Refractory Inappropriate Sinus Tachycardia Treated with Pulsed-field Ablation of the Sinus Node: A Breath of Fresh Air.

The pathogenesis of inappropriate sinus tachycardia is not well understood, and the symptoms of inappropriate sinus tachycardia can be difficult to manage. Here, we present a case of inappropriate sinus tachycardia refractory to medical therapy and discuss our approach to sinus node modification by catheter ablation.

Silent pulmonary veins at redo ablation for atrial fibrillation: Implications and approaches.

BACKGROUND: Pulmonary vein isolation (PVI) is the cornerstone of atrial fibrillation (AF) ablation. Despite promising success rates, redo ablation is sometimes required. At redo, PVs may be found to be isolated (silent) or reconnected. We studied patients with silent vs reconnected PVs at redo and analysed associations with adverse outcomes. METHODS: Patients undergoing redo AF ablations between 2013 and 2019 at our institution were included and stratified into silent PVs or reconnected PVs. The primary outcome was a composite of further redo ablation, non-AF ablation, atrioventricular nodal ablation, and death. Secondary outcomes included arrhythmia recurrence. RESULTS: A total of 467 patients were included with mean 4.6 ± 1.7 years follow-up, of whom 48 (10.3%) had silent PVs. The silent PV group had had more often undergone >1 prior ablation (45.8% vs 9.8%; p<0.001), had more persistent AF (62.5% vs 41.1%; p=0.005) and had more non-PV ablation performed both at prior ablation procedures and at the analysed redo ablation. The primary outcome occurred more frequently in those with silent PVs (25% vs 13.8%; p=0.053). Arrhythmia recurrence was also more common in the silent PV group (66.7% vs 50.6%; p=0.047). After multivariable adjustment, female sex (aHR 2.35 [95% CI 2.35-3.96]; p=0.001) and ischaemic heart disease (aHR 3.21 [95% CI 1.56-6.62]; p=0.002) were independently associated with the primary outcome, and left atrial enlargement (aHR 1.58 [95% CI 1.20-2.08]; p=0.001) and >1 prior ablation (aHR 1.88 [95% CI 1.30-2.72]; p<0.001) were independently associated with arrhythmia recurrence. Whilst a finding of silent PVs was not itself significant after multivariable adjustment, this provides an easily assessable parameter at clinically indicated redo ablation which informs the clinician of the likelihood of a worse future prognosis. CONCLUSIONS: Patients with silent PVs at redo AF ablation have worse clinical outcomes.

Picking the Locked Door: Experiences and Techniques in Transseptal Puncture Post-Atrial Septal Defect Occlusion.

The management of atrial septal defects (ASDs) has been revolutionized by the advent of percutaneous transvenous occlusion devices. This case series describes techniques required to perform a transeptal puncture safely and effectively in patients postimplantation of an atrial septal defect occluder to facilitate catheter ablation of atrial arrhythmias. (Level of Difficulty: Intermediate.).

The impact of steerable sheath visualization during catheter ablation for atrial fibrillation.

AIMS: Incorporating a steerable sheath that can be visualized using an electroanatomical mapping (EAM) system may allow for more efficient mapping and catheter placement, while reducing radiation exposure, during ablation procedures for atrial fibrillation (AF). This study evaluated fluoroscopy usage and procedure times when a visualizable steerable sheath was used compared with a non-visualizable steerable sheath for catheter ablation for AF. METHODS AND RESULTS: In this retrospective, observational, single-centre study, patients underwent catheter ablation for AF using a steerable sheath that is visualizable using the CARTO EAM (VIZIGO; n = 57) or a non-visualizable steerable sheath (n = 34). The acute procedural success rate was 100%, with no acute complications in either group. Use of the visualizable sheath vs. the non-visualizable sheath was associated with a significantly shorter fluoroscopy time [median (first quartile, third quartile), 3.4 (2.1, 5.4) vs. 5.8 (3.8, 8.6) min; P = 0.003], significantly lower fluoroscopy dose [10.0 (5.0, 20.0) vs. 18.5 (12.3, 34.0) mGy; P = 0.015], and significantly lower dose area product [93.0 (48.0, 197.9) vs. 182.2 (124.5, 355.0) µGy·m2; P = 0.017] but with a significantly longer mapping time [12.0 (9.0, 15.0) vs. 9.0 (7.0, 11.0) min; P = 0.004]. There was no significant difference between the visualizable and non-visualizable sheaths in skin-to-skin time [72.0 (60.0, 82.0) vs. 72.0 (55.5, 80.8) min; P = 0.623]. CONCLUSION: In this retrospective study, use of a visualizable steerable sheath for catheter ablation of AF significantly reduced radiation exposure vs. a non-visualizable steerable sheath. Although mapping time was longer with the visualizable sheath, the overall procedure time was not increased.

