Towards a better understanding of idiopathic epilepsy through metabolic fingerprinting of cerebrospinal fluid in dogs.

Cerebrospinal fluid metabolomics is a promising research technology in the elucidation of nervous system disorders. Therefore, in this work, a cerebrospinal fluid (CSF) metabolomics method using liquid chromatography coupled to mass spectrometry was optimized and validated to cover a wide range of metabolites. An acceptable coefficient of variance regarding instrumental, within-lab and intra-assay precision was found for 95, 70 and 96 of 102 targeted metabolites, together with 1256, 676 and 976 untargeted compounds, respectively. Moreover, approximately 75% of targeted metabolites and 50% of untargeted compounds displayed good linearity across different dilution ranges. Consequently, metabolic alterations in CSF of dogs with idiopathic epilepsy (IE) were studied by comparing CSF of dogs diagnosed with IE (Tier II) to dogs with non-brain related disease. Targeted metabolome analysis revealed higher levels of cortisol, creatinine, glucose, hippuric acid, mannose, pantothenol, and 2-phenylethylamine (P values < 0.05) in CSF of dogs with IE, whereas CSF of dogs with IE showed lower levels of spermidine (P value = 0.02). Untargeted CSF metabolic fingerprints discriminated dogs with IE from dogs with non-brain related disease using Orthogonal Partial Least Squares Discriminant Analysis (R2(Y) = 0.997, Q2(Y) = 0.828), from which norepinephrine was putatively identified as an important discriminative metabolite.

Episodic mandibular tremor in dogs: an idiopathic movement disorder or a manifestation of pain.

OBJECTIVE: Episodic mandibular tremor (EMT), manifested as teeth chattering, is not well described in dogs. The aim of this study was to describe clinical signs, MRI findings, and outcome of dogs with EMT. ANIMALS: 11 dogs retrospectively and 31 dogs in an online survey. METHODS: A retrospective multicenter study of dogs with EMT between 2018 and 2023 and prospective online questionnaire open to owners of pets with teeth chattering. RESULTS: All dogs had rapid and short-lasting (< 1 minute) episodes of EMT in the absence of other neurological signs. Lip smacking occasionally accompanied the tremor in 5 of 11 (45.5%) hospital dog cases. Excitement was a common trigger in 14 of 31 (45.2%) dogs from the survey. Cavalier King Charles Spaniel was the most common breed in both clinical and survey populations. Median age at presentation was 3 years for both hospital cases and the survey dogs. A concurrent medical condition was present in 8 of 11 (72.7%) hospital cases and 20 of 31 (64.5%) survey dogs. In 3 hospital dogs that underwent further investigations, no brain disease was present. CLINICAL RELEVANCE: EMT and its clinical features are presented for the first time, shedding light on a clinical sign that might resemble an idiopathic movement disorder or a manifestation of pain in dogs.

Idiopathic and structural episodic nonintentional head tremor in dogs: 100 cases (2004-2022).

BACKGROUND: Although idiopathic episodic head tremor (IEHT) in dogs is well-known, little is known about structural brain lesions causing structural episodic head tremor (SEHT). HYPOTHESIS/OBJECTIVES: Describe semiology, magnetic resonance imaging (MRI) findings and outcome of dogs with IEHT or SEHT. We hypothesized that structural lesions affecting the middle cranial fossa or mesencephalic aqueduct could lead to SEHT. ANIMALS: One hundred dogs with IEHT (n = 71) or SEHT (n = 29). METHODS: Retrospective, multicenter, study of dogs with episodic (nonintentional) head tremor and brain MRI between 2004 and 2022. RESULTS: Lesions on MRI in SEHT dogs were localized to the middle cranial fossa (15/29), cerebrocortex (3/29), brainstem (2/29), fourth ventricle (1/29) or multifocal (8/29) with thalamus involvement (6/8). Secondary compression of the mesencephalic aqueduct (19/29), third ventricle or interthalamic adhesion or both (14/29) was common. The most common underlying condition in dogs with SEHT was a pituitary mass. Dogs with SEHT were older, had additional neurological signs and were more likely to be euthanized after diagnosis (P < .001 for all) compared to IEHT dogs. Two SEHT dogs had only tremor. In IEHT dogs, 8/10 owners reported that the tremor decreased or abated over time (range, 106-2315 days) without treatment. Tremor remission occurred in SEHT dogs treated for underlying meningoencephalitis. CONCLUSIONS AND CLINICAL IMPORTANCE: Presence of additional neurological signs and older age may indicate an underlying structural cause for episodic (nonintentional) head tremor involving the mesencephalic aqueduct, third ventricle, interthalamic adhesion or some combination of these. An intracranial structural abnormality cannot be excluded in dogs with normal neurological examination.

