Allele frequency of a genetic risk variant for necrotizing meningoencephalitis in pug dogs from Europe and association with the clinical phenotype.

Introduction: Necrotizing meningoencephalitis (NME) in pugs is a potentially fatal disease, which needs lifelong treatment with immunosuppressive or immunomodulatory drugs and shares parallels with acute fulminating multiple sclerosis. Genetic variants of the DLA class II gene are associated with an increased risk for NME. Genetic testing is recommended prior to breeding. The aim of this study was to describe the current allele frequency of a previously identified NME risk variant in the European pug population. A secondary aim was to investigate the association of the NME risk variant with the clinical phenotype in pugs. Methods: Results of genetic testing for the CFA12:2605517delC variant in European pugs between 2012 and 2020 were retrieved (n = 5,974). A validated questionnaire was mailed to all submitters of samples for further information on neurological signs, diagnostic tests, and disease course. Results: The allele frequency of the CFA12 NME risk variant was 25.7% in the European pug population dogs; 7.4% of the dogs were homozygous and 36.7% were heterozygous for the NME risk variant on CFA12. Completed questionnaires were available in 203 dogs including 25 dogs with epileptic seizures or other neurological signs. The clinical phenotype was consistent with NME in 3.9% with a median age of onset of 1.0 years, and indicative of idiopathic epilepsy in 2.9% with a median onset of 2.5 years. Eleven dogs remained unclassified. Pugs with the NME phenotype were significantly more frequently homozygous for the NME risk variant on CFA12 compared to pugs ≥6 years without neurological signs or seizures (p = 0.008). Discussion: The CFA12:2605517delC genetic risk variant is widely distributed in the European pug population and frequently homozygous in pugs with a NME phenotype. The data support the clinical relevance of the CFA12:2605517delC genetic risk variant.

Clinical features, diagnosis, and survival analysis of dogs with glioma.

BACKGROUND: Gliomas in dogs remain poorly understood. OBJECTIVES: To characterize the clinicopathologic findings, diagnostic imaging features and survival of a large sample of dogs with glioma using the Comparative Brain Tumor Consortium diagnostic classification. ANIMALS: Ninety-one dogs with histopathological diagnosis of glioma. METHODS: Multicentric retrospective case series. Signalment, clinicopathologic findings, diagnostic imaging characteristics, treatment, and outcome were used. Tumors were reclassified according to the new canine glioma diagnostic scheme. RESULTS: No associations were found between clinicopathologic findings or survival and tumor type or grade. However, definitive treatments provided significantly (P = .03) improved median survival time (84 days; 95% confidence interval [CI], 45-190) compared to palliative treatment (26 days; 95% CI, 11-54). On magnetic resonance imaging (MRI), oligodendrogliomas were associated with smooth margins and T1-weighted hypointensity compared to astrocytomas (odds ratio [OR], 42.5; 95% CI, 2.42-744.97; P = .04; OR, 45.5; 95% CI, 5.78-333.33; P < .001, respectively) and undefined gliomas (OR, 84; 95% CI, 3.43-999.99; P = .02; OR, 32.3; 95% CI, 2.51-500.00; P = .008, respectively) and were more commonly in contact with the ventricles than astrocytomas (OR, 7.47; 95% CI, 1.03-53.95; P = .049). Tumor spread to neighboring brain structures was associated with high-grade glioma (OR, 6.02; 95% CI, 1.06-34.48; P = .04). CONCLUSIONS AND CLINICAL IMPORTANCE: Dogs with gliomas have poor outcomes, but risk factors identified in survival analysis inform prognosis and the newly identified MRI characteristics could refine diagnosis of tumor type and grade.

Antigens under cover-The preservation and demasking of selected antigens for successful poststaining immunocytochemistry of effusion, brain smears, and lymph node aspirates.

