Metabolic and toxic causes of canine seizure disorders: A retrospective study of 96 cases

[Acute poisonings in dogs - a retrospective case study over 5 years]

OBJECTIVE

The aim of this retrospective study was to analyze the clinical signs, confirmed or suspected toxicants, treatments and outcomes of poisoning cases in dogs presented over a 5-year period to the emergency service of a small animal referral center.

MATERIAL AND METHODS

Medical records of 634 dogs were evaluated for a history of confirmed or presumed poisoning, suspected toxicant, clinical signs, treatment, and patient outcome. The probability of poisoning was graded based on the patient history, clinical findings, toxicologic examination and - in some cases - investigation of gastrointestinal contents.

RESULTS

Most dogs were hospitalized (77%) due to poisoning with mostly unknown toxicants (33%), food residues (18%), rodenticides (10%), tremorgenic mycotoxins (8%), medications (7%) and various plants (7%), followed by recreational drugs (5%), chemicals (4%), molluscicides (3%), antiparasitics (2%), feces (2%), nuts (2%), or toxins of animal origin (1%). Patients were presented predominantly showing neurologic signs (56%), reduced general condition (39%), and cardiovascular or hydration status abnormalities (26%). The survival rate was 97%. Most dogs were clinically unremarkable at the time of hospital discharge (70%). An additional 18% of the survivors had no apparent complications by the time of discharge. Toxicant-related complications (20.5%) included hemorrhage (4%), hepatic (4%), renal (4%), respiratory (3%), gastrointestinal (3%), cardiovascular (3%), and/or central nervous system (3%) complications, or clinically relevant hypoglycemia (0.3%).

CONCLUSION AND CLINICAL RELEVANCE

In the present study, poisoning in dogs was mostly associated with the ingestion of food residues, but the causative toxicant remained unidentified in many cases. Neurological signs were the major clinical presentation. The survival rate (97%) in this study was higher compared to those reported by other investigators.

Seizures in 3 juvenile dogs after intravenous anesthetic drug withdrawal during weaning from mechanical ventilation suspected to be a sign of iatrogenic withdrawal syndrome

OBJECTIVE

To describe seizure activity in juvenile dogs successfully weaned from long-term mechanical ventilation.

CASE SERIES SUMMARY

Three juvenile dogs (all approximately 3 months old) underwent long-term mechanical ventilation with IV anesthesia for suspected noncardiogenic pulmonary edema. Within 24 hours of extubation and within 10 hours of discontinuing midazolam continuous infusions, all dogs experienced seizures, which is 1 sign of iatrogenic withdrawal syndrome. Each dog was treated with an anticonvulsant protocol, and none experienced seizures after being discharged.

NEW OR UNIQUE INFORMATION PROVIDED

Each dog received IV anesthesia, including fentanyl, dexmedetomidine, midazolam, and propofol, during mechanical ventilation and subsequently experienced seizures after successful weaning from mechanical ventilation. Juvenile dogs may be at risk for seizures after weaning from mechanical ventilation and IV anesthesia. Neurological monitoring and further research into an appropriate weaning protocol may prove beneficial in juvenile dogs requiring prolonged anesthesia.

"Resistance Is Futile": A Pilot Study into Pseudoresistance in Canine Epilepsy

Epilepsy is a common neurological disorder in veterinary practice, complicated by frequent occurrence of medication-resistant epilepsy. In human medicine, it has been noted that some patients with medication-resistant epilepsy have in fact other reasons for their apparent medication-resistance. The aim of this retrospective study was to describe the issue of pseudoresistance using as an example a population of dogs presented with presumed medication-resistant epilepsy and provide an in-depth review of what is known in human medicine about pseudoresistant epilepsy. One-hundred fifty-two cases were identified with medication-resistant epilepsy, of which 73% had true medication-resistant epilepsy and 27% patients had pseudoresistance. Low serum anti-seizure medication levels were the most common cause of pseudoresistance, present in almost half of the cases (42%), followed by inadequate choice of drugs or dosages (22%), misclassification (22%) or misdiagnosis (9%) of epilepsy and poor compliance (9%). All cases of pseudoresistance, except for one, responded to a modification of the initial therapy protocol. Pseudoresistance can bias clinical trials, misinform the clinical decision-making process, delay diagnosis and treatment, and misinform owners about their pets' prognosis. A substantial proportion of these cases can have improvement of their seizure frequency or achieve seizure freedom upon modification of their therapeutic protocol.

