CLINICAL CHALLENGES:Epileptic seizures are a relatively common neurological presentation in cats, yet determining the underlying cause can be challenging due to the broad range of differential diagnoses.Diagnostic approach:A systematic approach, including thorough history-taking, physical and neurological examination, and appropriate diagnostic testing, is critical to accurately identifying the underlying cause and guiding effective management strategies. AUDIENCE:This review is aimed at veterinarians who manage feline patients presenting with epileptic seizures and outlines their features and differentials, as well as a guide to diagnosis.

Molecular mimicry is hypothesized to play a key role in the pathogenesis of acute polyradiculoneuritis (APRN) in dogs, as in Guillain-Barré syndrome (GBS). GBS is linked to Campylobacter jejuni and cytomegalovirus, while Parvovirus B19 shows temporal and serological associations. In dogs, the cause of APRN is often unknown, although recent vaccination or ingestion of raw poultry contaminated with Clostridium perfringens is documented. Antiganglioside antibodies are potential serum biomarkers for APRN. Eight 2.5-month-old Sprocker littermates and a 3-month-old female Cockapoo developed severe gastrointestinal clinical signs and tested positive for canine parvovirus-2 (CPV-2) infection. Six littermates died, while two pups (one male, one female) and the Cockapoo recovered. Seven days later, the male puppy developed pelvic limb weakness progressing to flaccid tetraparesis over 24 h, followed by thoracic limb contracture. Both female pups, 10 days after recovering from illness, developed neuromuscular clinical signs that deteriorated for 9 days before improving. They presented with a short-strided, choppy gait with kyphosis, and the Cockapoo developed dysphonia. Both female puppies improved over several months. Antiganglioside antibodies were not detected in the two littermates at 1 and 3 months after clinical onset. Treatment included supportive care. Both littermates received prednisolone and methocarbamol, with only the female responding. The male was euthanized due to poor quality of life. Post-mortem examination revealed widespread muscular atrophy and axonal degeneration, with active regeneration detected on semi-thin tissue sections of nerves. This study described a peripheral neuropathy temporally associated with CPV-2 infection. Although a causal relationship cannot be established, the clinical course and pathological features are compatible with a post-infectious neuromuscular process.

BACKGROUND:Presumptive steroid-responsive radiculoneuritis (PSRRN) in dogs is a rare condition that is often difficult to distinguish from neoplasia due to overlapping clinical and imaging features. Differentiating between these etiologies is critical to determining prognosis. HYPOTHESIS/OBJECTIVES:To describe the clinical presentation, diagnostic findings, magnetic resonance imaging (MRI) characteristics, treatment, and outcomes in dogs with PSRRN affecting spinal nerves and nerve roots. ANIMALS:Fifteen dogs presented to 2 UK referral centers between 2019 and 2025. METHODS:Retrospective review of dogs with MRI findings consistent with nerves and nerve roots inflammation involving the C6-T2 or L4-S3 spinal cord segments and a minimum clinical follow-up of 12 months. RESULTS:Dogs had a mean duration of 8 weeks (range 4 days-24 weeks) of lameness and monoparesis, and a mean age of 50.6 months (range 12-104 months); 12/15 were male (6 neutered) and 3/15 female (2 neutered). German Shepherd dogs accounted for 4/15 cases. Magnetic resonance imaging consistently revealed contrast-enhancing, T2W, and short τ inversion recovery hyperintense lesions, frequently affecting the L7 and T1 nerves and roots. Lumbar cerebrospinal fluid analysis revealed albuminocytological dissociation in 4/5 dogs. All dogs responded to medical treatment, although 3/15 experienced relapse over a median follow-up of 25 months (range 12-50 months). CONCLUSIONS AND CLINICAL IMPORTANCE:Presumptive steroid-responsive radiculoneuritis should be considered in dogs with diffuse enlargement of spinal nerves and nerve roots and chronic monoparesis. Magnetic resonance imaging findings, while suggestive, are not pathognomonic and highlight the importance of considering inflammatory etiologies in the differential diagnosis of spinal nerve enlargement.

Two sessions at BVA Live from neurology specialist Mark Lowrie will help delegates differentiate between true spinal emergencies and the many conditions that can mimic them.

