Suspected tick-borne flavivirus meningoencephalomyelitis in dogs from the UK: six cases (2021).

OBJECTIVES: Tick-borne encephalitis virus and louping ill virus are neurotropic flaviviruses transmitted by ticks. Epidemiologically, tick-borne encephalitis is endemic in Europe whereas louping ill's predominant geographical distribution is the UK. Rarely, these flaviviruses affect dogs causing neurological signs. This case series aimed to describe the clinical, clinicopathological, and imaging findings, as well as the outcomes in six dogs with meningoencephalitis and/or meningomyelitis caused by a flavivirus in the UK in 2021. MATERIALS AND METHODS: Observational retrospective case-series study. Clinical data were retrieved from medical records of dogs with positive serological or immunohistochemical results from three different institutions from spring to winter 2021. RESULTS: Six dogs were included in the study. All dogs presented an initial phase of pyrexia and/or lethargy followed by progressive signs of spinal cord and/or intracranial disease. Magnetic resonance imaging showed bilateral and symmetrical lesions affecting the grey matter of the thalamus, pons, medulla oblongata, and thoracic or lumbar intumescences with none or mild parenchymal and meningeal contrast enhancement. Serology for tick-borne encephalitis virus was positive in five dogs with the presence of seroconversion in two dogs. The viral distinction between flaviviruses was not achieved. One dog with negative serology presented positive immunohistochemistry at post-mortem examination. Three dogs survived but presented neurological sequelae. Three dogs were euthanased due to the rapid progression of the clinical signs or static neurological signs. CLINICAL SIGNIFICANCE: These cases raise awareness of the presence of tick-borne encephalitis as an emergent disease or the increased prevalence of louping ill virus affecting dogs in the UK.

Serum anti-GM2 and anti-GalNAc-GD1a IgG antibodies are biomarkers for acute canine polyradiculoneuritis.

OBJECTIVES: A previous single-country pilot study indicated serum anti-GM2 and anti-GA1 anti-glycolipid antibodies as potential biomarkers for acute canine polyradiculoneuritis. This study aims to validate these findings in a large geographically heterogenous cohort. MATERIALS AND METHODS: Sera from 175 dogs clinically diagnosed with acute canine polyradiculoneuritis, 112 dogs with other peripheral nerve, cranial nerve or neuromuscular disorders and 226 neurologically normal dogs were screened for anti-glycolipid antibodies against 11 common glycolipid targets to determine the immunoglobulin G anti-glycolipid antibodies with the highest combined sensitivity and specificity for acute canine polyradiculoneuritis. RESULTS: Anti-GM2 anti-glycolipid antibodies reached the highest combined sensitivity and specificity (sensitivity: 65.1%, 95% confidence interval 57.6 to 72.2%; specificity: 90.2%, 95% confidence interval 83.1 to 95.0%), followed by anti-GalNAc-GD1a anti-glycolipid antibodies (sensitivity: 61.7%, 95% confidence interval 54.1 to 68.9%; specificity: 89.3%, 95% confidence interval 82.0 to 94.3%) and these anti-glycolipid antibodies were frequently present concomitantly. Anti-GA1 anti-glycolipid antibodies were detected in both acute canine polyradiculoneuritis and control animals. Both for anti-GM2 and anti-GalNAc-GD1a anti-glycolipid antibodies, sex was found a significantly associated factor with a female to male odds ratio of 2.55 (1.27 to 5.31) and 3.00 (1.22 to 7.89), respectively. Anti-GalNAc-GD1a anti-glycolipid antibodies were more commonly observed in dogs unable to walk (OR 4.56, 1.56 to 14.87). CLINICAL SIGNIFICANCE: Anti-GM2 and anti-GalNAc-GD1a immunoglobulin G anti-glycolipid antibodies represent serum biomarkers for acute canine polyradiculoneuritis.

The occurrence of cardiac abnormalities in canine steroid-responsive meningitis arteritis.