Out-of-hospital rescue medication in dogs with emergency seizure disorders: an owner perspective.

Background: Emergency seizure disorders such as status epilepticus and cluster seizures are unlikely to cease spontaneously while prolonged seizure activity become progressively more resistant to treatment. Early administration of rescue medication in canine epileptic patients, in particular benzodiazepines, at seizure onset by the owners can be life-saving and brain protecting. Clinical studies in dogs evaluating the use of rescue medication in hospital environment exist, however, the owner perspective has not been assessed to date. Hypothesis or objectives: To evaluate the use of rescue medication in dogs with seizure emergencies by the owner at home. Method: Observational study based on online surveys of owners of dogs with emergency seizure disorders. Results: The questionnaire was answered by 1,563 dog owners, of which 761 provided complete and accurate answers suitable for analysis. Of these, 71% administered diazepam, 19% midazolam, 6% levetiracetam, 3% lorazepam, and 4% more than one rescue or other medication. Overall, the success rates based on owners' perspective for intranasal midazolam and rectal diazepam were 97 and 63%, respectively. Owners reported a compliance level of 95 and 66% for intranasal midazolam and rectal diazepam administration, respectively. Conclusions and clinical importance: Even though rectal diazepam was the most used rescue medication in this survey population, intranasal midazolam was perceived by the owners as a better option regarding effectiveness, time to seizure cessation and owner compliance.

Generalized myokymia, or neuromyotonia, or both in dogs with or without spinocerebellar ataxia.

BACKGROUND: KCNJ10 and CAPN1 variants cause "spinocerebellar" ataxia in dogs, but their association with generalized myokymia and neuromyotonia remains unclear. OBJECTIVE: To investigate the association between KCNJ10 and CAPN1 and myokymia or neuromyotonia, with or without concurrent spinocerebellar ataxia. ANIMALS: Thirty-three client-owned dogs with spinocerebellar ataxia, myokymia neuromytonia, or a combination of these signs. METHODS: Genetic analysis of a cohort of dogs clinically diagnosed with spinocerebellar ataxia, myokymia or neuromyotonia. KCNJ10 c.627C>G and CAPN1 c.344G>A variants and the coding sequence of KCNA1, KCNA2, KCNA6, KCNJ10 and HINT1 were sequenced using DNA extracted from blood samples. RESULTS: Twenty-four Jack Russell terriers, 1 Jack Russell terrier cross, 1 Dachshund and 1 mixed breed with spinocerebellar ataxia were biallelic (homozygous) for the KCNJ10 c.627C>G variant. Twenty-one of those dogs had myokymia, neuromyotonia, or both. One Parson Russell terrier with spinocerebellar ataxia alone was biallelic for the CAPN1 c.344G>A variant. Neither variant was found in 1 Jack Russell terrier with ataxia alone, nor in 3 Jack Russell terriers and 1 Yorkshire terrier with myokymia and neuromyotonia alone. No other causal variants were found in the coding sequence of the investigated candidate genes in these latter 5 dogs. CONCLUSION: The KCNJ10 c.627C>G variant, or rarely the CAPN1 c.344G>A variant, was confirmed to be the causal variant of spinocerebellar ataxia. We also report the presence of the KCNJ10 c.627C>G variant in the Dachshund breed. In dogs with myokymia and neuromyotonia alone the reported gene variants were not found. Other genetic or immune-mediated causes should be investigated to explain the clinical signs of these cases.

VariantscanR: an R-package as a clinical tool for variant filtering of known phenotype-associated variants in domestic animals.

BACKGROUND: Since the introduction of next-generation sequencing (NGS) techniques, whole-exome sequencing (WES) and whole-genome sequencing (WGS) have not only revolutionized research, but also diagnostics. The gradual switch from single gene testing to WES and WGS required a different set of skills, given the amount and type of data generated, while the demand for standardization remained. However, most of the tools currently available are solely applicable for human analysis because they require access to specific databases and/or simply do not support other species. Additionally, a complicating factor in clinical genetics in animals is that genetic diversity is often dangerously low due to the breeding history. Combined, there is a clear need for an easy-to-use, flexible tool that allows standardized data processing and preferably, monitoring of genetic diversity as well. To fill these gaps, we developed the R-package variantscanR that allows an easy and straightforward identification and prioritization of known phenotype-associated variants identified in dogs and other domestic animals. RESULTS: The R-package variantscanR enables the filtering of variant call format (VCF) files for the presence of known phenotype-associated variants and allows for the estimation of genetic diversity using multi-sample VCF files. Next to this, additional functions are available for the quality control and processing of user-defined input files to make the workflow as easy and straightforward as possible. This user-friendly approach enables the standardisation of complex data analysis in clinical settings. CONCLUSION: We developed an R-package for the identification of known phenotype-associated variants and calculation of genetic diversity.

