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 containing calcium pyrophosphate (Ca-PP) and ß-tricalcium phosphate (ß-TCP) on cervical spinal fusion in a non-instrumented 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 approximately 2,6% of the surgeries. Synthetic bone graft (SBG) may enhance bony fusion and subsequently decrease the risk of pseudarthrosis. Recent studies on monetite-based synthetic bone grafts for use in large cranial defects in humans have shown promising bone healing results, necessitating further investigation of their use in cervical spinal fusion. METHODS: Four adult female Danish Göttingen mini-pigs 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 post-surgery, the animals were euthanized for further ex vivo qualitative histopathological and micro-CT evaluations. Fusion rates were compared using Fisher´s exact test at each time point. RESULTS: Increased interbody bony fusion rates were observed at synthetic bone graft levels (4/4) compared with control levels (0/4) evaluated by CT at 6- and 9-months post-surgery ( P = 0.029). Fusion was observed at all synthetic bone graft levels 12 months post-surgery and at only one control level. Histopathological evaluation confirmed high-quality interbody bony fusion at all synthetic bone graft levels, and fusion by spondylosis at one control level. CONCLUSION: This proof-of-concept study provides preliminary evidence of a novel, Ca-PP -and ß-TCP-containing monetite SBG that promotes bony fusion compared to a negative control in a clinically relevant porcine model of ACDF. LEVEL OF EVIDENCE: N/A.

Clinical Evaluation of a New Surgical Augmentation Technique for Transarticular Atlantoaxial Fixation for Treatment of Atlantoaxial Instability.

The feasibility of a newly developed augmentation of ventral fixation technique for surgical stabilization of atlantoaxial instability was clinically evaluated in a cohort of eleven dogs, and long-term clinical outcomes were retrospectively analyzed. The new technique combines wire/suture fixation through a transverse hole in the axis anchored by two screws placed in the alae atlantis or at the cranial end of plates used to bridge the atlantoaxial joint ventrally. A previous biomechanical study demonstrated good stability of this technique during shear loading, comparable to the stability achieved with other standard techniques. Ten dogs improved clinically after surgery and returned to a normal life within 3-6 months of surgery. One dog developed aphonia, dysphagia, and died of aspiration pneumonia three days after surgery. The augmentation of conventional ventral atlantoaxial fixation with the transverse bony corridor of the proximal axis body may be a valuable way to enhance stabilization of the atlantoaxial joint.

Surgical site infection after 769 Tibial Plateau Leveling Osteotomies.

Objective: To report surgical site infections (SSI) after Tibial Plateau Leveling Osteotomy (TPLO), treatment course, associated risk factors, bacterial isolates and antimicrobial resistance. Study design: Retrospective clinical cohort study. Study population: Six hundred and twenty seven dogs and 769 TPLO procedures. Methods: Data from electronic medical records of dogs undergoing TPLO between 2005 and 2015 at a single institution have been retrospectively reviewed. A generalized mixed logistic regression was used to determine possible risk factors. The Chi-Square test of independence was used to examine the relationship between the isolation of multidrug-resistant (MDR) bacteria and the development of major infections undergoing additional surgical treatment. To assess the correlation between number of SSI and number MDR isolate per year, Pearson's correlation coefficient was calculated. Results: The overall complication rate was 19.3% (n = 149). SSI was most frequent with 8.5% (n = 65). Major SSI occurred in 6.8% (n = 52) TPLO (80.0% SSI). Staphylococcus (S.) pseudintermedius (n = 37) and S. aureus (n = 10) were most frequently isolated. Multidrug-resistant bacteria were identified in 2.7% (n = 21) TPLO (32.3% SSI) but were not associated with major SSI (p = 0.426). There was a strong positive correlation between number of MDR isolates per year and number of SSI per year [r (9) = 0.79, p = 0.004]. Factors associated with SSI were previous TPLO in the contralateral stifle (p = 0.02, OR = 2.01, 95% CI = 1.11-3.64) and German Shepherd dogs (p = 0.035, OR = 4.41, 95% CI = 1.11-17.54). The use of non-locking implants was found to be protective (p = 0.02, OR = 0.179, 95% CI = 0.18-0.77). Clinical significance: Infection with multidrug-resistant bacteria is an emerging problem in veterinary practice and treatment is challenging. The incidence of major SSI was found to be high but was not associated with the isolation of MDR bacteria.

