Leticia Daniel

Long-term outcome after surgical ameroid ring constrictor placement for treatment of single extrahepatic portosystemic shunts in dogs

OBJECTIVE To report long-term clinical outcome in dogs treated for single congenital extrahepatic portosystemic shunt (CEHPSS) with a ameroid ring constrictor (ARC) and to identify perioperative variables associated with outcome. STUDY DESIGN Retrospective, multi-institutional study. ANIMALS Dogs (n = 206) with CEHPSS. METHODS Medical records of dogs with CEHPSS treated by ARC were reviewed for perioperative and short-term (<1 month) data. Long-term follow-up information was obtained by telephone interview with referring veterinarians and/or owners. Kaplan-Meier analysis was used to estimate median survival time. Factors associated with short-term survival, outcome grade, and total survival time were identified. RESULTS Fifteen dogs died <1 month after ARC placement. Follow-up data were obtained for 112 of 191 dogs that survived >1 month; median follow was 54 months (range, 1-175 months) and 103 (92%) dogs had no clinical signs. Estimated median survival time was 152 months. Variables significantly associated with short-term survival included being intact and a low total white blood cell (WBC) count. Variables significantly associated with a successful outcome included having surgery later in the study period and negative postoperative nuclear scintigraphy. In the long-term survival analyses, intact dogs and those with higher WBC counts and occlusion pressures and lower bile acid concentrations were more likely to survive. CONCLUSIONS Dogs with CEHPSS treated by ARC generally have a good prognosis and prolonged postoperative survival.

Correlation Between Liver Volume, Portal Vascular Anatomy, and Hepatic Perfusion in Dogs With Congenital Portosystemic Shunt Before and After Placement of Ameroid Constrictors

OBJECTIVE To correlate changes in hepatic volume, hepatic perfusion, and vascular anatomy of dogs with congenital extrahepatic portosystemic shunts, before and after attenuation with an ameroid constrictor. STUDY DESIGN Prospective study. ANIMALS Dogs (n = 22) with congenital extrahepatic portosystemic shunts. METHODS CT angiography and perfusion scans were performed before and after attenuation of a portosystemic shunt with an ameroid constrictor. Changes in hepatic volume, hepatic perfusion, and vascular anatomy were measured. Portal scintigraphy was performed in 8 dogs preoperatively and 22 dogs postoperatively. RESULTS Dogs with smaller preoperative liver volumes had greater increases in liver volume postoperatively compared with those with larger preoperative liver volumes. Hepatic arterial fraction was increased in dogs preoperatively and returned to normal range after shunt attenuation, and was correlated with increase in liver size and decreased shunt fraction. Three dogs with no visible portal vasculature preoperatively developed portal branches postoperatively. CONCLUSIONS Dogs with smaller preoperative liver volumes had the largest postoperative increase in liver volume. Hepatic arterial perfusion and portal scintigraphy correlate with liver volume and are indicators of successful shunt attenuation. Dogs without visible vasculature on CT angiography had visible portal vasculature postoperatively.

Video-Assisted Thoracoscopic Extirpation of the Tracheobronchial Lymph Nodes in Dogs.

OBJECTIVE To describe a technique for video-assisted thoracoscopic surgery (VATS) extirpation of the tracheobronchial lymph nodes (TBLN), and to describe the quality of biopsy specimens obtained. DESIGN Experimental study. ANIMALS Purpose-bred male hound-mix research dogs (n = 8). METHODS Dogs were randomized to groups of left-sided or right-sided VATS approaches. One lung ventilation was used and TBLN dissection was achieved using a vessel-sealing device. RESULTS TBLNs ipsilateral to the approach were successfully identified and removed thoracoscopically in 7 dogs. A 3-port technique was used in 6 dogs and 4 ports were used in 2 dogs. Observed complications included mild-moderate hemorrhage from the perinodal tissue controlled thoracoscopically (n = 2), inability to locate any TBLN (1), and difficulty achieving or maintaining one-lung ventilation (4). No other major complications occurred and all dogs recovered uneventfully. Median percentage surface area of the bisected lymph nodes affected by crush artifact was 20% (range, 0-40%). Areas of crush artifact were present in central (7/11) and peripheral (9/11) locations. CONCLUSIONS AND CLINICAL RELEVANCE Thoracoscopic TBLN extirpation is a feasible technique in dogs with normal TBLN and may be useful for obtaining more detailed staging on microscopic disease status in oncologic patients with normal-sized TBLNs. Further study is warranted to determine the feasibility and limitations of this technique in clinical patients with overt lymphadenopathy.