BACKGROUND: In clinical cytology, the applicability of an ancillary test such as immunocytochemistry is too often limited by low sample volume, poor cell representation, and sample preservation. Diagnosticians often read Romanowsky-stained cytology, although specific techniques such as immunocytochemistry are often essential for a definitive diagnosis. OBJECTIVES: The goal of the present study aimed to investigate if immunocytochemistry on previously-stained cytologic specimens was possible. Different pretreatments were examined to determine which treatment preserved antigenicity best. METHODS: One hundred and twenty-two impression smears and 64 fine-needle aspirate preparations of brain and lymph nodes were processed and evaluated microscopically. The impact of staining cytologic preparations with a modified Wright's stain, using a destaining method, performing a coverslipping and decoverslipping process, and subjecting smears to a microwave treatment (MWT) were examined for the immunolabeling of selected nuclear, cytoplasmic, and plasmalemmal antigens, as well as intracellular feline coronavirus (FCoV). Biotinylated secondary antibodies were used, and the bound primary antibody was visualized using an ABC amplification kit. RESULTS: Cellular antigens were reliably detected with immunocytochemistry after smears were stained with a Romansky stain and were coverslipped early after staining and stayed coverslipped until immediately before immunolabeling. The staining intensity reached the same levels as that of the controls if the films underwent MWT in citrate buffer. In contrast, FCoV antigen detection was abolished after any physicochemical interference. CONCLUSIONS: Poststaining immunocytochemistry represents a practical tool for additional investigations on prestained cytologic specimens when searching for cellular antigens. Paired untreated samples should be kept in case the workup requires testing for more vulnerable viral antigens.

Assessment of menace response in neurologically and ophthalmologically healthy cats.

OBJECTIVES: Assessment and interpretation of menace response (MeR) in cats can be challenging. The prevalence of abnormal MeR in healthy cats is unknown. The aim of this study was to prospectively evaluate MeR in visually healthy cats. METHODS: Fifty cats without history or clinical evidence of neurological or ophthalmological disease were assessed by two examiners: standing behind the cat (mode A), in front of the cat (mode B), and in front of the cat, covering the contralateral eye (mode C). MeR was scored from 1-5 (absent, weak, moderate, strong, complete). Examination modes were compared concerning presence and score (descriptive statistic, 95% confidence interval, χ2 test). This was compared to a three-level scoring system (negative, reduced, positive). Score reproducibility between the two examiners was assessed (Cohen's kappa [κ] test). Video footage allowed self-re-evaluation and evaluation of the second examiner (κ analysis). Learning/tiring effect (McNemar test), influence of age, body weight (Spearman's rho test), skull type (χ2 test) and being an indoor or outdoor cat (Mann-Whitney U-test) were evaluated. RESULTS: MeR was always elicited with at least one technique. Comparable results were obtained with the five- and three-level scoring systems. Mode A achieved strong/complete (positive) MeR in 84.5%, mode B in 82% and mode C in 60%. Exact score reproducibility between the two examiners was slight to fair (κ = 0.208-0.281). Intrarater agreement for video self-assessment (κ = 0.544-0.639), as well as inter-rater agreement (extrinsic video assessment), was moderate to substantial (κ = 0.584-0.645). No learning/tiring effect ( P = 0.530) or association with body weight ( P = 0.897), age ( P = 0.724), skull type ( P >0.05) and being an indoor/outdoor cat ( P = 0.511) were evident. CONCLUSIONS AND RELEVANCE: The majority of visually healthy cats revealed a strong/complete MeR when the contralateral eye remained uncovered, but 40% failed when the contralateral eye was covered. The most reliable examination mode was achieved standing behind the cat.

Diagnostic utility of cerebrospinal fluid immunocytochemistry for diagnosis of feline infectious peritonitis manifesting in the central nervous system.

