepsy. So far, seizure density and the occurrence of cluster seizures have been linked with a poor response to antiseizure medications. Moreover, evidence exists that the genetic background and alterations in epigenetic mechanisms might influence the efficacy of antiseizure medications in dogs with epilepsy. Further molecular, cellular, and network alterations that may affect intrinsic severity, pharmacokinetics, and -dynamics have been reported. However, the association with drug responsiveness has not yet been studied in detail. In summary, there is an urgent need to strengthen clinical and experimental research efforts exploring the mechanisms of resistance as well as their association with different etiologies, epilepsy types, and clinical courses.

Translational veterinary epilepsy: A win-win situation for human and veterinary neurology

Epilepsy is a challenging multifactorial disorder with a complex genetic background. Our current understanding of the pathophysiology and treatment of epilepsy has substantially increased due to animal model studies, including canine studies, but additional basic and clinical research is required. Drug-resistant epilepsy is an important problem in both dogs and humans, since seizure freedom is not achieved with the available antiseizure medications. The evaluation and exploration of pharmacological and particularly non-pharmacological therapeutic options need to remain a priority in epilepsy research. Combined efforts and sharing knowledge and expertise between human medical and veterinary neurologists are important for improving the treatment outcomes or even curing epilepsy in dogs. Such interactions could offer an exciting approach to translate the knowledge gained from people and rodents to dogs and vice versa. In this article, a panel of experts discusses the similarities and knowledge gaps in human and animal epileptology, with the aim of establishing a common framework and the basis for future translational epilepsy research.

Quality of life in dogs with idiopathic epilepsy and their owners with an emphasis on breed-A pilot study

Epilepsy in dogs is a common chronic and serious disorder and may have an impact on the quality of life of the owners as well as the dogs themselves. The aim of this pilot study was to investigate the QoL score of dogs suffering from idiopathic epilepsy and their owners and if possible, investigate whether a breed specific difference exists. Owners, either Dutch or Belgium, were asked to participate in a web based SurveyMonkey questionnaire. A total of 402 questionnaires representing 402 dogs with epilepsy were suitable for further analysis. Of the 402 dogs, 253 were males and 149 were females. Ninety-nine different breeds were represented. Fourteen breeds (177 dogs in total) were used to calculate breed specific scores; Australian Shepherd (n = 8), Beagle (n = 7), Belgian Tervuren dog (n = 9), Belgian Groenendaeler dog (n = 8), Border Collie (n = 38), Chihuahua (n = 9), Dachshund (n = 13), Drentsche Patrijshond (a Dutch partridge dog) (n = 14), French Bulldog (n = 12), Golden Retriever (n = 17), Labrador Retriever (n = 18), and Rottweiler (n = 12). For the Border Collie, there was a statistically significant correlation between "epilepsy related death," the severity of the seizures (p < 0.001) and cluster seizures (p < 0.001). The quality of life of the Border Collie was scored lower compared to all other dogs (p = 0.02). There were three breeds that had a minimal decrease in the overall quality of life score compared to all other dogs: the Chihuahua (p = 0.03), Dachshund (p = 0.001), and Golden retriever (p = 0.01). The score for "caring for my epileptic dog decreases my own QoL" was high for the Border Collie, Boxer, French Bulldog, and Rottweiler, but was only found to be statistically significantly higher in the Border Collie (p = 0.01). Scores for the Golden Retriever (p = 0.04) and Labrador (p = 0.006) were lower. In conclusion, this study reports breed specific quality of life scores of dogs with epilepsy and their owners, and underlines that breed by itself, is also an important factor when managing epilepsy in dogs.

Cross Sectional Survey of Canine Idiopathic Epilepsy Management in Primary Care in the United Kingdom

The aims of this study are to gain insight on how primary care veterinarians in the UK diagnose and treat canine idiopathic epilepsy (IE) and what they perceive as challenges in the management of canine IE. Two hundred and thirty-five primary care veterinarians took part in this survey. The questionnaire asked about the type of practice the respondent worked in, any relevant post-graduate qualifications, how many years' experience they had in practice and the participant's canine IE caseload. Participants were asked how they diagnose canine IE, how they select antiseizure drugs (ASDs) and how they assess outcome. The questionnaire also explored which information sources they have access to for deciding on canine IE treatment, challenges that may be faced when managing these cases and areas in which more support can be provided. 94.5% of participants (n = 222/235) managed <10 canine IE cases in a year and 87.8% (n = 206/235) used phenobarbital as their first line ASD. The reported mean initial phenobarbital dose was 2.1 mg/kg (standard deviation = 0.71) every 12 h. When considering how closely participants aligned with IVETF guidelines on the topics of diagnosis, ASD initiation and outcome assessment, on average participants would score around half of the available points. 53.2% (n = 125/235) of respondents recommended neutering in canine IE and 46.8% (n = 110/235) did not. 53.2% (n = 125/235) did not recommend any additional treatments for canine IE beyond use of ASDs. 23.4% recommended Purina Neurocare diet (n = 55/235), 12.8% recommended environmental modification (n = 30/235), and 6.8% (n = 16/235) recommend medium chain triglyceride supplements. In this study participants found managing client expectations to be most challenging alongside canine IE emergency management. The main limitation of this study is the relatively low response rate and therefore the results may not reflect the entire small animal veterinary profession in the UK. However, the results of this study represent a starting point to inform educational resources and support strategies to improve quality care of canine IE in primary care.