Limb-Sparing Surgery in Two Cats Using a Femoral Endoprosthesis with an Integrated Total Knee Replacement Implant.

OBJECTIVE: The aim of this study was to describe a novel limb-sparing technique for the management of feline bone neoplasia using a custom-made femoral endoprosthesis in combination with a total knee replacement (TKR) prosthesis. METHODS: Two cats with distal femoral bone tumours underwent pelvic limb salvage procedures with custom-made implants designed from patient-specific computed tomography images to replace the distal femur and the stifle. In case 1, the first-generation implant was a combination of a cemented femoral endoprosthesis with a uniaxial hinged cemented TKR prosthesis. Due to aseptic loosening of the endoprosthesis, revision was performed with a second-generation femoral endoprosthesis modified with a short intramedullary peg and a lateral bone plate for immediate stability. In case 2, a third-generation endoprosthesis with an intramedullary peg and two orthogonal bone plates for immediate stability, combined with a custom-designed rotationally hinged cemented TKR prosthesis, was used. Clinical and radiographic follow-up was recorded. RESULTS: After revision surgery in case 1 and with the third-generation implant in case 2, no complications were encountered. Both cats showed minor mechanical restriction of stifle range of motion and good clinical long-term outcome without local tumour recurrence. CONCLUSION: The combination of a femoral endoprosthesis and a TKR prosthesis can be a viable alternative for distal femoral limb salvage in cats.

Clinical Cohort Study in Canine Patients, to Determine the Average Platelet and White Blood Cell Number and Its Correlation with Patient's Age, Weight, Breed and Gender: 92 Cases (2019-2020).

Due to its easy preparation and that it is well tolerated, the use of autologous platelet-rich plasma (PRP) has become increasingly popular in regenerative medicine. However, there are still no clear guidelines on how it should be classified or whether the individual canine patient's clinical status can influence its quality. OBJECTIVE: This study aims to show if the weight, age, sex, neutered status or breed of canine patients have any correlation with the composition of PRP. DESIGN: A blinded count of the platelets and white blood cells (WBC) was performed from 111 samples from 92 client owned dogs undergoing treatment for degenerative joint disease (DJD). The results were analysed using Pearson correlation test, ANOVA test or Student T-test. RESULTS: There is a positive correlation between the number of platelets and WBC in canine patients of different breeds, but there was no significant difference on the platelet number and WBC number among the different breeds. The weight of the patient is also directly correlated to the platelet number (p = 0.003) but not WBC number. WBC number was negatively correlated to the weight of the patient. The sex and age of the patient did not affect platelets and WBC number, although WBC number is increased in non-neutered male population (p = 0.003). However, it would be interesting to investigate whether the growth factors released from the platelet granules are affected by patient variables in a canine population. CONCLUSIONS: Our results show that it is possible to obtain good quality autologous PRP, irrespective of age, sex, neutered status or weight of the patient, for PRP regenerative therapy.

Clinical outcomes following intra-articular injection of autologous adipose-derived mesenchymal stem cells for the treatment of osteoarthritis in dogs characterized by weight-bearing asymmetry.

