A systematic review of the safety of potassium bromide 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.

Whole blood trace element and toxic metal concentration in dogs with idiopathic epilepsy and healthy dogs: A case-control study

Background

Idiopathic epilepsy (IE) is the most common neurological disease in dogs. Multiple genes and environmental factors interact to cause clinical signs, although the pathogenesis remains poorly understood. Extensive evidence from recent decades shows that trace elements play a role in epilepsy in humans, and recently it was shown for the first time that also dogs with IE have altered trace element status. On the other hand, toxic metals may cause seizures but research on their role in canine IE is lacking. Therefore, we aimed to investigate trace element and toxic metal concentrations in whole blood from dogs that had been diagnosed with IE and compare them to those of healthy dogs.

Materials and methods

Whole blood concentrations of trace elements (selenium, zinc, copper, manganese, iron, and chromium) and toxic metals (arsenic, cadmium, mercury, and lead) were analyzed from 19 dogs that had been diagnosed with IE by board-certified neurologists and 19 healthy control dogs using inductively coupled plasma mass spectrometry. The concentrations in study and control group were compared using the Mann-Whitney U test.

Results

Dogs diagnosed with IE had significantly higher blood copper concentration (P = 0.007), higher copper/zinc ratio (P = 0.04), and higher selenium concentration (P < 0.001), as well as lower chromium concentration (P = 0.01) when compared to healthy dogs. Treatment of IE with potassium bromide was associated with a significant elevation in blood arsenic concentration (P = 0.01).

Conclusion

In conclusion, the present results support the role of altered trace element status in dogs diagnosed with IE and suggest that copper, selenium, and chromium may be involved in the pathogenesis of canine epilepsy or seizures. The results also suggest that potassium bromide may alter arsenic metabolism in dogs.

Voltage gated sodium channel inhibitors as anticonvulsant drugs: A systematic review on recent developments and structure activity relationship studies

Voltage-gated sodium channel blockers are one of the vital targets for the management of several central nervous system diseases, including epilepsy, chronic pain, psychiatric disorders, and spasticity. The voltage-gated sodium channels play a key role in controlling cellular excitability. This reduction in excitotoxicity is also applied to improve the symptoms of epileptic conditions. The effectiveness of antiepileptic drugs as sodium channel depends upon the reversible blocking of the spontaneous discharge without blocking its propagation. There are number of antiepileptic drug(s) which are in pipeline to flour the market to conquer abnormal neuronal excitability. They inhibit the seizures through the inhibition of complex voltage- and frequency-dependent ionic currents through sodium channels. Over the past decade, the sodium channel is one of the most explored targets to control or treat the seizure, but there has not been any game-changing discovery yet. Although there are large numbers of drugs approved for the treatment of epilepsy, however they are associated with several acute to chronic side effects. Many research groups have tirelessly worked for better therapeutic medication on this popular target to treat epileptic seizures. The review quotes briefly the developments of the approved examples of sodium channel blockers as anticonvulsant drugs. Medicinal chemists have tried the design and development of some more potent anticonvulsant drugs to minimize the toxicity that are discussed here, and an emphasis is given for their possible mechanism and the structure-activity relationship (SAR).

Bromide toxicosis (bromism) secondary to a decreased chloride intake after dietary transition in a dog with idiopathic epilepsy: a case report

Background

Bromide is a halide ion of the element bromine usually administered in the form of potassium salt as monotherapy or add-on treatment in epileptic dogs. It is excreted unchanged in the urine and undergoes tubular reabsorption in competition with chloride. Thus, dietary chloride content affects serum bromide concentrations. This is the first published clinical report of bromide toxicosis secondary to a dietary modification of chloride content in an epileptic dog treated with potassium bromide.

