Closure of the neuro-central synchondrosis and other physes in foal cervical spines.

BACKGROUND: The neuro-central synchondrosis (NCS) is a physis responsible for the growth of the dorsal third of the vertebral body and neural arches. When the NCS of pigs is tethered to model scoliosis, stenosis also ensues. It is necessary to describe the NCS for future evaluation of its potential role in equine spinal cord compression and ataxia (wobbler syndrome). OBJECTIVES: To describe the NCS, including when it and other physes closed in computed tomographic (CT) scans of the cervical spine of foals, due to its potential role in vertebral stenosis. STUDY DESIGN: Post-mortem cohort study. METHODS: The cervical spine of 35 cases, comprising both sexes and miscellaneous breeds from 153 gestational days to 438 days old, was examined with CT and physes scored from 6: fully open to 0: fully closed. The dorsal physis, physis of the dens and mid-NCS were scored separately, whereas the cranial and caudal NCS portions were scored together with the respective cranial and caudal vertebral body physes. RESULTS: The NCS was a pair of thin physes located in a predominantly dorsal plane between the vertebral body and neural arches. The mid-NCS was closed in C1 from 115 days of age, and in C2-C7 from 38 days of age. The dorsal physis closed later than the NCS in C1, and earlier than the NCS in C2-C7. The dens physis was closed from 227 days of age. The cranial and caudal physes were closing, but not closed from different ages in the different vertebrae of the oldest cases. MAIN LIMITATIONS: Hospital population. CONCLUSIONS: The NCS was a thin physis that contributed mainly to height-wise growth, but also width- and length-wise growth of the vertebral body and neural arches. The mid-NCS was closed in all cervical vertebrae from 115 days of age. The NCS warrants further investigation in the pathogenesis of vertebral stenosis.

HISTORIAL: La sincondrosis neuro­central (NCS) es la fisis responsable del crecimiento del tercio dorsal del cuerpo vertebral y de los arcos neurales. Cuando la NCS en cerdos se asocia a un modelo de escoliosis, también se produce estenosis. Es necesario describir la NCS para la futura evaluación de su rol potencial en la comprensión de la medula espinal equina y ataxia (síndrome de Wobbler). OBJETIVOS: Describir la NCS incluyendo cuando ella y otras fisis se cierran, por tomografía computarizada (CT) de la columna cervical de potrillos, debido a su rol potencial en la estenosis vertebral. DISEÑO DEL ESTUDIO: Estudio de cohorte post­mortem. MÉTODOS: La columna cervical de 35 casos, incluyendo ambos sexos y diferentes razas, desde 153 días gestacionales hasta 438 días de edad, fueron examinadas por CT y las fisis fueron dadas un puntaje de, 6: completamente abiertas a, 0: completamente cerradas. La fisis dorsal, la fisis del hueso odontoides y NCS media fueron evaluadas en forma separada, mientras las porciones de NCS craneal y caudal fueron evaluadas juntas con las respectiva fisis del cuerpo vertebral craneal y caudal. RESULTADOS: La NCS es un par de fisis delgadas localizadas predominantemente en el plano dorsal entre el cuerpo vertebral y los arcos vertebrales. La NCS media estaba cerrada en C1 desde los días 115 de edad, y en C2­C7 a partir de los 38 días de edad. La fisis dorsal se cerró más tarde que la NCS en C1, y antes que la NCS en C2­C7. La fisis del hueso odontoides estaba cerradas a partir de los 227 días de edad. Las fisis craneal y caudal estaban cerrándose, pero no estaban cerradas a distintas edades en las diferentes vertebras en los casos mayores de edad. LIMITACIONES PRINCIPALES: Población de hospital CONCLUSIONES: La NCS es una fisis delgada que contribuye principalmente al crecimiento en altura, pero también en ancho y largo del cuerpo vertebral y arcos vertebrales. La NCS media estaba cerrada en todas las vértebras cervicales a partir de los 115 días de edad. La NCS merece ser investigada más en la patogénesis de la estenosis vertebral. Palabras Clave: ataxia, tomografía computarizada, caballo, osteocondrosis, estenosis, crecimiento vertebral.