Objectives The aim of the study was to evaluate whether an ante-mortem diagnosis of central nervous system (CNS) feline infectious peritonitis (FIP) is possible via immunocytochemical staining (ICC) of feline coronavirus antigen (FCoV) within macrophages of cerebrospinal fluid (CSF). Methods Prospectively, CSF samples of 41 cats were investigated, including cats with histopathologically confirmed FIP and neurological signs (n = 10), cats with confirmed FIP without CNS involvement (n = 11), cats with neurological signs but another confirmed CNS disease (n = 17), and cats without neurological signs and a disease other than FIP (n = 3). ICC staining of CSF macrophages was performed in all cats. Sensitivity, specificity, positive (PPV) and negative predictive values (NPV) of CSF ICC were calculated. Results Of 10 samples from cats with CNS FIP, eight had detectable CSF macrophages, seven of which were positive for FCoV. Ten of 11 samples from cats with confirmed FIP without neurological signs had macrophages in the CSF, with all 10 being ICC-positive. In cats with other CNS disorders, 11/17 had macrophages, two of which stained positively. In cats with diseases other than FIP and without neurological disorders, 2/3 revealed macrophages, with one cat showing positive ICC staining. Diagnosis of FIP via CSF ICC had a sensitivity of 85.0% and a specificity of 83.3%. PPV and NPV were 85.0% and 83.3%. Conclusions and relevance CSF ICC is a highly sensitive test for ante-mortem diagnosis of FIP manifesting in the CNS. However, CNS ICC specificity is too low to confirm FIP and the method should only be applied in conjunction with other features such as CSF cytology. CNS ICC could be helpful to discover pre-neurological stages of CNS FIP.

Detection of feline coronavirus spike gene mutations as a tool to diagnose feline infectious peritonitis.

Objectives Feline infectious peritonitis (FIP) is an important cause of death in the cat population worldwide. The ante-mortem diagnosis of FIP in clinical cases is still challenging. In cats without effusion, a definitive diagnosis can only be achieved post mortem or with invasive methods. The aim of this study was to evaluate the use of a combined reverse transcriptase nested polymerase chain reaction (RT-nPCR) and sequencing approach in the diagnosis of FIP, detecting mutations at two different nucleotide positions within the spike (S) gene. Methods The study population consisted of 64 cats with confirmed FIP and 63 cats in which FIP was initially suspected due to similar clinical or laboratory signs, but that were definitively diagnosed with another disease. Serum/plasma and/or effusion samples of these cats were examined for feline coronavirus (FCoV) RNA by RT-nPCR and, if positive, PCR products were sequenced for nucleotide transitions within the S gene. Results Specificity of RT-nPCR was 100% in all materials (95% confidence interval [CI] in serum/plasma 83.9-100.0; 95% CI in effusion 93.0-100.0). The specificity of the sequencing step could not be determined as none of the cats of the control group tested positive for FCoV RNA. Sensitivity of the 'combined RT-nPCR and sequencing approach' was 6.5% (95% CI 0.8-21.4) in serum/plasma and 65.3% (95% CI 50.4-78.3) in effusion. Conclusions and relevance A positive result is highly indicative of the presence of FIP, but as none of the control cats tested positive by RT-nPCR, it was not possible to confirm that the FCoV mutant described can only be found in cats with FIP. Further studies are necessary to evaluate the usefulness of the sequencing step including FCoV-RNA-positive cats with and without FIP. A negative result cannot be used to exclude the disease, especially when only serum/plasma samples are available.

Nodo-paranodopathy, internodopathy and cleftopathy: Target-based reclassification of Guillain-Barré-like immune-mediated polyradiculoneuropathies in dogs and cats.