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.

Mechanical ventilation in dogs and cats with tick paralysis

Respiratory failure from tick paralysis (TP) is an important cause of mortality in cats and dogs in Australia, occurring from a combination of respiratory muscle paralysis, upper respiratory tract obstruction and pulmonary disease. Patients may require positive-pressure ventilation in management of any combination of hypoxemia, hypoventilation or respiratory fatigue, but may also require airway management due to laryngeal paralysis. No single ventilation strategy is recommended due to the heterogenous disease presentations. Lung protective ventilation should be used in patients with pulmonary disease. Due to local and systemic effects of TP, patients are at higher risk of complications such as aspiration pneumonia and corneal ulceration and may have additional intravenous fluid and nutritional considerations. Treatment with hyperimmune serum is associated with improved outcomes. Prognosis is considered good with documented survival to discharge (STD) of 52.6-77% for animals with TP ventilated with lung disease and 90.5% for animals without lung disease. Median reported duration of ventilation for TP ranges from 23 to 48 h (range 3 h-10 days). The severity of individual neuromuscular signs and the presence of associated conditions such as aspiration pneumonia and laryngeal paralysis may necessitate longer periods of mechanical ventilation. This review aims to summarize the current recommendations regarding indications, management and prognosis of cats and dogs undergoing MV for TP and to identify areas for future research.

Phenotype of Idiopathic Epilepsy in Great Swiss Mountain Dogs in Germany—A Retrospective Study

Genetic predisposition of idiopathic epilepsy (IE) has been demonstrated in individual breeds. According to the responsible breeding association in Germany, the average incidence of registered Great Swiss Mountain Dogs (GSMDs) with seizures between the years 1999 and 2019 is 2.56%, a genetic predisposition in this breed is suspected. To describe the seizure phenotype and to examine seizure causes, a retrospective, questionnaire-based study was performed. In cooperation with the Swiss Mountain Dog Association of Germany e.V. (SSV e.V.), 114 questionnaires filled in by owners of GSMD displaying seizures and filled in by their respective veterinarians between the years 2005–2021 were evaluated. Seizure characteristics, clinical and further examinations, treatment, treatment responses, and pedigree information were collected. In this study, 94 (83.06%) dogs had IE (suspected genetic epilepsy) confirmed with confidence level TIER 1, 2, or 3. The remaining 20 dogs showed the signs of structural epilepsy, reactive seizures, or epilepsy of unknown cause and were therefore excluded from further analysis. The average age at seizure onset was 28.83 months. Male GSMDs were significantly more often affected by IE than females. The most common seizure type was focal evolving into generalized seizures (64.5%). Seizures often began with vomiting, retching, or salivation. Cluster seizures (CS) (48.9%) and status epilepticus (SE) (37.2%) were observed in a large proportion of dogs. During the observation time, a total of 49 animals (52.13%) died. Out of those, 19 dogs (20.21%) were euthanized in SE or during CS and 14 dogs (14.9%) died spontaneously during CS or SE. The median age at death was 4 years, and the median survival time for the time, when the dog was suffering from seizures, was found to be 18 months. Both occurrence of CS (p = 0.0076) and occurrence of SE (p = 0.0859) had an impact on survival time. In GSMD, idiopathic epilepsy presents with a severe phenotype with frequently occurring CS and SE. This study could serve as basis for further genetic evaluations as well as to provide individual treatment recommendations.

Th17 cell-mediated immune response in a subpopulation of dogs with idiopathic epilepsy

BACKGROUND

Canine idiopathic epilepsy (IE) is a common neurological disease with severe impact on the owner´s and the dog's quality of life. A subpopulation of dogs with IE does not respond to antiseizure drugs (non-responder). Th17 cells (T helper cells) and their proinflammatory Interleukin-17 (IL-17) are part of the immune system and previous studies showed their involvement in the pathogenesis of several autoimmune diseases. Non-responder might have an abnormal immune response against structures of the central nervous system. To discover a new aetiology of canine IE and thereby optimising the therapy of intractable IE, this prospective study aimed to investigate Th17 cells and IL-17 in dogs with IE. The underlying hypothesis was that in some dogs with IE a Th17 cell-mediated immune response could be detectable.