Detection and Phylogenetic Analysis of Orf Virus and Muskox Rhadinovirus 1 from Muskoxen (Ovibos moschatus) in the Canadian Arctic.

Orf virus (genus Parapoxvirus) has been associated with gross skin lesions on muskoxen (Ovibos moschatus) from Victoria Island, Nunavut, Canada, where muskox populations are experiencing population declines. Orf virus causes painful proliferative and necrotizing dermatitis upon viral replication and shedding, which may lead to animal morbidity or mortality through secondary infections and starvation. Herpesvirus, known to cause gross lesions on skin and mucosa during active viral replication, has also been documented in muskoxen but to date has not been associated with clinical disease. Our objective was to characterize the variation of orf virus and herpesvirus in wild muskoxen of the Canadian Arctic. Tissue samples including gross skin lesions from the nose, lips, and/or legs were opportunistically collected from muskoxen on Victoria Island, Nunavut and Northwest Territories, and mainland Nunavut, Canada, from 2015 to 2017. Sampled muskoxen varied in age, sex, location, hunt type, and body condition. Tissues from 60 muskoxen were tested for genetic evidence of orf virus and herpesvirus infection using PCR targeting key viral genes. Tissues from 38 muskoxen, including 15 with gross lesions, were also examined for histological evidence of orf virus and herpesvirus infection. Eleven muskoxen (10 from Victoria Island and one from mainland Nunavut) with gross lesions had microscopic lesions consistent with orf virus infection. Muskox rhadinovirus 1, a gammaherpesvirus endemic to muskoxen, was detected in 33 (55%) muskoxen including 17 with gross lesions. In all tissues examined, there was no histological evidence of herpesvirus-specific disease. Sequencing and characterization of amplified PCR products using phylogenetic analysis indicated that a strain of orf virus, which appears to be unique, is likely to be endemic in muskoxen from Victoria Island and mainland Nunavut. Many of the muskoxen are also subclinically infected with a known muskox-endemic strain of herpesvirus.

Novel Calcium Phosphate Promotes Interbody Bony Fusion in a Porcine Anterior Cervical Discectomy and Fusion Model.

STUDY DESIGN: Experimental porcine anterior cervical discectomy and fusion (ACDF) model: a proof-of-concept study. OBJECTIVE: The effect of monetite synthetic bone graft (SBG) containing calcium pyrophosphate and ß-tricalcium phosphate on cervical spinal fusion in a noninstrumented two-level large animal model. SUMMARY OF BACKGROUND DATA: ACDF is the gold standard surgical technique for the treatment of degenerative cervical spinal diseases. However, pseudarthrosis associated with increased patient morbidity occurs in ∼2.6% of the surgeries. SBG may enhance bony fusion and subsequently decrease the risk of pseudarthrosis. Recent studies on monetite-based SBGs for use in large cranial defects in humans have shown promising bone healing results, necessitating further investigation of their use in cervical spinal fusion. MATERIALS AND METHODS: Four adult female Danish Göttingen minipigs received partial cervical anterior discectomy and intervertebral defects at an upper and lower level. One defect was filled with SBG, and the other was left empty. Bony fusion was evaluated using computed tomography (CT) at three-month intervals for 12 months. Fifteen months postsurgery, the animals were euthanized for further ex vivo qualitative histopathologic and micro-CT evaluations. Fusion rates were compared using the Fisher exact test at each time point. RESULTS: Increased interbody bony fusion rates were observed at SBG levels (4/4) compared with control levels (0/4) evaluated by CT at 6 and 9 months postsurgery ( P =0.029). Fusion was observed at all SBG levels 12 months postsurgery and at only one control level. Histopathologic evaluation confirmed high-quality interbody bony fusion at all SBG levels and fusion by spondylosis at one control level. CONCLUSION: This proof-of-concept study provides preliminary evidence of a novel, calcium pyrophosphate-containing, and ß-tricalcium phosphate-containing monetite SBG that promotes bony fusion compared with a negative control in a clinically relevant porcine model of ACDF.