Case presentation

A 3-year-old 55-kg neutered male Tibetan Mastiff was evaluated because of a 1-month history of progressive signs including ataxia, lethargy and behaviour changes. The dog was successfully treated for idiopathic epilepsy since the age of 1-year-old with phenobarbital and potassium bromide. Two months prior to presentation, the owners decided to change the dog’s diet without veterinary advice. Physical examination was unremarkable. A 12-kg weight gain was recorded since last follow-up (8 months). Neurological examination revealed severe symmetric 4-limbs ataxia with altered vigilance and intermittent episodes of hyperactivity and aggressive behaviour without significant abnormality of cranial nerves. Serum bromide concentration was high and increased by 103 % since last follow-up. Nutritional evaluation revealed a 53 % decrease of chloride content in the diet before and after dietary transition. Bromide toxicosis was suspected, due to bromide reduced clearance secondary to the decreased dietary chloride content. Potassium bromide treatment was lowered by 15 % without further dietary changes. Neurologic signs progressively improved over the next month, without any seizure. After two months, the serum bromide concentration lowered to the same level measured before dietary modification. After four months, neurological examination was unremarkable.

Conclusions

Dietary chloride content can directly influence serum bromide concentrations, therefore affecting seizure control or contributing to unexpected adverse effects. In the present case, a reduction in chloride intake markedly increased serum bromide concentrations causing bromism. Dietary changes should be avoided in dogs treated with potassium bromide to maintain stable serum bromide levels.

Treatment with potassium bromide mitigates ataxia and reduces tremor in lambs with perennial ryegrass toxicosis

Aims: To assess the use of potassium bromide (KBr) as a therapeutic intervention for perennial ryegrass toxicosis (PRGT) in lambs fed ryegrass seed containing lolitrem B. Methods: Male lambs aged 10-12 months (n = 43) were assigned to receive ryegrass seed containing lolitrem B, at a dose of 0.16 mg/kg/day (Groups 2, 3 and 4), or lucerne chaff and molasses (Groups 1 and 5). Lambs in Groups 2 and 3 were observed for clinical signs and gait changes until defined signs of PGRT were observed, when they were transferred, with lambs in Group 1, to the Testing phase of the trial. Lambs in Group 3 were then treated with a single oral dose of 300 mg/kg bromide. Lambs in Groups 4 and 5 received KBr daily from the start of the trial (540 mg/kg bromide over 3 days then 20 mg/kg daily) and were transferred to the Testing phase after 18 days. Clinical examination and gait assessment, and surface electromyography of the triceps muscle, measuring root-mean-square (RMS) voltages, were carried out on Days 0, 1 and 2 of the Testing phase followed by necropsy, histopathology, measurement of concentrations of bromide in serum and CSF and faecal cortisol metabolites (FCM). Results: In Group 3 lambs, mean composite gait scores decreased between Testing phase Day 0 and Days 1 and 2 (p < 0.001), but increased in lambs in Group 2 between Day 0 and Day 2 (p = 0.015). Scores for lambs in Group 3 on Day 2 were lower than for lambs in Group 2 (p < 0.001). Mean RMS voltages on Day 2 were higher in lambs in Group 2 than Group 3 (p = 0.045). Mean concentrations of bromide in serum were >800 µg/mL in lambs in Groups 3 and 4 on Day 2. Concentrations of FCM were higher in lambs from Group 2 than in Groups 1 or 5, but were similar in Groups 2, 3 and 4. Histopathological findings in the cerebellum of lambs from Groups 2, 3 and 4 were similar, showing pyknosis of neurons within the granular layer of the cerebellum and Purkinje neuron proximal axonal spheroid formation. Conclusions and clinical relevance: A single oral dose of 300 mg/kg bromide in lambs with neurological signs of PRGT resulted in reduced composite gait scores and reduced RMS voltages, indicating a significant improvement in clinical signs of ataxia, movement disorder and muscle tremor associated with the neurotoxic effects of lolitrem B.