Recent views on Guillain-Barré syndrome (GBS) question the accuracy of classification into axonal and demyelinating subtypes that represent convergent neurophysiological phenotypes rather than immunological targets. Instead it has been proposed to clarify the primarily affected fibre subunit in nerve biopsies. As nerve biopsies rarely are part of routine work-up in human patients we evaluated tissues taken from companion animals affected by GBS-like polyradiculoneuropathy to screen for distribution of immune cells, targeted fibre components and segregating non-inflammatory lesions. We identified that immune responses were directed either at Schmidt-Lanterman clefts, the paranode-node complex or both. Based on infiltrative and non-inflammatory changes, four subtypes and/or stages were distinguished, some of which indicate localisation of primary target antigens while others represent convergent late stage pictures, as a consequence to epitope spreading. The impact of histological subtyping onto clinical management and prognosis remains to be evaluated in future clinical trials. Natural development and clinical manifestation of large animal dysimmune neuropathy may reflect human Guillain-Barré syndrome more accurately than experimental models and therefore provide complementary clues for translational research.

Intracranial Intra-arachnoid Diverticula and Cyst-like Abnormalities of the Brain.

Primary intracranial cystic or cyst-like lesions include intra-arachnoid, epidermoid, dermoid, and choroid plexus cysts. Differentiation of these cystic lesions can usually be accomplished by imaging studies alone; however, some cysts are similar in appearance and require histopathology for definitive diagnosis. Clinical signs often reflect the location of the cysts within the intracranial cavity rather than the type of cyst. If clinical signs are significant and progressive, surgical removal is warranted and may be successful, although cystic contents could be harmful if allowed to contact surrounding brain parenchyma or meninges.

Detection of feline coronavirus in cerebrospinal fluid for diagnosis of feline infectious peritonitis in cats with and without neurological signs.

OBJECTIVES: The objective of this study was to evaluate the sensitivity and specificity of a real-time reverse transcriptase polymerase chain reaction (real-time RT-PCR) detecting feline coronavirus (FCoV) RNA in cerebrospinal fluid (CSF) of cats with and without neurological and/or ocular signs for the diagnosis of feline infectious peritonitis (FIP). METHODS: This prospective case-control study included 34 cats. Nineteen cats had a definitive histopathological diagnosis of FIP (seven of these with neurological and/or ocular signs), and 15 cats had other diseases but similar clinical signs (three of these with neurological and/or ocular signs). Real-time RT-PCR was performed on the CSF of all cats, and sensitivity, specificity, and positive (PPV) and negative predictive values (NPV) were calculated. RESULTS: Real-time RT-PCR of CSF showed a specificity of 100% in diagnosing FIP, a sensitivity of 42.1%, a PPV of 100% and an NPV of 57.7%. The sensitivity of the real-time RT-PCR of CSF in cats with neurological and/or ocular signs was 85.7%. CONCLUSIONS AND RELEVANCE: Although it is known that RT-PCR can give false positive results, especially if performed using serum or plasma, this real-time RT-PCR detecting FCoV RNA in CSF can be considered a reliable specific tool for the diagnosis of FIP. If only cats with neurological involvement are evaluated, the sensitivity of this real-time RT-PCR in CSF is also high.

Inferior cerebellar hypoplasia resembling a Dandy-Walker-like malformation in purebred Eurasier dogs with familial non-progressive ataxia: a retrospective and prospective clinical cohort study.

Cerebellar malformations can be inherited or caused by insults during cerebellar development. To date, only sporadic cases of cerebellar malformations have been reported in dogs, and the genetic background has remained obscure. Therefore, this study`s objective was to describe the clinical characteristics, imaging features and pedigree data of a familial cerebellar hypoplasia in purebred Eurasier dogs. A uniform cerebellar malformation characterized by consistent absence of the caudal portions of the cerebellar vermis and, to a lesser degree, the caudal portions of the cerebellar hemispheres in association with large retrocerebellar fluid accumulations was recognized in 14 closely related Eurasier dogs. Hydrocephalus was an additional feature in some dogs. All dogs displayed non-progressive ataxia, which had already been noted when the dogs were 5-6 weeks old. The severity of the ataxia varied between dogs, from mild truncal sway, subtle dysmetric gait, dysequilibrium and pelvic limb ataxia to severe cerebellar ataxia in puppies and episodic falling or rolling. Follow-up examinations in adult dogs showed improvement of the cerebellar ataxia and a still absent menace response. Epileptic seizures occurred in some dogs. The association of partial vermis agenesis with an enlarged fourth ventricle and an enlarged caudal (posterior) fossa resembled a Dandy-Walker-like malformation in some dogs. Pedigree analyses were consistent with autosomal recessive inheritance.