METHODS

57 dogs with IE and 10 healthy dogs (control group, C) were enrolled in the study. EDTA blood was taken to measure Th17 cells by flow cytometry. IL-17 was measured in 35 cerebrospinal fluid (CSF) and 33 serum samples using an enzyme-linked immunosorbent assay (ELISA). It was investigated whether there was a significant increase of stimulated Th17 cells in blood samples or of IL-17 in serum and CSF samples of dogs with IE in comparison to C. Correlations between the amount of Th17 cells/μL or IL-17 and different clinical parameters e.g. seizure frequency, seizure type, seizure severity or treatment response were evaluated. Additionally, Th17 cells/μL were randomly controlled of 17 dogs with IE and were examined for changes over time and in relation to treatment response.

RESULTS

Ten dogs with IE had strongly elevated stimulated Th17 cells/μL within the blood (>100 Th17 cells/μL). A slight positive correlation between stimulated Th17 cells/μL and seizure severity (p = 0.046; rSpear = 0.27) was proven in these dogs. In addition, 4/10 dogs with elevated Th17 levels experienced cluster seizures and status epilepticus in comparison to 9% of the dogs with non-elevated Th17 levels (<100 Th17 cells/μL). Dogs with IE had significantly higher IL-17 values in CSF and serum samples compared to C (p<0.001; p<0.002; respectively).

CONCLUSION

In single dogs with IE, strongly increased amounts of Th17 cells were detectable and dogs with elevated Th17 cells seemed to have a greater risk for experiencing a combination of cluster seizures and status epilepticus. Therefore, an underlying Th17-cell mediated immune response was suspected and hence anti-inflammatory drugs could be indicated in these single cases with intractable epilepsy.

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

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

Investigation of hypomagnesaemia prevalence and underlying aetiology in a hospitalised cohort of dogs with ionised hypocalcaemia

OBJECTIVES

Calcium is the most abundant mineral in the body and plays a critical role in a wide range of physiological processes. Low concentrations of ionised calcium, the most metabolically available form of calcium, have been linked to an increased risk of adverse clinical outcomes in dogs. Magnesium plays an important role in parathyroid hormone function. The objective of this study was to define the prevalence and aetiology of hypomagnesaemia in a hospitalised cohort of dogs with ionised hypocalcaemia (IHC).

METHODS

A total magnesium reference interval was established using serum biochemistry results from 346 clinically healthy dogs. The clinical records of dogs with IHC were reviewed, and concurrent serum magnesium concentrations were recorded alongside clinical signs and underlying aetiology. The prevalence, clinical presentation and aetiology of hypomagnesaemia were examined in the IHC population.

RESULTS

Two hundred and ninety-five IHC dogs were identified. Hypomagnesaemia was identified in 22%. Total magnesium concentration was significantly higher in dogs with renal disease. The most common cause of concurrent hypomagnesaemia and IHC was gastrointestinal diseases.

CONCLUSION

Low concentrations of serum magnesium occur in approximately one fifth of all dogs with IHC. Further studies are required to clarify the link between magnesium status, IHC and clinical outcome.

[Diagnostics in epilepsy - potential of magnetic resonance imaging]

Epilepsy is a common neurologic disease frequently encountered by small animal practitioners. The disease comprises a multiplicity of clinical presentations and etiologies and often necessitates a comprehensive as well as cost-intensive diagnostic workup. This is mandatory in order to be able to diagnose or exclude a metabolic cause of the seizures and to distinguish between idiopathic and structural epilepsy. The examination by means of magnetic resonance imaging (MRI) represents a central component of the diagnostic workup, which in turn has essential effects on treatment and prognosis. In order to achieve standardized examination and comparable results, it is of utmost importance to use defined MRI protocols. Accordingly, communication and interaction between clinical institutions may be facilitated and as of yet undetected structural changes might be recorded in future MRI techniques. This review article sets particularly emphasis on the definition and classification of epilepsy as well as its diagnostic imaging procedures and refers to statistics and specialists' recommendations for the diagnostic workup in dogs.