Bone formation beyond the skeletal envelope using calcium phosphate granules packed into a collagen pouch-a pilot study.

In this proof-of-concept, bone neoformation beyond the skeletal envelope is explored by using a collagen pouch (n= 6) packed with calcium phosphate (CaP) granules placed over the frontal bone in sheep (n= 3). At 13 weeks, macroscopic examination showed specimens covered by an adherent fibrinous envelope with slight vascularization. Histology revealed colonization of the implant by newly formed woven bone and fibrous connective tissue. Surface osteoblasts as well as material-filled macrophages, lymphocytes, polymorphonuclear cells and giant cells were also found in large quantities surrounding the newly formed bone tissue inside the collagen pouch. On the side facing the recipient bone, the collagen membrane had to a large extent been resorbed and bridging bone formation was clearly visible between the test article and recipient bone. On the other side facing soft tissue, the collagen pouch remained intact with a visible fibrous capsule. This study demonstrated that the use of a collagen sleeve as a container for CaP granules allows for good neoformation beyond the skeletal envelope with bridging bone formation clearly visible between the test article and recipient bone. Additionally, in this model, macrophages rather than osteoclasts appear to modulate CaP granule resorption and remodeling into new bone. This construct opens new perspectives for treatment methods that could be used for bone augmentation and restoration of cranio-maxillofacial defects and malformations.

Recurrence rate of intervertebral disc disease in surgically treated French Bulldogs: a retrospective study (2009-2019).

BACKGROUND: Intervertebral disc disease (IVDD) is a common diagnosis and well-investigated pathological condition in French Bulldogs with neurological deficiencies. However there is currently only one recently published retrospective descriptive study looking for recurrence rates of IVDD in French Bulldogs. Medical reports of French Bulldogs with a first episode of IVDD and surgical treatment were evaluated and reviewed for clinical signs of recurrence. Risk factors for Total-Recurrence, Cervical- and Thoracolumbar-Recurrence were evaluated by means of logistic regression models. The aim of this study was to assess frequency and risk factors associated with the recurrence of IVDD in French Bulldogs. RESULTS: One hundred twenty-seven French Bulldogs with a first episode of IVDD and surgical treatment were evaluated. 52.7% (67/127) of these patients showed signs of recurrence. The recurrence rate in the cervical spine was slightly lower (47%) compared to the thoracolumbar spine (56.6%). A significant association with recurrence could be found for the factor age: French Bulldogs with a first episode of IVDD ≤ 3 years seem to be prone for Total-Recurrence (P = 0.002) and Cervical-Recurrence (with ORs ranging from 0.02 to 0.03 for patients older than 3 years). 50% of the recurrences (median) occurred within the first 12 month after the first episode of IVDD. CONCLUSIONS: Recurrence of IVDD can be expected in more than half of French Bulldogs affected by IVDD. Especially young French Bulldogs are prone for recurrence in cervical spine. Almost every fourth patient with IVDD suffers from a recurrence within 12 months. Future dog owners should be informed about the risk of IVDD and the early onset of recurrences in French Bulldogs.

Immunization with a Multivalent Listeria monocytogenes Vaccine Leads to a Strong Reduction in Vertical Transmission and Cerebral Parasite Burden in Pregnant and Non-Pregnant Mice Infected with Neospora caninum.

