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.

The effect of oral zonisamide treatment on serum phenobarbital concentrations in epileptic dogs

Zonisamide is used in dogs for the treatment of epileptic seizures. It is predominantly metabolised by CYP450 hepatic enzymes. When used concurrently with phenobarbital (PB), zonisamide clearance is increased and its elimination half-life decreases. However, the effect that zonisamide may have on serum PB concentrations in dogs has not been previously described. Eight dogs diagnosed with idiopathic epilepsy and two dogs with structural epilepsy commenced zonisamide at 8.0 mg/kg/12 h [7.4-10 mg/kg/12 h] following an increase in the frequency of epileptic seizures. Nine dogs were receiving PB every 12 h (4.2 mg/kg/12 h [3.8-6 mg/kg/12 h]), and one dog was receiving PB every 8 h (6 mg/kg/8 h). Following the addition of zonisamide and despite no increase in PB dosage, an increase in phenobarbital serum PB concentration was observed in 9 out of 10 dogs in subsequent measurements. In five dogs, phenobarbital serum concentrations were raised to concentrations higher than the reported hepatotoxic concentrations (trough>35 mg/L). This required a reduction in daily doses of PB. This case series suggests that zonisamide affects the metabolism of PB and causes an increase in PB serum concentrations over time.

Ketogenic diets: A systematic review of current scientific evidence and possible applicability in dogs and cats

Ketogenic diets (KD) have been used in the treatment of epilepsy in humans for around a century and, more recently, they have been implanted for cancer patients, as well as in the treatment of obesity. This type of diet consists of high-fat levels, an adequate amount of protein and restricted carbohydrates, or high medium-chain triglycerides. Recently, the ketogenic diet has gained attention in veterinary medicine and studies were published evaluating the effects of KD in dogs with epilepsy. The objective of this review was to highlight recent studies about the application of KD in dogs and cats, to describe the neurobiochemical mechanisms through which KD improves epilepsy crisis, and their adverse effects. Studies were identified by a systematic review of literature available on PubMed, Embase, and Scopus. All cohort and case-control studies were included, and all articles were exported to Mendeley® citation manager, and duplicates were automatically removed. Seven articles and three conference abstracts conducted with dogs were included in the present study. There is evidence that the consumption of diets with medium-chain triglycerides increases the concentration of circulating ketone bodies and improves epilepsy signs, although these diets have higher carbohydrate and lower fat content when compared to the classic KD.

Immune-Mediated Hemolytic Anemia and Clinically Suspected Acute Pancreatitis in Dogs, a Pilot Study

Acute pancreatitis can be a complication of massive hemolysis, above all when intravascular in nature. Therefore, the aim of this study was to investigate the association between canine immune mediated hemolytic anemia (IMHA) and clinically suspected acute pancreatitis (CSAP) and the role of calculated free plasma hemoglobin (Hbfp) in CSAP occurrence/development. In this cohort study the records of 95 dogs with IMHA and 95 sick dogs with pathologies other than IMHA were compared for CSAP occurrence/development. At presentation, 12/95 dogs with IMHA met criteria for CSAP, while only 3/95 sick control dogs met these criteria (χ2 =1.58, P = .008). Within 7 days of hospitalization 9 additional dogs with IMHA had developed CSAP. The Hbfp was calculated and compared for dogs with IMHA that had/developed CSAP and for those without CSAP. In dogs with IMHA, a calculated Hbfp concentration ≥ 0.08 g/dL resulted in an increased relative risk (RR) of having/developing CSAP (RR = 2.54, 95% CI, 1.51-4.29; P = .003). No significant effect on short-term prognosis in dogs with IMHA was found between those having/developing CSAP and those without CSAP. This study showed that dogs with IMHA have an increased risk of having CSAP and Hbfp concentration may be involved in the pathogenesis of acute pancreatitis.

Long-term nutritional management of an obese German Spitz with paroxysmal dyskinesia, calcium oxalate urolithiasis, and suspected pancreatitis—A case report

Background

To our knowledge, this is the first description of long-term nutritional management in a dog with paroxysmal dyskinesia.

