Browsing by Author "Lanz, Otto I."

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    Assessment of the Measurement Repeatability and Sensitivity of a Noninvasive Blood Perfusion Measuring Probe
    Comas, Caroline Marie (Virginia Tech, 2005-07-07)
    Blood perfusion is the local, non-directional blood flow through tissue. It is measured as the volumetric flow rate of blood through a given volume of tissue. One method that has been developed for measuring blood perfusion is a probe that measures the temperature response of the tissue when a thermal event is applied. From the temperature response, the blood perfusion and contact resistance can be estimated by comparing the experimental response to a predicted response, and employing Gaussian minimization techniques to estimate the blood perfusion and contact resistance. The objective of this research was to assess the measurement repeatability and sensitivity of the blood perfusion probe by testing the probe on phantom tissue, such that the effects of physiologic or pathologic conditions on the blood perfusion could be eliminated. Another objective was to conduct a preliminary in vivo study using rats for the purpose of establishing proper experimental protocols for future testing of the blood perfusion probe. A phantom tissue test stand comprised of porous material and water to simulate tissue and blood, respectively, was constructed for the phantom study. Inlet flow rates into the porous media ranging between 0 cc/min and 30 cc/min were tested. To test the measurement repeatability 7 flow rates (0, 5, 10, 15, 20, 25 and 30 cc/min) were tested on two different days. To test the measurement sensitivity of the probe, flow rates between 0 and 10 cc/min, and 15 and 20 cc/min were tested at intervals of 1 cc/min. From the phantom study it was concluded that the probe displayed good measurement repeatability, as the trend in perfusion as a function of inlet flow rates for both days was found to be the same. It was also found that the data collected using the probe yielded significantly different perfusion estimates for different flow rates, as statistical analyses show that the average perfusion differences between flow rates are truly independent within a 90% confidence interval, for flow differences above 4 cc/min. It was found that for flow rates below 4 cc/min the probe sensitivity was significantly reduced. For the in vivo study it was concluded that the probe can be used to obtain estimates of perfusion from rats. This preliminary study also served to establish proper experimental protocols for future tests.
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    Assessment of the Repeatability and Sensitivity of the Thermoelectric Perfusion Probe
    Ellis, Brent Earl (Virginia Tech, 2006-12-06)
    The Thermoelectric Perfusion Probe is a completely electronic system that cyclically heats and cools tissue to measure blood perfusion. The probe produces the thermal event with a thermoelectric cooler and then measures the resulting heat flux and temperatures: the arterial temperature and the sensor temperature (the temperature between the heat flux gage and the skin). The Thermoelectric Perfusion Probe was validated and calibrated on a phantom tissue test stand, a system that simulates perfusion with known, controlled flow. With the new pressed sensor technology, a thermocouple sealed to a heat flux gage, the sensor temperature and the heat flux are simultaneously recorded. The pressed sensor tests validated the program used to predict perfusion for the Thermoelectric Perfusion Probe. This perfusion estimation program can determine the tissues perfusion regardless of how the thermal event is created (i.e. convective cooling, convective heating, conductive heating). Based on experimentation, the Thermoelectric Perfusion Probe displays good repeatability and sensitivity for continuously measuring perfusion. The sensitivity and repeatability of the Thermoelectric Perfusion Probe was proven when the perfusion estimates were compared to the perfusion estimates predicted by the Convective Perfusion Probe, a previously validated perfusion probe, and the CFD Flow Model, a computational model of the phantom tissue test stand.