Neospora caninum is an apicomplexan parasite that causes abortion and stillbirth in cattle. We employed the pregnant neosporosis mouse model to investigate the efficacy of a modified version of the attenuated Listeria monocytogenes vaccine vector Lm3Dx_NcSAG1, which expresses the major N. caninum surface antigen SAG1. Multivalent vaccines were generated by the insertion of gra7 and/or rop2 genes into Lm3Dx_NcSAG1, resulting in the double mutants, Lm3Dx_NcSAG1_NcGRA7 and Lm3Dx_NcSAG1_NcROP2, and the triple mutant, Lm3Dx_NcSAG1_NcGRA7_NcROP2. Six experimental groups of female BALB/c mice were inoculated intramuscularly three times at two-week intervals with 1 × 107 CFU of the respective vaccine strains. Seven days post-mating, mice were challenged by the subcutaneous injection of 1 × 105N. caninum NcSpain-7 tachyzoites. Non-pregnant mice, dams and their offspring were observed daily until day 25 post-partum. Immunization with Lm3Dx_NcSAG1 and Lm3Dx_NcSAG1_NcGRA7_NcROP2 resulted in 70% postnatal pup survival, whereas only 50% and 58% of pups survived in the double mutant-vaccinated groups. Almost all pups had died at the end of the experiment in the infection control. The triple mutant was the most promising vaccine candidate, providing the highest rate of protection against vertical transmission (65%) and CNS infection. Overall, integrating multiple antigens into Lm3Dx_SAG1 resulted in lower vertical transmission and enhanced protection against cerebral infection in dams and in non-pregnant mice.

Endoscopy-assisted resection of a sphenoid-wing meningioma using a 3D-printed patient-specific pointer in a dog: A case report.

A 9-year-old female mixed-breed dog presented for treatment of a presumed sphenoid-wing meningioma. Clinical signs included tonic-clonic seizures lasting <1 min, which had started 3 months previously. The physical examination results were unremarkable. An eccentrically located neoplastic cystic structure in the right sphenoid bone region suggestive of a meningioma and peritumoural brain oedema was observed in pre-operative magnetic resonance imaging (MRI). Prior to surgery, a three-dimensional (3D) patient-specific pointer (PSP) was designed using computed tomography (CT) images and computer-aided 3D design software. After a targeted approach and exposure of the lateral part of the right temporal lobe by a craniectomy guided by the 3D-PSP, complete macroscopic piecemeal resection of the meningioma could be performed using endoscopy-assisted brain surgery. Post-operative MRI confirmed complete excision of the tumor. Anticonvulsive therapy was discontinued after 90 days, and the dosage of anticonvulsants was tapered 2 weeks after surgery. At a follow-up examination 225 days post-operatively, recurrence of seizures was not observed, and the absence of tumor recurrence was confirmed by a repeat MRI examination. To the best of our knowledge, this is the first report in veterinary medicine describing a successful resection of a sphenoid-wing meningioma using a 3D-PSP. 3D-PSP-assisted craniectomy may be a surgical option for some canine skull-based tumors, such as sphenoid wing meningiomas.

Preliminary Studies on the Intrahepatic Anatomy of the Venous Vasculature in Cats.

Hepatic surgeries are often performed in cats to obtain a disease diagnosis, for the removal of masses, or for the treatment of shunts. Whereas the vascular anatomy of the liver has been studied in dogs, such evidence is lacking in cats. The current study used corrosion casts of portal and hepatic veins and computed tomography (CT) analysis of the casts to identify and describe the intrahepatic anatomy in healthy cat livers (n = 7). The results showed that feline livers had a consistent intrahepatic portal and venous anatomy, with only minor disparities in the numbers of secondary and tertiary branches. The feline portal vein consistently divided into two major branches and not three, as previously described in the literature for cats. The finding of a portal vein originating from the right medial lobe branch leading to the quadrate lobe in 4/7 specimens is a novelty of the feline anatomy that was not previously described in dogs. Partial to complete fusion of the caudate process of the caudate and the right lateral lobe, with a lack of clear venous separation between the lobes, was present in two specimens. These findings allowed a detailed description of the most common intrahepatic venous patterns in cats. Further anatomical studies should be encouraged to confirm the present findings and to investigate the utility of this information in surgical settings.

Novel transforaminal approach allows surgical decompression of an atlantoaxial band in dogs: a cadaveric study and clinical cases.