Case summary

An obese 9-year-old, male entire, German Spitz was presented for dietary management after being diagnosed with calcium oxalate urolithiasis and suspected pancreatitis. Since he was seven years old, the dog has had a history of neurological signs, which were thought to be epileptic seizures. He was treated with phenobarbital and potassium bromide and was clinically controlled. For his nutritional advice, aiming to minimize one of the most important risk factors for the diseases, a weight loss program was started and successfully executed. However, 10 months later, the dog restarted presenting neurological episodes at a high frequency (3x/week). Based on videos and the characteristics of the neurological signs, the dog was diagnosed with paroxysmal dyskinesia. To investigate the role of gluten intake on this patient's neurological signs, a dietary trial with a commercial hypoallergenic diet (gluten-free; hydrolyzed protein) was followed. During the 3 months of the dietary trial, four neurologic episodes related to food indiscretion occurred. Upon the decrease in neurological episodes, the anti-seizure drugs were slowly discontinued. During this period, the dog presented only two neurologic episodes that were related to the days that the anti-seizure drugs were decreased. For 4 months the dog remained episode-free. However, a change in the dog's diet to another gluten-free diet (higher fat) led the dog to vomit and experience another neurologic episode. Once the dog was back to the previous gluten-free diet, it clinically improved, and no other clinical signs were reported by the client during the next 5 months.

Conclusion

Although a relationship between gluten and paroxysmal dyskinesia cannot be confirmed, the dog's improvement after the nutritional management and the removal of the anti-seizure therapy is supportive of dietary association.

New insights into the etiology, risk factors, and pathogenesis of pancreatitis in dogs: Potential impacts on clinical practice

While most cases of pancreatitis in dogs are thought to be idiopathic, potential risk factors are identified. In this article we provide a state‐of‐the‐art overview of suspected risk factors for pancreatitis in dogs, allowing for improved awareness and detection of potential dog‐specific risk factors, which might guide the development of disease prevention strategies. Additionally, we review important advances in our understanding of the pathophysiology of pancreatitis and potential areas for therapeutic manipulation based thereof. The outcome of pathophysiologic mechanisms and the development of clinical disease is dependent on the balance between stressors and protective mechanisms, which can be evaluated using the critical threshold theory.

Investigating owner use of dietary supplements in dogs with idiopathic epilepsy

Epilepsy is the most common chronic neurological disorder in dogs. Some diets have been shown to have a positive impact upon the seizure activity in dogs with idiopathic epilepsy (IE), while other diets and dietary supplements (DS), although marketed as providing health benefits, lack conclusive scientific evidence on their actual beneficial effects. A web-based owner questionnaire was designed to assess how and why owners of dogs with IE use different dietary regimes and DS. The study cohort, with 297 valid responses, consisted mainly of pure-breed (82.5%) male neutered (52.9%) dogs. Over two-thirds of owners (67.7%) changed their dog's diet after their dog received a diagnosis of IE. Nearly half of the owners (45.8%) reported giving DS, the most common being coconut oil or derived medium-chain triglyceride oil (71.3%). Some owner justifications of DS use included improvement of seizure frequency (88.2%), seizure severity (61.8%) and protection from potential drug side effects (62.5%). Many owners give DS to their dog with IE. The pharmacokinetic properties of anti-epileptic drugs, such as efficacy, absorption and clearance can be influenced by other medications, diets and possibly by DS. We propose that use of DS should be considered and monitored by veterinary surgeons in epilepsy management.

Canine pancreatic lipase immunoreactivity concentrations associated with intervertebral disc disease in 84 dogs

OBJECTIVE

To determine the differences in serum canine pancreatic lipase immunoreactivity between dogs with intervertebral disc herniation and healthy control dogs.

MATERIALS AND METHODS

Eighty-four client-owned dogs with intervertebral disc herniation, diagnosed by neurologic examination and imaging, and 18 healthy control dogs. Samples of whole blood were collected within 90 minutes of admission. Serum canine pancreatic lipase immunoreactivity concentrations were measured by a commercial immunoassay and evaluated for association with intervertebral disc herniation, signalment, neurolocalisation and the preadmission administration of glucocorticosteriods or non-steroidal anti-inflammatory drugs.

RESULTS

Serum canine pancreatic lipase immunoreactivity concentrations were statistically increased in dogs with intervertebral disc herniation (P<0·01, n=38). A subgroup of dogs (19/38) with elevated canine pancreatic lipase immunoreactivity concentrations was re-evaluated between 2 and 4 weeks later, and 15 had resolution of clinical signs and values less than 200 μg/L. Serum canine pancreatic lipase immunoreactivity concentrations were not significantly correlated with clinical gastrointestinal disease, neurolocalisation or the preadmission administration of corticosteroids or non-steroidal anti-inflammatory drugs.