Owner compliance in canine epilepsy

BACKGROUND

Poor medication compliance by human epilepsy patients is one of the leading causes of treatment failure and increased seizure frequency. The aim of this cross-sectional study was to analyse owner compliance in pharmacological treatment of canine idiopathic epilepsy and to identify factors associated with poor compliance.

METHODS

The number of antiseizure drug tablets was recorded to determine if the patient received sufficient tablets to cover the time period between prescriptions and to assess compliant prescription cycles. Additionally, compliance was assessed by an online survey of owners.

RESULTS

For the prescription monitoring data from 94 cases from three small animal practices in the United Kingdom revealed an overall median compliance of 56%. Thirt-three per cent of owners were >80% compliant, while 21% were 100% compliant. During a non-compliant prescription cycle, a patient missed a median of 6 days (0.11-519 days) of treatment. Patients on polytherapy had higher compliance rates than on monotherapy (p = 0.031). The survey (229 respondents from online canine epilepsy groups) showed that low daily dosing was associated with better compliance (p = 0.049).

CONCLUSION

Owner compliance was subpar in this study and could represent a significant issue in epilepsy management, which needs to be considered by veterinary surgeons when treating canine epilepsy.

How Owners of Epileptic Dogs Living in Italy Evaluate Their Quality of Life and That of Their Pet: A Survey Study

Epilepsy is the most common chronic neurological disorder of dogs and requires a substantial commitment by the pet owner. The aim of this study was to evaluate how Italian owners of epileptic dogs receiving long-term treatment perceived their own quality of life (QoL) and that of their pet, using a list of key questions. A questionnaire was sent to owners of dogs affected by recurrent seizures and treated with antiepileptic drugs for at least three months. The questions included signalment, medical history and physical, social and psychological aspects associated with managing an epileptic dog. Eighty complete questionnaires were obtained. Most owners surveyed had a positive opinion on their dog's QoL and they did not believe that commitment to managing their animals was a limitation of QoL. Dog QoL, seizure, frequency and severity were considered the most important factors in evaluating the efficacy of the antiepileptic treatment. The evaluation of the different aspects of QoL can help veterinary professionals understand the need for correct and exhaustive information provided to owners and the development of therapeutic plans and follow up, corresponding to the needs of dogs and owners.

Prevalence and clinical characteristics of phenobarbitone-associated adverse effects in epileptic cats

OBJECTIVES

The study objective was to investigate the prevalence and clinical characteristics of phenobarbitone-associated adverse effects in epileptic cats.

METHODS

The medical records of two veterinary referral clinics from 2007 to 2017 were searched for cats fulfilling the inclusion criteria of a diagnosis of epilepsy, treatment with phenobarbitone and available follow-up information on the occurrence of adverse effects. Follow-up information was obtained from the medical records of the primary veterinarian and referral institutions and a questionnaire completed by the cats' owners.

RESULTS

Seventy-seven cats met the inclusion criteria. Fifty-eight were affected by idiopathic epilepsy and 19 by structural epilepsy. One or more of the following adverse effects were reported in 47% of the cats: sedation (89%); ataxia (53%); polyphagia (22%); polydipsia (6%); polyuria (6%); and anorexia (6%). Logistic regression analyses revealed significant associations between adverse effect occurrence and both phenobarbitone starting dosage and administration of a second antiepileptic drug (AED). For each 1 mg/kg q12h increment of phenobarbitone, the likelihood of adverse effects increased 3.1 times. When a second AED was used, the likelihood of adverse effects increased 3.2 times. No association was identified between epilepsy aetiology and adverse effect occurrence. An idiosyncratic adverse effect, characterised by severe neutropenia and granulocytic hypoplasia, was diagnosed in one cat. This resolved following phenobarbitone discontinuation.

CONCLUSIONS AND RELEVANCE

The prevalence of phenobarbitone-associated adverse effects was 47%. Sedation and ataxia were most common. These are type A adverse effects and are predictable from phenobarbitone's known pharmacological properties. In the majority of cases, adverse effects occurred within the first month of treatment and were transient. Idiosyncratic (type B) adverse effects, which were not anticipated given the known properties of the drug, occurred in one cat. Increased phenobarbitone starting dosage and the addition of a second AED were significantly associated with the occurrence of adverse effects.