Phenotypic and genetic aspects of hereditary ataxia in dogs.

Hereditary ataxias are a large group of neurodegenerative diseases that have cerebellar or spinocerebellar dysfunction as core feature, occurring as an isolated sign or as part of a syndrome. Based on neuropathology, this group of diseases has so far been classified into cerebellar cortical degenerations, spinocerebellar degenerations, cerebellar ataxias without substantial neurodegeneration, canine multiple system degeneration, and episodic ataxia. Several new hereditary ataxia syndromes are described, but most of these diseases have similar clinical signs and unspecific diagnostic findings, wherefore achieving a definitive diagnosis in these dogs is challenging. Eighteen new genetic variants associated with these diseases have been discovered in the last decade, allowing clinicians to reach a definitive diagnosis for most of these conditions, and allowing breeding schemes to adapt to prevent breeding of affected puppies. This review summarizes the current knowledge about hereditary ataxias in dogs, and proposes to add a "multifocal degenerations with predominant (spino)cerebellar component" category regrouping canine multiple system degeneration, new hereditary ataxia syndromes that do not fit in 1 of the previous categories, as well as specific neuroaxonal dystrophies and lysosomal storage diseases that cause major (spino)cerebellar dysfunction.

Identification of a Novel Idiopathic Epilepsy Risk Locus and a Variant in the CCDC85A Gene in the Dutch Partridge Dog.

(1) Idiopathic epilepsy (IE) is thought to have a genetic cause in several dog breeds. However, only two causal variants have been identified to date, and few risk loci are known. No genetic studies have been conducted on IE in the Dutch partridge dog (DPD), and little has been reported on the epileptic phenotype in this breed. (2) Owner-filled questionnaires and diagnostic investigations were used to characterize IE in the DPD. A genome-wide association study (GWAS) involving 16 cases and 43 controls was performed, followed by sequencing of the coding sequence and splice site regions of a candidate gene within the associated region. Subsequent whole-exome sequencing (WES) of one family (including one IE-affected dog, both parents, and an IE-free sibling) was performed. (3) IE in the DPD has a broad range in terms of age at onset, frequency, and duration of epileptic seizures. Most dogs showed focal epileptic seizures evolving into generalized seizures. A new risk locus on chromosome 12 (BICF2G630119560; praw = 4.4 × 10-7; padj = 0.043) was identified through GWAS. Sequencing of the GRIK2 candidate gene revealed no variants of interest. No WES variants were located within the associated GWAS region. However, a variant in CCDC85A (chromosome 10; XM_038680630.1: c.689C > T) was discovered, and dogs homozygous for the variant (T/T) had an increased risk of developing IE (OR: 6.0; 95% CI: 1.6-22.6). This variant was identified as likely pathogenic according to ACMG guidelines. (4) Further research is necessary before the risk locus or CCDC85A variant can be used for breeding decisions.

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

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

Serum anti-GM2 and anti-GalNAc-GD1a ganglioside IgG antibodies are biomarkers for immune-mediated polyneuropathies in cats.

Recent work identified anti-GM2 and anti-GalNAc-GD1a IgG ganglioside antibodies as biomarkers in dogs clinically diagnosed with acute canine polyradiculoneuritis, in turn considered a canine equivalent of Guillain-Barré syndrome. This study aims to investigate the serum prevalence of similar antibodies in cats clinically diagnosed with immune-mediated polyneuropathies. The sera from 41 cats clinically diagnosed with immune-mediated polyneuropathies (IPN), 9 cats with other neurological or neuromuscular disorders (ONM) and 46 neurologically normal cats (CTRL) were examined for the presence of IgG antibodies against glycolipids GM1, GM2, GD1a, GD1b, GalNAc-GD1a, GA1, SGPG, LM1, galactocerebroside and sulphatide. A total of 29/41 IPN-cats had either anti-GM2 or anti-GalNAc-GD1a IgG antibodies, with 24/29 cats having both. Direct comparison of anti-GM2 (sensitivity: 70.7%; specificity: 78.2%) and anti-GalNAc-GD1a (sensitivity: 70.7%; specificity: 70.9%) antibodies narrowly showed anti-GM2 IgG antibodies to be the better marker for identifying IPN-cats when compared to the combined ONM and CTRL groups (P = .049). Anti-GA1 and/or anti-sulphatide IgG antibodies were ubiquitously present across all sample groups, whereas antibodies against GM1, GD1a, GD1b, SGPG, LM1 and galactocerebroside were overall only rarely observed. Anti-GM2 and anti-GalNAc-GD1a IgG antibodies may serve as serum biomarkers for immune-mediated polyneuropathies in cats, as previously observed in dogs and humans.