CLINICAL SIGNIFICANCE

These results suggest that serum canine pancreatic lipase immunoreactivity concentrations are significantly elevated in dogs with intervertebral disc herniation.

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.

Proteinuria and lipoprotein lipase activity in Miniature Schnauzer dogs with and without hypertriglyceridemia

Spontaneous hyperlipidemia in rats causes glomerular disease. Idiopathic hypertriglyceridemia (HTG) is prevalent in Miniature Schnauzers, but its relationship with proteinuria is unknown. Decreased activity of major lipid metabolism enzymes, lipoprotein lipase (LPL) and hepatic lipase (HL), may play a role in the cyclic relationship between hyperlipidemia and proteinuria. These enzymes have also not been previously investigated in Miniature Schnauzers. The aims of this study were to determine the relationship between HTG and proteinuria in Miniature Schnauzers and to measure LPL and HL activities in a subset of dogs. Fifty-seven Miniature Schnauzers were recruited (34 with and 23 without HTG). Fasting serum triglyceride concentrations and urine protein-to-creatinine ratios (UPC) were measured in all dogs, and LPL and HL activities were determined in 17 dogs (8 with and 9 without HTG). There was a strong positive correlation between triglyceride concentration and UPC (r = 0.77-0.83, P < 0.001). Proteinuria (UPC ≥ 0.5) was present in 60% of dogs with HTG and absent from all dogs without HTG (P < 0.001). Proteinuric dogs were not azotemic or hypoalbuminemic. Dogs with HTG had a 65% reduction in LPL activity relative to dogs without HTG (P < 0.001); HL activity did not differ. Proteinuria occurs with HTG in Miniature Schnauzers and could be due to lipid-induced glomerular injury. Reduced LPL activity may contribute to the severity of HTG, but further assay validation is required.

Canine Pancreas-Specific Lipase and C-reactive Protein in Dogs Treated With Anticonvulsants (Phenobarbital and Potassium Bromide)

Animals treated with anticonvulsant drugs may have increased canine pancreas-specific lipase (cPLI) values. Inflammatory conditions and specifically acute pancreatitis are of major concern in these animals. Elevation in C-reactive protein is being associated with inflammatory status in dogs and it has been correlated with the clinical severity of pancreatitis. In the present study, we investigated if there is a correlation between the cPLI increase, changes in C-reactive protein and hepatic enzymes, as well as the incidence of severe acute pancreatitis (AP) in dogs with anticonvulsant treatment (phenobarbital, or potassium bromide or both). Increased values of pancreas-specific lipase were found in 6.8% of the animals in treatment with anticonvulsants, and this increase is correlated with the increase in triglycerides, alkaline phosphatase, and alanine aminotransferase but not with C-reactive protein levels, which suggests a possible induction or release phenomenon rather than a clear severe AP. C-reactive protein levels did not affect cPLI values on the population studied. Only 2 animals had clinical and analytical data suggestive of AP, indicating a low prevalence (0.6%). In conclusion, cPLI may be increased in a low percentage of animals with anticonvulsants treatment and its increase may not be associated with severe AP. It may be induced by the anticonvulsants drugs; however, further studies are advised to rule out other possible causes that increased cPLI.

The preanalytic phase in veterinary clinical pathology

This article presents the general causes of preanalytic variability with a few examples showing specialists and practitioners that special and improved care should be given to this too often neglected phase. The preanalytic phase of clinical pathology includes all the steps from specimen collection to analysis. It is the phase where most laboratory errors occur in human, and probably also in veterinary clinical pathology. Numerous causes may affect the validity of the results, including technical factors, such as the choice of anticoagulant, the blood vessel sampled, and the duration and conditions of specimen handling. While the latter factors can be defined, influence of biologic and physiologic factors such as feeding and fasting, stress, and biologic and endocrine rhythms can often not be controlled. Nevertheless, as many factors as possible should at least be documented. The importance of the preanalytic phase is often not given the necessary attention, although the validity of the results and consequent clinical decision making and medical management of animal patients would likely be improved if the quality of specimens submitted to the laboratory was optimized.

Topiramate as an add-on antiepileptic drug in treating refractory canine idiopathic epilepsy

OBJECTIVES

To evaluate the efficacy and safety of topiramate as an add-on therapy in dogs with refractory idiopathic epilepsy.