Behavioral Changes Under Levetiracetam Treatment in Dogs

In veterinary medicine levetiracetam (LEV) is a well-tolerated antiepileptic drug (AED) with only mild to moderate side effects. Behavioral changes are rarely reported in animals. In contrast, in human medicine the impact of LEV on behavior has frequently been described. Since in the Clinic for Small Animals at the University of Veterinary Medicine Hannover single canine patients were observed with behavioral abnormalities after LEV treatment, it was hypothesized that levetiracetam induces behavioral changes or causes an intensifying of pre-existing behavioral abnormalities in dogs with epileptic seizures. This monocentric retrospective study evaluated the incidence of behavioral changes in epileptic dogs treated with the antiepileptic drug LEV based on information obtained in a questionnaire completed by dog owners. Eighty-four client-owned dogs with recurrent seizures receiving LEV as monotherapy, add on treatment or pulse therapy met inclusion criteria. Approximately half of the dogs in the study population were reported to have preexisting behavioral changes before treatment with LEV, and some of these dogs were reported to experience a worsening of behavioral changes (14/44) or the emergence of new behaviors after initiation of LEV therapy (4/44). One quarter of the dogs without pre-existing behavioral abnormalities developed behavioral changes associated with the administration of LEV (10/40). Based on these results, the authors conclude that behavioral changes can occur in dogs being administered LEV, and this should be taken into consideration when discussing treatment options with owners.

Epileptic seizure frequency and semiology in dogs with idiopathic epilepsy after initiation of imepitoin or phenobarbital monotherapy

The aim of this study was to evaluate changes in epileptic seizures (ES) frequency and semiology in antiepileptic-medication (AEM)-naïve dogs with idiopathic epilepsy (DIE) after initiation of imepitoin (IMP) or phenobarbital (PB) monotherapy. In this observational prospective cohort study, inclusion criteria were as follows: diagnosis of idiopathic epilepsy (based on clinical, laboratory and magnetic resonance imaging investigations) in AEM-naïve dogs and presence of a detailed ES-diary. Exclusion criteria were: occurrence of cluster seizures (CS) or status epilepticus (SE) prior to treatment initiation and concurrent disease and/or treatments. Thirty-one DIE commenced IMP at 10-20mg/kg/12h and 30 dogs commenced PB at 2.50-3.30mg/kg/12h. AEM dosage was increased over time (up to IMP 30mg/kg/12h and PB 5.20mg/kg/12h). All dogs experienced generalised-tonic-clonic ES. In the IMP-group, pre-treatment median ES-frequency was 1.50ES/month (range, 1-4ES/month); post-treatment median ES-frequency was 0.95ES/m (range, 1ES/6m-3ES/m); n=21/31 (67.70%) dogs developed CS 1-18 months after initiation of treatment; n=7/31 (22.60%) dogs experienced unacceptable adverse events in the first month of treatment which required switching to an alternative AEM; and n=3/31(9.70%) dogs did not develop CS with a 3year follow-up. In the PB-group, pre-treatment median ES-frequency was 2.46ES/month (range, 1-7ES/month); post-treatment median ES-frequency was 0.36ES/month (range, 0ES/3years-1ES/month); n=11/30 (36.70%) dogs developed CS between 12-25 months after initiation of treatment. Nineteen of 30 (63.30%) dogs did not develop CS with a 3-year follow-up; three of these 19 dogs were ES free. In this study, AEM-naïve DIE receiving imepitoin-monotherapy developed CS significantly more frequently and earlier in the course of the disease, and developed aggression and required earlier discontinuation of monotherapy than AEM-naïve DIE receiving phenobarbital-monotherapy.

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.

Polirradiculoneuropatia periférica desmielinizante associada ao uso de carbamazepina em cão: relato de caso

RESUMO Diversos fármacos são utilizados no tratamento da epilepsia e, assim como outros medicamentos, podem induzir a ocorrência de efeitos adversos, alguns tão graves que geram a necessidade de descontinuidade e substituição da terapia. A carbamazepina pode levar a alterações nos sistemas cardiovascular, respiratório e neurológico, sendo descritos na literatura casos de indução de miastenia gravis como distúrbio neuromuscular. Este estudo relata o caso de um cão que desenvolveu polirradiculoneuropatia desmielinizante, tendo como provável desencadeante a terapia com carbamazepina. O paciente apresentou tetraplegia, ausência de reflexos espinhais nos quatro membros, fraqueza cervical, diminuição do reflexo palpebral bilateral e esforço respiratório. A eletroneuromiografia demonstrou sinais de desmielinização. Este, portanto, é o primeiro relato de associação entre carbamazepina e polirradiculoneuropatia desmielinizante em cão.

In vitro and in vivo experimental models employed in the discovery and development of antiepileptic drugs for pharmacoresistant epilepsy