AIMS: This study investigates the effects of intra-articular injection of adipose-derived mesenchymal stem cells (AdMSCs) and platelet-rich plasma (PRP) on lameness, pain, and quality of life in osteoarthritic canine patients. METHODS: With informed owner consent, adipose tissue collected from adult dogs diagnosed with degenerative joint disease was enzymatically digested and cultured to passage 1. A small portion of cells (n = 4) surplus to clinical need were characterized using flow cytometry and tri-lineage differentiation. The impact and degree of osteoarthritis (OA) was assessed using the Liverpool Osteoarthritis in Dogs (LOAD) score, Modified Canine Osteoarthritis Staging Tool (mCOAST), kinetic gait analysis, and diagnostic imaging. Overall, 28 joints (25 dogs) were injected with autologous AdMSCs and PRP. The patients were followed up at two, four, eight, 12, and 24 weeks. Data were analyzed using two related-samples Wilcoxon signed-rank or Mann-Whitney U tests with statistical significance set at p < 0.05. RESULTS: AdMSCs demonstrated stem cell-like characteristics. LOAD scores were significantly lower at week 4 compared with preinjection (p = 0.021). The mCOAST improved significantly after three months (p = 0.001) and six months (p = 0.001). Asymmmetry indices decreased from four weeks post-injection and remained significantly lower at six months (p = 0.025). CONCLUSION: These improvements in quality of life, reduction in pain on examination, and improved symmetry in dogs injected with AdMSCs and PRP support the effectiveness of this combined treatment for symptom modification in canine OA for six months. Cite this article: Bone Joint Res 2021;10(10):650-658.

Custom-built constrained uniaxial and rotating hinge total knee replacement in cats: Clinical application, design principles, surgical technique, and clinical outcome.

OBJECTIVE: To describe the design principles and evolution, surgical technique, and outcome for custom constrained (uniaxial and rotating hinge) total knee replacement (TKR) in cats. STUDY DESIGN: Retrospective case series. ANIMALS: Nine cats with traumatic stifle luxation (n = 8) or severe distal femoral deformity (n = 1) were considered suitable candidates. METHODS: Cats that met eligibility criteria and received a custom TKR between 2009 and 2018 by a single surgeon were included in this case series. Three generations of implant were used. Implant positioning was assessed by postoperative orthogonal radiography. Functional outcome was determined by clinical assessment, owner interview, and a feline musculoskeletal pain index questionnaire. RESULTS: Median clinical follow-up time was 12 months (range, 4-41); follow-up time was increased to 29 months (range, 22-47) when results of functional questionnaires with owner were included. Median radiographic follow-up was 12 months (range, 4-25). One cat had a catastrophic outcome. Three cats had good outcomes, and five cats had excellent outcomes. CONCLUSION: Most cats treated with custom-built TKR achieved good to excellent outcomes. CLINICAL SIGNIFICANCE: Custom TKR is a viable option for the treatment of severe pathologies of the feline stifle. Additional research is required to fully evaluate implant suitability.

Kinematics of a Novel Canine Cervical Fusion System.

OBJECTIVE: The aim of this study was to determine the biomechanical behaviour of a novel distraction-fusion system, consisting of an intervertebral distraction screw, pedicle locking screws and connecting rods, in the canine caudal cervical spine. STUDY DESIGN: Biomechanical study in cadaveric canine cervicothoracic (C3-T3) spines (n = 6). Cadaveric spines were harvested, stripped of musculature, mounted on a four-point bending jig, and tested using non-destructive four-point bending loads in extension (0-100 N), flexion (0-60 N) and lateral bending (0-40 N). Angular displacement was recorded from reflective optical trackers rigidly secured to C5, C6 and C7. Data for primary and coupled motions were collected from intact spines and following surgical stabilization (after ventral annulotomy and nucleotomy) with the new implant system. RESULTS: As compared with the intact spine, instrumentation significantly reduced motion at the operated level (C5-C6) with a concomitant non-significant increase at the adjacent level (C6-C7). CONCLUSION: The combination of a locking pedicle screw-rod system and intervertebral spacer provides an alternative solution for surgical distraction-stabilization in the canine caudal cervical spine and supports the feasibility of using this new implant system in the management of disc-associated cervical spondylomyelopathy in dogs. The increase in motion at C6-C7 may suggest the potential for adjacent level effects and clinical trials should be designed to address this.

