Impaired bone quality characterized by apatite orientation under stress shielding following fixing of a fracture of the radius with a 3D printed Ti-6Al-4V custom-made bone plate in dogs

Custom-made implants have recently gained attention in veterinary medicine because of their ability to properly fit animal bones having a wide variety of shapes and sizes. The effect of custom-made implants on bone soundness and the regeneration process is not yet clear. We fabricated a 3D printed Ti-6Al-4V custom-made bone plate that fits the shape of the dog radius, and placed it into the radius where an osteotomy had been made. The preferential orientation of the apatite c-axis contributes to the mechanical integrity of the bone and is a reliable measure of bone quality. We determined this parameter as well as the bone shape and bone mineral density (BMD). The bone portion which lies parallel to the bone plate exhibited bone resorption, decreased BMD, and significant degradation of apatite orientation, relative to the portion outside the plate, at 7 months after the operation. This demonstrates the presence of stress shielding in which applied stress is not transmitted to bone due to the insertion of a stiff bone plate. This reduced stress condition clearly influences the bone regeneration process. The apatite orientation in the regenerated site remained different even after 7 months of regeneration, indicating insufficient mechanical function in the regenerated portion. This is the first study in which the apatite orientation and BMD of the radius were evaluated under conditions of stress shielding in dogs. Our results suggest that assessment of bone repair by radiography can indicate the degree of restoration of BMD, but not the apatite orientation.Impaired bone quality characterized by apatite orientation under stress shielding following fixing of a fracture of the radius with a 3D printed Ti-6Al-4V custom-made bone plate in dogs. Keiichiro Mie et al. PLOS ONE. 2020. 9(2) doi.org/10.1371/journal.pone.023767

Contrast-enhanced computed tomography characterization of canine rectal neoplasms

Differential diagnosis of rectal neoplasms is necessary to determine an appropriate treatment plan. In humans, computed tomography (CT) is used to evaluate colorectal neoplasms. This retrospective study assessed the CT features of canine rectal neoplasms, including seventeen inflammatory polyps, six adenocarcinomas, three B-cell lymphomas and four leiomyomas on triple-phase CT. A mass lesion was observed in all seventeen cases of inflammatory polyps (100%), two of six adenocarcinomas (33%), and all four cases of leiomyoma (100%). Wall thickening was observed in four of six (67%) adenocarcinoma cases and all three (100%) lymphoma cases. The leiomyoma was more likely to show obstruction than inflammatory polyps, adenocarcinomas, and lymphomas. Homogeneous enhancement was detected in zero of seventeen (0%) inflammatory polyp cases, two of six (33%) adenocarcinoma cases, all three (100%) lymphoma cases, and all four (100%) leiomyoma cases in all post contrast phases. Lymphadenopathy was detected in three adenocarcinoma cases (50%) and three lymphoma cases (100%). Inflammatory polyps indicated a heterogeneous radial-enhancement mass. Leiomyomas indicated a homogeneous enhancement mass with bowel obstruction. In wall thickening lesions, adenocarcinoma indicated twolayer thickened annular lesions and lymphoma indicated homogeneous thickened annular lesions but less enhancement than the mucosa. These findings may help confirm the diagnosis and reduce the use of invasive biopsy procedures

Computed tomography may detect liver infiltration of canine diffuse hepatic lymphoma

[Background] In dogs, hepatic lymphoma is characterized by neoplastic lymphocyte infiltration into the liver. Reports on the computed tomography (CT) findings of the liver for canine hepatic lymphoma are few, with only one study of multiple liver lesions type. [Objectives] The purpose of this study was to retrospectively assess the CT findings of the liver in canine diffuse hepatic lymphoma. [Methods] As control, five dogs without abnormalities in the liver were included. CT data were analysed, and the following were noted: presence of edge bluntness of the liver, presence of periportal collar sign, the liver size:body weight (BW) ratio and the mean attenuation of liver lesions on pre-contrast, arterial-phase, portal-phase and equilibrium-phase post-contrast images. [Results] On CT examination, edge bluntness of the liver was significantly detected in lymphoma (4/5, 80%), as opposed to the control (0/5, 0%) (p = 0.048, φ = 0.82). The periportal collar sign was detected in lymphoma (3/5, 60%), as opposed to the control (0/5, 0%) (p = 0.17, φ = 0.65). The liver size:BW ratio of lymphoma cases was significantly higher compared to that of the control cases (p = 0.0002, r = 0.92). The mean Hounsfield unit of lymphoma cases in the pre-contrast, arterial-phase, portal-phase and equilibrium-phase images were significantly lower than in the control cases (p = 0.005, r = 0.81; p = 0.0003, r = 0.91; p = 0.01, r = 0.75 and p = 0.02, r = 0.71, respectively). [Conclusions] Hepatic lymphoma should be a differential for a blunted and enlarged liver with hypoattenuation on CT examination