Inhibition and facilitation of nociceptively evoked muscular activity by fentanyl or dexmedetomidine in isoflurane-anaesthetized pigs

OBJECTIVE

To investigate motor and cardiovascular responses to dexmedetomidine or fentanyl in isoflurane-anaesthetized pigs.

STUDY DESIGN

Experimental, balanced, block randomized, two-group design.

ANIMALS

A group of 16 crossbred pigs, 55 ± 8 days (mean ± standard deviation) old.

METHODS

Deltoid electromyography (EMG) was recorded during isoflurane anaesthesia. Electrical stimulation using 5, 10, 20 and 40 mA of the distal right thoracic limb elicited a nociceptive withdrawal reflex (NWR), quantified by the area under the curve (AUC) for the simulation intensity versus EMG amplitude response curve. Latency to movement evoked by clamping a claw for maximum 60 seconds was noted. Arterial blood pressure and pulse rate were recorded. Data were sampled at baseline and during dexmedetomidine 0.25, 0.5, 1.0, 2.0, 4.0 and 8.0 μg kg^-1 hour^-1 or fentanyl 5, 10, 20, 40, 80 and 160 μg kg^-1 hour^-1 infusions. The influence of infusion rate on NWR AUC and spontaneous EMG was analysed using a mixed model, with p < 5%.

RESULTS

NWR AUC increased at fentanyl 5 μg kg^-1 hour^-1 but decreased at fentanyl 40, 80 and 160 μg kg^-1 hour^-1 and dexmedetomidine 4.0 and 8.0 μg kg^-1 hour^-1. All pigs at fentanyl 80 μg kg^-1 hour^-1, and three pigs at dexmedetomidine 8.0 μg kg^-1 hour^-1 had mechanical latencies greater than 60 seconds. Spontaneous EMG activity increased accompanied by visually evident 'shivering' at fentanyl 5, 10 and 20 μg kg^-1 hour^-1 but decreased at dexmedetomidine 2, 4 and 8 μg kg^-1 hour^-1. Clinically relevant effects of increasing infusion rates on blood pressure or pulse rate were not observed.

CONCLUSION AND CLINICAL RELEVANCE

If anaesthetic plane or antinociception is evaluated in pigs, response to claw clamping and NWR will not necessarily give uniform results when comparing drugs. If only one method is used, results should be interpreted cautiously.

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.

A Missense Variant in ALDH5A1 Associated with Canine Succinic Semialdehyde Dehydrogenase Deficiency (SSADHD) in the Saluki Dog

Dogs provide highly valuable models of human disease due to the similarity in phenotype presentation and the ease of genetic analysis. Seven Saluki puppies were investigated for neurological abnormalities including seizures and altered behavior. Magnetic resonance imaging showed a diffuse, marked reduction in cerebral cortical thickness, and symmetrical T2 hyperintensity in specific brain regions. Cerebral cortical atrophy with vacuolation (status spongiosus) was noted on necropsy. Genome-wide association study of 7 affected and 28 normal Salukis revealed a genome-wide significantly associated region on CFA 35. Whole-genome sequencing of three confirmed cases from three different litters revealed a homozygous missense variant within the aldehyde dehydrogenase 5 family member A1 (ALDH5A1) gene (XM_014110599.2: c.866G>A; XP_013966074.2: p.(Gly288Asp). ALDH5A1 encodes a succinic semialdehyde dehydrogenase (SSADH) enzyme critical in the gamma-aminobutyric acid neurotransmitter (GABA) metabolic pathway. Metabolic screening of affected dogs showed markedly elevated gamma-hydroxybutyric acid in serum, cerebrospinal fluid (CSF) and brain, and elevated succinate semialdehyde in urine, CSF and brain. SSADH activity in the brain of affected dogs was low. Affected Saluki dogs had striking similarities to SSADH deficiency in humans although hydroxybutyric aciduria was absent in affected dogs. ALDH5A1-related SSADH deficiency in Salukis provides a unique translational large animal model for the development of novel therapeutic strategies.

