A prospective observational longitudinal study of new-onset seizures and newly diagnosed epilepsy in dogs

A six-month prospective, randomised, double-blinded, placebo-controlled, crossover, dietary trial design to investigate the potential of psychobiotics on seizure semiology and comorbidities in canine epilepsy: study protocol

BACKGROUND

Epilepsy is the most common chronic neurological disease in dogs. More than two-thirds of these patients suffer from associated behavioural comorbidities. The latter could have their origin in partially overlapping pathomechanisms, with the intestinal microbiome as a potential key link between them. The current arsenal of drugs for epilepsy management remains limited. Most canine patients continue to have seizures despite treatment and the occurrence of comorbidities is not sufficiently addressed, limiting quality of life of affected dogs and owners. Therefore, novel additional epilepsy management options are urgently needed. The microbiome-gut-brain axis may serve as a new target for the development of innovative multimodal therapeutic approaches to overcome current shortcomings in epilepsy management.

METHODS

A six-month prospective, randomised, double-blinded, placebo-controlled, crossover, dietary trial was designed to investigate the potential of the psychobiotic Bifidobacterium longum on behavioural comorbidities in canine epilepsy. Seizure semiology will be evaluated as a secondary outcome measure. Thirty-four privately owned dogs are planned to be included in the ongoing study meeting the following inclusion criteria: Dogs displaying increased anxiety/fear behaviour since the start of the idiopathic epilepsy. Tier II confidence level of the International Veterinary Epilepsy Task Force for the diagnosis of idiopathic epilepsy, with a maximum seizure interval of 3 month and a minimum of three generalised seizures within that period and chronically treated with at least one antiseizure drug without improvement in seizure frequency Each dog will receive the allocated supplement (probiotic vs. placebo) alongside its normal diet for a 3-month period. After a three-week wash out period, the second phase starts by administering the respective other supplement for another 3 months.

DISCUSSION

The current study considers modern high-quality standards for epilepsy medication trials. Common biasing effects should be limited to a possible minimum (regression-to-the mean effect, placebo effect, observer effect), ensuring a high validity and accuracy of the acquired results, thus enabling a representative nature of the efficacy of Bifidobacterium longum as add-on supplement for dogs suffering from epilepsy and its comorbidities. This publication should provide a description of the study procedure and data acquisition methods, including prognosed statistical analysis.

Pregabalin Add-On vs. Dose Increase in Levetiracetam Add-On Treatment: A Real-Life Trial in Dogs With Drug-Resistant Epilepsy

Epilepsy is a common neurological disorder affecting 0.6–0.75% of dogs in veterinary practice. Treatment is frequently complicated by the occurrence of drug-resistant epilepsy and cluster seizures in dogs with idiopathic epilepsy. Only few studies are available to guide treatment choices beyond licensed veterinary drugs. The aim of the study was to compare antiseizure efficacy and tolerability of two add-on treatment strategies in dogs with drug-resistant idiopathic epilepsy. The study design was a prospective, open-label, non-blinded, comparative treatment trial. Treatment success was defined as a 3-fold extension of the longest baseline interseizure interval and to a minimum of 3 months. To avoid prolonged adherence to a presumably ineffective treatment strategy, dog owners could leave the study after the third day with generalized seizures if the interseizure interval failed to show a relevant increase. Twenty-six dogs (mean age 5.5 years, mean seizure frequency 4/month) with drug-resistant idiopathic epilepsy and a history of cluster seizures were included. Dogs received either add-on treatment with pregabalin (PGB) 4 mg/kg twice daily (14 dogs) or a dose increase in levetiracetam (LEV) add-on treatment (12 dogs). Thirteen dogs in the PGB group had drug levels within the therapeutic range for humans. Two dogs in the PGB group (14.3%; 2/14) and one dog in the LEV group (8.3%; 1/12) achieved treatment success with long seizure-free intervals from 122 to 219 days but then relapsed to their early seizure frequency 10 months after the study inclusion. The overall low success rates with both treatment strategies likely reflect a real-life situation in canine drug-resistant idiopathic epilepsy in everyday veterinary practice. These results delineate the need for research on better pharmacologic and non-pharmacologic treatment strategies in dogs with drug-resistant epilepsy.

Prevalence of Brain Magnetic Resonance Imaging Diagnoses and Correlation With Signalment and Presenting Complaint in Dogs

Since magnetic resonance imaging (MRI) was introduced, it has become increasingly available and technologically improved. Studies have documented the prevalence of specific pathologies, however no previous veterinary studies have investigated the prevalence and distribution of pathology across all MRIs performed at a single institution. The present study aimed to evaluate the prevalence of MRI-diagnosed brain lesions and correlate these to patient signalment and presenting complaint. Archived MRI brain scans from 805 dogs were reviewed retrospectively. One board-certified veterinary radiologist at the institution retrospectively evaluated all reports to determine the most clinically pertinent imaging diagnosis for each case. Breed, age, and presenting complaint were obtained from the medical record for each patient. The most common imaging diagnoses across all dogs reviewed were no significant findings (35.16%), asymmetric encephalopathy or meningoencephalopathy (19.75%), and extra-axial intracranial mass (11.18%). Age of dogs differed by diagnosis (p <0.0001), with the median age of dogs diagnosed with a brain mass being greater than that of dogs with no significant findings and dogs with asymmetric encephalopathy or meningoencephalopathy (both p <0.0083). In dogs presenting with seizures, the odds of a brain mass increased with each additional year of age [p <0.0001, odds ratio 1.26 (95% CI 1.16–1.37)], whereas the odds of no significant finding [p <0.0001, OR 0.87 (0.82–0.93)] decreased. Our findings provide overview information on the types of disease observed in the clinical population and allow us to detect correlations between imaging diagnoses, presenting complaints, and signalment.