Laparoscopic Extirpation of the Medial Iliac Lymph Nodes in Normal Dogs

OBJECTIVE To describe a surgical technique for laparoscopic medial iliac lymph node (MILN) extirpation, and to describe the quality of biopsy specimens obtained. DESIGN Experimental study. ANIMALS Purpose-bred male hound-mix research dogs (n = 8). METHODS Dogs were randomized to groups of left or right-sided laparoscopic surgical approaches. Three transperitoneal portals were established with the dogs in lateral recumbency, and ipsilateral MILN dissection was achieved under CO2 pneumoperitoneum using a vessel-sealing device. RESULTS MILN ipsilateral to the approach were successfully identified and removed laparoscopically in 8 dogs. Observed complications included mild to moderate hemorrhage that was controlled laparoscopically in 4 dogs, and tearing of the MILN capsule during retraction and dissection in 3 dogs. No other major complications occurred and all dogs recovered uneventfully. Areas of either minor peripheral (9/9) or central (4/9) pinch artifact affected a median percentage of 5% of surface area (range, 5-30%) of bisected lymph nodes. CONCLUSIONS Laparoscopic MILN extirpation is feasible in dogs with normal MILN and may serve as a minimally invasive approach for excisional biopsy in the diagnostic staging of canine onocologic patients with normal-sized MILN. This lateral laparoscopic approach allows dissection of the ipsilateral MILN but precludes removal of the contralateral MILN. Minimal handling of the lymph node during dissection and removal is required to reduce the risk of capsular tear, or introduction of possible histologic artifact by tissue crush that may impact diagnosis.

COMPUTED TOMOGRAPHIC PNEUMOCOLONOGRAPHY IN NORMAL DOGS

Objectives of this prospective study were to describe effects of varying technical components that may contribute to an optimal protocol for computed tomographic pneumocolonography (CTP) in dogs, and to develop a standardized methodology for CTP as a future potential diagnostic tool in canine clinical patients with large bowel disease. Eight purpose-bred intact male hound cross-research dogs were enrolled and randomized to groups based on variables of pressure/body position (n = 4) and insufflation time (n = 4). For each segment of large bowel (rectum, colorectal junction, descending colon, transverse colon, ascending colon), the adequacy of bowel preparation, % of bowel lumen filled with fecal material, and bowel tortuosity or folding were assessed. Measurements of bowel wall thickness (cm), cross-sectional bowel lumen diameter (cm), and cross-sectional bowel luminal area (cm(2) ) were obtained at standardized locations within the large bowel. False discovery rates (FDR) were calculated to adjust for multiple testing. Values of FDR < 0.05 were considered significant. Differences in mean cross-sectional area and diameter and bowel wall thickness under increasing pressure were not significant after adjusting for multiple testing; some had raw p values <0.05. Ascending colon diameter and ascending colon area significantly increased with insufflation time (FDR < 0.05). No other response variables showed a significant change with insufflation time. The optimal insufflation pressure for maintaining pneumocolon in this study was determined to be 20 mmHg. CTP is a feasible technique to provide consistent distension for imaging of the large bowel and further study on application of CTP in clinical patients is warranted.