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    Bead size has a greater effect on in vitro elution from antimicrobial-impregnated calcium sulfate beads than drug concentration
    Olsen, Ronald S.; Sawyere, Dominique M.; Davis, Jennifer L.; Lanz, Otto I.; Werre, Stephen R. (American Veterinary Medical Association, 2023-05)
    OBJECTIVE To compare the elution characteristics of amikacin-impregnated calcium sulfate (CaSO4) beads based on different drug concentrations and bead size configurations. SAMPLE Six groups of amikacin-impregnated CaSO4 beads and one negative control group. PROCEDURES Amikacin-impregnated CaSO4 beads were formed with either 500 mg (low-concentration) or 1 g (high-concentration) of amikacin per 15 g CaSO4 hemihydrate powder. The number of beads necessary to approximate 150 mg of amikacin for each of the 3 bead sizes (3 mm, 5 mm, and 7 mm) at both low and high concentrations were placed in 6 mL of phosphate-buffered saline. The saline was sampled at 14 time points over 28 days. Amikacin concentrations were determined using liquid chromatography-mass spectrometry. RESULTS Smaller beads reached higher mean peak concentrations than larger beads (P < .0006). Peak concentrations for the low-and high-concentration groups were 20.5 mg/mL and 27.4 mg/mL, 13.1 mg/mL and 14.0 mg/mL, and 8.85 mg/mL and 6.75 mg/mL for the 3 mm, 5 mm, and 7 mm beads, respectively. Bead size also affected the length of therapeutic duration, lasting 6 days for the 3 mm and 5 mm beads and 9 days for the 7 mm beads. However, this was only statistically evident among the high-concentration beads (P < .044). Antimicrobial concentration within the same bead sizes did not affect elution. CLINICAL RELEVANCE Amikacin-impregnated CaSO4 beads achieved extreme supratherapeutic eluent concentrations. While additional studies are needed, bead size significantly affected elution with smaller beads reaching higher peak concentrations and 7 mm, high-concentration beads demonstrating a longer therapeutic duration than smaller beads.
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    A Biomechanical Comparison of 3.5 Locking Compression Plate Fixation to 3.5 Limited Contact Dynamic Compression Plate Fixation in a Canine Cadaveric Distal Humeral Metaphyseal Gap Model
    Filipowicz, Dean (Virginia Tech, 2008-05-30)
    Objective- To compare the biomechanical properties of 3.5 locking compression plate (LCP) fixation to 3.5 limited contact dynamic compression plate (LC-DCP) fixation in a canine cadaveric, distal humeral metaphyseal gap model in static axial compression and cyclic axial compression and torsion. Study Design- Biomechanical in vitro study. Sample Population- 30 paired humeri from adult, medium to large breed dogs. Methods- Testing was performed monotonically to failure in axial compression on ten pairs of humeri, cyclically in axial compression for 10,000 cycles on ten pairs and cyclically in torsion for 500 cycles on the last ten pairs. Results- Humeral constructs stabilized with LCPs were significantly stiffer than those plated with LC-DCPs when loaded in axial compression (P=0.0004). When cyclically loaded in axial compression over 10,000 cycles, the LC-DCP constructs were significantly stiffer than those constructs stabilized with LCPs (P=0.0029). Constructs plated with LC-DCPs were significantly more resistant to torsion over 500 cycles than those plated with LCPs (P<0.0001), though no difference was detected during the first 280 cycles. Conclusions- The increased stiffness of LCP constructs in monotonic loading compared to constructs stabilized with non-locking plates may be attributed to the stability afforded by the plate-screw interface of locking plates. The LCP constructs demonstrated less stiffness in dynamic testing in this model, likely due to plate-bone offset secondary to non-anatomic contouring and occasional incomplete seating of the locking screws when using the torque-limiting screw driver. Clinical Relevance- LCPs yield less stiff fixation under dynamic loading than conventional LC-DCPs when applied to severely comminuted, metaphyseal fractures. Improving anatomical contouring of the plate and insuring complete screw insertion into the locking plate hole may improve stiffness when using LCPs in comminuted fractures.
