Juvenile-onset motor polyneuropathy in Siberian cats

Presumptive motor neuron degeneration in an adult cat

An 8-year-old neutered male Bengal cat was referred because of a 1-year history of progressive and relapsing generalized muscle weakness and muscle atrophy. Before referral, the cat was treated with immunosuppressive doses of oral prednisolone, intermittently for 6 mo, and had responded well when the immunosuppressive dose was maintained. Generalized paresis, diffuse muscle atrophy, and diminished spinal reflexes were present in all limbs, consistent with a generalized lower motor neuron disease. Histopathologic evaluation of muscle biopsies confirmed a pattern of muscle fiber atrophy consistent with chronic and severe denervation. No specific abnormalities were identified in the nerve biopsy or within intramuscular nerve branches. A presumptive antemortem diagnosis of an adult-onset motor neuron degeneration resembling amyotrophic lateral sclerosis (ALS) or spinal muscle atrophy was suspected. However, given the response to immunosuppressive doses of corticosteroids, an autoimmune process or other degenerative process could not be definitively excluded. Key clinical message: In this case, an adult cat had a chronic, progressive history of lower motor neuron weakness and absent spinal reflexes; biopsies revealed a neurogenic pattern of muscle fiber atrophy and histologically normal peripheral nerve and intramuscular nerve branches. Although reports of motor neuron disease are rare in the veterinary literature, this case report highlights the importance of muscle and nerve biopsies that lead to a presumptive diagnosis of motor neuron degeneration.

Immune-mediated polyneuropathy in cats: Clinical description, electrodiagnostic assessment, and treatment

BACKGROUND

Suspected immune-mediated polyneuropathy has been increasingly reported in cats, especially in the last decade, but the condition remains poorly understood.

OBJECTIVES

Refine the clinical description and review the classification of this condition based on electrodiagnostic investigation and evaluate the benefit of corticosteroid treatment and L-carnitine supplementation.

ANIMALS

Fifty-five cats presented with signs of muscular weakness and electrodiagnostic findings consistent with polyneuropathy of unknown origin.

METHODS

Retrospective, multicenter study. Data from the medical records were reviewed. The owners were contacted by phone for follow-up at the time of the study.

RESULTS

The male-to-female ratio was 2.2. The median age of onset was 10 months, with 91% of affected cats being <3 years of age. Fourteen breeds were represented in the study. The electrodiagnostic findings supported purely motor axonal polyneuropathy. Histological findings from nerve biopsies were consistent with immune-mediated neuropathy in 87% of the tested cats. The overall prognosis for recovery was good to excellent, as all but 1 cat achieved clinical recovery, with 12% having mild sequelae and 28% having multiple episodes during their lifetime. The outcome was similar in cats with no treatment when compared with cats receiving corticosteroids or L-carnitine supplementation.

CONCLUSIONS AND CLINICAL IMPORTANCE

Immune-mediated motor axonal polyneuropathy should be considered in young cats with muscle weakness. This condition may be similar to acute motor axonal neuropathy in Guillain-Barré syndrome patients. Based on our results, diagnostic criteria have been proposed.

Identification of a putative haplotype associated with recumbency in Holstein calves

Thirty-four Holstein calves from multiple farms were found recumbent during the neonatal period with no detectable neurologic, infectious, or metabolic abnormalities. Most calves did not survive beyond 6 wk of age. The objective of this study was to conduct a genome-wide association and pedigree analysis to determine if a genetic origin was plausible. There were 101,917 DNA markers for 18 affected calves and 26 unaffected family controls available for analysis. Genome-wide association, homozygosity screening, and a parental based transmission disequilibrium test were conducted in PLINK. A genomic region on the end of chromosome 16 that contained 78 markers based on a recessive inheritance model and that spanned 5.1 million bp was considered the most probable region for a genetic defect; the region was narrowed to 2.1 million bp following homozygosity screening and the transmission disequilibrium test with all affected calves homozygous in the candidate region and 1 homozygous control. A genotyped sire and 2 dams with imputed genotypes were heterozygous in the candidate region. A common sire born in 2008 was identified that was present for both paternal and maternal lineages of all affected calves; nearly all lineages traced through a prolific son born in 2010 who was genotyped and was heterozygous for the candidate region. Therefore, a possible genetic defect with incomplete penetrance on chromosome 16 that results in recumbency has been identified. Further efforts with an increase in families represented are needed to confirm a genetic basis, and identify the mutation and mode of inheritance.