Epilepsy is one of the most common chronic, recurrent and progressive neurological diseases. In spite of the large number of antiepileptic drugs currently available for the suppression of seizures, about one-third of patients develop drug-resistant epilepsy, even when they are administered the most appropriate treatment available. Thus, nonclinical models can be valuable tools for the elucidation of the mechanisms underlying the development of pharmacoresistance and also for the development of new therapeutic agents that may be promising therapeutic approaches for this unmet medical need. Up today, several epilepsy and seizure models have been developed, exhibiting similar physiopathological features of human drug-resistant epilepsy; moreover, pharmacological response to antiepileptic drugs clinically available tends to be similar in animal models and humans. Therefore, they should be more intensively used in the preclinical discovery and development of new candidates to antiepileptic drugs. Although useful, in vitro models cannot completely replicate the complexity of a living being and their potential for a systematic use in antiepileptic drug screening is limited. The whole-animal models are the most commonly employed and they can be classified as per se drug-resistant due to an inherent poor drug response or be based on the selection of subgroups of epileptic animals that respond or not to a specific antiepileptic drug. Although more expensive and time-consuming, the latter are chronic models of epilepsy that better exhibit the disease-associated alterations found in human epilepsy. Several antiepileptic drugs in development or already marketed have been already tested and shown to be effective in these models of drug-resistant epilepsy, constituting a new hope for the treatment of drug-resistant epilepsy. This review will provide epilepsy researchers with detailed information on the in vitro and in vivo nonclinical models of interest in drug-resistant epilepsy, which may enable a refined selection of most relevant models for understanding the mechanisms of the disease and developing novel antiepileptic drugs.

Effects of three infusion fluids with different sodium chloride contents on steady-state serum concentrations of bromide in dogs

Potassium bromide overdose (bromism) in the management of canine epilepsy has been known. However, a protocol to reduce bromide concentrations rapidly has not been previously established. The effects of three infusion fluids with different chloride contents on the steady-state serum concentrations of bromide in beagles were determined. After stabilization of the serum bromide concentrations, seven dogs were infused with saline (Na⁺ 154 mmol/L; Cl^- 154 mmol/L), lactated Ringer's (Na⁺ 131 mmol/L; Cl^- 110 mmol/L), or maintenance solutions (Na⁺ 35 mmol/L; Cl^- 35 mmol/L) at a rate of 2 or 10 ml kg^-1  hr^-1 for 5 hr. Serum and urine were collected hourly, and the bromide concentrations were measured. When saline and lactated Ringer's solutions were infused at a rate of 10 ml kg^-1  hr^-1 for 5 hr, serum bromide concentrations were decreased by 14.24% and urine bromide concentrations by 17.63%, respectively. Of all compositions of infusion fluids, only sodium and chloride contents were associated with the decreased serum concentrations and the increased renal clearance of bromide. In summary, saline and lactated Ringer's solutions reduced serum bromide concentrations in a sodium chloride-dependent manner in dogs were found when infused at 10 ml kg^-1  hr^-1 for 5 hr.

MANAGEMENT OF A REEVE'S MUNTJAC ( MUNTIACUS REEVESI) WITH SEIZURES USING LEVETIRACETAM

This report describes the diagnosis and management of idiopathic epilepsy in a 4-yr-old intact female Reeve's muntjac ( Muntiacus reevesi). The patient was initially witnessed to have isolated paroxysmal events consistent with epileptic seizures (altered consciousness, lateral recumbency, tonic/clonic movement of limbs) lasting less than 3 min with an immediate return to normal consciousness. The seizure frequency increased to >3 seizures within 24 hr and phenobarbital 3 mg/kg orally every 12 hr was started. Because of continued epileptic seizures and low serum phenobarbital levels, the dose was increased until significant elevations of aspartate aminotransferase (AST) and alkaline phosphatase (ALP) were detected. Levetiracetam 40 mg/kg orally every 12 hr was initiated and the phenobarbital was weaned and discontinued. One breakthrough seizure has been witnessed in the 10 mo since starting levetiracetam.

Evaluation of the Impacts of Epilepsy in Dogs on Their Caregivers

Epilepsy is a common problem in dogs, and management of this chronic disorder requires a substantial commitment on the part of the pet owner. The aim of this study was to evaluate the impact of epilepsy in dogs on their owners, utilizing an online survey tool. A questionnaire was developed to explore a variety of factors, including seizure history, treatment, outcome, quality of life, costs associated with therapy, and sources of support. A total of 225 responses were obtained. The majority of respondents reported positive scores for overall quality of life, although scores were significantly lower for dogs with poorly controlled epilepsy and medication-related adverse effects. The median monthly expenditure for antiepileptic medication was $51-75. Despite the considerable financial burden placed on the dog owner, monthly medication cost was not associated with quality of life score. Few published reports follow dogs with epilepsy after diagnosis, and there is a growing need to understand the issues associated with long-term management of this population. The results of this study provide useful information that can help veterinary professionals educate owners and set expectations regarding treatment of seizures and quality of life for dogs with epilepsy.