OBJECTIVES: To document the prevalence of cardiac abnormalities in dogs with steroid-responsive meningitis arteritis and to assess resolution of these abnormalities following corticosteroid therapy. MATERIALS AND METHODS: Steroid-responsive meningitis arteritis was diagnosed based on signalment, physical examination findings, complete blood count, biochemistry and CSF analysis. Echocardiography, C-reactive protein and cardiac troponin I were measured in all cases before and 10 to 14 days after commencing corticosteroid therapy. Fibrinogen was also measured in a proportion of dogs. RESULTS: Fourteen dogs were prospectively enrolled. Increased cardiac troponin I was identified in five of 14 dogs and echocardiographic abnormalities were detected in 12 of 14 dogs, including spontaneous echo contrast (12 of 14), mild pericardial effusion (five of 14) and mildly decreased fractional shortening (five of 14). All dogs had increased C-reactive protein and fibrinogen was increased in 11 of 12. Corticosteroid treatment was associated with clinical improvement and normalisation of C-reactive protein in all dogs. The cardiac troponin I levels normalised in four of five and fibrinogen had normalised in all five dogs which were retested. Spontaneous echo contrast improved or completely resolved in 12 of 12 and pericardial effusion resolved in five of five dogs. Fractional shortening normalised in two of five dogs. CLINICAL SIGNIFICANCE: Cardiac changes are common in dogs with steroid-responsive meningitis arteritis and most resolve with therapy. Further investigation into the cause and significance of these changes is necessary in determining whether antithrombotic therapy or positive inotropic therapy is indicated.

Serological prevalence of toxoplasmosis and neosporosis in dogs diagnosed with suspected meningoencephalitis in the UK.

OBJECTIVES: To assess the prevalence of antibodies to Toxoplasma gondii and Neospora caninum in a population of dogs with a diagnosis of suspected inflammatory meningoencephalitis. MATERIALS AND METHODS: Medical records of three referral centres were reviewed from 2008 to 2016 to identify a cohort of dogs diagnosed and treated for suspected inflammatory meningoencephalitis after testing for evidence of exposure to these pathogens. RESULTS: In our sample of 400 dogs the prevalence for exposure (IgG>1:50) to Toxoplasma gondii was 8/201 (3∙98%). Active infection (IgG titre >1:400 or/and an IgM titre >1:64 and/or positive PCR in CSF) was suspected in 1/400 (0∙25%). The prevalence for exposure [Indirect fluorescent antibody (IFA) titre >1:50] and active infection (IFA titres ≥⃒1:400 and/or positive PCR in CSF) with Neospora caninum were 14/201 (6∙96%) and 9/400 (2∙25%), respectively. CLINICAL SIGNIFICANCE: In view of the low prevalence of protozoan infections, the risk associated with starting immunosuppressive medication in dogs with evidence of inflammatory meningitis or encephalitis in the UK appears low.

C7 vertebra homeotic transformation in domestic dogs - are Pug dogs breaking mammalian evolutionary constraints?

The number of cervical vertebrae in mammals is almost constant at seven, regardless of their neck length, implying that there is selection against variation in this number. Homebox (Hox) genes are involved in this evolutionary mammalian conservation, and homeotic transformation of cervical into thoracic vertebrae (cervical ribs) is a common phenotypic abnormality when Hox gene expression is altered. This relatively benign phenotypic change can be associated with fatal traits in humans. Mutations in genes upstream of Hox, inbreeding and stressors during organogenesis can also cause cervical ribs. The aim of this study was to describe the prevalence of cervical ribs in a large group of domestic dogs of different breeds, and explore a possible relation with other congenital vertebral malformations (CVMs) in the breed with the highest prevalence of cervical ribs. By phenotyping we hoped to give clues as to the underlying genetic causes. Twenty computed tomography studies from at least two breeds belonging to each of the nine groups recognized by the Federation Cynologique Internationale, including all the brachycephalic 'screw-tailed' breeds that are known to be overrepresented for CVMs, were reviewed. The Pug dog was more affected by cervical ribs than any other breed (46%; P < 0.001), and was selected for further analysis. No association was found between the presence of cervical ribs and vertebral body formation defect, bifid spinous process, caudal articular process hypoplasia/aplasia and an abnormal sacrum, which may infer they have a different aetiopathogenesis. However, Pug dogs with cervical ribs were more likely to have a transitional thoraco-lumbar vertebra (P = 0.041) and a pre-sacral vertebral count of 26 (P < 0.001). Higher C7/T1 dorsal spinous processes ratios were associated with the presence of cervical ribs (P < 0.001), supporting this is a true homeotic transformation. Relaxation of the stabilizing selection has likely occurred, and the Pug dog appears to be a good naturally occurring model to further investigate the aetiology of cervical ribs, other congenital vertebral anomalies and numerical alterations.