Estimation of the prevalence of idiopathic epilepsy and structural epilepsy in a general population of 900 dogs undergoing MRI for epileptic seizures

Due to variation in study designs the prevalence of idiopathic epilepsy (IE) and structural epilepsy (SE) in dogs is largely unknown. The objective was to provide estimates of the prevalence of IE and SE in a large population of dogs undergoing MRI for epileptic seizures. A retrospective study on 900 dogs undergoing MRI for seizures was performed. MRI scans, summary clinical history and neurological examination from the VetCT database were reviewed and a diagnosis assigned by board-certified radiologists. Structural lesions were identified as a cause of seizures in 45.1 per cent (n=406) of cases. No structural lesions were identified in 54.9 per cent (n=494) of cases with presumed IE diagnosed in 53.8 per cent (n=484) of dogs. Dogs between six months and six years were more often associated with IE (P<0.001), small breeds were overrepresented with suspected inflammatory brain disease (P=0.001) and large entire dogs more often diagnosed with extra-axial neoplasms (P=0.001). Over 31.0 per cent of dogs with suspected IE were six years or older. This study is the largest of its kind in dogs and provides accurate estimates of underlying causes of epilepsy. MRI findings should be considered in the context of a detailed clinical history and neurological examination.

Retrospective evaluation of the use of hemodialysis in dogs with suspected metaldehyde poisoning (2012-2017): 11 cases

OBJECTIVE

To evaluate dogs treated with hemodialysis for severe metaldehyde intoxication and to compare them with conventionally-managed patients.

DESIGN

Retrospective study (2012-2017).

SETTING

University teaching hospital.

ANIMALS

Data from 18 dogs with severe metaldehyde intoxication were analyzed. Eleven dogs were treated with intermittent hemodialysis and 7 managed conventionally.

INTERVENTIONS

None.

MEASUREMENT AND MAIN RESULTS

Metaldehyde poisoning was diagnosed based on clinical signs and toxicological analysis or presence of turquoise material in the gastrointestinal content. Clinical signs, additional treatments, dialysis prescription, duration of anesthesia and hospitalization, complications, and outcome were documented. Results were analyzed by t-test, Mann-Whitney U-test, and Chi-square test. P < 0.05 was considered significant. Dialysis was performed for median (range) 180 min (150-420 min) with median of 2.28 L/kg (1.66-4.48 L/kg) blood volume processed. In the hemodialysis group, anesthesia was discontinued at a median of 3.0 hours (1.5-6.7 h) after starting dialysis. The conventional-group received general anesthesia for a median of 17.5 hours (7.0-30.5 h). No further anticonvulsive treatment was necessary for the hemodialysis group. Time to hospital discharge was shorter in dialyzed dogs (median 18 h; 15-41 h) compared to conventionally treated dogs (median 89 h; 61-168 h; P = 0.0014). Aspiration pneumonia was reported in 5 conventionally treated dogs and none of the dialyzed dogs (P = 0.001). Five dialyzed dogs developed hematoma at the dialysis catheter site. One dog in each group was euthanized.

CONCLUSION

Hemodialysis significantly decreases the requirement for anesthesia and length of hospitalization in dogs with metaldehyde intoxication. Aspiration pneumonia occurred less often in dialyzed patients. Prospective studies are warranted to confirm the clinical utility of hemodialysis in dogs with metaldehyde poisoning.

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.

Clinical Risk Factors for Early Seizure Recurrence in Dogs Hospitalized for Seizure Evaluation

BACKGROUND

Epileptic seizures are a common cause for neurological evaluations in dogs.

HYPOTHESIS/OBJECTIVES

To determine the timing, frequency, and risk factors for early seizure recurrence (ESR) among dogs admitted to the hospital for seizure evaluation and to facilitate rapid decision making about whether dogs should be placed in the intensive care unit (ICU) or day ward.

ANIMALS

Nine-hundred twenty-two dogs referred for seizure investigation; 214 patients were included.

METHODS

Retrospective study. Medical records between 2000 and 2017 were reviewed to determine risk factors for ESR. Findings were compared among dogs diagnosed with idiopathic epilepsy (IE), structural epilepsy (StE) and reactive seizures (RS), as well as in all selected cases together.