OBJECTIVE:The aims of this study were two-fold. First, to describe a modified technique of subdural shunt (SDS) placement for canine thoracolumbar arachnoid diverticula (TL-AD). Second, to compare outcome and recurrence of dogs following durotomy and debridement of meningeal attachments alone or in combination with SDS. ANIMALS:A total of 27 surgically managed TL-AD affected dogs. STUDY DESIGN:Retrospective non-randomized descriptive case series. METHODS:Magnetic resonance imaging (MRI) TL-AD diagnosed dogs undergoing surgery, with 4-8 weeks postoperative recheck and follow-up time of >6 months. Two groups were compared: a control group, where durotomy and debridement of subdural adhesions alone was performed; a shunting group (SG) where SDS was utilized. The surgical technique was adapted from Meren et al., differing in access (hemilaminectomy), incision shape (longitudinal) and no suturing of the SDS or dura. RESULTS:A total of 12 dogs were included in the control group and 14 in the SG. One case, excluded, developed suspected postoperative surgical infection that resolved when the SDS was removed. Immediate postoperative and short-term outcome was not significantly different between groups. In the SG, long-term outcome was significantly better with dogs having improved neurologically (85.7% vs. 41.7%), and the rate of recurrence was lower (14.3% vs. 41.7%) although this last difference was not statistically significant (p = .19). Recurrence occurred at a median of 36 months from surgery (9-62), 5/7 recurrent cases were Pugs. CONCLUSION:The adapted technique was successful in addressing TL-AD associated neurological signs in the long-term, as well as reducing recurrence of TL-AD. CLINICAL SIGNIFICANCE:Shunt-placement appears to have a positive role in outcome and possibly recurrence prevention in cases of TL-AD.

BackgroundA considerable body of published research on meningoencephalitis of unknown origin (MUO) exists; however, certain fundamental aspects relating to the epidemiology remain poorly characterized. These include the frequency of MUO diagnosis at referral level, reliable demographic risk factors, and the extent to which proposed diagnostic criteria are applied in referral clinical settings.MethodsBased on 1,121 MUO cases (from 01 January 2017 to 31 December 2021) treated at 13 referral centers in England and 750,000 control dogs from the VetCompass Programme, this study investigated a range of demographic risk factors using multivariable logistic regression analysis. Additionally, we report on clinical methods used for diagnosis.ResultsMeningoencephalitis of unknown origin represented 2.21% (95% CI: 2.08–2.34) of new neurological referrals (1,121/50721). Clinical diagnosis included both magnetic resonance imaging (MRI) and cerebrospinal fluid (CSF) analysis in 1026 (91.5%) cases. Of these, 961 (89.3%) showed results indicative of MUO in both MRI and CSF. Abnormal MRI but normal CSF were found in 55 cases (5.4%), while normal MRI and abnormal CSF were found in 36 cases (3.5%). Both normal MRI and normal CSF were reported in 19 cases (1.5%). Screening for infectious disease was carried out in 1037 (92.5%) of cases. The diagnosis of MUO peaked at 4 years (median 4.33, IQR 2.50–6.92, range 0.30–15.00) and declined after age 10. Welsh Springer Spaniel (OR 23.76, 95% CI 10.37–54.43), Maltese (OR 20.53, 95% CI 14.53–29.01), Papillon (OR 17.48, 95% CI 7.66–39.91), Boston Terrier (OR 17.31, 95% CI 11.17–26.82), and French Bulldog (OR 9.14, 95% CI 7.14–11.71) had the highest MUO odds compared to crossbreed dogs. Brachycephalic breeds had 2.56 times higher odds (95% CI 2.23–2.95) than mesocephalic breeds. Dogs ≥15 kg had lower odds than those <10 kg.ConclusionThis study provides the largest referral-based analysis of MUO cases to date, offering updated insights into breed predispositions and clinical diagnosis. This more precise characterization of the demographic factors adds valuable context for future research design, particularly in breed-focused investigations and risk stratification. By documenting current diagnostic practices used by referral specialists, this work lays the foundation for greater consistency in case recognition and offers practical guidance for structuring future MUO clinical trials.