Phenobarbital administration every eight hours: improvement of seizure management in idiopathic epileptic dogs with decreased phenobarbital elimination half-life

Estimated prevalence of canine idiopathic epilepsy is 0.6 per cent in the first-opinion canine population in the UK. Phenobarbital monotherapy has been reported to reduce/eradicate seizure activity in 60-93 per cent of idiopathic epileptic dogs (IEDs). The objective of this study was to evaluate safety and efficacy of the administration of phenobarbital orally every eight hours in IEDs with phenobarbital elimination half-life less than 20 hours. Medical records of 10 IEDs in which steady state trough serum phenobarbital levels were within the reference range and phenobarbital elimination half-life had become less than 20 hours following prolonged administration every 12 hours were reviewed. Side effects and seizure frequency when phenobarbital was administered every 12 hours or 8 hours were compared. In all dogs the side effects of the antiepileptic medication treatment improved. When phenobarbital was administered every eight hours, 9/10 dogs experienced improvement in seizure frequency and 8/10 dogs maintained seizure freedom for a period three times longer than the longest interictal interval period previously recorded. Reduction in the severity and number of clusters of seizures was recorded in one of the remaining two dogs. The administration of phenobarbital orally every eight hours in IEDs with decreased phenobarbital elimination half-life appears safe and can improve seizure management. The results of this study were presented in abstract form (poster) for the 28th symposium of the European Society of Veterinary Neurology - European College of Veterinary Neurology (ESVN), September 18-19, 2015, Amsterdam, Netherlands.

Canine versus human epilepsy: are we up to date?

In this paper we analyse and compare features of canine and human epilepsy and we suggest new tools for better future understanding of canine epilepsy. The prevalence of epileptic seizures in dogs ranges between 0.5% and 5.7% and between 1% and 3% in the human population. Studies on human epilepsy provide a ready-made format for classification, diagnosis and treatment in veterinary epilepsy. Human studies highlight the value of a thorough seizure classification. Nevertheless, a matter of concern in canine epilepsy is the limited information regarding seizure description and classification because of the lack of EEG-video recording. Establishment of a consensus protocol for ambulatory home video-recording in dogs who suffer from epilepsy, mainly considering indications, duration of monitoring, the sufficient essential training for an optimal interpretation of ictal semiology and the methodology of recordings is needed. The ultimate goal is that the information gathered by these videos will be analysed to describe the epileptic seizures thoroughly, recognize patterns and move towards a better understanding and therefore classification of canine epileptic seizures.

Comparing the effects of first-line antiepileptic drugs on the gait of dogs with idiopathic epilepsy

Idiopathic epilepsy (IE) is a common chronic neurological disease of the dog. Previous studies of anti-epileptic drug (AED) treatment have indicated that acceptable AED adverse effects are as important to owners as reductions in seizure frequency. AEDs in both dogs and human beings are frequently associated with the adverse-effect ataxia. The aim of this study was to compare ataxia levels in dogs with IE treated chronically with phenobarbitone or imepitoin, the two currently available first-line AED treatments. The gait of 6 imepitoin-treated dogs, 8 phenobarbitone-treated dogs and 10 age-matched healthy control dogs were compared. Fifty strides from a walking gait were analysed for each dog, quantifying ataxia via the variability in six established gait parameters. Three variables differed significantly between groups: lateral distance between (i) pelvic paw placements, (ii) thoracic paw placements and (iii) stance time, which were significantly more variable in the phenobarbitone-treated dogs than imepitoin-treated or control dogs. These results indicate that dogs treated with phenobarbitone experience ataxia compared with controls and imepitoin-treated dogs. Conversely, there was no difference between imepitoin-treated dogs and controls. These results along with further research are needed to quantify AEDs adverse effects, to help vets and owners make more informed drug-choices.

Antiepileptic drugs' tolerability and safety--a systematic review and meta-analysis of adverse effects in dogs

Background

The safety profile of anti-epileptic drugs (AEDs) is an important consideration for the regulatory bodies, owners and prescribing clinicians. Information on their adverse effects still remains limited. A systematic review including a meta-analytic approach was designed to evaluate existing evidence for the safety profile of AEDs in canine patients. Electronic searches of PubMed, CAB Direct and Google scholar were carried out without date or language restrictions. Conference proceedings were also searched. Peer-reviewed full-length studies reporting adverse effects of AEDs in epileptic and healthy non-epileptic dogs were included. Studies were allocated to three groups based on their design. Individual studies were evaluated based on the quality of evidence (study design, study group sizes, subject enrolment quality and overall risk of bias) and the outcome measures reported (proportion of specific adverse effects for each AED, prevalence and 95 % confidence interval of the affected population in each study and comparative odds ratio of adverse effects for AEDs).

Results

Ninety studies, including six conference proceedings, reporting clinical outcomes of AEDs’ adverse effects were identified. Few studies were designed as blinded randomised controlled clinical trials. Many studies included low canine populations with unclear criteria of subject enrolment and short treatment periods. Direct comparisons suggested that imepitoin and levetiracetam might have a better safety profile than phenobarbital, whilst the latter might have a better safety profile than potassium bromide. However, none of these comparisons showed a statistically significant difference. Comparisons between other AEDs were not possible as a considerable amount of studies lacked power calculations or adequate data to allow further statistical analysis. Individual AED assessments indicated that levetiracetam might be one of the safest AEDs, followed by imepitoin and then phenobarbital and potassium bromide; these findings were all supported by a strong level of evidence. The safety profile in other AEDs was variable, but weak evidence was found to permit firm conclusions or to compare their safety to other AEDs.