OBJECTIVES: To describe a novel transforaminal approach for surgical excision of the atlantoaxial (AA) band and examine its feasibility, safety, and mechanical advantages in an ex vivo study and clinical cases. SAMPLES: 26 canine cadavers and 2 canine patients with AA bands. PROCEDURES: The transforaminal approach via the first intervertebral foramen was designed to avoid damaging the dorsal AA ligament (DAAL) and dorsal laminas to maintain joint stability. The cadaveric study started on December 2020 and lasted 3 months. The ligamentum flavum (LF) was removed using a novel approach; then, gross examination was conducted to verify the potential damage to the spinal cord and associated structures and the adequacy of LF removal. Subsequently, the ex vivo tension test of the DAAL was conducted to establish whether the approach induced mechanical damage to the ligaments. Finally, 2 dogs diagnosed with an AA band were surgically treated with the transforaminal approach. RESULTS: In the cadaveric study, postsurgical evaluation verified the subtotal removal of LF without damage to the dura mater. There were no significant differences in the mechanical properties of the DAAL, including the ultimate strength (P = .645) and displacement (P = .855), between the surgical and intact groups during the ex vivo tension test. In clinical cases, clinical signs and neurologic grades improved until the final follow-up. CLINICAL RELEVANCE: The described surgical procedure using a transforaminal approach appears to sufficiently permit the removal of an AA band while reducing damage to the DAAL and spinal cord. Our study highlights the feasibility of the transforaminal approach.

Evaluation of Paraspinal Musculature in Small Breed Dogs with and without Atlantoaxial Instability Using Computed Tomography.

OBJECTIVE: The aim of this study was to evaluate differences in paraspinal musculature between dogs with and without atlantoaxial instability (AAI) using computed tomography scans. STUDY DESIGN: Retrospective multicentre study evaluating transverse reconstructed computed tomography scans of 83 small breed dogs (34 with and 49 without AAI) for the cross-sectional paraspinal musculature area at three levels (Occiput/C1, mid-C1, mid-C2). Ratio of moments, dorsal-to-ventral muscle-area ratios (d-v-ratio) and ratios of the dorsal and ventral musculature to C2 height (d-C2-ratio and v-C2-ratio) were evaluated for differences between groups using multivariate analysis of variance (p < 0.05) taking the head-neck position into account. RESULTS: Dogs with AAI showed a significantly lower d-v-ratio at levels 2 and 3, d-C2-ratio at level 2 and ratio of moments at all levels. When head-neck positions were analysed separately, ratio of moments was significantly lower in affected dogs at level 1 and 2. Also lower was d-C2-ratio at level 2, but only in flexed positioning. The head-neck position had a significant influence on ratio of moments and d-v-ratio at all three levels and on d-C2-ratio at level 1. CONCLUSION: Significant changes in muscle area were observed only for the hypaxial muscles at the C1 level, indicating a limited role of muscular adaption in AAI patients. Our results confirm an altered ratio of moments in dogs with AAI. The head-neck position has a significant impact and should be taken into account when evaluating spinal musculature.

Accuracy and Safety of Neuronavigation for Minimally Invasive Stabilization in the Thoracolumbar Spine Using Polyaxial Screws-Rod: A Canine Cadaveric Proof of Concept.

OBJECTIVES: The main aim of this study was to evaluate the feasibility of minimally invasive stabilization with polyaxial screws-rod using neuronavigation and to assess accuracy and safety of percutaneous drilling of screw corridors using neuronavigation in thoracolumbar spine and compare it between an experienced and a novice surgeon. STUDY DESIGN: Feasibility of minimally invasive polyaxial screws-rod fixation using neuronavigation was first performed in the thoracolumbar spine of two dogs. Accuracy and safety of drilling screw corridors percutaneously by two surgeons from T8 to L7 in a large breed dog using neuronavigation were established by comparing entry and exit points coordinates deviations on multiplanar reconstructions between preoperative and postoperative datasets and using a vertebral cortical breach grading scheme. RESULTS: Feasibility of minimally invasive stabilization was demonstrated. For the experienced surgeon, safety was 100% and mean (standard deviation) entry point deviations were 0.3 mm (0.8 mm) lateral, 1.3 mm (0.8 mm) ventral and 0.7 mm (1.8 mm) caudal. The exit points deviations were 0.8 mm (1.9 mm) lateral, 0.02 mm (0.9 mm) dorsal and 0.7 mm (2.0 mm) caudal. Significant difference in accuracy between surgeons was found in the thoracic region but not in the lumbar region. Accuracy and safety improvement are noted for the thoracic region when procedures were repeated by the novice. CONCLUSION: This proof of concept demonstrates that using neuronavigation, minimally invasive stabilization with polyaxial screws-rod is feasible and safe in a large breed dog model.