An 11-month-old male castrated shorthaired cat was presented with a tremor in both pelvic limbs, which only occurred when standing (ie, countering gravity) or during active extension of the stifle. General clinical and neurological examinations were normal aside from the tremor of the pelvic limbs, which disappeared on performing a weight-bearing lifting test. Needle electromyography of both pelvic limbs in the conscious state confirmed a low-frequency (6 Hz) tremor. The cat was diagnosed with pseudo-orthostatic tremor. The tremor amplitude waxed and waned over time. The cat remained ambulatory and playful, but often assumed lateral recumbency and seemed to have difficulty jumping. Treatment with gabapentin (10-20 mg/kg PO q8h) for 3 weeks followed by clonazepam (0.1 mg/kg PO q12h) for 1 day (with unacceptable adverse effects) did not result in improvement.

Background: Myasthenia gravis (MG) and congenital myasthenic syndromes (CMS) are characterised by severe muscle weakness and impaired neuromuscular transmission. CMS in dogs represent a heterogeneous group of genetic disorders affecting the motor endplate – the specialised synapse between motor neurons and skeletal muscle fibres. These disorders arise from genetic mutations in presynaptic, synaptic and postsynaptic proteins, with clinical presentations and diagnostic criteria varying across breeds. MG, on the other hand, is an autoimmune disease primarily mediated by autoantibodies targeting nicotinic acetylcholine receptors (nAChRs). While most MG patients are seropositive for nAChR antibodies, seronegative cases occur, and the absence of these antibodies does not exclude the diagnosis. Aim of the article: This article reviews the pathophysiology, clinical features and diagnostic approaches for both MG and CMS, along with the role of immunosuppressive therapies and anticholinesterase treatments in managing these conditions. Understanding the molecular basis and treatment strategies for MG and CMS allows for accurate diagnosis and improved outcomes in affected dogs and cats.

Abstract Neuroaxonal dystrophy (NAD) is a group of inherited neurodegenerative disorders characterized primarily by the presence of spheroids (swollen axons) throughout the central nervous system. In humans, NAD is heterogeneous, both clinically and genetically. NAD has also been described to naturally occur in large animal models, such as dogs. A newly recognized disorder in Miniature American Shepherd dogs (MAS), consisting of a slowly progressive neurodegenerative syndrome, was diagnosed as NAD via histopathology. Affected dogs were typically young adults and displayed an abnormal gait characterized by pelvic limb weakness and ataxia. A combined GWAS and autozygosity mapping approach, together with whole-genome sequencing, identified the underlying genetic cause as a 1-bp deletion in RNF170 (ring finger protein 170), which perfectly segregates in an autosomal recessive pattern. This deletion is predicted to create a frameshift (XM_038559916.1:c.367delG) and early truncation of the RNF170 protein (XP_038415844.1:(p.Ala123Glnfs*11). A significant LOD score of 9.70 in an extended pedigree confirms the linkage of the deletion variant with the canine phenotype. Several RNF170 variants have been identified in human patients with analogous clinical syndromes, indicating that this novel MAS NAD serves as an excellent large animal model for equivalent human diseases, particularly since affected dogs demonstrate a relatively long lifespan, which represents an opportunity for therapeutic trials. The age of this canine RNF170 variant is estimated at approximately 30 years, before the reproductive isolation of the MAS breed. This carries implications for the standard Australian Shepherd, the breed from which MAS were developed.

Thoracolumbar hydrated nucleus pulposus extrusion (TL-HNPE) is an increasingly recognised pathology with a substantial lack of literature describing its features. The aim of this retrospective case-control study was to analyse the clinical and magnetic resonance imaging (MRI) features of dogs with TL-HNPE compared to dogs affected with thoracolumbar intervertebral disc extrusion (TL-IVDE). Data from dogs diagnosed with TL-HNPE and TL-IVDE via MRI at two referral hospitals, were retrospectively collected and compared in terms of clinical signs and MRI features. Cases diagnosed with TL-IVDE were deemed controls. The MRI features of the affected IVD space, herniated IVD material, affected overlying spinal cord and local epaxial musculature were evaluated for each group. Fifty-one cases with TL-HNPE and 105 randomly selected cases of TL-IVDE were included. Several signalment and neurological signs were identified as statistically distinct between groups in univariate analysis. Multivariate analysis identified that dogs affected with TL-HNPE were typically older, less likely to be chondrodystrophic (62.2 % vs. 91 %), more frequently experiencing a peracute onset (90.2 % vs. 61.9 %) often attributed to a suspected trauma linked with exercise (37.3 % vs. 10.5 %), being less frequently progressive (41.2 % vs. 86.5 %) and with herniated disc material less frequently lateralised (72.6 % vs. 89.5 %) than cases with TL-IVDE. MRI-identifiable intervertebral disc degeneration was found in every TL-IVDE case but only in 60 % of TL-HNPE cases. TL-HNPEs were associated to significantly less spinal cord compression and less hyperalgesia than TL-IVDE.