Probable Sudden Unexpected Death in Dogs With Epilepsy (pSUDED)

Sudden unexpected death in human epileptic patients (SUDEP) is defined as death related to recurrent unprovoked seizures, death occurring unexpectedly, and suddenly in a patient with reasonable state of health, without an obvious medical cause of death, trauma, asphyxia, or intractable status epilepticus, and in post mortem examination no obvious reason for death can be found. “Probable SUDEP” (pSUDEP) is defined as SUDEP not confirmed pathologically. The adapted abbreviation for dogs is used in the following: “pSUDED” (probable sudden unexpected death in dogs with epilepsy). The aim of the present monocentric retrospective study using an online questionnaire was to evaluate the occurrence of pSUDED. Data of canine patients presented with seizures between 01/1998 and 05/2018 were retrospectively analyzed and classified according to their etiology (n = 1,503). Owners were contacted by telephone to participate in answering a validated questionnaire. A total of 509 owners were reached, and 373 owners completed the questionnaire. In addition to signalement (e.g., breed), special attention was paid to the frequency and presentation of seizures and seizures in the context of death. Fifty-one percent (191/373) of the dogs were dead at the endpoint of the study. A large proportion of the dogs was euthanized (149/191) because of seizure severity or health problems unrelated to seizures. Idiopathic epilepsy (IE) was diagnosed in 19/34 dogs which died unexpectedly. Of these seven animals had to be excluded for further investigation of pSUDED because of status epilepticus or aspiration pneumonia as a result of the seizures. In 12 dogs with IE the last seizure event occurred between 6 h and ~3 months before death. pSUDED was suspected in these dogs and an occurrence rate of 4.5–10% was calculated. pSUDED appears in a similar occurrence rate as human SUDEP and should be considered as a possible complication in epileptic dogs. The results of this study suggest that dogs with IE but especially those with brachycephalic syndrome and cluster seizures have an increased risk to die of pSUDED. Owners of dogs with seizures should be educated about the risk of sudden death in dogs with epilepsy.

Seizures in dogs under primary veterinary care in the United Kingdom: Etiology, diagnostic testing, and clinical management

Background

Although seizures are common in dogs, limited published information is available on the classifications of seizures, diagnostic approaches, or clinical management of seizure‐affected patients in the veterinary primary care setting.

Objectives

Explore seizure etiology, diagnostic testing, and clinical management of seizure‐affected dogs in the primary care veterinary setting.

Animals

A total of 455 553 dogs in VetCompass.

Methods

Cross‐sectional analysis by cohort clinical data.

Results

From 2834 incident seizure cases, we identified 579 (20.5%) dogs with epilepsy based on the International Veterinary Epilepsy Task Force (IVETF) classification system, including 484 (17.1%) with idiopathic epilepsy, 95 (3.4%) with structural epilepsy, and 179 dogs (6.3%) with reactive seizures. In their clinical first opinion records, 245 (8.6%) cases were recorded with epilepsy. Overall, 1415 (49.9%) cases received diagnostic evaluation equivalent to or higher than IVETF Tier 1 diagnostic testing.

Being <12 years of age and being insured were risk factors for receiving IVETF Tier 1 or higher diagnostic evaluation among seizure cases. Anti‐seizure drug (ASD) treatment was not prescribed for 1960/2834 (69.2%) dogs in association with the incident seizure event. Of the remainder, 719 (25.3%) dogs received 1 ASD, whereas 155 (5.5%) an ASD combination.

Conclusion and clinical importance

The differences between seizure classifications in the clinical records and those retrospectively assigned by the researchers support the need for clearer diagnostic guidelines in clinical practice. Insured dogs and dogs <12 years of age were more likely to receive advanced diagnostic evaluation, suggesting that financial and perceived prognostic factors influence case management.

Diagnostic utility of cerebrospinal fluid analysis in dogs with suspected idiopathic epilepsy

BACKGROUND

Idiopathic epilepsy (IE) is the most common cause of repeated seizures in dogs. The International Veterinary Epilepsy Task Force consensus guidelines recommend performing magnetic resonance imaging (MRI) of the brain and cerebrospinal fluid (CSF) analysis as part of a tier II diagnosis of IE, and these procedures have documented risks. The aim of this retrospective study was to identify how often dogs with suspected IE have abnormalities on CSF analysis.