Comparison of Fat Harvested from Flank and Falciform Regions for Stem Cell Therapy in Dogs.

BACKGROUND: Adipose tissue has recently gained attention as a source of mesenchymal stem cells (AdMSCs) for applications in treating degenerative joint disease in veterinary patients. This study aimed to quantify the stromal vascular fractions (SVFs) and colony forming units (CFU) of AdMSCs from the falciform and flank regions and compare dogs of different ages and weights. METHODS: Fat tissue was harvested from the flank (21 dogs) and falciform regions (17 dogs). The fat tissue was enzymatically digested and the number of nucleated cells in the SVF was counted. The SVF was cultured in vitro and the cell growth was assessed by counting the CFU per gram of fat and the aspect ratio of the cells. CONCLUSIONS: There was no significant difference in the number of nucleated cells in the SVF from the two sites. The CFU/g of fat from falciform was 378.9 ± 293 g and from flank was 486.8 ± 517 g, and this was also insignificant. Neither age nor weight of the patient had an impact on the SVF or CFU/g. No surgical complications were reported from either of the sites. Harvesting fat for stem cell therapy for intra-articular therapy of degenerative joint disease can be an easy and fast process when obtaining the fat either from the flank or the falciform region, and it is not age or weight dependent. The harvest site for clinical canine patients can be left to the surgeon's discretion and comfort.

Correction of pes varus deformity in a Miniature Dachshund by true spherical osteotomy with a dome saw blade.

CASE DESCRIPTION: A 6-month-old male Miniature Dachshund was referred for examination and correction of a unilateral pes varus deformity. CLINICAL FINDINGS: Clinical examination and diagnostic imaging revealed varus, procurvatum, and internal torsion of the distal aspect of the left tibia causing intermittent lameness. TREATMENT AND OUTCOME: True spherical osteotomy performed with a dome-shaped saw allowed correction of the deformity in 3-D, and orthogonal internal plate fixation provided stabilization. No intraoperative or immediate postoperative complications developed. Outcome as judged by the clinician and the owners was satisfactory 2 weeks after surgery and excellent at each subsequent assessment. The patient remained free of clinical signs at the last follow-up 30 months after surgery. CLINICAL RELEVANCE: To the authors' knowledge, this case represented the first time a true spherical osteotomy was used to correct a pes varus deformity in a canine patient.

Treatment of a large osseous defect in a feline tarsus using a stem cell-seeded custom implant.

The aim of this study is to describe the treatment of an infected segmental bone defect in a cat using a novel, custom-designed titanium implant seeded with adipose-derived stem cells (AdMSCs) to facilitate osseous ingrowth and preserve limb function. Large bone defects occur secondary to trauma, infection, or neoplasia and often result in amputation. We established a novel autologous AdMSC-impregnated trabecular metal spacer made using 3D printing, to bridge the distal tibia and metatarsal bones in the left pelvic limb of a cat that had previously undergone right pelvic limb amputation. Six months postoperatively, there was radiographic evidence of bone growth and implant integration. A titanium spacer seeded with AdMSCs successfully encouraged bone ingrowth in a large defect site and successfully preserved limb function. However, further studies are needed to justify the use of differentiated stem cell impregnated mesh as a framework to bridge large bone defects.

Guidelines for the Execution of True Spherical Osteotomies Using a Modified Dome Blade Design.