Does Hepatic Steatosis Have an Impact on the Short Term Hepatic Response After Complete Attenuation of Congenital Extrahepatic Portosystemic Shunts? A Prospective Study of 20 Dogs

OBJECTIVE To evaluate the relationship between hepatic steatosis and increase in liver size and resolution of shunting after surgical attenuation of congenital extrahepatic portosystemic shunts in dogs. STUDY DESIGN Prospective study. ANIMALS Dogs (n = 20) with congenital extrahepatic portosystemic shunts. METHODS Shunts were attenuated using ameroid ring constrictors. Portal blood flow and liver volume were evaluated using computed tomography before and ≥8 weeks after surgery. Hepatic steatosis was quantified by stereological point counting of lipid droplets and lipogranulomas (LG) in liver biopsies stained with Oil-red-O. Associations between steatosis and preoperative liver volume, liver growth after surgery, and development of acquired shunts were evaluated. RESULTS Acquired shunts developed in 2 dogs (10%). Dogs with larger preoperative liver volumes relative to bodyweight had fewer lipid droplets per tissue point (P = .019). LG per tissue point were significantly associated with age: 0.019 ± 0.06 for dogs <12 months versus 0.25 ± 0.49 for dogs >12 months (P = .007). There was a significant positive association between liver growth after surgery and the number of LG/month of age in dogs >12 months (P = .003). There was no association between steatosis, presence of macrosteatosis, the number of LG or development of acquired shunts. CONCLUSIONS This preliminary study suggests that the presence of hepatic lipidosis and LG has no demonstrable effect on development of acquired shunts or the magnitude of increase in liver volume after attenuation of congenital extrahepatic portosystemic shunts in dogs.

Mechanical properties of canine osteosarcoma-affected antebrachia

Objective: To determine the influence of neoplasia on the biomechanical properties of canine antebrachia. Study design: Ex vivo biomechanical study. Sample population: Osteosarcoma (OSA)‐affected canine antebrachia (n = 12) and unaffected canine antebrachia (n = 9). Methods: Antebrachia were compressed in axial loading until failure. A load‐deformation curve was used to acquire the structural mechanical properties of neoplastic and unaffected specimens. Structural properties and properties normalized by body weight (BW) and radius length were compared using analysis of variance (ANOVA). Modes of failure were compared descriptively. Results: Neoplastic antebrachia fractured at, or adjacent to, the OSA in the distal radial diaphysis. Unaffected antebrachia failed via mid‐diaphyseal radial fractures with a transverse cranial component and an oblique caudal component. Structural mechanical properties were more variable in neoplastic antebrachia than unaffected antebrachia, which was partially attributable to differences in bone geometry related to dog size. When normalized by dog BW and radial length, strength, stiffness, and energy to yield and failure, were lower in neoplastic antebrachia than in unaffected antebrachia. Conclusions: OSA of the distal radial metaphysis in dogs presented for limb amputation markedly compromises the structural integrity of affected antebrachia. However, biomechanical properties of affected bones was sufficient for weight‐bearing, as none of the neoplastic antebrachia fractured before amputation. The behavior of tumor invaded bone under cyclic loading warrants further investigations to evaluate the viability of in situ therapies for bone tumors in dogs.

CT Pneumocolonography In Normal Dogs

Objectives of this prospective study were to describe effects of varying technical components that may contribute to an optimal protocol for computed tomographic pneumocolonography (CTP) in dogs, and to develop a standardized methodology for CTP as a future potential diagnostic tool in canine clinical patients with large bowel disease. Eight purpose-bred intact male hound cross-research dogs were enrolled and randomized to groups based on variables of pressure/body position (n = 4) and insufflation time (n = 4). For each segment of large bowel (rectum, colorectal junction, descending colon, transverse colon, ascending colon), the adequacy of bowel preparation, % of bowel lumen filled with fecal material, and bowel tortuosity or folding were assessed. Measurements of bowel wall thickness (cm), cross-sectional bowel lumen diameter (cm), and cross-sectional bowel luminal area (cm(2) ) were obtained at standardized locations within the large bowel. False discovery rates (FDR) were calculated to adjust for multiple testing. Values of FDR < 0.05 were considered significant. Differences in mean cross-sectional area and diameter and bowel wall thickness under increasing pressure were not significant after adjusting for multiple testing; some had raw p values <0.05. Ascending colon diameter and ascending colon area significantly increased with insufflation time (FDR < 0.05). No other response variables showed a significant change with insufflation time. The optimal insufflation pressure for maintaining pneumocolon in this study was determined to be 20 mmHg. CTP is a feasible technique to provide consistent distension for imaging of the large bowel and further study on application of CTP in clinical patients is warranted.