Suspected air embolism through the thoracic ventral internal vertebral venous plexus during hemilaminectomy in dogs.

Venous air embolism entering via the ventral internal vertebral venous plexus was suspected during thoracic spinal surgery in two dogs. In both cases, air was seen bubbling from a pool of blood on the floor of the vertebral canal accompanied by sudden cardiopulmonary disturbances: low end-tidal carbon dioxide pressure, tachycardia and reduction in oxygen in the blood. One dog became dyspnoeic and one died.

Magnetic resonance imaging findings in epileptic cats with a normal interictal neurological examination: 188 cases.

Epilepsy is a common neurological condition in dogs and cats. Although an increased likelihood of significant brain lesions with age has been identified in neurologically normal dogs with epileptic seizures, the underlying aetiology of epileptic seizures in cats that present with normal physical and neurological examinations remains unknown. In this cross-sectional study, the authors examined MRI findings in a large population of cats with a normal interictal physical and neurological examination. They hypothesised that age would have an impact on the prevalence of detectable lesions. First, following the guidelines for dogs and in accordance with previous studies, the authors divided the cats into three age groups (aged one year or younger, between one and six, and older than six) and calculated the proportion of cats with a detectable lesion on MRI in these groups. In the first group, 3/32 cats (9.4 per cent) had significant MRI abnormalities that were all consistent with congenital malformation; in the second group, only 5/92 (5.4 per cent) MRI scans were abnormal and in the third group, 15/ 65 (23.1 per cent) cats showed abnormal findings that were predominantly lesions of neoplastic origin. Second, to investigate the impact of age further, data were investigated as a continuous variable using receiver operating characteristic analysis. This indicated an optimal cut-off age of five years, above which MRI abnormalities were more likely, with an increase in the odds of a significant structural lesion increasing by 14 per cent per year.

Prevalence of thoracic vertebral malformations in French bulldogs, Pugs and English bulldogs with and without associated neurological deficits.

Congenital vertebral malformations are common incidental findings in small breed dogs. This retrospective observational study evaluated the type and prevalence of thoracic vertebral malformations in 171 neurologically normal and 10 neurologically abnormal screw-tailed brachycephalic dogs. Neurologically normal dogs underwent CT for reasons unrelated to spinal disease, while affected dogs underwent MRI. Imaging studies were reviewed and vertebral malformations including hemivertebrae, block vertebrae, transitional vertebrae, and spina bifida were documented. The group of clinically normal dogs consisted of 62 French bulldogs, 68 Pugs and 41 English bulldogs. The group of affected dogs consisted of one French bulldog and nine Pugs. Overall, 80.7% of neurologically normal animals were affected by at least one vertebral malformation. There was a significant influence of breed, with thoracic vertebral malformations occurring more often in neurologically normal French bulldogs (P <0.0001) and English bulldogs (P = 0.002). Compared to other breeds, hemivertebrae occurred more often in neurologically normal French bulldogs (93.5%; P < 0.0001 vs. Pugs; P = 0.004 vs. English bulldogs) and less often in neurologically normal Pugs (17.6%; P = 0.004 vs. English bulldogs). Neurologically normal Pugs were more often diagnosed with transitional vertebrae and spina bifida compared to other breeds (P <0.0001 for both malformations). Of Pugs included in the study, 4.7% were diagnosed with clinically relevant thoracic vertebral malformations. When compared to the general veterinary hospital population, this was significantly more than the other two breeds (P = 0.006). This study indicates that thoracic vertebral malformations occur commonly in neurologically normal screw-tailed brachycephalic dogs. While hemivertebrae are often interpreted as incidental diagnostic findings, they appear to be of greater clinical importance in Pugs compared to other screw-tailed brachycephalic breeds.

Clinical Features, Imaging Characteristics, and Long-term Outcome of Dogs with Cranial Meningocele or Meningoencephalocele.