OBJECTIVES: The purpose of this study was to explore the trigonometric principles of the spherical osteotomy, establish guidelines for its application and test the guidelines on bone models using a new blade design. We propose a new rule of osteotomies incorporating the outlined geometric principles, and applicable to the use of spherical cuts in veterinary orthopaedic surgery. MATERIALS AND METHODS: The trigonometric principles for the execution of neutral, closing and opening spherical osteotomies were explored in silico. A modification of the existing commercially available dome blade was designed and manufactured such that it facilitated the performance of spherical osteotomy with a minimized blade radius. A pilot study was performed whereby the modified dome blade was used to create spherical osteotomy in canine radial bone models. The surfaces of the osteotomy models were laser-scanned using a three-dimensional (3D) scanner; the resultant scans were imported into and analysed using a commercial 3D analysis software. The accuracy of osteotomy execution was measured as the distance between the targeted centre of osteotomy and the actual centre of osteotomy as found on the 3D scans. RESULTS: By utilizing the geometric principles of spherical osteotomy, an accurate osteotomy position was achieved. The centre of the spherical cut performed on bone models was confirmed to be within 5% tolerance of the location as planned in silico demonstrating the accurate and relevant clinical application of geometric principles. CLINICAL SIGNIFICANCE: The trigonometric guidelines for the execution of spherical osteotomy can be applied in a pre-clinical environment with accuracy. The new guidelines combined with the proposed new rule for spherical osteotomy utilizing the new blade design are translatable into clinical application, permitting the surgeon to accurately plan osteotomy application while mitigating the significant loss of bone-to-bone contact during correction of torsional deformities inherent in the principles of dome osteotomy use.

Electrodiagnostic findings in dogs with apparently painful lumbosacral foraminal stenosis.

BACKGROUND: Development of management strategies for lumbosacral stenosis in dogs is hampered by the lack of objective diagnostic criteria and outcome measures. OBJECTIVE: To explore the suitability of electrodiagnostic tests as ancillary diagnostic aids, inclusion criteria, or outcome measures. SAMPLE POPULATION: Sixty-one client-owned dogs with clinical signs of lumbosacral foraminal stenosis. METHODS: A blinded, cross-sectional cohort study. Fifty-one dogs exhibiting apparent lumbosacral pain or pelvic limb lameness with no detected orthopedic cause had blinded review of magnetic resonance imaging (MRI), allowing classification as affected with foraminal stenosis (25 dogs), unaffected (20 dogs), or another diagnosis (6 dogs). The presence of electromyographic changes and tibial neurography variables were compared between groups. RESULTS: Cord dorsum potential onset latency, F-wave onset latency (both corrected for limb length), and F-ratio were increased in dogs with lumbosacral foraminal stenosis versus those without, although there was overlap of the values between groups. The proportion of dogs with electromyographic changes was not significantly greater in MRI-affected dogs. CONCLUSION: Electrophysiological testing is a useful ancillary test, either to provide stricter inclusion criteria and outcome measures or to aid clinical decision-making in equivocal cases.

Synthetic osteochondral resurfacing for treatment of large caudocentral osteochondritis dissecans lesions of the humeral head in 24 dogs.

OBJECTIVE: To report the outcome of dogs with large, caudocentral, osteochondritis dissecans (OCD) lesions of the humeral head treated with synthetic osteochondral resurfacing (SOR) implants. STUDY DESIGN: Retrospective case series. ANIMALS: Twenty-four client-owned large breed or giant dogs. METHODS: The medical records of all dogs treated with first generation (G1) and second generation (G2) SOR implants were reviewed. All dogs were assessed with clinical examination and imaging 12 weeks after surgery. Assessment of outcome was based on subjective assessment of lameness, scoring of postoperative radiographs, and the Liverpool Osteoarthritis in Dogs (LOAD) questionnaire. RESULTS: Osteochondral resurfacing was performed with a G1 implant in 13 dogs (15 shoulders) and a G2 implant in 11 dogs (13 shoulders). Lameness resolved in all dogs treated with G1 implants and in 10 dogs treated with G2 implants by 12 weeks after surgery. One dog treated with a G2 implant was found to have an implant-associated infection, requiring implant removal. No recurrence of lameness was reported in 9 limbs treated with G1 implants and 10 limbs treated with G2 implants that were available for clinical review at a median time of 387 and 365 days, respectively, after surgery. Mean postoperative LOAD scores were 4.2 of 52 and 5.2 of 52 in dogs treated with a G1 or a G2 implant, respectively. CONCLUSION: Synthetic resurfacing was technically feasible in all joints of this study and resulted in good clinical results. CLINICAL SIGNIFICANCE: The use of SOR implants seems viable to treat large caudocentral OCD lesions of the humeral head in dogs and warrants prospective comparison with conventional arthroscopic treatment.