Biopsy Characteristics, Subtypes, and Prognostic Features in 107 Cases of Feline Presumed Immune-Mediated Polyneuropathy

Inflammatory polyradiculoneuropathy (IMPN) is one of the causes of sudden onset of neuromuscular signs such as para-/tetraparesis in young cats. Even though most cases have a favorable outcome, persistent deficits, relapses, and progressive courses are occasionally seen. As clinical presentation does not always appear to predict outcome and risk of recurrence, this study was initiated to screen for prognostic biopsy findings in a large cohort of histologically confirmed IMPN cases with clinical follow-up. In total, nerve and muscle specimens of 107 cats with biopsy diagnosis of presumed autoreactive inflammatory polyneuropathy and 22 control cases were reviewed by two blinded raters for a set of 36 histological parameters. To identify patterns and subtypes of IMPN, hierarchical k-means clustering of 33 histologic variables was performed. Then, the impact of histological parameters on IMPN outcome was evaluated via an univariate analysis to identify variables for the final multivariate model. The data on immediate outcome and follow-up were collected from submitting neurologists using a purpose-designed questionnaire. Hierarchical k-means clustering sorted the tissues into 4 main categories: cluster 1 (44/129) represents a purely inflammatory IMPN picture, whereas cluster 2 (47/129) was accompanied by demyelinating features and cluster 3 (16/129) by Wallerian degeneration. Cluster 4 (22/129) reflects normal tissues from non-neuropathic control cats. Returned questionnaires provided detailed information on outcome in 63 animals. They were categorized into recovered and non-recovered. Thereby, fiber-invasive infiltrates by mononuclear cells and mild fiber loss in intramuscular nerve branches correlated with higher probabilities of recovery. Remyelination in semithin sections, on the other hand, is correlated with a less favorable outcome. Animals grouping in cluster 1 had a tendency to a higher probability of recovery compared to other clusters. In conclusion, diagnosis of feline IMPN from nerve and muscle biopsies allowed for the identification of histologic features that were positively or negatively correlated with outcome.

Clinical Course and Diagnostic Findings of Biopsy Controlled Presumed Immune-Mediated Polyneuropathy in 70 European Cats

There is a paucity of information on the clinical course and outcome of young cats with polyneuropathy. The aim of the study was to describe the clinical features, diagnostic investigations, and outcome of a large cohort of cats with inflammatory polyneuropathy from several European countries. Seventy cats with inflammatory infiltrates in intramuscular nerves and/or peripheral nerve biopsies were retrospectively included. Information from medical records and follow up were acquired via questionnaires filled by veterinary neurologists who had submitted muscle and nerve biopsies (2011-2019). Median age at onset was 10 months (range: 4-120 months). The most common breed was British short hair (25.7%), followed by Domestic short hair (24.3%), Bengal cat (11.4%), Maine Coon (8.6%) and Persian cat (5.7%), and 14 other breeds. Male cats were predominantly affected (64.3%). Clinical signs were weakness (98.6%) and tetraparesis (75.7%) in association with decreased withdrawal reflexes (83.6%) and, less commonly, cranial nerve signs (17.1%), spinal pain/hyperesthesia (12.9%), and micturition/defecation problems (14.3%). Onset was sudden (30.1%) or insidious (69.1%), and an initial progressive phase was reported in 74.3%. Characteristic findings on electrodiagnostic examination were presence of generalized spontaneous electric muscle activity (89.6%), decreased motor nerve conduction velocity (52.3%), abnormal F-wave studies (72.4%), pattern of temporal dispersion (26.1%) and unremarkable sensory tests. The clinical course was mainly described as remittent (49.2%) or remittent-relapsing (34.9%), while stagnation, progressive course or waxing and waning were less frequently reported. Relapses were common and occurred in 35.7% of the cats' population. An overall favorable outcome was reported in 79.4% of patients. In conclusion, young age at the time of diagnosis and sudden onset of clinical signs were significantly associated with recovery (p < 0.05). Clinical and electrodiagnostic features and the remittent-relapsing clinical course resembles juvenile chronic inflammatory demyelinating polyneuropathy (CIDP), as seen in human (children/adolescents), in many aspects.

Juvenile-onset motor polyneuropathy in Siberian cats

BACKGROUND

Polyneuropathies are infrequently described in cats. There is a genetic predisposition in several breeds.

OBJECTIVE

To clinically characterize a novel motor polyneuropathy in a family of Siberian cats.

ANIMALS

Thirteen closely related Siberian cats, 4 clinically affected and 9 clinically unaffected individuals.

METHODS

Retrospective study. Clinical data and pedigree information were obtained from the medical records and breeder. Electrodiagnostic testing and muscle and peripheral nerve biopsy samples were obtained from 1 affected cat. Follow-up information was obtained for all affected cats.

RESULTS

Onset of signs was 4 to 10 months in affected cats. Clinical signs were progressive or waxing/waning neuromuscular weakness (4/4), normal sensory function (4/4), and variably decreased withdrawal reflexes (3/4). All cats returned to normal neurologic function within 1 to 4 weeks. All cats had a recurrence of weakness (3/4 had 1 recurrent episode, 1/4 had 3 relapses) from which they recovered fully. In 1 cat, electromyography and motor nerve conduction studies showed multicentric spontaneous activity, normal motor nerve conduction velocity, reduced compound muscle action potential amplitude, and polyphasia. Histologic evaluation of muscle and nerve in that cat showed mild muscle atrophy consistent with recent denervation, endoneurial and perineurial edema, and mild mononuclear cell infiltration within intramuscular nerve branches and a peripheral nerve. Pedigree analysis suggests an autosomal recessive mode of inheritance, although neither a genetically complex/polygenic condition nor an acquired inflammatory polyneuropathy can be ruled-out.

CONCLUSIONS AND CLINICAL IMPORTANCE

We describe a motor polyneuropathy in juvenile Siberian cats characterized by self-limiting weakness with potential relapse.