Hippocampal sclerosis in feline epilepsy.

Hippocampal sclerosis (HS) refers to loss of hippocampal neurons and astrogliosis. In temporal lobe epilepsy (TLE), HS is a key factor for pharmacoresistance, even though the mechanisms are not quite understood. While experimental TLE models are available, there is lack of models reflecting the natural HS development. Among domestic animals, cats may present with TLE-like seizures in natural and experimental settings. With this study on the prevalence, segmental pattern and clinicopathological correlates of feline HS, we evaluated the translational value for human research. Evaluation schemes for human brains were applied to epileptic cats. The loss of neurons was morphometrically assessed and the degree of gliosis was recorded. Hippocampal changes resembling human HS were seen in about one third of epileptic cats. Most of these were associated with infiltrative diseases such as limbic encephalitis. Irrespective of the etiology and semiology of seizures, total hippocampal sclerosis was the most prevalent form seen in epileptic animals. Other HS types also occur at varying frequencies. Segmental differences to human HS can be explained by species-specific synaptic connectivities and a different spectrum of etiologies. All these variables require consideration when translating results from feline studies regarding seizure-associated changes of the temporal lobe and especially HS.

Clinical course of acute canine polyradiculoneuritis following treatment with human IV immunoglobulin.

Treatment of dogs with acute canine polyradiculoneuritis (ACP) is restricted to physical rehabilitation and supportive care. In humans with Guillain-Barré syndrome, the counterpart of ACP, randomized trials show that IV immunoglobulin (IVIg) speeds recovery. The authors of the current study hypothesized that dogs with ACP would tolerate IVIg well and recover faster than dogs managed with supportive treatment only. Sixteen client-owned dogs with ACP were treated with IVIg, and 14 client-owned dogs served as a retrospective control group. Diagnosis was confirmed using clinical features, electrodiagnostics, cerebrospinal fluid analysis, and muscle/nerve biopsies. The duration of the initial progressive phase, the time from IVIg administration until the dogs were ambulating without assistance, and the duration of the complete episode were evaluated. Adverse reactions (anaphylaxis, mild hematuria) were observed in two dogs. Dogs treated with IVIg were ambulating without assistance after a median of 27.5 days (range, 15-127 days) from onset of clinical signs. The control group was ambulatory without assistance at a median of 75.5 days (range, 5-220 days). Even though this result is not statistically significant, there is a clear trend toward faster recovery in dogs treated with IVIg.

Imaging diagnosis: pituitary apoplexy in a cat.

A 7-year-old male neutered domestic short-haired cat had depression for 5 months and acute blindness. A lesion at the level of the rostral and middle cranial fossae was suspected. A large pituitary mass compressing the optic chiasm was detected in magnetic resonance images and there was also evidence of recent intratumoral hemorrhage, leading to a diagnosis of pituitary apoplexy; these findings were confirmed at postmortem examination. Pituitary apoplexy is a clinical syndrome characterized by acute neurologic signs related to hemorrhagic infarction within a pituitary tumor. Pituitary apoplexy should be considered in patients with acute onset of blindness and altered mental status.

Slowly progressive lymphohistiocytic meningoencephalomyelitis in 21 adult cats presenting with peculiar neurological signs.