Conclusions

This systematic review provides objective evaluation of the most commonly used AEDs’ adverse effects. Adverse effects usually appeared mild in all AEDs and subsided once doses and/or serum levels were monitored or after the AED was withdrawn. Although phenobarbital might be less safe than imepitoin and levetiracetam, there was insufficient evidence to classify it as an AED with a high risk of major adverse effects. It is important for clinicians to evaluate both AEDs’ effectiveness and safety on an individual basis before the selection of the appropriate monotherapy or adjunctive AED therapy.

Cutaneous Adverse Drug Reactions in Dogs Treated with Antiepileptic Drugs

Epilepsy is one of the most common neurologic disorders in dogs and life-long treatment with antiepileptic drugs (AED) is frequently required. Adverse events of AED targeting the skin are only rarely reported in veterinary medicine and the true incidence and spectrum of cutaneous reactions in epileptic dogs remains unknown. In this study, we hypothesized that cutaneous reactions commonly occur in epileptic dogs and are related to AED treatment. A retrospective case review of 185 dogs treated for epilepsy identified 20.0% with simultaneous appearance of dermatologic signs. In a subsequent prospective case investigation (n = 137), we identified newly appearing or distinct worsening of skin lesions following initiation of AED therapy in 10.9% of dogs treated for epilepsy (95% CI 6.8–17.7%). Cutaneous lesions were classified as probably drug-induced in 40.0% of these cases. Patch testing and intradermal testing were further investigated as potential diagnostic methods to confirm AED hypersensitivity. They were of high specificity but sensitivity and positive predictive value appeared inappropriate to recommend their routine use in clinical practice.

2015 ACVIM Small Animal Consensus Statement on Seizure Management in Dogs

This report represents a scientific and working clinical consensus statement on seizure management in dogs based on current literature and clinical expertise. The goal was to establish guidelines for a predetermined, concise, and logical sequential approach to chronic seizure management starting with seizure identification and diagnosis (not included in this report), reviewing decision‐making, treatment strategies, focusing on issues related to chronic antiepileptic drug treatment response and monitoring, and guidelines to enhance patient response and quality of life. Ultimately, we hope to provide a foundation for ongoing and future clinical epilepsy research in veterinary medicine.

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.

International veterinary epilepsy task force consensus proposal: outcome of therapeutic interventions in canine and feline epilepsy

Common criteria for the diagnosis of drug resistance and the assessment of outcome are needed urgently as a prerequisite for standardized evaluation and reporting of individual therapeutic responses in canine epilepsy. Thus, we provide a proposal for the definition of drug resistance and partial therapeutic success in canine patients with epilepsy. This consensus statement also suggests a list of factors and aspects of outcome, which should be considered in addition to the impact on seizures. Moreover, these expert recommendations discuss criteria which determine the validity and informative value of a therapeutic trial in an individual patient and also suggest the application of individual outcome criteria. Agreement on common guidelines does not only render a basis for future optimization of individual patient management, but is also a presupposition for the design and implementation of clinical studies with highly standardized inclusion and exclusion criteria. Respective standardization will improve the comparability of findings from different studies and renders an improved basis for multicenter studies. Therefore, this proposal provides an in-depth discussion of the implications of outcome criteria for clinical studies. In particular ethical aspects and the different options for study design and application of individual patient-centered outcome criteria are considered.

International Veterinary Epilepsy Task Force consensus proposal: medical treatment of canine epilepsy in Europe

In Europe, the number of antiepileptic drugs (AEDs) licensed for dogs has grown considerably over the last years. Nevertheless, the same questions remain, which include, 1) when to start treatment, 2) which drug is best used initially, 3) which adjunctive AED can be advised if treatment with the initial drug is unsatisfactory, and 4) when treatment changes should be considered. In this consensus proposal, an overview is given on the aim of AED treatment, when to start long-term treatment in canine epilepsy and which veterinary AEDs are currently in use for dogs. The consensus proposal for drug treatment protocols, 1) is based on current published evidence-based literature, 2) considers the current legal framework of the cascade regulation for the prescription of veterinary drugs in Europe, and 3) reflects the authors' experience. With this paper it is aimed to provide a consensus for the management of canine idiopathic epilepsy. Furthermore, for the management of structural epilepsy AEDs are inevitable in addition to treating the underlying cause, if possible.

Disposition of Extended Release Levetiracetam in Normal Healthy Dogs After Single Oral Dosing

Background

Levetiracetam is an anticonvulsant used for control of canine epilepsy. An extended release preparation should improve dosing convenience.

Objectives

To determine the disposition of extended release levetiracetam in normal dogs after single dosing.

Animals

Pharmacokinetic study: 16 healthy, adult dogs.

Methods

Using a partially randomized crossover study, levetiracetam (30 mg/kg) was administered intravenously (IV) and orally (PO) as extended release preparation with or without food. Blood was collected for 24 hours (IV) or 36 hours (PO). Serum levetiracetam was quantitated by immunoassay and data were subjected to noncompartmental analysis.