BACKGROUND: The term meningoencephalocele (MEC) describes a herniation of cerebral tissue and meninges through a defect in the cranium, whereas a meningocele (MC) is a herniation of the meninges alone. HYPOTHESIS/OBJECTIVES: To describe the clinical features, magnetic resonance imaging (MRI) characteristics, and outcomes of dogs with cranial MC and MEC. ANIMALS: Twenty-two client-owned dogs diagnosed with cranial MC or MEC. METHODS: Multicentric retrospective descriptive study. Clinical records of 13 institutions were reviewed. Signalment, clinical history, neurologic findings and MRI characteristics as well as treatment and outcome were recorded and evaluated. RESULTS: Most affected dogs were presented at a young age (median, 6.5 months; range, 1 month - 8 years). The most common presenting complaints were seizures and behavioral abnormalities. Intranasal MEC was more common than parietal MC. Magnetic resonance imaging identified meningeal enhancement of the protruded tissue in 77% of the cases. Porencephaly was seen in all cases with parietal MC. Cerebrospinal fluid (CSF) analysis identified mild abnormalities in 4 of 11 cases. Surgery was not performed in any affected dog. Seventeen patients were treated medically, and seizures were adequately controlled with anti-epileptic drugs in 10 dogs. Dogs with intranasal MEC and mild neurologic signs had a fair prognosis with medical treatment. CONCLUSION AND CLINICAL IMPORTANCE: Although uncommon, MC and MEC should be considered as a differential diagnosis in young dogs presenting with seizures or alterations in behavior. Medical treatment is a valid option with a fair prognosis when the neurologic signs are mild.

Surgical Anatomical Landmarks of the Thoracolumbar Vertebral Column on Magnetic Resonance Imaging in Dogs.

Magnetic resonance imaging (MRI) in veterinary medicine profoundly improved spinal cord disease investigation in canine patients. We aimed to further describe the anatomical landmarks of the thoracolumbar junction in sagittal MRI sequences. MRI studies from 90 dogs were reviewed retrospectively, representing a broad cross section of breeds and body weights. The ratio of the distance from the dorsal aspect of the vertebral canal to the dorsal aspect of the transverse process or rib articulation relative to the length of L2 vertebra was determined for T12, T13, L1 and L2 vertebrae. A statistically significant difference was noted with the transverse processes being more ventrally located than the cranial fovea costalis. The lumbar transverse processes and rib articulations dramatically varied in shape, being oval or round, respectively. The sagittal image at the level of the lateral margin of the articular facet joint proved to be the most consistent for review of these structures.

Osseous associated cervical spondylomyelopathy at the C2-C3 articular facet joint in 11 dogs.

In dogs, vertebral canal stenosis at C2-C3 due to articular facet joint degeneration is only sporadically identified. The authors' aims were to review the clinical presentation, MRI characteristics, treatment and outcome of dogs presenting with this condition. Eleven cases were eligible for inclusion. Neurological examination revealed tetraparesis and proprioceptive ataxia in all 4 limbs in 3/11, proprioceptive tetra-ataxia only in 4/11, pelvic limb proprioceptive ataxia in 2/11 and no gait abnormalities in 2/11 dogs. Cervical hyperaesthesia was present in 7/11 dogs. MRI revealed bilateral articular facet joint degeneration in 10/11 cases and unilateral degeneration in one. Surgery was performed in six cases and medical management elected in five. Long-term follow-up information was available for 11 animals. Four of the surgical cases are alive and have no neurological deficits, one was euthanased for an unrelated condition and one lost to follow-up. Of the cases managed medically, three are alive showing no neurological deficits, one is alive still displaying neurological deficits and one euthanased for an unrelated condition whilst still ataxic. This study shows that both medical and surgical management can result in good outcomes in dogs with vertebral canal stenosis resulting from articular facet joint degeneration at the level of C2-C3.

Magnetic resonance imaging of the lentiform nuclei in dogs with portosystemic shunts.

OBJECTIVES: To develop and evaluate a method to quantify the T1-weighted magnetic resonance imaging signal intensity of the lentiform nuclei in dogs, and to determine if there is any significant difference in this signal intensity between dogs with portosystemic shunts and a control group. MATERIALS AND METHODS: A retrospective blinded study was performed to investigate the reliability and use of a quantitative method for assessing the T1-weighted magnetic resonance imaging signal intensity of the lentiform nuclei in dogs with and without portosystemic shunts. The lentiform nuclei index (mean lentiform nucleus signal intensity/mean white matter signal intensity) was calculated for nine dogs with portosystemic shunts and a control group of 14 dogs. RESULTS: The intra- and inter-observer intraclass correlation coefficients were considered excellent (>0 · 75), suggesting that the lentiform nuclei index is a reliable method. The dogs with portosystemic shunts had a higher lentiform nuclei index than the control group (P = 0 · 0127). CLINICAL SIGNIFICANCE: This method of quantifying the T1-weighted magnetic resonance imaging signal intensity of the lentiform nuclei was reliable and showed that dogs with portosystemic shunts tend to have increased signal intensity. Further prospective studies are necessary to investigate the clinical significance and applications of these findings.