Determination of cutoff values on computed tomography and magnetic resonance images for the diagnosis of atlantoaxial instability in small-breed dogs.

OBJECTIVE: To determine cutoff values for the diagnosis of atlantoaxial instability (AAI) based on cross-sectional imaging in small-breed dogs. STUDY DESIGN: Retrospective multicenter study. SAMPLE POPULATION: Client-owned dogs (n = 123) and 28 cadavers. METHODS: Dogs were assigned to three groups: a control group, a "potentially unstable" group, and an AAI-affected group, according to imaging findings and clinical signs. The ventral compression index (VCI), cranial translation ratio (CTR), C1-C2 overlap, C1-C2 angle, atlantoaxial distance, basion-dens interval, dens-to-axis length ratio (DALR), power ratio, and clivus canal angles were measured on CT or T2-weighted magnetic resonance (MR) images. Receiver operating characteristic (ROC) analysis was performed to define cutoff values in flexed (≥25°) and extended (<25°) head positions. RESULTS: Cutoff values for the VCI of ≥0.16 in extended and ≥0.2 in flexed head positions were diagnostic for AAI (sensitivity of 100% and 100%, specificity of 94.54% and 96.67%, respectively). Cutoff values for the other measurements were defined with a lower sensitivity (75%-96%) and specificity (70%-97%). A combination of the measurements did not increase the sensitivity and specificity compared with the VCI as single measurement. CONCLUSION: Cutoff values for several imaging measurements were established with good sensitivity and specificity. The VCI, defined as the ratio between the ventral and dorsal atlantodental interval, had the highest sensitivity and specificity in both head positions. CLINICAL SIGNIFICANCE: The use of defined cutoff values allows an objective diagnosis of AAI in small-breed dogs. The decision for surgical intervention, however, should remain based on a combination of clinical and imaging findings.

Clinical signs, MRI findings and long-term outcomes of foraminal and far lateral thoracolumbar intervertebral disc herniations in dogs.

BACKGROUND: As they have been seldomly described in the veterinary literature, the aims of this retrospective study were to describe the clinical presentation, MRI findings and long-term outcome after medical or surgical treatment of dogs presenting with foraminal and far lateral thoracolumbar intervertebral disc herniations. METHODS: Retrospective multicentre study of dogs diagnosed with foraminal and far lateral thoracolumbar intervertebral disc herniations between 2009 and 2020 in seven referral hospitals. RESULTS: Thirty-seven dogs were included. Dachshunds and mixed breeds were most affected. Median age at presentation and duration of clinical signs were 6 years and 14 days, respectively. Pain was the most frequent clinical finding (92%), particularly on spinal palpation and/or hip manipulation, followed by pelvic limb lameness (71%). Eighty-seven percent of herniations occurred at L5-L6 or L6-L7. A good to excellent outcome was seen in 95% of surgically and 90% of medically treated dogs. CONCLUSION: Although much less frequently recognised than herniation affecting the vertebral canal, foraminal and far lateral thoracolumbar intervertebral disc herniations should be considered in the differential diagnosis list of chondrodystrophic dogs presenting with pain and pelvic limb lameness. Most dogs had a good to excellent outcome following medical or surgical treatment.

Effect of dog-related parameters on the flexion test outcome: A large cohort retrospective study on physiological and orthopedic pathological-related factors.