Cervical vertebral malformations in 9 dogs: radiological findings, treatment options and outcomes.

BACKGROUND: Disregarding atlantoaxial instability in toy breed dogs associated with dens malformation and cervical spondylomyelopathy; cervical vertebral malformations are rare and poorly characterised in veterinary medicine and consequently treatment strategies and clinical outcome are sparsely documented. RESULTS: Electronic clinical records at our veterinary referral hospital between April 2009 and November 2018 were searched for patients presented with cervical myelopathy secondary to an underlying suspected vertebral malformation/instability. Nine dogs met the inclusion criteria. Two dogs were diagnosed with atlantoaxial pseudoarthrosis, two dogs with a syndrome similar to Klippel-Feil in humans, two dogs with congenital cervical fusion, two dogs with congenital C2-C3 canal stenosis and deficiencies of the dorsal arch of the atlas and laminae of the axis and one with axial rotatory displacement. Tetraparesis, proprioceptive deficits, cervical hyperesthesia and cervical scoliosis were the most common clinical signs. The axis was the most commonly affected vertebrae (8/9 patients). Patients diagnosed with Klippel-Feil-like Syndrome were the younger (average of 262.5 days) and patients diagnosed with fused vertebrae the oldest (average of 2896 days) in our studied population (average of 1580.8 days). CONCLUSION: Cervical vertebral malformations are rare, or alternatively, being underdiagnosed in veterinary medicine. Patients diagnosed with Klippel-Feil-like Syndrome had a successful medium and long-term outcome with conservative management. Surgical treatment was often indicated for the other conditions presented in this study due to spinal instability and/or myelopathy. Stabilisations via ventral approaches were revealed to be safe. Multicentre and prospective studies are necessary in veterinary medicine to better characterise clinical outcomes in cervical vertebral malformations.

Ventral distraction-stabilization in 5 continuous sites for the treatment of cervical spondylomyelopathy in a Great Dane.

OBJECTIVE: To report the combined use of novel and commercially available implants for ventral distraction-stabilization of 5 continuous compressive sites in a Great Dane with cervical spondylomyelopathy (CSM). STUDY DESIGN: Case report. ANIMALS: One 4-year-old male Great Dane weighing 78 kg. METHODS: A tetraparetic 4-year-old Great Dane with osseous-associated CSM (OA-CSM) with 5 sites of dorsolateral compression was presented for surgical intervention. Custom designed Fitz intervertebral traction screws (FITS) and a commercially available polyaxial spinal system were used for ventral distraction-stabilization of all lesions. Multiple neurological reevaluations were performed, with the final evaluation at 27 months postoperatively. Preoperative, immediate-postoperative, and 27 month-postoperative computed tomography (CT) images were retrospectively reviewed to compare the vertebral canal dimensions at the affected sites. RESULTS: Multilevel distraction-stabilization technique resulted in improvement of the dog's neurological function by 10 days postoperatively. The vertebral canal measurements were revealed to have improved in over half of the measured variables when the 27-month-postoperative images were compared with the preoperative CT images. Increased vertebral canal dimensions were observed immediately after surgery, and some of these measurements continued to improve by 27 months postoperatively. CONCLUSION: Ventral distraction-stabilization technique with custom-designed FITS and a polyaxial spinal system resulted in both clinical improvement and objective improvement in spinal canal measurements in an OA-CSM-affected Great Dane. CLINICAL SIGNIFICANCE: An indirect decompression technique can eliminate dynamic movements and result in regression of vertebral canal bony proliferation in dogs with OA-CSM.

Hemipelvic and proximal femoral limb salvage endoprosthesis with tendon ongrowth in a dog.