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    Biomechanical evaluation of two methods of surgical stabilization of the atlantoaxial joint
    Kopf, Kelli Michaela (Virginia Tech, 2013-08-20)
    Several methods of surgical stabilization of the atlantoaxial joint are described in the veterinary literature. Threaded acrylic pins placed ventrally together with polymethylmethacrylate (PMMA) is a well-established technique that has been widely used in clinical cases. However, Kishigami tension bands are a less technically demanding procedure with potentially fewer complications. The purpose of this study was to biomechanically compare these two techniques in ventral-to-dorsal bending in both mature and immature dogs. Seventeen normal canine cadavers <15kg were collected and radiographed to determine skeletal maturity. The cervical spines were dissected leaving bony and ligamentous structures intact. Eight mature spines and 9 immature spines were randomly divided into two groups. In one group a Kishigami tension band was applied over the dorsal arch of the atlas and attached to the spinous process of the axis using orthopedic wire. In the second group, six acrylic pins were placed ventrally in the atlas, axis, and transarticularly. The pins were then cut and covered with PMMA. The specimens were potted in custom steel pots and biomechanically analyzed in ventral-to-dorsal four-point bending. Load-displacement curves representing the degree of stiffness were compared between the groups. Stabilization using ventral pins and PMMA had a significantly greater stiffness than a Kishigami tension band when bending in ventral to dorsal bending. Within the stabilized vertebral segment, there was no significant difference between the stiffness of immature vs. mature bone. Further analysis in torsion and analysis in abnormal dogs will be helpful in establishing the clinical significance of these findings.
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    Cefazolin Concentration in Surgically Created Wounds Treated with Negative Pressure Wound Therapy Compared to Surgically Created Wounds Treated with Nonadherent Wound Dressings
    Coutin, Julia Viviana (Virginia Tech, 2014-06-25)
    Our objective was to compare cefazolin concentrations in biopsied tissue samples collected from surgically created wounds treated with negative pressure wound therapy to those collected from surgically created wounds treated with nonadherent dressings. The study design was a prospective, controlled, experimental study. The animal population included 12 female spayed beagles. We hypothesized there would be a difference between the cefazolin concentrations of wounds treated with negative pressure wound therapy when compared to the cefazolin concentrations of wounds treated with nonadherent dressings. Surgical methods were as follows: Full thickness cutaneous wounds were created on each antebrachium (n=24). Following surgery, cefazolin (22 mg/kg) was administered intravenously to each of the dogs and continued every 8 hours during the study. The right wound was randomly assigned to group I or group II while the wound on the contralateral antebrachium was assigned to the other group. Group I wounds were treated with negative pressure wound therapy (NPWT) and group II wounds were treated with nonadherent dressings for 3 days. Dressings were changed and tissue biopsies obtained from wound beds at 24-hour intervals for both groups. Cefazolin wound tissue and plasma concentrations were measured by liquid chromatography mass spectrometry (LC-MS/MS). Blood samples for measuring plasma cefazolin concentrations were collected prior to biopsy sampling. At the time of surgery and at each bandage change, wound beds were swabbed and submitted for aerobic and anaerobic culture. Our results revealed that after initiating cefazolin treatment, wound tissue antibiotic concentrations between treatment groups were not significantly different at any sampling time. Similarly, after initiating cefazolin treatment, plasma cefazolin concentrations were not significantly different at any sampling time for individual dogs. We concluded that using a canine experimental model, NPWT treatment of surgically created wounds does not statistically impact cefazolin tissue concentrations when compared to conventional nonadherent bandage therapy
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    A Comparison of Liver Biopsy Techniques in Dogs
    Kemp, Stephanie D. (Virginia Tech, 2013-05-15)
    Background: The liver biopsy technique in dogs that consistently provides samples adequate for accurate histopathologic interpretation and the variability of histopathology among lobes is unknown. Hypothesis:  Liver biopsy specimens obtained via punch, cup biopsy, and 14 gauge needle biopsy would result in similar histopathologic diagnoses to those found on deeply sectioned samples of liver obtained at necropsy and that discordant results would not differ between lobes.   Animals:  Seventy dogs undergoing necropsy. Methods: Liver specimens were obtained from the left lateral liver lobe with an 8 mm punch, a cup, and a 14 gauge needle. Two larger tissue samples were then collected near the center of the left lateral lobe and used as a histologic standard for comparison.  Samples were also obtained from all remaining lobes. Histopathologic features and numbers of portal triads in each sample were compared. Results: The mean number of portal triads were 2.9 in needle biopsies, 3.4 in cup biopsies, 12 in punch biopsies, and 30.7 in the necropsy samples. Sixty-six percent of needle biopsies,  60% of laparoscopic cup samples, and 69% of punch samples were in agreement with the necropsy samples, differences that were not significantly different. The corresponding kappa coefficient were 0.59 for needle biopsies, 0.52 for cup biopsies, and 0.62 for punch biopsies.  Discordant results did not differ between the liver lobes. Conclusions and Clinical Relevance:  A single biopsy using any of the tested techniques is insufficient for reliable diagnosis of liver disease in the dog.  Multiple biopsies from 2 lobes is recommended.