Objectives: This retrospective study evaluates the dog-related factors of variation influencing the outcome of the flexion test (FT), when performed to localize pain to a joint area, on a large group of canine orthopedic patients. Materials and methods: The selection criteria for this retrospective study were dogs undergoing a FT in a referral orthopedic clinic between 2009 and 2020 with a complete medical record. The canine FT, described in a previously published protocol, was performed on dogs presented with an orthopedic problem. In summary, a dog's joint, identified as suspected of an orthopedic problem according to the clinical examination, was flexed for 1 min before walking 15 m on a hard and even surface. The FT was considered positive if the lameness increased after the application of the FT and negative when it remained unchanged. Statistical analysis was performed to determine which of the following criteria could influence the outcome of the flexion test: age, gender, neutered status, weight category, tested joint and initial lameness score. Results: Over 1,161 patients' files were collected and analyzed for this research. The FT showed 82.8% (95%IC: 80.5-84.9) of true positives and 17.2% of false negatives. None of the patient's intrinsic characteristics influenced the outcome of the test (age, gender, neutered status, and weight category). The orthopedic parameters, such as the initial lameness score and the tested joint, showed to have a statistically significant influence on the outcome of the test. Clinical relevance: The FT is an easy-to-perform technique presenting reliable results on most joints. This test presents an interest when performed in addition to a complete orthopedic examination to localize pain to a joint area. Only the orthopedic pathological-related parameters such as the lameness score and the tested joint seem to influence the outcome of the FT. The FT is not influenced by the physiological-related characteristic of the patient (age, weight category, sex, and neutered status).

Epidemiological study of congenital malformations of the vertebral column in French bulldogs, English bulldogs and pugs.

BACKGROUND: Congenital vertebral body malformations (CVBMs) have retrospectively been investigated in British and American canine populations. This study prospectively evaluates occurrence, localization, type and characteristic of CVBM along the entire vertebral column in a cohort of French Bulldogs, English Bulldogs and Pug dogs from Germany. METHODS: Prospective clinical and radiological screenings for CVBM were performed in brachycephalic dogs presented for reasons unrelated to neurological problems. Neurological and orthopaedic examinations as well as radiographs in two orthogonal planes of the entire vertebral column including the tail were performed in all dogs. Cobb angle and vertebral step were determined. Associations between CVBM, tail malformation, neurological deficits and occurrence of concurrent orthopaedic diseases were investigated. RESULTS: A total of 707 VBMs were identified in the whole vertebral column of 169 of 265 brachycephalic dogs. The most common types of CVBMs were ventral wedge shape (48%), dorsal wedge shape (14%) and shortened vertebral body (14%). A new type of malformation was investigated: dorsal wedge shape vertebrae. There was significant association between severe tail malformations with CVBM. Neurological deficits were significantly associated with ventrolateral wedge shape, dorso lateral hemivertebrae, Cobb angle > 30% and vertebral step ≥1.75 mm. Orthopaedic conditions were not significantly associated with CVBM. CONCLUSION: Kyphotic Cobb angle and vertebral step are radiological findings associated with neurological deficits. We propose severe tail malformation as an easy and accurate selection factor for determining breeding dogs.

Novel immortalization approach defers senescence of cultured canine adipose-derived mesenchymal stromal cells.

In the last decades, the scientific community spared no effort to elucidate the therapeutic potential of mesenchymal stromal cells (MSCs). Unfortunately, in vitro cellular senescence occurring along with a loss of proliferative capacity is a major drawback in view of future therapeutic applications of these cells in the field of regenerative medicine. Even though insight into the mechanisms of replicative senescence in human medicine has evolved dramatically, knowledge about replicative senescence of canine MSCs is still scarce. Thus, we developed a high-content analysis workflow to simultaneously investigate three important characteristics of senescence in canine adipose-derived MSCs (cAD-MSCs): morphological changes, activation of the cell cycle arrest machinery, and increased activity of the senescence-associated ß-galactosidase. We took advantage of this tool to demonstrate that passaging of cAD-MSCs results in the appearance of a senescence phenotype and proliferation arrest. This was partially prevented upon immortalization of these cells using a newly designed PiggyBac™ Transposon System, which allows for the expression of the human polycomb ring finger proto-oncogene BMI1 and the human telomerase reverse transcriptase under the same promotor. Our results indicate that cAD-MSCs immortalized with this new vector maintain their proliferation capacity and differentiation potential for a longer time than untreated cAD-MSCs. This study not only offers a workflow to investigate replicative senescence in eukaryotic cells with a high-content analysis approach but also paves the way for a rapid and effective generation of immortalized MSC lines. This promotes a better understanding of these cells in view of future applications in regenerative medicine.