Bromide alleviates fatty acid-induced lipid accumulation in mouse primary hepatocytes through the activation of PPARα signals

Increased plasma free fatty acids (FFAs) and liver triglyceride (TG) accumulations have been implicated in the pathogenesis of hepatic steatosis. On the other hand, trace elements function as essential cofactors that are involved in various biochemical processes in mammals, including metabolic homeostasis. Notably, clinical and animal studies suggest that the plasma levels of bromide negatively correlate with those of TG, total cholesterol (TC) and high‐density lipoprotein‐cholesterol (HDL‐C). However, the effect of bromide on lipid accumulation and the direct molecular target responsible for its action remains unknown. Oil red O (ORO) and Nile red staining were used to detect the effect of bromide on lipid accumulation in mouse primary hepatocytes (PHs) treated with different doses of sodium bromide (NaBr) in the presence of FFAs (0.4 mM oleate/palmitic acid 1:1). Spectrophotometric and fluorometric analyses were performed to assess cellular TG concentrations and rates of fatty acid oxidation (FAO), respectively, in mouse PHs. We found that bromide decreased FFA‐induced lipid accumulation and increased FFA‐inhibited oxygen consumptions in mouse PHs in a dose‐dependent manner via activation of PPARα. Mechanical studies demonstrated that bromide decreased the phosphorylation levels of JNK. More importantly, the PPARα‐specific inhibitor GW6471 partially abolished the beneficial effects of bromide on mouse PHs. Bromide alleviates FFA‐induced excessive lipid storage and increases rates of FAO through the activation of PPARα/JNK signals in mouse PHs. Therefore, bromide may serve as a novel drug in the treatment of hepatic steatosis.

Gastric dilatation and enterotoxemia in ten captive felids

CASE DESCRIPTION 10 large felids at 8 facilities were determined or suspected to have developed gastric dilatation with or without enterotoxemia over a 20-year period. Four felids were found dead with no premonitory signs. CLINICAL FINDINGS 4 felids (2 male snow leopards [Uncia uncia], 1 male Amur tiger [Panthera tigris altaica], and 1 male Sumatran tiger [Panthera tigris sumatrae]) were found dead or died before they could be evaluated. Six felids had hematemesis (1 male and 1 female African lion [Panthera leo] and 1 male jaguar [Panthera onca]) or abdominal distention and signs of lethargy with or without vomiting (1 male African lion, 1 male Malayan tiger [Panthera tigris jacksoni], and 1 female Sumatran tiger). Gastric dilatation was radiographically and surgically confirmed in the male Malayan and female Sumatran tigers and the jaguar. TREATMENT AND OUTCOME In 3 felids with an antemortem diagnosis, the gastric dilatation resolved with decompressive laparotomy but then recurred in 1 felid, which subsequently died. Three others died at various points during hospitalization. Although Clostridium perfringens type A was recovered from 3 of the 5 felids for which microbial culture was performed, and 2 felids had a recent increase in the amount fed, no single factor was definitively identified that might have incited or contributed to the gastric dilatation. CLINICAL RELEVANCE Gastric dilatation was a life-threatening condition in the large felids of this report, causing sudden death or clinical signs of hematemesis, abdominal distention, or vomiting. Even with rapid diagnosis and surgical decompression, the prognosis was poor. Research is needed into the factors that contribute to this emergent condition in large felids so that preventive measures might be taken.

An Evidence-Based Rapid Review of Surgical Techniques for Correction of Prolapsed Nictitans Glands in Dogs