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    A Comparison of Liver Sampling Techniques in Dogs
    Kemp, Stephanie D.; Zimmerman, Kurt L.; Panciera, David L.; Monroe, William E.; Leib, Michael S.; Lanz, Otto I. (American College of Veterinary Internal Medicine, 2015-01)
    Background: The liver sampling technique in dogs that consistently provides samples adequate for accurate histopathologic interpretation is not known. Hypothesis/ Objectives: To compare histopathologic results of liver samples obtained by punch, cup, and 14 gauge needle to large wedge samples collected at necropsy. Animals: Seventy dogs undergoing necropsy. Methods: Prospective study. Liver specimens were obtained from the left lateral liver lobe with an 8 mm punch, a 5 mm cup, and a 14 gauge needle. After sample acquisition, two larger tissue samples were collected near the center of the left lateral lobe to be used as a histologic standard for comparison. Histopathologic features and numbers of portal triads in each sample were recorded. Results: The mean number of portal triads obtained by each sampling method were 2.9 in needle samples, 3.4 in cup samples, 12 in punch samples, and 30.7 in the necropsy samples. The diagnoses in 66% of needle samples, 60% of cup samples, and 69% of punch samples were in agreement with the necropsy samples, and these proportions were not significantly different from each other. The corresponding kappa coefficients were 0.59 for needle biopsies, 0.52 for cup biopsies, and 0.62 for punch biopsies. Conclusion and Clinical Importance: The histopathologic interpretation of a liver sample in the dog is unlikely to vary if the liver biopsy specimen contains at least 3- 12 portal triads. However, in comparison large necropsy samples, the accuracy of all tested methods was relatively low.
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    Comparison of Postoperative Pain Following Ovariohysterectomy via Harmonic Scalpel-Assisted Laparoscopy Versus Traditional Celiotomy In Dogs
    Hancock, Robert Byron (Virginia Tech, 2005-05-09)
    The objective of this study was to compare the effects of postoperative pain following ovariohysterectomy via harmonic scalpel assisted laparoscopy (HALO) and traditional ovariohysterectomy (OVH) in dogs. The study was designed as a randomized, blinded, prospective study. Sixteen, purpose-bred, intact female, Beagle dogs were used to complete the study. Dogs were placed into two groups. Group 1 included (8 dogs) that underwent ovariohysterectomy via HALO. Group 2 included (8 dogs) that underwent ovariohysterectomy via traditional OVH. Physiologic data, abdominal nociceptive threshold scores, and University of Melbourne pain scores (UMPS) were recorded at 2, 6, 12, 24, 48, and 72 hours following surgery. Blood samples for plasma cortisol, glucose, and creatine phosphokinase (CPK) were taken at the time of the incision and 2, 6, 12, 24, 48, and 72 hours following surgery. No significant surgical complications were encountered in either group. The HALO mean surgical time was significantly longer (55.7 minutes) than the traditional OVH (31.7 minutes). No significant differences were observed between the two groups for the pain measures of heart rate, respiratory rate, temperature, CPK, and glucose. The OVH group had significantly higher mean plasma cortisol levels at hour 2 following surgery than the HALO group (P=0.0001). The mean UMPS were significantly higher in the OVH group than the HALO group at all postoperative times (P=0.0001). Mean nociceptive threshold measurements revealed significantly higher tolerated palpation pressures in the HALO than the OVH group at all postoperative times, except hour 72 (P=0.0002). Dogs in this study appeared to be less painful with HALO procedures versus traditional OVH. The harmonic scalpel coagulated ovarian and uterine vessels completely with minimal collateral damage to surrounding tissues. The clinical relevance of this study demonstrates that harmonic scalpel-assisted laparoscopic ovariohysterectomy is a safe alternative to traditional OVH and offers a minimally invasive and less painful method of surgery.