METHOD

Prospective, open label, non-comparative clinical trial of topiramate in dogs with idiopathic epilepsy and poor seizure control despite therapeutic serum concentrations of phenobarbital and potassium bromide. The efficacy of topiramate was evaluated by comparing seizure and seizure day frequencies during a retrospective 2-month period with a prospective short-term follow-up of 6 months. An additional long-term follow-up period ranging from 3 to 9 months was conducted on dogs that responded to topiramate therapy during the short-term follow-up.

RESULTS

Ten dogs were included. Five (50%) responded to topiramate therapy during the short-term follow-up showing a significant (P=0·04) decrease of 66% in seizure frequency. Three of the five dogs remained responders during the long-term follow-up. Weight loss, sedation and ataxia were the most common adverse effects of topiramate therapy, but in dogs with moderate sedation or ataxia, signs subsided in a few weeks to few months to mild sedation or ataxia.

CLINICAL SIGNIFICANCE

Topiramate may be effective as an add-on medication in treating canine idiopathic epilepsy. Apart from sedation and ataxia reported in some of the dogs, topiramate was well-tolerated.

Chronic pancreatitis in dogs: a retrospective study of clinical, clinicopathological, and histopathological findings in 61 cases

The objective of this study was to characterize the clinical, clinicopathological, and histopathological findings of dogs with chronic pancreatitis. The necropsy database at Texas A&M University was searched for reports of dogs with histological evidence of chronic pancreatitis defined as irreversible histologic changes of the pancreas (i.e. fibrosis or atrophy). A reference necropsy population of 100 randomly selected dogs was used for signalment and concurrent disease comparisons. Cases were categorized as clinical or incidental chronic pancreatitis based on the presence of vomiting, decreased appetite, or both vs. neither of these signs. All archived pancreas samples were scored histologically using a published scoring system. Sixty-one dogs with chronic pancreatitis were included. The most frequent clinical signs were lethargy, decreased appetite, vomiting, and diarrhea. Compared to the reference necropsy population, chronic pancreatitis cases were more likely to be older, neutered, of the non-sporting/toy breed group, and to have concurrent endocrine, hepatobiliary, or neurological disease. Clinical cases had significantly higher histological scores for pancreatic necrosis and peripancreatic fat necrosis, and were significantly more likely to have hepatobiliary or endocrine disease as well as increased liver enzyme activities, or elevated cholesterol and bilirubin concentrations. In conclusion, clinical disease resulting from chronic pancreatitis might be related to the presence of pancreatic necrosis and pancreatic fat necrosis. The signalment, presentation, and concurrent diseases of dogs with chronic pancreatitis are similar to those previously reported for dogs with acute pancreatitis.

A systematic review of the safety of potassium bromide in dogs

OBJECTIVE

To critically evaluate and summarize available information on the safety of potassium bromide in dogs.

DESIGN

Systematic review.

SAMPLE

111 references reporting safety information relevant to potassium bromide published between 1938 and 2011.

PROCEDURES

PubMed searches without date limitations were conducted with the terms "potassium bromide" and "sodium bromide" in December 2009 and October 2011. Additional articles were identified through examination of article reference lists and book chapters on seizures in dogs and pharmacology.

RESULTS

Reversible neurologic signs were the most consistently reported toxicoses and were generally associated with adjunctive potassium bromide treatment or high serum bromide concentrations. Dermatologic and respiratory abnormalities were rare in dogs. Insufficient information was available to assess the effects of potassium bromide on behavior or to determine the incidence of vomiting, weight gain, polyphagia, pancreatitis, polyuria, polydipsia, or reproductive abnormalities associated with potassium bromide administration. Evidence suggested that administration of potassium bromide with food may alleviate gastrointestinal irritation and that monitoring for polyphagia, thyroid hormone abnormalities, and high serum bromide concentrations may be beneficial.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggested that potassium bromide is not an appropriate choice for treatment of every dog with seizures and that practitioners should tailor therapeutic regimens and clinical monitoring to each dog. Abrupt dietary changes or fluid therapy may compromise seizure control or increase the likelihood of adverse events. Availability of an appropriately labeled, approved potassium bromide product could provide better assurance for veterinarians and their clients of the quality, safety, and effectiveness of the product for veterinary use.