Spinocerebellar ataxia in the Bouvier des Ardennes breed is caused by a KCNJ10 missense variant.

BACKGROUND: In Belgian Malinois, a KCNJ10 variant causes progressive spinocerebellar degeneration. HYPOTHESIS/OBJECTIVES: Describe the clinical, diagnostic, pathological and genetic features of spinocerebellar degeneration in the Bouvier des Ardennes breed. ANIMALS: Five affected Bouvier des Ardennes puppies with spinocerebellar ataxia (SCA), 8 healthy related dogs, and 63 healthy unrelated Bouvier des Ardennes. METHODS: Sequential case study. RESULTS: Clinical signs started at 6 weeks of age in 1 puppy with severe signs of cerebellar disease, and at 7 to 10 weeks of age in the 4 remaining puppies with milder signs of spinocerebellar disease. The first puppy displayed severe intention tremors and rapidly progressive generalized hypermetric ataxia, whereas the 4 others developed a milder progressive SCA. Euthanasia after progression to nonambulatory status was performed by 8 weeks of age in the first puppy, and before 11 months of age in the 4 remaining puppies. Histopathology revealed cerebellar spongy degeneration and a focal symmetrical demyelinating myelopathy. All cases were homozygous for KCNJ10 XM_545752.6:c.986T>C(p.(Leu329Pro)), which is pathogenic for SCA with (or without) myokymia, seizures or both (SAMS) and spongy degeneration and cerebellar ataxia (SDCA) 1 in Belgian Malinois dogs. All sampled parents were heterozygous and none of the healthy dogs were homozygous for this recessive variant. This variant has an allele frequency of 15% in the 63 healthy dogs studied. CONCLUSIONS AND CLINICAL IMPORTANCE: Inherited spinocerebellar degeneration also affects the Bouvier des Ardennes breed and is caused by a KCNJ10 variant. It can present with a spectrum of severity grades, ranging from severe cerebellar to milder spinocerebellar signs.

CT diagnosis of occipital condyle fracture in a dog presented for severe cervical hyperesthesia.

A 9-month-old male entire Doberman Pinscher presented with acute onset of severe cervical hyperesthesia after a fall. Neurological examination revealed a normal gait with low head carriage and severe cervical hyperesthesia. A CT scan of the cervical vertebral column revealed the presence of a comminuted fracture at the dorsomedial aspect of the right occipital condyle and sclerosis of the underlying bone. Medical management was initiated consisting of an external bandage, strict rest, and pain medication. Due to the lack of clinical improvement, the dog was euthanized 2 months after diagnosis. Histopathology of the lesion was compatible with a healing fracture.

The role of nutrition in canine idiopathic epilepsy management: Fact or fiction?

In the last decade, nutrition has gained interest in the management of canine idiopathic epilepsy (IE) based on growing scientific evidence. Diets can serve their functions through many pathways. One potential pathway includes the microbiota-gut-brain axis, which highlights the relationship between the brain and the intestines. Changing the brain's energy source and a number of dietary sourced anti-inflammatory and neuroprotective factors appears to be the basis for improved outcomes in IE. Selecting a diet with anti-seizure effects and avoiding risks of proconvulsant mediators as well as interference with anti-seizure drugs should all be considered in canine IE. This literature review provides information about preclinical and clinical evidence, including a systematic evaluation of the level of evidence, suggested mechanism of action and interaction with anti-seizure drugs as well as pros and cons of each potential dietary adaptation in canine IE.

A Nonsense Variant in the DMD Gene Causes X-Linked Muscular Dystrophy in the Maine Coon Cat.