CT‐derived indices of canine osteosarcoma‐affected antebrachial strength

Objective To improve the prediction of fractures in dogs with bone tumors of the distal radius by identifying computed tomography (CT) indices that correlate with antebrachial bone strength and fracture location. Study design Prospective experimental study. Animals Dogs with antebrachial osteosarcoma (n = 10), and normal cadaver bones (n=9). Methods Antebrachia were imaged with quantitative CT prior to biomechanical testing to failure. CT indices of structural properties were compared to yield force and maximum force using Pearson correlation tests. Results Straight beam failure (Fs), axial rigidity, curved beam failure (Fc), and craniocaudal bending moment of inertia (MOICrCd) CT indices most highly correlated (0.77 > R > 0.57) with yield and maximum forces when iOSA-affected and control bones were included in the analysis. Considering only OSA-affected bones, Fs, Fc, and axial rigidity correlated highly (0.85 > R > 0.80) with maximum force. In affected bones, the location of minimum axial rigidity and maximum MOICrCd correlated highly (R > 0.85) with the actual fracture location. Conclusions CT-derived axial rigidity, Fs, and MOICrCd have strong linear relationships with yield and maximum force. These indices should be further evaluated prospectively in OSA-affected dogs that do, and do not, experience pathologic fracture.Objective: To improve the prediction of fractures in dogs with bone tumors of the distal radius by identifying computed tomography (CT) indices that correlate with antebrachial bone strength and fracture location. Study design: Prospective experimental study. Animals: Dogs with antebrachial osteosarcoma (n = 10), and normal cadaver bones (n=9). Methods: Antebrachia were imaged with quantitative CT prior to biomechanical testing to failure. CT indices of structural properties were compared to yield force and maximum force using Pearson correlation tests. Results: Straight beam failure (Fs), axial rigidity, curved beam failure (Fc), and craniocaudal bending moment of inertia (MOICrCd) CT indices most highly correlated (0.77 > R > 0.57) with yield and maximum forces when iOSA‐affected and control bones were included in the analysis. Considering only OSA‐affected bones, Fs, Fc, and axial rigidity correlated highly (0.85 > R > 0.80) with maximum force. In affected bones, the location of minimum axial rigidity and maximum MOICrCd correlated highly (R > 0.85) with the actual fracture location. Conclusions: CT‐derived axial rigidity, Fs, and MOICrCd have strong linear relationships with yield and maximum force. These indices should be further evaluated prospectively in OSA‐affected dogs that do, and do not, experience pathologic fracture.

Assessment of 3 Bowel Preparation Protocols for Computed Tomography Pneumocolonography in Normal Dogs.

OBJECTIVE To investigate the effects of 3 different bowel preparation protocols on interpretation of computed tomography (CT) pneumocolonography images. STUDY DESIGN Experimental crossover design. ANIMALS Intact male, hound-cross, research colony dogs (n=4). METHODS All dogs received the 3 different bowel preparation protocols for CT pneumocolonography in the same order, with a minimum of 2 weeks between protocols. For each segment of large bowel, the subjective adequacy of bowel cleansing was assessed, residual fecal and bowel volumes were calculated, and the density of fecal material in the bowel lumen was measured. Linear mixed effect models that included a random dog effect were used to evaluate mean differences in outcome measures across protocols. RESULTS No dogs experienced any clinical problems associated with the protocols or CT pneumocolonography. Bowel cleansing was considered adequate for CT pneumocolonography interpretation for all 3 protocols. There was a significant effect of protocol on residual fecal volumes and the fecal:bowel volume ratio, with the 2 protocols that included an extended fast producing the lowest total residual fecal volumes. There was a significant effect of protocol on maximum measured density of residual fecal material with the 2 protocols including iodinated contrast having the highest density. CONCLUSIONS All protocols were sufficient for CT pneumocolonography interpretation and contrast-tagging of residual fecal material was successful with oral iopamidol administration. An at-home bowel cleansing protocol may provide adequate bowel cleansing for CT pneumocolonography image interpretation.