Twenty-one cats presented with a history of slowly progressive neurological signs characterised by a stiff extended tail, behavioural changes, and spastic and ataxic gait. All cats had outdoor access and lived in the same geographical rural area in north-east Scotland. Histological findings were consistent with lymphohistiocytic meningoencephalomyelitis. Immunohistochemistry ruled out 15 pathogens and showed a significant expression of the interferon-inducible Mx protein, suggesting an as yet unidentified infective or environmental immunogenic trigger as the possible causative agent. The late age at onset (mean 9 years), the very slow progression of clinical signs (mean 11 months) and the peculiar clinical presentation (particularly the posture of the tail) have not been reported previously in cats with lymphohistiocytic meningoencephalomyelitis.

Imaging diagnosis--Ventriculo-peritoneal shunt associated infection in a dog.

Ventriculo-peritoneal shunting is a surgical treatment for hydrocephalus. Complications of this procedure are not well described in dogs. The most common complication in humans is infection, which can be fatal if not diagnosed and treated quickly. We describe the magnetic resonance (MR) imaging characteristics of a shunt-associated cerebral infection in a dog. The MR features of the infection included hyperintensity of the lining of the ventricular system visible on a T2-weighted FLAIR sequence and marked linear contrast enhancement of the ependymal layer on T1-weighted sequences, similar to that described in people.

Surgical technique, postoperative complications and outcome in 14 dogs treated for hydrocephalus by ventriculoperitoneal shunting.

OBJECTIVE: To report frequency and type of complications, and outcome in dogs with severe neurologic signs secondary to internal, suspected obstructive hydrocephalus treated by ventriculoperitoneal (VP) shunting. STUDY DESIGN: Case series. ANIMALS: Dogs (n=14). METHODS: Medical records (2001-2006) was reviewed for dogs that had VP shunting. Inclusion criteria were complete medical record, progressive forebrain signs unresponsive to medical treatment, normal metabolic profile, negative antibody titers and/or cerebrospinal PCR for Toxoplasma gondii, Neospora caninum, and canine distemper virus, magnetic resonance images of the brain, confirmed diagnosis of VP shunting, and follow-up information. RESULTS: Hydrocephalus was idiopathic in 5 dogs and acquired (interventricular tumors, intraventricular hemorrhage, inflammatory disease) in 9 dogs. Four dogs developed complications 1 week to 18 months postoperatively, including ventricular catheter migration, infection, shunt under-drainage, kinking of the peritoneal catheter, valve fracture, and abdominal skin necrosis. Three of these dogs had 1 or more successful revision surgeries and 1 dog was successfully treated with antibiotics. All, but 1 dog, were discharged within 1 week of surgery, and had substantial neurologic improvement. Median survival time for all dogs was 320 days (1-2340 days), for dogs with idiopathic hydrocephalus, 274 (60-420) days and for dogs with secondary hydrocephalus, 365 (1-2340) days. CONCLUSIONS: VP shunting was successful in relieving neurologic signs in most dogs and postoperative complications occurred in 29%, but were resolved medically or surgically.

Prevalence, heritability and genetic correlations of congenital sensorineural deafness and pigmentation phenotypes in the Border Collie.

The objectives of this study were to estimate prevalence, heritability and genetic correlations of congenital sensorineural deafness (CSD) and pigmentation phenotypes in the Border Collie. Entire litters of Border Collies that presented to the Animal Health Trust (1994-2008) for assessment of hearing status by brain stem auditory evoked response (BAER) at 4-10 weeks of age were included. Heritability and genetic correlations were estimated using residual maximum likelihood (REML). Of 4143 puppies that met the inclusion criteria, 97.6% had normal hearing status, 2.0% were unilaterally deaf and 0.4% were bilaterally deaf. Heritability of deafness as a trichotomous trait (normal/unilaterally deaf/bilaterally deaf) was estimated at 0.42 using multivariate analysis. Genetic correlations of deafness with iris colour and merle coat colour were 0.58 and 0.26, respectively. These results indicate that there is a significant genetic effect on CSD in Border Collies and that some of the genes determining deafness also influence pigmentation phenotypes.