Diagnostic Exercise: Circling and Behavioral Changes in a Cat.

A 4-year old spayed male domestic shorthair cat was presented with a history of circling and behavioral changes. Neurologic examination showed mild proprioceptive deficits. The lesion was localized in the forebrain, and magnetic resonance imaging revealed the presence of a large midline intracranial mass extending from the frontal lobe to the tentorial region of the brain. Euthanasia was elected due to poor prognosis. Histopathologic evaluation confirmed the presence of a mass composed by sheets and aggregates of large round/polygonal cells and multinucleate cells associated with deposits of cholesterol clefts, scattered hemorrhages and hemosiderin-laden macrophages. Immunohistochemistry showed that the round/polygonal cells and multinucleate cells were strongly positive for major histocompatibility complex class II antigen, variably positive for CD18, and occasionally positive for S100. Subsets of spindle cells showing variable expression of vimentin, S100, and neuron-specific enolase were also present. The final diagnosis was cholesterol granuloma. Differential diagnosis with meningioma is discussed.

A review of canine atlantoaxial joint subluxation.

Atlantoaxial subluxation was first reported in dogs nearly fifty years ago. Since that time a better understanding of the aetiologies predisposing to joint laxity and instability has been achieved. Surgeons however are still trying to address the problems associated with stabilizing this joint which by nature is often required in small juvenile dogs. This review describes the various techniques used, discussing the associated benefits and complications thereby allowing the clinician to make an informed decision on the best treatment for the individual patient.

The cutaneous trunci reflex for localising and grading thoracolumbar spinal cord injuries in dogs.

OBJECTIVES: To evaluate the accuracy of the cutaneous trunci reflex to localise thoracolumbar spinal cord injuries and to assess the correlation between focal loss (cut-off) of the reflex and clinical severity of thoracolumbar spinal cord injury. METHODS: Prospective study of 41 dogs with thoracolumbar spinal cord injuries investigated by magnetic resonance imaging. Linear regression analysis was performed to determine the relationship between the vertebral level of the cutaneous trunci reflex cut-off and the maximal and cranial lesion extent. The association between cutaneous trunci reflex cut-off and spinal cord injury severity was tested using a Mann-Whitney U test. RESULTS: Cutaneous trunci reflex cut-off was evident in 33 (80%) of dogs. The cut-off level was 0 to 4 vertebrae caudal to the maximal spinal cord lesion in all dogs. In 16 (48.5%) dogs the cut-off was either 2 or 3 vertebrae caudal to the lesion. The presence of a cut-off significantly correlated with increasing severity (P=0.0001). Loss of the reflex occurred at less severe grades than loss of ambulation and in dogs with ambulatory paresis it was significantly (P=0.0084) associated with increasing severity. CLINICAL SIGNIFICANCE: The cutaneous trunci reflex allows localisation of thoracolumbar spinal cord lesions within four vertebrae and facilitates clinical segregation of dogs with ambulatory paresis into mild and severe categories.

Aetiology and long-term outcome of juvenile epilepsy in 136 dogs.

The aetiology and outcome of dogs with juvenile-onset seizures were investigated. One hundred and thirty-six dogs whose first seizure occurred before the age of one year were investigated. One hundred and two dogs were diagnosed with idiopathic epilepsy (IE), 23 with symptomatic epilepsy (SE), nine with reactive seizures (RS) and two with probable symptomatic epilepsy (pSE). The outcome was known in 114 dogs; 37 per cent died or were euthanased as a consequence of seizures. The mean survival time of this population of dogs was 7.1 years. Factors that were significantly associated with survival outcome included the diagnosis of SE and the number of antiepileptic drugs (AEDs) used before investigation. The use of one AED before investigation and a diagnosis of SE were associated with a negative outcome, whereas receiving no AED medications before referral was associated with a longer survival. For dogs with IE, survival time was shortened if the dog was a border collie or with a history of status epilepticus;receiving no AEDs before referral in the IE group was associated with a positive outcome. Seizure-free status was achieved in 22 per cent of dogs diagnosed with IE. While the survival times were longer than previously reported in canine epilepsy, similar remission rates to those reported in childhood epilepsy, where a 70 per cent remission rate is documented, were not seen in the canine juvenile population.