Background: Neuroaxonal dystrophy (NAD) is a group of inherited neurodegenerative disorders characterized primarily by the presence of spheroids (swollen axons) throughout the central nervous system. In humans, NAD is heterogeneous, both clinically and genetically. NAD has also been described to naturally occur in large animal models, such as dogs. A newly recognized disorder in Miniature American Shepherd dogs (MAS), consisting of a slowly progressive neurodegenerative syndrome, was diagnosed as NAD via histopathology. Objectives: To describe the clinical and pathological phenotype together with the identification of the underlying genetic cause. Methods: Clinical and postmortem evaluations, together with a genome-wide association study and autozygosity mapping approach, followed by whole-genome sequencing. Results: Affected dogs were typically young adults and displayed an abnormal gait characterized by pelvic limb weakness and ataxia. The underlying genetic cause was identified as a 1-bp (base pair) deletion in RNF170 encoding ring finger protein 170, which perfectly segregates in an autosomal recessive pattern. This deletion is predicted to create a frameshift (XM_038559916.1:c.367delG) and early truncation of the RNF170 protein (XP_038415844.1:(p.Ala123Glnfs*11)). The age of this canine RNF170 variant was estimated at similar to 30 years, before the reproductive isolation of the MAS breed. Conclusions: RNF170 variants were previously identified in human patients with autosomal recessive spastic paraplegia-85 (SPG85); this clinical phenotype shows similarities to the dogs described herein. We therefore propose that this novel MAS NAD could serve as an excellent large animal model for equivalent human diseases, particularly since affected dogs demonstrate a relatively long lifespan, which represents an opportunity for therapeutic trials. (c) 2024 The Author(s). Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

BACKGROUND:Some paroxysmal movement disorders remain without an identified genetic cause. OBJECTIVES:The aim was to identify the causal genetic variant for a paroxysmal dystonia-ataxia syndrome in Weimaraner dogs. METHODS:Clinical and diagnostic investigations were performed. Whole genome sequencing of one affected dog was used to identify private homozygous variants against 921 control genomes. RESULTS:Four Weimaraners were presented for episodes of abnormal gait. Results of examinations and diagnostic investigations were unremarkable. Whole genome sequencing revealed a private frameshift variant in the TNR (tenascin-R) gene in an affected dog, XM_038542431.1:c.831dupC, which is predicted to truncate more than 75% of the open read frame. Genotypes in a cohort of 4 affected and 70 unaffected Weimaraners showed perfect association with the disease phenotype. CONCLUSIONS:We report the association of a TNR variant with a paroxysmal dystonia-ataxia syndrome in Weimaraners. It might be relevant to include sequencing of this gene in diagnosing humans with unexplained paroxysmal movement disorders. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

OPINION article Front. Vet. Sci., 04 January 2023Sec. Veterinary Neurology and Neurosurgery Volume 9 - 2022 | https://doi.org/10.3389/fvets.2022.1062114

BACKGROUND The Basset Hound is the largest chondrodystrophic breed predisposed to thoracolumbar intervertebral disc extrusion (TL-IVDE). However, literature describing this particular breed in terms of incidence, signalment, anatomical location, clinical severity and short-term outcome of TL-IVDE is lacking. METHODS The medical histories of Dachshunds and Basset Hounds presenting to three neurology departments were retrospectively assessed. Information collected for each dog included signalment, whether it had received a diagnosis of TL-IVDE, duration of clinical signs, affected discs and anatomical region and neurological grading at presentation and discharge. RESULTS A total of 270 Dachshunds and 188 Basset Hounds were included for incidence analysis. Of these, 154 Dachshunds and 68 Basset Hounds with confirmed TL-IVDE were included for signalment, anatomical location, clinical severity and short-term outcome analysis. Statistical analysis indicated a significantly higher incidence of TL-IVDE in Dachshunds than in Basset Hounds (77.4% vs. 36.2%, p < 0.05). Basset Hounds presenting to a neurology department were older (median 87.5 months vs. 66.5 months), had a greater proportion of midlumbar IVDE (L2-L5) and were more frequently ambulatory at discharge than Dachshunds. Only one Basset Hound presented as paraplegic without nociception, compared with 16 Dachshunds (1.5% vs. 10.4%). LIMITATIONS The study had a retrospective design and included multicentric non-standardised cases. CONCLUSION TL-IVDE incidence was higher in Dachshunds than in Basset Hounds. Basset Hounds were older at presentation, frequently affected more caudally in the vertebral column and more frequently ambulatory at discharge than Dachshunds. The differences found in this study could aid in the development of preventive strategies.

