Effects of extensive circumferential periosteal stripping on the microstructure and mechanical properties of the murine femoral cortex.

Extensive periosteal stripping (PS) is a risk factor for post-radiation pathologic fracture following surgery for extremity soft tissue tumors. The purpose of this study was to determine the effects of PS on bone structure and mechanical properties. Thirty-one skeletally mature mice underwent PS, with circumferential removal of periosteum from an 8-mm segment of the mid-diaphysis of the left femur. Thirty-one control mice underwent sham surgery in which the femur was isolated without manipulation of the periosteum. At 2, 6, 12, or 26 weeks following surgery, the left femora were examined by micro-CT to quantify cortical thickness (CtTh), cross-sectional area (CSA), bone volume (BV), and polar moment of inertia (PMI). Three-point mechanical bend testing was performed and peak load, stiffness, and energy to failure were determined. PS resulted in significantly decreased CtTh, CSA, BV, and PMI at all time points. Peak load, stiffness, and energy to failure were significantly reduced at 2, 6, and 12 weeks. There were no significant differences in mechanical properties at 26 weeks. In this mouse model, extensive circumferential PS resulted in sustained changes in bone structure that were still evident after 6 months, accompanied by reductions in bone strength that persisted for at least 3 months.

Complications of upper airway surgery in companion animals.

Surgery of the upper airway is performed in dogs for the correction of brachycephalic airway syndrome and laryngeal paralysis and for temporary or permanent tracheostomy. Although technically simple to perform, upper airway surgeries can lead to the development of significant postoperative complications. This article reviews complications associated with common surgical conditions of the upper airway. It involves a discussion of brachycephalic airway syndrome and associated respiratory and gastrointestinal complications. It also covers laryngeal paralysis with a focus on unilateral arytenoid lateralization and the complication of aspiration pneumonia. The condition of acquired laryngeal webbing/stenosis and potential treatment options is also discussed. Finally, tracheostomies and associated complications in dogs and cats are reviewed.

Effects of renal autograft ischemic storage and reperfusion on intraoperative hemodynamic patterns and plasma renin concentrations in clinically normal cats undergoing renal autotransplantation and contralateral nephrectomy.

OBJECTIVE: To evaluate the effect of the duration of cold Ischemia on the renin-angiotensin system during renal transplantation In cats and to define the potential Influence of vasoactive factors in renal tissue following cold ischemic storage versus warm ischemic storage. ANIMALS: 10 purpose-bred 6-month-old sexually Intact female cats. PROCEDURES: 10 cats underwent renal autotransplantation after 30 minutes (n=5) or 3 hours (5) of simple, ex vivo cold storage of renal autographs. Following autograft reperfusion, direct hemodynamic variables were measured with a telemetric Implant and samples were collected for plasma renin concentration. Activation of vascular-related genes (renin, endothelin, and angiotensin converting enzyme) relative to 2-hour simple cold or warm ischemia was also evaluated. RESULTS: No significant difference between groups was detected In any of the hemodynamic variables or postreperfusion plasma renin concentrations measured in this study relative to the duration of cold ischemic storage. There was also no difference between warm- and cold-stored kidneys in the expression of vascular-related genes. CONCLUSIONS AND CLINICAL RELEVANCE: Prolonged renal Ischemia for clinically relevant durations does not appear to predispose clinically normal cats to altered hemodynamics or high plasma renin concentrations following graft reperfusion. Activation of vasoactive genes does not appear to be Influenced by type of Ischemia over 2 hours.

Effects of renal autograft ischemia and reperfusion associated with renal transplantation on arterial blood pressure variables in clinically normal cats.

OBJECTIVE: To evaluate the effect of renal autograft ischemia and reperfusion associated with renal transplantation on pulse rate and pressure and arterial blood pressure variables in clinically normal cats. ANIMALS: 10 cats. PROCEDURES: A radiotelemetric implant was placed in each cat to measure hemodynamic variables; baseline data were recorded before surgery. Standard heterotopic renal implantation and contralateral nephrectomy were performed (day 0). Autografts were stored in cold sucrose phosphate solution for 30 minutes (n = 5) or 3 hours (5); cats were anephric during this period. Hemodynamic variables were recorded every 5 minutes for up to 16 days after surgery; mean daily values were calculated. RESULTS: Data from 6 cats were available for analysis. Two cats developed ureteral obstructions and became azotemic at 111 and 197 hours after kidney reperfusion. Mean serum creatinine and BUN concentrations were greater than baseline values on days 1 and 2. Although changes from baseline hemodynamic values were detected in some cats, arterial blood pressure measurements did not change significantly from baseline at any time point. Compared with baseline data, mean pulse rate was increased on days 1 and 2 and days 6 through 12; mean pulse pressure was increased on days 1 and 2. CONCLUSIONS AND CLINICAL RELEVANCE: In clinically normal cats, hypertension was not induced by clinically relevant periods of ischemia-reperfusion injury of renal autografts and was not an inherent consequence of the transplantation process. Causes of marked posttransplantation hypertension in cats with chronic kidney disease require further investigation.