(1) Feline dystrophin-deficient muscular dystrophy (ddMD) is a fatal disease characterized by progressive weakness and degeneration of skeletal muscles and is caused by variants in the DMD gene. To date, only two feline causal variants have been identified. This study reports two cases of male Maine coon siblings that presented with muscular hypertrophy, growth retardation, weight loss, and vomiting. (2) Both cats were clinically examined and histopathology and immunofluorescent staining of the affected muscle was performed. DMD mRNA was sequenced to identify putative causal variants. (3) Both cats showed a significant increase in serum creatine kinase activity. Electromyography and histopathological examination of the muscle samples revealed abnormalities consistent with a dystrophic phenotype. Immunohistochemical testing revealed the absence of dystrophin, confirming the diagnosis of dystrophin-deficient muscular dystrophy. mRNA sequencing revealed a nonsense variant in exon 11 of the feline DMD gene, NC_058386.1 (XM_045050794.1): c.1180C > T (p.(Arg394*)), which results in the loss of the majority of the dystrophin protein. Perfect X-linked segregation of the variant was established in the pedigree. (4) ddMD was described for the first time in the Maine coon and the c.1180C>T variant was confirmed as the causal variant.

Cannabidiol in canine epilepsy.

The anticonvulsant effect of cannabidiol (CBD), which has been confirmed by findings from animal models and human trials, has attracted the interest of veterinary practitioners and dog owners. Moreover, social media and public pressure has sparked a renewed awareness of cannabinoids, which have been used for epilepsy since ancient times. Unfortunately, at this moment veterinarians and veterinary neurologists have difficulty prescribing cannabinoids because of the paucity of sound scientific studies. Pharmacokinetic studies in dogs have demonstrated a low oral bioavailability of CBD and a high first-pass effect through the liver. Administering CBD in oil-based formulations and/or with food has been shown to enhance the bioavailability in dogs, rats and humans. Tolerability studies in healthy dogs and dogs with epilepsy have demonstrated that CBD was safe and well tolerated with only mild to moderate adverse effects. In this context, it should be noted that the quality of available CBD varies widely, underscoring the importance of pharmaceutical quality and its control. One clinical trial in dogs with drug-resistant idiopathic epilepsy failed to confirm a difference in response rates between the CBD group and the placebo group, while in another cross-over trial a ≥ 50 % reduction in epileptic seizure frequency was found in six of 14 dogs in the treatment phase, a reduction that was not observed during the placebo phase. Based on the current state of knowledge it is not possible to provide clear-cut recommendations for the use of CBD in canine epilepsy. Randomized controlled canine trials with large sample sizes are needed to determine the range of therapeutic plasma concentrations, develop evidence-based dosing regimens, determine the efficacy of cannabidiol in drug-refractory epilepsy, and explore potential associations between treatment effects and different etiologies, epilepsy types, and drug combinations.

Neurostimulation as a Method of Treatment and a Preventive Measure in Canine Drug-Resistant Epilepsy: Current State and Future Prospects.

Modulation of neuronal activity for seizure control using various methods of neurostimulation is a rapidly developing field in epileptology, especially in treatment of refractory epilepsy. Promising results in human clinical practice, such as diminished seizure burden, reduced incidence of sudden unexplained death in epilepsy, and improved quality of life has brought neurostimulation into the focus of veterinary medicine as a therapeutic option. This article provides a comprehensive review of available neurostimulation methods for seizure management in drug-resistant epilepsy in canine patients. Recent progress in non-invasive modalities, such as repetitive transcranial magnetic stimulation and transcutaneous vagus nerve stimulation is highlighted. We further discuss potential future advances and their plausible application as means for preventing epileptogenesis in dogs.

SLC25A12 Missense Variant in Nova Scotia Duck Tolling Retrievers Affected by Cerebellar Degeneration-Myositis Complex (CDMC).

We investigated two litters of distantly related Nova Scotia Duck Tolling Retrievers (NSDTR), of which four puppies were affected by cerebellar signs with or without neuromuscular weakness. The phenotype was termed cerebellar degeneration­myositis complex (CDMC). We suspected a heritable condition and initiated a genetic analysis. The genome of one affected dog was sequenced and compared to 565 control genomes. This search yielded a private protein-changing SLC25A12 variant in the affected dog, XM_038584842.1:c.1337C>T, predicted to result in the amino acid change XP_038440770.1:(p.Pro446Leu). The genotypes at the variant co-segregated with the phenotype as expected for a monogenic autosomal recessive mode of inheritance in both litters. Genotyping of 533 additional NSDTR revealed variant allele frequencies of 3.6% and 1.3% in a European and a North American cohort, respectively. The available clinical and biochemical data, together with current knowledge about SLC25A12 variants and their functional impact in humans, mice, and dogs, suggest the p.Pro446Leu variant is a candidate causative defect for the observed phenotype in the affected dogs.