METHODS

Dogs aged between 6 months and 6 years that were presented with a history of two or more seizures with at least 24 h between seizure episodes, a normal neurologic examination, no evidence of toxic or metabolic causes, a normal MRI scan (including contrast administration) and CSF analysis were included.

RESULTS

Eighty-two dogs were included. Of these, nine dogs (10.9%) had abnormalities on CSF analysis: five of nine dogs (55.5%) had albuminocytologic dissociation, three of nine dogs (33.3%) had mild increases in total nucleated cell count (TNCC), and one of nine dogs (11.1%) had mild increase in both total protein and TNCC. Cytology in dogs with elevated TNCC revealed a mononuclear pleocytosis. One of the nine dogs with abnormal CSF had a seizure within the 24 h before investigations, and six of nine dogs had a seizure within 1 month before investigation.

CONCLUSION

CSF analysis can play an important role in the diagnostic investigation of the underlying causes of repeated seizures. However, in dogs with a normal inter-ictal neurological examination and MRI scan, it rarely reveals significant abnormalities, and the risk of performing a CSF tap may outweigh the potential diagnostic gain.

Evaluation of fecal Lactobacillus populations in dogs with idiopathic epilepsy: a pilot study

Background

Idiopathic epilepsy is a common neurological disorder of dogs characterized by recurrent seizures for which no underlying basis is identified other than a presumed genetic predisposition. The pathogenesis of the disorder remains poorly understood, but environmental factors are presumed to influence the course of disease. Within the growing body of research into the microbiota-gut-brain axis, considerable attention has focused on the protective role of Lactobacilli in the development and progression of neurological disease. Investigations into the association between the gut microbiome and epilepsy are in their infancy, but some preliminary findings support a role for Lactobacilli in drug resistant epilepsy. To date, there are no published studies evaluating the gut microbiome in dogs with epilepsy. This pilot study was undertaken to evaluate fecal Lactobacillus populations in dogs with idiopathic epilepsy compared to healthy dogs.

Results

Fecal samples were obtained from 13 pairs of dogs, consisting of a drug-naïve epileptic dog and a healthy dog from the same household and maintained on the same diet. Evaluation of large-scale microbial patterns based on 16S rRNA gene amplicon sequencing identified a household effect in the study population. Differential prevalence testing at the 16S rRNA gene sequence variant and genus levels did not identify any statistically significant differences between epileptic and control dogs. Quantitative PCR of Lactobacillus species isolated through culture revealed no statistically significant difference between the epileptic and control dogs (median concentration, 3.8 log₁₀ CFU/g feces and 4.6 log₁₀ CFU/g feces, respectively). Lactobacillus in culture was not killed by exposure to phenobarbital, potassium bromide, zonisamide, or levetiracetam.

Conclusions

This pilot study did not identify any difference in large-scale microbial patterns or relative or absolute abundance of Lactobacillus species in drug-naïve epileptic dogs compared to healthy dogs. Further studies are warranted to evaluate the role of the gut microbiome in disease progression and treatment response in dogs with epilepsy. Lactobacilli in culture were not killed or inhibited from growing when exposed to phenobarbital, potassium bromide, zonisamide or levetiracetam, suggesting that antiepileptic drug administration is less likely to be a confounding factor in future studies evaluating the role of Lactobacillus in epilepsy.

Seizure occurrence in dogs under primary veterinary care in the UK: prevalence and risk factors

Background

Primary‐care veterinary clinical records can offer data to determine generalizable epidemiological data on seizures occurrence in the dog population.

Objectives

To identify and examine epidemiologic characteristics of seizure occurrence in dogs under primary veterinary care in the UK participating in the VetCompass™ Programme.

Animals

455,553 dogs in VetCompass™’.

Methods

A cross‐sectional analysis estimated the 1‐year period prevalence and risk factors for dogs with seizures during 2013.

Results

The overall 1‐year period prevalence for dogs having at least one seizure during 2013 was 0.82% (95% CI 0.79‐0.84). Multivariable modelling identified breeds with elevated odd ratios [OR] compared with the Labrador Retriever (e.g. Pug OR: 3.41 95% CI 2.71‐4.28, P < 0.001). Males had higher risk for seizures (Male/Entire OR: 1.47 95% CI 1.30–1.66; Male/Neutered OR: 1.34 95% CI 1.19–1.51) compared to entire females. Age (3.00 ‐ ≤ 6.00 OR: 2.13 95% CI 1.90‐2.39, P < 0.001, compared to animals aged 0.50–≤ 3.00 years), and bodyweight (≥ 40.00kg, OR: 1.24 95% CI 1.08–1.41, P = 0.002, compared to animals weighing < 10.0 kg) were identified as risk factors for seizures.

Conclusion and clinical Importance

Seizures are a relatively common clinical finding in dogs. The results for breed, age, sex and bodyweight as risk factors can assist veterinarians in refining differential diagnosis lists for dogs reported with behaviors that may have been seizures. In addition, the prevalence values reported here can support pharmacovigilance with baseline data from the overall population.

A Review: Emergency Management of Dogs With Suspected Epileptic Seizures

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