A 9-year-old male neutered Cockapoo was presented with an acute and progressive history of exercise induced weakness involving all limbs, and bilateral decreased ability to blink. Investigations revealed generalized myasthenia gravis alongside the presence of a thymoma and a cholangiocellular carcinoma. Symptomatic treatment through pyridostigmine bromide was used to control clinical signs, and complete surgical removal of the thymoma and cholangiocellular carcinoma was performed. Serum acetylcholine receptor antibody concentration was measured serially. Clinical remission defined as resolution of clinical signs alongside discontinuation of treatment was achieved by day 251 (8.2 months). Immune remission defined as normalization of serum acetylcholine receptor antibody concentration alongside resolution of clinical signs and discontinuation of treatment was achieved by day 566 (18.5 months). Neurological examination was normal, and the owners did not report any clinical deterioration during the final follow-up appointment on day 752 (24 months), hence outcome was considered excellent. This is the first report describing the temporal evolution of serum acetylcholine receptor antibody concentration in a dog with thymoma-associated myasthenia gravis which achieved immune remission following thymectomy. Treatment was successfully discontinued without any evidence of clinical deterioration thereafter despite serum acetylcholine receptor antibody concentration not normalizing for another 315 days (10 months).

Paradoxical pseudomyotonia has previously been described in the English Cocker Spaniel (ECS) and English Springer Spaniel (ESS) breeds, without the identification of potentially causative variants. This disease is characterised by episodes of exercise-induced generalised myotonic-like muscle stiffness, phenotypically similar to congenital pseudomyotonia in cattle, and paramyotonia congenita and Brody disease in people. Four additional affected ESS dogs with paradoxical pseudomyotonia are described in this report, together with the identification of the autosomal recessive c.126C>A(p.(Cys42Ter)) SLC7A10 nonsense variant as candidate disease-causing variant in both ECS and ESS. The variant has an estimated prevalence of 2.5% in both breeds in the British study samples, but was not identified in the Belgian study samples. Genetic testing-based breeding should be a useful tool to eliminate this disease in the future, although an effective treatment option is available for severely affected dogs.

EDITORIAL article Front. Vet. Sci., 30 October 2023Sec. Veterinary Neurology and Neurosurgery Volume 10 - 2023 | https://doi.org/10.3389/fvets.2023.1323496

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.

AbstractBackgroundThe aims of this retrospective study were to estimate interobserver agreement in detecting disc calcification with computed tomography (CT) and to compare the number of calcified intervertebral discs identified on CT and radiography in healthy British Dachshund dogs that underwent a screening programme. The current screening programme uses radiography to identify calcified intervertebral discs.MethodsHealthy Dachshunds aged between 2 and 5 years presenting for spinal radiography and CT as part of a disc scoring scheme were included. The spinal radiographs were scored by an independent assessor as per the screening programme protocol. The CT images were blinded and reviewed by three different observers of differing levels of experience. The number of discs identified as being calcified was then compared between imaging modalities and between observers.ResultsThirteen dogs were included. Overall, 146 calcified discs were identified by CT compared with 42 by radiography. There was an almost perfect agreement among the three observers identifying calcified discs with CT images (k = 0.92). There was a significant difference between the radiography scores and CT scores.ConclusionsThis study demonstrated a significant difference in the number of calcified intervertebral discs identified in the vertebral column of a small population of healthy Dachshunds between CT and radiography. Given the high agreement between the observers with CT, this may be a reliable method for assessing disc calcification in Dachshund dogs and could be a good candidate for future breeding schemes.