Prolapsed nictitans gland (PNG) is an important ocular condition of dogs. Various surgical interventions have been described, but effective technique is currently considered to be a matter of personal clinician preference. The aim of this rapid review was to evaluate existing peer-reviewed evidence of effectiveness for surgical techniques and their subsequent effects on quantitative and clinical lacrimal outcomes for PNG. We performed a structured bibliographic search of CAB Abstracts, PubMed, and Medline using terms relevant to dogs, nictitans gland, and surgery on 13 September 2017. Included studies were assessed for study design, reporting characteristics, surgical techniques, and surgical and lacrimal outcomes. Fifteen of three hundred fifteen identified studies were eligible for inclusion. Seven different replacement techniques were identified, along with gland excision. All studies were observational or descriptive, with the exception of a single crossover trial. Outcomes reporting was heterogeneous and provided limited detail on lacrimal outcomes or on breed propensity for recurrence. Insufficient data precluded comparison of techniques for either surgical failure rates or lacrimal outcomes, although proportional meta-analysis yielded an overall failure rate of 3% (95% CI 1–7%) for the Morgan’s pocket procedure. Improved reporting of veterinary surgical studies will improve evidence appraisal and synthesis, as well as reduce potential sources of bias.

Effect of acute and long term potassium bromide administration on spatial working memory in rat

Potassium bromide (KBr), an old antiepileptic agent, is illegally used in pharmaceutical or food industries to improve the product appearance. KBr has been proven to influence several pathways which are important in memory formation. Therefore, the present study aimed to evaluate the effect of KBr on spatial working memory using object recognition task (ORT). Rats received a single dose of KBr (50, 100 or 150 mg/kg), per oral, in acute treatment. KBr long term effects were also studied in animals receiving 50 mg/kg/day of KBr for 28 consecutive days. At the end of treatments, animals underwent two trials of ORT, five min each. In the first trial (T₁), animals encountered with two identical objects for exploration. After 1 h, the animals were exposed to a familiar and an unfamiliar object (T₂). The exploration times for discrimination (D) and recognition (R) as well as the frequency of exploration for any objects were determined. Acute administration of 150 mg/kg of KBr significantly decreased the discrimination and recognition indices (RI and DI) (P < 0.01) compared to the control. However, lower doses failed to influence the animals’ performance in the test. In addition, long term administration of KBr remarkably diminished the DI and RI and the frequency of exploration (P < 0.05). The results of this study indicate that acute doses of KBr as high as 150 mg/kg are required to hamper memory function in ORT. However, cognitive impairment occured with lower doses of KBr when the duration of treatment is extended.

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.

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.

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.

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.

Canine pancreatic-specific lipase concentrations in clinically healthy dogs and dogs with naturally occurring hyperadrenocorticism

Background

Specificity of canine pancreatic lipase immunoreactivity (cPLI) assays in dogs with hyperadrenocorticism (HAC) is unknown.

Hypothesis

Results of cPLI assays differ for clinically healthy dogs and dogs with HAC.

Animals

Seventeen healthy dogs and 20 dogs with HAC diagnosed by ACTH stimulation test results without evidence of clinical pancreatitis.

Methods

Dogs were enrolled between December 2009 and November 2010. Serum cPLI concentrations were determined by quantitative (Spec cPL test, SPEC) and semiquantitative (SNAP cPL test, SNAP) assays. Results were categorized as normal, equivocal, or abnormal (SPEC) or negative or positive (SNAP). Associations between group and cPLI were assessed using Fisher's exact test or the Mann–Whitney U‐test. Spearman rank correlation coefficients (ρ) were determined for SNAP and SPEC results. Significance was set at P < .05.

Results

Spec cPL test concentrations were significantly (P < .001) higher in dogs with HAC (491.1 μg/L) than in healthy dogs (75.2 μg/L), with more abnormal SPEC results in HAC dogs (P < .001). There were more (P = .002) positive SNAP results in dogs with HAC (55%) than in healthy dogs (6%). SNAP and SPEC results were highly correlated (ρ = 0.85; P < .001).

Conclusions and Clinical Importance

Dogs with HAC had higher SPEC concentrations and more positive SNAP results than clinically healthy dogs with normal ACTH stimulation test results. Specificity of SPEC and SNAP assays in HAC dogs without clinical pancreatitis were 65 and 45%, respectively. Pending further study, SNAP and SPEC results should be interpreted cautiously in dogs with HAC to avoid false diagnosis of concurrent pancreatitis.

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.