Comparison of Dorsal-to-Ventral Ratios of the Cervical Paraspinal Musculature in French Bulldogs With and Without Cervical Intervertebral Disk Disease and Two Other Breeds Based on CT Scan Measurements.

Objective: To objectively assess the cervical paraspinal musculature of French bulldogs (FBs) using computed tomography (CT) scan-based measurements, outline differences in other breeds published in the literature, and investigate the potential influence of its cervical paraspinal musculature on predisposed sites for intervertebral disk disease. Animals: Thirty FBs that underwent CT scans of the cervical spine from the skull to C7/T1 were enrolled. Fifteen dogs were patients suffering from intervertebral disk herniation (IVDH group), and 15 dogs underwent CT scans due to brachycephalic obstructive airway syndrome (BOAS group). Methods: At the level of each cervical intervertebral disk from C2/C3 to C7/T1, measurements were performed and statistically analyzed. On the sagittal CT scan reconstruction, the height ratio of the dorsal to ventral paraspinal musculature and the angle of the disk axis to vertebral body length were assessed. On the transverse plane, the area ratio of the dorsal and ventral paraspinal musculature and the ratio of force moments were determined at each intervertebral disk level. Finally, ratios were compared to the values of Labrador retrievers and dachshunds published by Hartmann et al. (1). Results: Comparing the two FB groups, one significant difference was detected in the mean height ratio of the dorsal to ventral paraspinal musculature at the level of C5/C6 (P = 0.0092) and C6/C7 (P = 0.0076), with IVDH FBs having the more prominent dorsal paraspinal musculature. At the level of C3/C4, a significantly less prominent dorsal paraspinal musculature in FBs than in dachshunds (P = 0.0058) and a significantly steeper disk to vertebral body angulation were observed (P = 0.0005). Conclusion: Although some incidental differences were found, most parameters did not significantly differ between the BOAS and IVDH FBs. Significant conformational differences in the cervical paraspinal musculature and disk to vertebral body length angulation were found between FBs and two other breeds (chondrodystrophic and non-chondrodystrophic). This study's findings suggest that the paraspinal musculature is an additional biomechanical influencing factor on the preferential sites of IVDH in the cervical spine and that other major factors exist in IVDH development, especially in FBs.

Safety of a Novel Listeria monocytogenes-Based Vaccine Vector Expressing NcSAG1 (Neospora caninum Surface Antigen 1).

Listeria monocytogenes (LM) has been proposed as vaccine vector in various cancers and infectious diseases since LM induces a strong immune response. In this study, we developed a novel and safe LM-based vaccine vector platform, by engineering a triple attenuated mutant (Lm3Dx) (ΔactA, ΔinlA, ΔinlB) of the wild-type LM strain JF5203 (CC 1, phylogenetic lineage I). We demonstrated the strong attenuation of Lm3Dx while maintaining its capacity to selectively infect antigen-presenting cells (APCs) in vitro. Furthermore, as proof of concept, we introduced the immunodominant Neospora caninum (Nc) surface antigen NcSAG1 into Lm3Dx. The NcSAG1 protein was expressed by Lm3Dx_SAG1 during cellular infection. To demonstrate safety of Lm3Dx_SAG1 in vivo, we vaccinated BALB/C mice by intramuscular injection. Following vaccination, mice did not suffer any adverse effects and only sporadically shed bacteria at very low levels in the feces (<100 CFU/g). Additionally, bacterial load in internal organs was very low to absent at day 1.5 and 4 following the 1st vaccination and at 2 and 4 weeks after the second boost, independently of the physiological status of the mice. Additionally, vaccination of mice prior and during pregnancy did not interfere with pregnancy outcome. However, Lm3Dx_SAG1 was shed into the milk when inoculated during lactation, although it did not cause any clinical adverse effects in either dams or pups. Also, we have indications that the vector persists more days in the injected muscle of lactating mice. Therefore, impact of physiological status on vector dynamics in the host and mechanisms of milk shedding requires further investigation. In conclusion, we provide strong evidence that Lm3Dx is a safe vaccine vector in non-lactating animals. Additionally, we provide first indications that mice vaccinated with Lm3Dx_SAG1 develop a strong and Th1-biased immune response against the Lm3Dx-expressed neospora antigen. These results encourage to further investigate the efficiency of Lm3Dx_SAG1 to prevent and treat clinical neosporosis.