RESULTS

Fifty percent of dogs had a seizure while hospitalized. In the group 53.1 and 52.2% in the StE group, whereas in the RS 40.44% had ESR. The average time to ESR was 7 hours. In IE group, abnormal postictal neurological examination with prosencephalon signs predicted ESR. In StE group, a single generalized or focal seizure 72 hours before hospital admission and abnormal neurologic examination predicted ESR. In the RS group, ERS was predicted by long-term antiepileptic monotheraphy. When all dogs were analyzed together, abnormal neurological examination, the occurrence of cluster seizures, status epilepticus, or combination of them 72 hours before presentation predicted ESR.

CONCLUSIONS AND CLINICAL IMPORTANCE

Epileptic seizures recurred in 50% of patients within a mean time of 7 hours. In general, when cluster seizures, status epilepticus or both occurred 72 hours before presentation and neurological examination was abnormal upon presentation, the dog should be placed in ICU for observation.

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

Background

Seizures are common in dogs and can be caused by non-epileptic conditions or epilepsy. The clinical course of newly diagnosed epilepsy is sparsely documented.

The objective of this study was to prospectively investigate causes for seizures (epileptic and non-epileptic) in a cohort of dogs with new-onset untreated seizures, and for those dogs with newly diagnosed epilepsy to investigate epilepsy type, seizure type and the course of disease over time, including the risk of seizure recurrence. Untreated client-owned dogs experiencing new-onset seizures were prospectively enrolled in a longitudinal observational study including clinical investigations and long-term monitoring at the Copenhagen University Hospital for Companion Animals. A baseline clinical assessment was followed by investigator/owner contact every eight weeks from inclusion to death or end of study. Inclusion of dogs was conducted from November 2010 to September 2012, and the study terminated in June 2014.

Results

One hundred and six dogs were included in the study. Seventy-nine dogs (74.5%) were diagnosed with epilepsy: 61 dogs (77.2%) with idiopathic epilepsy, 13 dogs (16.5%) with structural epilepsy and five dogs (6.3%) with suspected structural epilepsy. A non-epileptic cause for seizures was identified in 13 dogs and suspected in 10 dogs. Four dogs in which no cause for seizures was identified experienced only one seizure during the study. In dogs with idiopathic epilepsy 60% had their second epileptic seizure within three months of seizure onset. Twenty-six dogs with idiopathic epilepsy (43%) completed the study without receiving antiepileptic treatment. The natural course of idiopathic epilepsy (uninfluenced by drugs) was illustrated by highly individual and fluctuating seizure patterns, including long periods of remission. Cluster seizures motivated early treatment. In a few dogs with a high seizure frequency owners declined treatment against the investigators advice.

Conclusions

Epilepsy is the most likely diagnosis in dogs presenting with new-onset seizures. The course of idiopathic epilepsy is highly individual and might not necessarily require long-term treatment. This must be considered when advising owners about what to expect with regard to treatment and prognosis.

Medical and Surgical Emergencies in Ferrets

In the last few years, significant improvement in diagnosis and treatment of ferret emergencies has occurred. Scientific advances demonstrated the need of specific practices when dealing with emergencies in ferrets. The risk of overdiagnosis of hypoglycemia with human portable blood glucose meters is a clear example. The purpose of this article is to describe the current approach to common medical and surgical emergencies in ferrets.

International veterinary epilepsy task force consensus proposal: diagnostic approach to epilepsy in dogs

This article outlines the consensus proposal on diagnosis of epilepsy in dogs by the International Veterinary Epilepsy Task Force. The aim of this consensus proposal is to improve consistency in the diagnosis of epilepsy in the clinical and research settings. The diagnostic approach to the patient presenting with a history of suspected epileptic seizures incorporates two fundamental steps: to establish if the events the animal is demonstrating truly represent epileptic seizures and if so, to identify their underlying cause. Differentiation of epileptic seizures from other non-epileptic episodic paroxysmal events can be challenging. Criteria that can be used to make this differentiation are presented in detail and discussed. Criteria for the diagnosis of idiopathic epilepsy (IE) are described in a three-tier system. Tier I confidence level for the diagnosis of IE is based on a history of two or more unprovoked epileptic seizures occurring at least 24 h apart, age at epileptic seizure onset of between six months and six years, unremarkable inter-ictal physical and neurological examination, and no significant abnormalities on minimum data base blood tests and urinalysis. Tier II confidence level for the diagnosis of IE is based on the factors listed in tier I and unremarkable fasting and post-prandial bile acids, magnetic resonance imaging (MRI) of the brain (based on an epilepsy-specific brain MRI protocol) and cerebrospinal fluid (CSF) analysis. Tier III confidence level for the diagnosis of IE is based on the factors listed in tier I and II and identification of electroencephalographic abnormalities characteristic for seizure disorders. The authors recommend performing MRI of the brain and routine CSF analysis, after exclusion of reactive seizures, in dogs with age at epileptic seizure onset <6 months or >6 years, inter-ictal neurological abnormalities consistent with intracranial neurolocalisation, status epilepticus or cluster seizure at epileptic seizure onset, or a previous presumptive diagnosis of IE and drug-resistance with a single antiepileptic drug titrated to the highest tolerable dose.

