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Reconstructive surgical techniques are used in both general and referral veterinary practice to facilitate closure of challenging wound defects. During veterinary studies, there are often limited opportunities for students to practice these techniques on live patients or cadavers. Surgical models, including suture pads and ovariohysterectomy models, have been successfully incorporated into veterinary teaching, providing students with additional practice. Models to simulate veterinary reconstructive surgical techniques are lacking. In the current study, a single pedicle advancement flap model was designed. The design consisted of a silicone model secured by a plate, providing tension. Fifth-year veterinary science students ( n = 34) were surveyed to assess the model's impact on surgical technique and confidence. Students were also assessed to determine surgical technique using the models. It was hypothesized that students who had two additional practice sessions using the models (Trial group, n = 17) would show greater improvement in technique than students who had no practice sessions between assessments (Control group, n = 17). Students strongly agreed (median score 5/5) that using the model helped to reinforce the subdermal plexus flap technique and improved their confidence in performing a subdermal plexus flap. Students from both groups performed significantly better in the follow-up assessment compared to the initial assessment. No significantly greater improvement was observed in technique between the control and the trial groups. Results suggest that the students’ reconstructive surgical technique improved after a single practice session and that the single pedicle advancement flap model can be used synergistically with other teaching methods.

OBJECTIVE To investigate putative associations between oral melanoma size and variables of histologic grade such as mitotic index, nuclear atypia, junctional activity, ulceration, lymphatic invasion, and degree of pigmentation. SAMPLE 59 samples of oral melanomas from dogs sourced from 6 diagnostic laboratories within Australia. PROCEDURES The size of each melanoma was microscopically measured, and each sample was evaluated for variables of histologic grade including mitotic index, nuclear atypia, junctional activity, ulceration, lymphatic invasion, and degree of pigmentation by a veterinary pathologist. The association between tumor size and histologic outcomes was then statistically evaluated. RESULTS A significant relationship was identified between the size of oral melanomas and a single variable of histologic grade, lymphatic invasion, with larger tumors more likely to show lymphatic invasion. Further analysis revealed 2 applicable size thresholds for different clinical scenarios. Results indicated lymphatic invasion can confidently be ruled out for tumors < 6.5 mm in diameter (100% sensitivity) and ruled in for tumors ≥ 24.5 mm in diameter (100% specificity). CONCLUSIONS AND CLINICAL RELEVANCE An association was found for oral melanomas of dogs between tumor size and lymphatic invasion.

After trauma, fractured bone starts healing directly through bone union or indirectly through callus formation process. Intramembranous and endochondral ossification are two commonly known mechanisms of indirect healing. The present study investigated the bone fracture healing under intramembranous and endochondral ossification by developing theoretical models in conjunction with performing a series of animal experiments. Using experimentally determined mean bone densities in sheep tibia stabilized by the Locking Compression Plate (LCP) fixation system, the research outcomes showed that intramembranous and endochondral ossification can be described by Hill Function with two unique sets of function parameters in mechanical stimuli mediated fracture healing. Two different thresholds exist within the range of mechanical simulation index which could trigger significant intramembranous and endochondral ossification, with a relatively higher bone formation rate of endochondral ossification than that of intramembranous ossification. Furthermore, the increase of flexibility of the LCP system and the use of titanium LCP could potentially promote uniform bone formation across the fracture gap, ultimately better healing outcomes.

The maintenance of friction between locking plates and bone is not essential, so that they can be applied with a gap between the plate and underlying bone. We hypothesised that the presence of a gap under a locking plate with a conical coupling mechanism would reduce fixation stability or allow uncoupling of the locking screws from the plate.Locking plates with two conically coupled locking screws were applied to 6 pairs of adult canine femora. One of each pair had plate to bone contact and the contralateral construct had a 2 mm plate to bone gap. Constructs were cyclically loaded in cantilever bending with 10 percent incremental increases every 1000 cycles at 2 Hz, starting at 250 N. The constructs were fatigued to failure. To evaluate fatigue life of the conical coupling, testing was repeated with aluminium tubing replacing the bone, to eliminate screw-bone cutout failure.The mean sustained loads and cycles to failure in the contact group (420.80, standard error [SE] 14.97 N; 7612.00, SE 574.70 cycles) were significantly greater than in the gap group (337.50, SE 14.97 N; 4252.00, SE 574.70 cycles), (p0.001). Failure mode of all bone constructs was via screw cutout from the bone. Aluminium tubing constructs failed via screw or plate fatigue and breaking, with one construct having elevation of the plate over the screw head.Elevation of locking plates with a conical coupling system by 2 mm from the bone reduced construct fatigue life but did not result in screw head uncoupling from the plate.

Introduction Studying mechanical changes occurring during fracture repair with locking plates, and associated cortical-periosteal vascular changes, is vital for understanding bone healing. Methods Paired femora (n=6 pair) had conical coupling locking plates applied. One of each pair had a plate-bone distance (PBD): 0 mm and the other: 2 mm. Constructs were cyclically loaded to failure. Testing was repeated with aluminium tubing replacing bone, eliminating screw-bone cutout. All constructs were examined under stereo zoom and scanning electron microscope, at the screw-implant, screw-bone/metal interfaces. Blood flow in sheep cortical bone was assessed using stable isotope microspheres. Vascular mapping of the hind limb via contrast computer tomography (CT) and radiographic imaging was performed. The final in vivo study assessed two models for examining periosteal capillary perfusion beneath locking plates, with and without an ostectomy. CT and histological studies were performed. Results Biomechanical study: mean sustained loads in the 0 mm PBD group (420.8 Newtons, 7612 cycles) were significantly greater than in the 2 PBD mm group (337.5 Newtons, 4252 cycles) p