Hereditary myotonia in cats associated with a new homozygous missense variant p.Ala331Pro in the muscle chloride channel ClC-1.

Three-related cats were evaluated for a history of short-strided gait and temporary recumbency after startle. Neurological examination, electromyography (EMG), muscle biopsies, and a chloride voltage-gated channel 1 (CLCN1) molecular study were performed. Clinically, all 3 cats presented myotonia with warm-up phenomenon and myotonic discharges during EMG examination. Muscle biopsies showed normal muscle architecture and variation in the diameter of myofiber size with the presence of numerous hypertrophic fibers. The molecular study revealed a missense variant (c.991G>C, p.Ala331Pro) in exon 9 of the CLCN1 gene, responsible for the first chloride channel extracellular loop. This mutation was screened in 104 control phenotypically normal unrelated cats, and all were wildtype. The alanine at this position is conserved in ClC-1 (chloride channel protein 1) in different species, and 2 mutations at this amino acid position are associated with human myotonia. This is the third CLCN1 mutation described in the literature associated with hereditary myotonia in cats and the first in domestic animals located in an extracellular muscle ClC-1 loop.

Hereditary myotonia in American Bulldog associated with a novel frameshift mutation in the CLCN1 gene.

Hereditary myotonia (HM) is a genetic disorder that occurs due to mutations in the chloride channel and results in delayed relaxation of the skeletal muscles. HM has been described in 12 dog breeds, and in five of them, molecular studies of this disorder were performed and mutations in the CLCN1 gene were described. In this study, an affected American Bulldog with HM clinically characterized by muscle hypertrophy, myotonic discharges, and nondystrophic myotonia with a "warm-up" phenomenon was evaluated, and the candidate canine CLCN1 gene was sequenced. The molecular analysis revealed a frameshift mutation NM_001003124.2:c.436_437insCTCT that resulted in a frameshift and a premature stop codon NP_001003124.1:pTyr146SerfsTer49 . Two aberrant alternative CLCN1 transcripts were observed in an affected dog, the expected transcript with the 4 bp insertion, NM_001003124.2:r.436_437insctct, and an unexpected transcript containing parts of intron 6 in addition to the insertion in exon 4, NM_001003124.2:[r.436_437insctct;r.774_775ins79]. In conclusion, the frameshift mutation in the CLCN1 gene is associated with autosomal recessive HM in American Bulldog and this study constitutes the first description of the disease in this breed.

Uso da cola n-butil cianoacrilato na sulcoplastia de recessäo em coelhos: avaliaçäo histológica / Use of n-butyl cyanoacrylate glue in the recession sulcoplasty in rabbits: histologic study

O trabalho teve por objetivos analisar a cola composta por n-butil cianoacrilato, como um auxiliar na fixaçäo da cunha óssea no procedimento da sulcoplastia de recessäo e sua interferência no processo cicatricial. Foram utilizados nove coelhos da raça Norfolk, machos, com peso inicial entre 3,0 e 3,5 kg. Após anestesia epidural, realizou-se acesso parapatelar medial e seccionou-se uma cunha ósseo-cartilaginosa em formato de V no sulco da tróclea. No joelho direito, antes da colocaçäo da cunha em seu leito, foram aplicadas duas gotas da cola, ao passo que, no joelho esquerdo, considerado controle, a cunha foi apenas recolocada. Para realizaçäo da técnica de exame anatomopatológico, foram submetidos à eutanásia três animais aos cinco, 15 e 30 dias de pós-operatório. Na avaliaçäo macroscópica, notou-se, em ambos os joelhos, a estabilizaçäo da cunha ósseo-cartilaginosa em seu leito receptor nos diferentes momentos de observaçäo. Pelo exame histológico foi possível concluir que a cola näo induziu o aparecimento de processo inflamatório acentuado e reaçäo do tipo corpo estranho, mas interferiu negativamente, retardando o processo cicatricial.

Avaliação eletroneuromiográfica em gatos normais e submetidos ao hiperparatireoidismo secundário nutricional / Electroneuromyographic evaluation in healthy cats and in those submitted to the nutritional secondary hyperparathyroidism

O trabalho teve por objetivos estudar a condução nervosa motora e a transmissão neuromuscular e eletromiografia de repouso em gatos normais (grupo I), submetidos a hiperparatireoidismo secundário nutricional (grupo II). Para estudo normativo (grupo I), foram utilizados 10 gatos, aparentemente saudáveis, sem raça definida, sendo seis machos e quatro fêmeas, com idades entre 4 e 5 meses e peso médio de 1,67kg. No grupo II, empregaram-se 10 gatos, sem raça definida, sendo cinco machos e cinco fêmeas, com idade aproximada inicial entre 2 e 3 meses e peso inicial médio de 820 gramas. Após um período de adaptação de 10 dias, foram alimentados por 60 dias com coração bovino moído e cru, visando a indução de hiperparatireoidismo secundário nutricional. Foi possível concluir que latência, amplitude e velocidade de condução nervosa motora e os achados eletromiográficos das atividades insercional e espontânea de gatos com hiperparatireoisdismo secundário nutricional, apresentaram um padrão similar aos de gatos normais da mesma idade. Para estimulações repetitivas a 3Hz, observou-se tendência global a decremento dos potenciais de ação musculares compostos e a 10 Hz houve tendência de incremento ou decremento; entretanto, tais variações apresentaram-se dentro dos limites de normalidade.

The aim of this study was to evaluate the motor nerve conduction velocity, neuromuscular transmission, and electromyography at rest in healthy cats (group I) and in cats submitted to the nutritional secondary hyperparathyroidism (group II). Ten mongrel cats, six males and four females, aged between 4 and 5 months and average body weight of 1.67 kg were used to establish normal pattern (group I). Ten mongrel cats, five males and five females, initial age between 2 and 3 months, old and initial body weight of 820 grams were used in group II. After 10 days of adaptation period, the group II animals were fed with raw heart beef for 60 days to induce the nutritional secondary hyperparathyroidism. It was possible to conclude that the motor nerve conduction velocity, and electromyographic findings of insertional and spontaneous activities of cats with nutritional secondary hyperparathyroidism showed similar pattern to healthy cats at the same age. Using repetitive stimulation at 3Hz it was observed global tendency to decrement of the compound muscle action potentials, and using repetitive stimulation at 10Hz a tendency to decrement or increment occurred; though, the variations were at normal limit.