This consensus article represents the basis for a more standardised diagnostic approach to the seizure patient. These recommendations will evolve over time with advances in neuroimaging, electroencephalography, and molecular genetics of canine epilepsy.

A clinical and diagnostic approach to the patient with seizures

Seizures are one of the most common neurologic problems encountered by the small animal practitioner. Successful management of the patient with seizure is facilitated by an appropriate diagnostic workup to identify underlying causes when they exist. Veterinary patients with seizures can be divided in to 3 main categories based on underlying cause: those with primary epilepsy, those with structural epilepsy, and those with reactive seizures. Additionally, some patients may be given a label of unknown epilepsy when they do not meet the criteria for a diagnosis of primary epilepsy, but no structural or reactive cause of seizures can be identified. This article reviews the key clinical findings associated with each of the 3 main categories of seizures and suggests a standardized approach to the diagnostic workup for patients with seizure based on their signalment and neurologic examination findings.

Clinical characterization of epilepsy of unknown cause in cats

BACKGROUND

The diagnosis of feline epilepsy of unknown cause (EUC) requires a thorough diagnostic evaluation, otherwise the prevalence of EUC could be overestimated.

HYPOTHESIS

Feline EUC is a clinically defined disease entity, which differs from feline hippocampal necrosis by the absence of magnetic resonance imaging (MRI) signal alteration of the hippocampus. The objectives of this study were (1) to evaluate the prevalence of EUC in a hospital population of cats by applying well-defined inclusion criteria, and (2) to describe the clinical course of EUC.

ANIMALS

Eighty-one cats with recurrent seizures.

METHODS

Retrospective study--medical records were reviewed for cats presented for evaluation of recurrent seizures (2005-2010). Inclusion criteria were a defined diagnosis based on laboratory data, and either MRI or histopathology. Final outcome was confirmed by telephone interview with the owner. Magnetic resonance images were reviewed to evaluate hippocampal morphology and signal alterations.

RESULTS

Epilepsy of unknown cause was diagnosed in 22% of cats with epilepsy. Physical, neurologic, and laboratory examinations, and either 1.5 T MRI and cerebrospinal fluid analysis or postmortem examination failed to identify an underlying cause. Cats with EUC had a higher survival rate (P < .05) and seizure remission occurred frequently (44.4%).

CONCLUSION AND CLINICAL IMPORTANCE

A detailed clinical evaluation and diagnostic imaging with MRI is recommended in any cat with recurrent seizures. The prognosis of cats with normal MRI findings and a clinical diagnosis of EUC are good. Standardized imaging guidelines should be established to assess the hippocampus in cats.

Suspected exercise-induced seizures in a young dog

A 12-month-old female neutered crossbreed was referred for investigation of seizure-like episodes occurring only at intense exercise. Thorough medical, neurological and cardiac investigations were performed and excluded the most commonly known causes of seizure-like activity. The dog was fitted with an ambulatory electrocardiography device and underwent another exercise-induced seizure. The electrocardiogram during the episode revealed a sinus tachycardia at approximately 300 beats/minute. A video recording of the episode revealed generalised tonic clonic limb activity with jaw chomping and frothing at the mouth typical of seizure activity. Antiepileptic medications were not prescribed and the owner was advised not to exercise the dog intensely. The dog responded well and did not seizure after 12 months of mild-moderate off-lead exercise. As all the seizures in this case were triggered by intense physical activity, it is suggested that this may be a new form of reflex seizure activity.

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

PURPOSE

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

METHODS

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

KEY FINDINGS

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

SIGNIFICANCE

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