Results

Pharmacokinetic parameters for fasted versus fed animals, respectively, were (mean ± SEM): C_max = 26.6 ± 2.38 and 30.7 ± 2.88 μ/mL, T_max = 204.3 ± 18.9 and 393.8 ± 36.6 minutes, t_1/2 = 4.95 ± 0.55 and 4.48 ± 0.48 hours, MRT = 9.8 ± 0.72 and 10 ± 0.64 hours, MAT = 4.7 ± 0.38 and 5.6 ± 0.67 hours, and F = 1.04 ± 0.04 and 1.26 ± 0.07%. Significant differences were limited to T_max (longer) and F (greater) in fed compared to fasted animals. Serum levetiracetam concentration remained above 5 μ/mL for approximately 20 hours in both fasted and fed animals.

Conclusions and Clinical Importance

Extended release levetiracetam (30 mg/kg q12h), with or without food, should maintain concentrations above the recommended minimum human therapeutic concentration.

Addisonian crisis in a dog treated with phenobarbitone

BACKGROUND

A 2-year-old intact female Irish Setter was presented with a 1-week history of anorexia, lethargy, vomiting and diarrhoea. Previous medical therapy included a 3-week treatment with phenobarbitone for suspected idiopathic epilepsy. In humans, phenobarbitone accelerates metabolism of both exogenous and endogenous steroids.

CASE REPORT

Based on history, the physical examination showing abnormal mentation and laboratory abnormalities including azotaemia, hyponatraemia and hyperkalaemia, Addisonian crisis was suspected. An adrenocorticotropic hormone stimulation test was performed and confirmed the diagnosis. Treatment with intravenous fluid therapy, glucocorticoids and mineralocorticoids led to a resolution of clinical signs in 3 days.

CONCLUSION

To the authors' current knowledge, this is the first reported case of Addisonian crisis in a dog most probably related to phenobarbitone administration. As Addisonian crisis can be life-threatening, clinicians should be aware of this adverse effect of phenobarbitone and use it cautiously in dogs with borderline hypoadrenocorticism.

Treatment in canine epilepsy--a systematic review

Background

Various antiepileptic drugs (AEDs) are used for the management of canine idiopathic epilepsy (IE). Information on their clinical efficacy remains limited. A systematic review was designed to evaluate existing evidence for the effectiveness of AEDs for presumptive canine IE. Electronic searches of PubMed and CAB Direct were carried out without date or language restrictions. Conference proceedings were also searched. Peer-reviewed full-length studies describing objectively the efficacy of AEDs in dogs with IE were included. Studies were allocated in two groups, i.e. blinded randomized clinical trials (bRCTs), non-blinded randomized clinical trials (nbRCTs) and non-randomized clinical trials (NRCTs) (group A) and uncontrolled clinical trials (UCTs) and case series (group B). Individual studies were evaluated based on the quality of evidence (study design, study group sizes, subject enrolment quality and overall risk of bias) and the outcome measures reported (in particular the proportion of dogs with ≥50% reduction in seizure frequency).

Results

Twenty-six studies, including two conference proceedings, reporting clinical outcomes of AEDs used for management of IE were identified. Heterogeneity of study designs and outcome measures made meta-analysis inappropriate. Only four bRCTs were identified in group A and were considered to offer higher quality of evidence among the studies. A good level of evidence supported the efficacy of oral phenobarbital and imepitoin and fair level of evidence supported the efficacy of oral potassium bromide and levetiracetam. For the remaining AEDs, favorable results were reported regarding their efficacy, but there was insufficient evidence to support their use due to lack of bRCTs.

Conclusions

Oral phenobarbital and imepitoin in particular, as well as potassium bromide and levetiracetam are likely to be effective for the treatment of IE. However, variations in baseline characteristics of the dogs involved, significant differences between study designs and several potential sources of bias preclude definitive recommendations. There is a need for greater numbers of adequately sized bRCTs evaluating the efficacy of AEDs for IE.

Clinical risk factors associated with anti-epileptic drug responsiveness in canine epilepsy

The nature and occurrence of remission, and conversely, pharmacoresistance following epilepsy treatment is still not fully understood in human or veterinary medicine. As such, predicting which patients will have good or poor treatment outcomes is imprecise, impeding patient management. In the present study, we use a naturally occurring animal model of pharmacoresistant epilepsy to investigate clinical risk factors associated with treatment outcome. Dogs with idiopathic epilepsy, for which no underlying cause was identified, were treated at a canine epilepsy clinic and monitored following discharge from a small animal referral hospital. Clinical data was gained via standardised owner questionnaires and longitudinal follow up data was gained via telephone interview with the dogs’ owners. At follow up, 14% of treated dogs were in seizure-free remission. Dogs that did not achieve remission were more likely to be male, and to have previously experienced cluster seizures. Seizure frequency or the total number of seizures prior to treatment were not significant predictors of pharmacoresistance, demonstrating that seizure density, that is, the temporal pattern of seizure activity, is a more influential predictor of pharmacoresistance. These results are in line with clinical studies of human epilepsy, and experimental rodent models of epilepsy, that patients experiencing episodes of high seizure density (cluster seizures), not just a high seizure frequency pre-treatment, are at an increased risk of drug-refractoriness. These data provide further evidence that the dog could be a useful naturally occurring epilepsy model in the study of pharmacoresistant epilepsy.