Biomechanical evaluation of two dorsal and two ventral stabilization techniques for atlantoaxial joint instability in toy-breed dogs.

OBJECTIVE: To compare the biomechanical properties of atlantoaxial joints (AAJs) in canine vertebral column specimens stabilized with 4 techniques (dorsal wire, modified dorsal clamp, ventral transarticular pin, and augmented ventral transarticular pin fixation) after transection of the AAJ ligaments. SAMPLE: 13 skull and cranial vertebral column segments from 13 cadaveric toy-breed dogs. PROCEDURES: Vertebral column segments from the middle aspect of the skull to C5 were harvested and prepared; AAJ ligament and joint capsule integrity was preserved. The atlantooccipital joint and C2 to C5 vertebral column segments were fixed with 2 transarticular Kirschner wires each. The occipital bone and caudalmost aspect of each specimen were embedded in polymethylmethacrylate. Range of motion of the AAJ under shear loading conditions up to 15 N was determined for each specimen during the third of 3 loading cycles with intact ligaments, after ligament transection, and after stabilization with each technique in random order. For each specimen, a load-to-failure test was performed with the fixation type tested last. RESULTS: All stabilization techniques except for dorsal clamp fixation were associated with significantly decreased AAJ range of motion, compared with results when ligaments were intact or transected. The AAJs with dorsal wire, ventral transarticular pin, and augmented ventral transarticular pin fixations had similar biomechanical properties. CONCLUSIONS AND CLINICAL RELEVANCE: Dorsal wire, ventral transarticular pin, and augmented ventral transarticular pin fixation increased rigidity, compared with results for AAJs with intact ligaments and for AAJs with experimentally created instability. Additional studies are needed to assess long-term stability of AAJs stabilized with these techniques.

Investigation of timing of surgery and other factors possibly influencing outcome in dogs with acute thoracolumbar disc extrusion: a retrospective study of 1501 cases.

BACKGROUND: Intervertebral disc extrusions in the thoracolumbar region are a common spinal neurologic disorder in dogs and usually considered a neurological emergency. Several factors, like timing of surgery, have previously been analysed in order to determine the effect on outcome and time of recovery. Most studies have investigated one defined population of dogs and the influence of a single factor on the overall outcome. In this retrospective study, a large cohort of dogs and the influence of one or combinations of several factors on outcome and time of recovery were analysed. RESULTS: The bivariate analysis demonstrated a significant association between the following variables and the time of recovery: the time span between the onset of clinical signs and surgery (Cramers Phi [Formula: see text] = 0.14; P = 0.003), the grade of severity ([Formula: see text] = 0.23; P < 0.001) and the implementation of physical rehabilitation ([Formula: see text] = 0.2; P < 0.001). However, the analysis of a multivariable regression model demonstrated that a significant correlation only exists between the time span between the onset of clinical signs and surgery and the overall outcome (P = 0.007), as well as between the grade of severity and the time of recovery (P < 0.001). The percentage of dogs with lacking deep pain perception (DPP) that had to be euthanised due to their neurological condition, decreased from 20.0 to 2.9% when physical rehabilitation was implemented. Additionally, the proportion of dogs (same group) that improved to reach an ambulatory status increased from 80.0 to 91.4%. CONCLUSION: The results of the bivariate analysis demonstrated several correlations between some variables and overall outcome or time of recovery, whereas the multivariable regression model demonstrated only two associations. The time span between the onset of clinical signs and surgery was significantly associated with the overall outcome. We therefore suggest that a surgical intervention should be performed without unreasonable delay. Due to the correlation between the grade of severity and time of recovery, owners of dogs with more severe neurological deficits prior to surgery should be informed about the presumably prolonged time of recovery.