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    Computed Tomographic Features in a Case of Bilateral Neoplastic Cryptorchidism with Suspected Torsion in a Dog
    Stokowski, Scott; Ruth, Jeffrey D.; Lanz, Otto I.; Ziglioli, Vincent (2016)
    An 11-year-old male German Shepherd dog presented for inappetence and weight loss. Physical examination and initial bloodwork revealed palpable abdominal masses, mild non-regenerative anemia, and thrombocytopenia. Survey radiography and abdominal ultrasonography confirmed the presence of bilateral abdominal masses and lymphadenopathy. Contrast-enhanced computed tomography (CT) was performed in order to further investigate the origin of the intraabdominal masses, confirming two enlarged cryptorchid testes, one of which had an associated CT "whirl sign." Histopathology of the testes and lymph nodes revealed bilateral malignant Sertoli cell tumors and seminomas with lymph node metastasis of both neoplasms. The purpose of this case report is to discuss the benefits of CT in the diagnosis of cryptorchid testes and describe an additional organ that may display CT "whirl sign."
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    Cytokine and Growth Factor Concentrations in Canine Autologous Conditioned Serum
    Sawyere, Dominique M. (Virginia Tech, 2016-05-27)
    The object of this study was to compare growth factor and cytokine profiles in canine autologous conditioned serum (ACS) to canine plasma. Blood collected from 16 medium to large breed dogs was used to produce ACS (Orthokine® vet irap 10 syringes) and citrated plasma (control). Canine-specific ELISA assays were run per manufacturers’ instructions for interleukin (IL)-10, IL-4, tumor necrosis factor (TNF)-α, insulin-like growth factor (IGF)-1, fibroblast growth factor (FGF)-2, transforming growth factor (TGF)-β1, IL-1β, and interleukin-1 receptor antagonist (IL-1ra). Serum, in addition to plasma and ACS, was collected from an additional 6 dogs for TNF-α, IL-1β, and IL-1ra analysis (total of 22 dogs). Data were analyzed for differences in cytokine concentrations between ACS, plasma, and serum using the Wilcoxon signed-rank test with significance set at P<.05.There was a large variability in growth factor and cytokine concentrations between individual dogs in both plasma and ACS. There were no significant differences in IL-10, TNF-α, IGF-1, FGF-2, and TGF-β1 concentrations between ACS, plasma, or serum. ACS concentrations of IL-1β (median, range; 46.3 pg/mL, 0-828.8) and IL-4 (0.0 pg/mL, 0-244.1) were significantly increased compared to plasma (36.6 pg/mL, 0-657.1 and 0.0 pg/mL, 0-0, respectively). IL-1ra concentrations in ACS (median, range; 3458.9 pg/mL, 1,243.1-12,089.0) were significantly higher than plasma (692.3 pg/mL, 422.5- 1,475.6), as was the IL-1ra:IL-1β ratio (39.9 and 7.2, respectively).
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    Densitometric Comparison of Autogenous Cancellous Bone Graft and Extracorporeal Shock Wave Therapy in the Tibial Tuberosity Advancement Procedure in Dogs
    Barnes, Katherine Hirose (Virginia Tech, 2015-07-01)
    Objectives: To compare optical values in the osteotomy gap created after a Tibial Tuberosity Advancement (TTA) treated with autogenous cancellous bone graft (ACBG), extracorporeal shock wave therapy (ESWT), a combination of ACBG and ESWT, and absence of both ACBG and ESWT using densitometry. Methods: Dogs presenting for surgical repair of a cranial cruciate ligament rupture were randomly assigned to one of four groups; TTA with ACBG (TTA-G), TTA with ACBG and ESWT (TTA-GS), TTA with ESWT (TTA-S), and TTA with no additional therapy (TTA-O). Mediolateral radiographs at 0, 4 and 8 weeks after surgery were evaluated to compare healing of the osteotomy gap via densitometry. An analysis of variance (ANOVA) statistical analysis was used to compare the densitometric values between groups. Results: At 4 weeks after surgery, a significant difference in osteotomy gap density was noted between TTA-GS (8.4 millimeters of Aluminum equivalent [mmAleq]) and TTA-S (6.1mmAleq), and between TTA-GS (8.4 mmAleq) and TTA-O (6.4 mmAleq). There were no significant differences noted between groups at the 8 week recheck. Clinical Significance: There were no significant differences in the osteotomy gap density at 8 weeks after surgery regardless of the treatment modality used. The combination of ACBG and ESWT may lead to increased density of the osteotomy gap in the first 4 weeks after surgery. Densitometry using an aluminum step wedge is a feasible method for comparison of bone healing after TTA in dogs.