Phenotypic Characterization of Idiopathic Epilepsy in Border Collies.

The prevalence of idiopathic epilepsy (IE) within the Border Collie (BC) dog breed is high. The aim of this retrospective study was to describe the phenotype of BCs with IE and assess correlations between phenotypic variables and owner-provided quality-of-life (QoL) scores. Data of BCs diagnosed with IE during the period of five consecutive years were retrospectively analyzed. All the dogs were presented at least once to a veterinary neurology specialist at one of three veterinary referral hospitals and most were under the continued medical care of that specialist. Owners were requested to complete a standardized online questionnaire including quality-of-life (QoL) scoring questions. Data of a total of 116 BC dogs were included for analysis. The median age at onset of the first epileptic seizure (ES) was 33.5 months (6-188). A total of 34/86 (40%) of medically treated dogs received 1 antiseizure medication (ASM) and 52/86 (60%) received ≥2 ASMs. Phenobarbital was the most commonly employed ASM, used in 70/86 of treated dogs (81%). Four or more side effects were observed in 20/86 (23%) of treated dogs. Age at onset of first ES was significantly lower for dogs having experienced cluster seizures (CSs), status epilepticus (SE), or both (median 27 months) vs. dogs that had not experienced CS or SE (median 43 months). The QoL of BC with IE was scored with a median score of 7 out of 10. Owners scored their dog's QoL to have declined by a median of 30% during the course of life with IE with 39% (37/95) of owners scoring their dog's QoL to have declined by ≥50%. This study confirms the association of age at onset of first ES with the severity of epilepsy (e.g., presence of CS and/or SE) and further characterizes the phenotype of IE in BC dogs. QoL of BC can be heavily impacted by IE.

Pharmacokinetics of Cannabidiol Following Intranasal, Intrarectal, and Oral Administration in Healthy Dogs.

The therapeutic potential of cannabidiol (CBD), a non-psychtropic component of the Cannabis sativa plant, is substantiated more and more. We aimed to determine the pharmacokinetic behavior of CBD after a single dose via intranasal (IN) and intrarectal (IR) administration in six healthy Beagle dogs age 3-8 years old, and compare to the oral administration route (PO). Standardized dosages applied for IN, IR and PO were 20, 100, and 100 mg, respectively. Each dog underwent the same protocol but received CBD through a different administration route. CBD plasma concentrations were determined by ultra-high performance liquid chromatography-tandem mass spectrometry before and at fixed time points after administration. Non-compartmental analysis was performed on the plasma concentration-time profiles. Plasma CBD concentrations after IR administration were below the limit of quantification. The mean area under the curve (AUC) after IN and PO CBD administration was 61 and 1,376 ng/mL*h, respectively. The maximal plasma CBD concentration (Cmax) after IN and PO CBD administration was 28 and 217 ng/mL reached after 0.5 and 3.5 h (Tmax), respectively. Significant differences between IN and PO administration were found in the Tmax (p = 0.04). Higher AUC and Cmax were achieved with 100 mg PO compared to 20 mg IN, but no significant differences were found when AUC (p = 0.09) and Cmax (p = 0.44) were normalized to 1 mg dosages. IN administration of CBD resulted in faster absorption when compared to PO administration. However, PO remains the most favorable route for CBD delivery due to its more feasible administration. The IR administration route is not advised for clinical application.

Defining and overcoming the therapeutic obstacles in canine refractory status epilepticus.

Status epilepticus (SE) can be effectively resolved if diagnosis and treatment are addressed at an early stage, although this is not always possible in clinical practice. If untreated, continuous seizure activity leads to refractory SE which does not respond to antiseizure medication. Although refractory SE is a life-threatening emergency, there is a lack of veterinary consensus on its appropriate management. Classical therapeutic approaches often fail to prevent the progression of SE. One of the main reasons for failure or inadequate response, is a lack of understanding of the fundamental progressive pathophysiology occurring during SE. If the therapeutic approach is focussed on the specific pathophysiologic alterations responsible for initiating and maintaining continuous seizure activity, SE could be successfully resolved during its early stages, preventing progression to a refractory state. The aim of this review is to detail the underlying pathophysiology of SE at its different temporal stages in order to determine a more effective therapeutic approach.