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.

Imepitoin as novel treatment option for canine idiopathic epilepsy: pharmacokinetics, distribution, and metabolism in dogs

Imepitoin is a novel anti-epileptic licensed in the European Union for the treatment of canine idiopathic epilepsy. The aim of this study was to characterize the pharmacokinetics of imepitoin in dogs and to evaluate the interaction with drug metabolizing enzymes. Upon administration of imepitoin tablets at a dose of 30 mg/kg to beagle dogs, high plasma levels were observed within 30 min following oral dosing, with maximal plasma concentrations of 14.9–17.2 μg/mL reached after 2–3 h. In a crossover study, co-administration of imepitoin tablets with food reduced the total AUC by 30%, but it did not result in significant changes in T_max and C_max, indicating lack of clinical relevance. No clinically relevant effects of sex and no accumulation or metabolic tolerance were observed upon twice daily dosing. Following single dose administration of 10–100 mg/kg, dose linearity was found. Administering [¹⁴C] imepitoin, high enteral absorption of 92% and primary fecal excretion were identified. Plasma protein binding was only 55%. At therapeutic plasma concentrations, imepitoin did not inhibit microsomal cytochrome P450 family liver enzymes in vitro. In rats, no relevant induction of liver enzymes was found. Therefore, protein binding or metabolism-derived drug–drug interactions are unlikely. Based on these data, imepitoin can be dosed twice daily, but the timing of tablet administration in relation to feeding should be kept consistent.

Serum bromide concentrations following loading dose in epileptic dogs

OBJECTIVE

To determine serum bromide concentrations following an oral loading dose in dogs.

METHODS

Retrospective review of clinical records of dogs suffering from seizures that were treated with bromide. A loading dose of 600 mg/kg potassium bromide was administered orally in 17 to 48 hours together with a maintenance dose of 30 mg/kg/day. Blood samples were collected within 24 hours after completing the protocol and serum bromide concentrations were determined by ultra-violet gold chloride colorimetric assay.

RESULTS

Thirty-eight dogs were included in the study. The median age was 3 (range, 0 · 2 to 10) years and bodyweight 21 · 8 (3 · 45 to 46 · 2) kg. The median serum bromide concentration was 1 · 26 (0 · 74 to 3 · 6) mg/mL. Thirty-two dogs (84 · 2%) had serum bromide concentrations within the therapeutic interval (1 to 3 mg/mL). The serum concentration in five dogs (13 · 2%) was just under the minimal therapeutic value and in one dog (2 · 6%) it exceeded the maximal therapeutic value (3 · 6 mg/mL).

CLINICAL RELEVANCE

Following this oral loading dose protocol, serum bromide concentrations reach the therapeutic range in the majority of dogs. This indicates that the suggested protocol is effective in achieving therapeutic concentrations rapidly in epileptic dogs.

Is switching from brand name to generic formulations of phenobarbital associated with loss of antiepileptic efficacy?: a pharmacokinetic study with two oral formulations (Luminal(®) vet, Phenoleptil(®)) in dogs

Background

In human medicine, adverse outcomes associated with switching between bioequivalent brand name and generic antiepileptic drug products is a subject of concern among clinicians. In veterinary medicine, epilepsy in dogs is usually treated with phenobarbital, either with the standard brand name formulation Luminal® or the veterinary products Luminal® vet and the generic formulation Phenoleptil®. Luminal® and Luminal® vet are identical 100 mg tablet formulations, while Phenoleptil® is available in the form of 12.5 and 50 mg tablets. Following approval of Phenoleptil® for treatment of canine epilepsy, it was repeatedly reported by clinicians and dog owners that switching from Luminal® (human tablets) to Phenoleptil® in epileptic dogs, which were controlled by treatment with Luminal®, induced recurrence of seizures. In the present study, we compared bioavailability of phenobarbital after single dose administration of Luminal® vet vs. Phenoleptil® with a crossover design in 8 healthy Beagle dogs. Both drugs were administered at a dose of 100 mg/dog, resulting in 8 mg/kg phenobarbital on average.

Results

Peak plasma concentrations (C_max) following Luminal® vet vs. Phenoleptil® were about the same in most dogs (10.9 ± 0.92 vs. 10.5 ± 0.77 μg/ml), and only one dog showed noticeable lower concentrations after Phenoleptil® vs. Luminal® vet. Elimination half-life was about 50 h (50.3 ± 3.1 vs. 52.9 ± 2.8 h) without differences between the formulations. The relative bioavailability of the two products (Phenoleptil® vs. Luminal® vet.) was 0.98 ± 0.031, indicating that both formulations resulted in about the same bioavailability.

Conclusions

Overall, the two formulations did not differ significantly with respect to pharmacokinetic parameters when mean group parameters were compared. Thus, the reasons for the anecdotal reports, if true, that switching from the brand to the generic formulation of phenobarbital may lead to recurrence of seizures are obviously not related to a generally lower bioavailability of the generic formulation, although single dogs may exhibit lower plasma levels after the generic formulation that could be clinically meaningful.