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    Determining ideal staple size for small intestinal surgery in cats
    Hiebert, Elizabeth C. (Virginia Tech, 2022-03-08)
    Background: The use of stapling equipment for intestinal surgery in cats is rarely reported, and appropriate staple sizes for cat intestine are unknown. Objective: To determine staple cartridge sizes for thoracoabdominal (TA) and endoscopic gastrointestinal anastomosis (EndoGIA) that will simultaneously prevent leakage of small intestinal contents while also allowing for sufficient vascular permeability past the staple lines for intestinal healing. Methods: Two sizes of EndoGIA cartridges (2.0/2.5/3.0mm and 3.0/3.5/4.0mm) and two sizes of TA cartridges (2.5mm and 3.5mm), applied in a transverse manner across fresh cadaveric cat jejunum, were evaluated via intestinal burst pressure testing for maximum intraluminal pressure prior to leaking, and via infusion of an intravascular dye at normal arterial pressures to determine percentage of vascular patency past the staple lines. Vascular patency was compared not only from pre-and post-staple segments of the same intestinal sample, but also EndoGIA vascular patency was evaluated against TA vascular patency. Results: Two cats met study criteria. All samples had intraluminal burst pressures over twice the chosen minimum (of 30mmHg). Vascular patency post- staple line ranged from 0-90.8%, with the most consistently high numbers noted with the TA 3.5mm cartridges. No EndoGIA cartridge had a post- staple line vascular patency higher than 31.1%, and no intravascular dye was noted in any post- staple line sample in the EndoGIA 2.0/2.5/3.0mm group. Conclusions: While statistical analysis of the dataset was unable to be performed due to low numbers of samples for comparison, both intestinal intraluminal burst pressure trends and intravascular dye patterns suggested both the TA 3.5mm cartridge and (to a lesser extent) the 3.0/3.5/4.0mm EndoGIA cartridge could provide the ideal combination of intraluminal seal without restriction of vascular access for healing. The intravascular dye infusion technique, developed during this research, shows promise as a future instrument to determine vascular patterns around intestinal implants in cadaveric cat specimens.
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    Development of a Phantom Tissue for Blood Perfusion Measurements and Noninvasive Blood Perfusion Estimation in Living Tissue
    Mudaliar, Ashvinikumar (Virginia Tech, 2007-01-23)
    A convenient method for testing and calibrating surface perfusion sensors has been developed. A phantom tissue model is used to mimic the non-directional blood flow of tissue perfusion. A computational fluid dynamics (CFD) model was constructed in Fluent to design the phantom tissue and validate the experimental results. The phantom perfusion system was used with a perfusion sensor based on the clearance of thermal energy. A heat flux gage measures the heat flux response of tissue when a thermal event (convective cooling) is applied. The blood perfusion and contact resistance are estimated by a parameter estimation code. From the experimental and analytical results, it was concluded that the probe displayed good measurement repeatability and sensitivity. The experimental perfusion measurements in the tissue were in good agreement with those of the CFD models and demonstrated the value of phantom tissue system. This simple, cost effective, and noninvasive convective blood perfusion system was then tested in animal models. The perfusion system was evaluated for repeatability and sensitivity using isolated rat liver and exposed rat kidney tests. Perfusion in the isolated liver tests was varied by controlling the flow of the perfusate into the liver, and the perfusion in the exposed kidney tests was varied by temporarily occluding blood flow through the renal artery and vein. The perfusion estimated by the convective perfusion probe was in good agreement with that of the metered flow of perfusate into the liver model. The liver tests indicated that the probe can be used to detect small changes in perfusion (0.005 ml/ml/s). The probe qualitatively tracked the changes in the perfusion in kidney model due to occlusion of the renal artery and vein.