OBJECTIVE: To report the clinical application of a hemipelvic and proximal femoral endoprosthesis for limb salvage. STUDY DESIGN: Retrospective case report. ANIMAL: One 5-year-old, neutered female, flat coated retriever with a malignant neoplasia of the left coxofemoral joint. METHODS: An invasive soft tissue mass (histiocytic sarcoma) with bone lysis of the femoral head and acetabulum was noted on radiographs, computed tomography (CT), and MRI. Custom-designed hemipelvic and proximal femoral endoprostheses were produced from CT images and manufactured with hydroxyapatite coated surfaces to allow tissue integration. The proximal femoral implant allowed tendon ongrowth and muscle attachment. The pelvic implant was anchored to the ilium and ischium with screws, and the femoral implant was cemented. Chemotherapy consisted of lomustine (CCNU). RESULTS: No evidence of implant loosening or local/thoracic metastases was noted on radiographs or CT at 6 weeks and at 3, 6, 9, and 12 months after surgery. A neurapraxia resolved 14 weeks postoperatively. Intensive rehabilitation was performed. At 12 months, activity was unrestricted with minimal residual lameness. The dog was euthanized at 14 months for metastatic disease. CONCLUSION: Limb salvage with a hemipelvic and proximal femoral endoprosthesis resulted in limb function and survival for 14 months. CLINICAL SIGNIFICANCE: Neoplasia involving the bones of the coxofemoral joint traditionally requires hemipelvic resection and pelvic limb amputation. This report provides evidence that limb salvage can result in satisfactory levels of activity.

Treatment of calvarial defects by resorbable and non-resorbable sonic activated polymer pins and mouldable titanium mesh in two dogs: a case report.

BACKGROUND: To date, calvarial defects in dogs have traditionally been addressed with different types of implants including bone allograft, polymethylmethacrylate and titanium mesh secured with conventional metallic fixation methods. This report describes the use of an absorbable and non absorbable novel polymer fixation method, Bonewelding® technology, in combination with titanium mesh for the repair of calvarial defects in two dogs. The clinical outcomes and comparative complication using resorbable and non-resorbable thermoplastic pins were compared. CASE PRESENTATION: This report of two cases documents the repair of a traumatic calvarial fracture in an adult male Greyhound and a cranioplasty following frontal bone tumor resection in an adult female Cavalier King Charles Spaniel with the use of a commercially available titanium mesh secured with an innovative thermoplastic polymer screw system (Bonewelding®). The treatment combination aimed to restore cranial structure, sinus integrity and cosmetic appearance. A mouldable titanium mesh was cut to fit the bone defect of the frontal bone and secured with either resorbable or non-resorbable polymer pins using Bonewelding® technology. Gentamycin-impregnated collagen sponge was used intraoperatively to assist with sealing of the frontal sinuses. Calvarial fracture and post-operative implant positioning were advised using computed tomography. A satisfactory restoration of skull integrity and cosmetic result was achieved, and long term clinical outcome was deemed clinically adequate with good patient quality of life. Postoperative complications including rostral mesh uplift with minor associated clinical signs were encountered when resorbable pins were used. No postoperative complications were experienced in non-resorbable pins at 7 months follow-up, by contrast mesh uplift was noted 3 weeks post-procedure in the case treated using absorbable pins. CONCLUSIONS: The report demonstrates the innovative use of sonic-activated polymer pins (Bonewelding® technology) alongside titanium mesh is a suitable alternative technique for skull defect repair in dogs. The use of Bonewelding® may offer advantages in reduction of surgical time. Further, ultrasonic pin application may be less invasive than alternative metallic fixation and potentially reduces bone trauma. Polymer systems may offer enhanced mesh-bone integration when compared to traditional metallic implants. The use of polymer pins demonstrates initial potential as a fixation method in cranioplasty. Initial findings in a single case comparison indicate a possible advantage in the use of non-absorbable over the absorbable systems to circumvent complications associated with variable polymer degradation, further long term studies with higher patient numbers are required before reliable conclusions can be made.