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    Development of the Passive Perfusion Probe for Non-Invasive Blood Perfusion Measurement
    Ricketts, Patricia Lynn (Virginia Tech, 2007-05-03)
    A non-invasive blood perfusion system has been developed and tested in a phantom tissue and an animal model. The system uses a small sensor with a laminated flat thermocouple to measure the heat transfer response to an arbitrary thermal event (convective or conductive) imposed on the tissue surface. Blood perfusion and contact resistance are estimated by comparing heat flux data with a mathematical model of the tissue. The perfusion system was evaluated for repeatability and sensitivity using both a phantom tissue test stand and exposed rat liver tests. Perfusion in the phantom tissue tests was varied by controlling the flow of water into the phantom tissue test section, and the perfusion in the exposed liver tests was varied by temporarily occluding blood flow through the portal vein. The phantom tissue tests indicated that the probe can be used to detect small changes in perfusion (0.009 ml/ml/s). The probe qualitatively tracked the changes in the perfusion of the liver model due to occlusion of the portal vein.
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    Diagnostic Imaging of Foreign Bodies and Compartmentalization in the Canine Manus
    Ober, Christopher Patrick (Virginia Tech, 2009-03-17)
    Injury of the manus is an important cause of morbidity and function loss in dogs, especially working breeds. These injuries may cause foreign body retention and can lead to persistent infection. Accurate methods for diagnosis and localization of pathology in this anatomically complex region are critical to minimize patient morbidity, guide surgical planning, and improve case outcomes. The anatomy of the canine manus was evaluated with computed tomography (CT), magnetic resonance imaging (MRI), and transverse anatomic sections. Most structures identified on transverse sections were visible on both CT and MRI images. Detail in the osseous structures was better in CT images, while MRI provided increased contrast of soft-tissue structures. To test the hypothesis that diagnostic accuracies of CT, MRI, and ultrasound differ for detection of acute wooden foreign bodies in the canine manus, we inserted wooden splinters into canine cadaver manus and imaged each manus with all three modalities. Receiver operating characteristic curve analysis demonstrated that CT was most accurate for detection of acute wooden foreign bodies, followed in turn by ultrasound and MRI. Diseases in the human hand and foot are often confined by soft-tissue spaces, but similar structures have not been described in the dog. To determine if these spaces are present in the canine manus, we injected contrast medium into likely spaces and compartments in cadaver specimens, imaged the limbs with CT, and dissected the injected manus specimens. We found thirteen discrete soft-tissue spaces and five myofascial compartments that are similar to those described in the human hand. To test the hypothesis that spread of disease in the canine manus can be modeled and predicted, we injected cadaver interdigital web spaces with contrast medium, imaged them with CT, and dissected them. We found that the pattern of contrast agent spread, as a model of infection, was predictable and unique to the initial injection site. Findings from these cadaver studies improve our understanding of anatomy, imaging of wooden foreign bodies, and likely patterns of disease extension in the canine manus. Future studies are needed to test the utility of this information for surgical planning in affected clinical patients.
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    Effect of 9 mm Tibial Tuberosity Advancement on Cranial Tibial Translation in the Canine Cranial Cruciate Ligament Deficient Stifle
    Miller, Jonathan Mark (Virginia Tech, 2009-05-09)
    Objective-To assess the effect of 9 mm tibial tuberosity advancement (TTA) on cranial tibial translation (CTT) in cranial cruciate ligament (CCL) deficient canine stifles. Study Design-In vitro cadaveric study. Animals-Twelve canine pelvic limbs. Methods-Each stifle was placed in a jig at 135° with a simulated quadriceps force and tibial axial force, and the distance of CTT was measured with the CCL intact (iCCL), transected (tCCL), and after performing a TTA using a 9 mm cage. In addition, a material testing machine was used to assess the force required to elicit CTT in each scenario. Results-The mean CTT for iCCL was 0.42 mm, 1.58 mm after severing the CCL, and 1.06 mm post TTA. The tCCL CTT measured without any quadriceps force was 2.59 mm. Differences between the intact and tCCL (p<0.0001) and tCCL and TTA (p=0.0003) were significant. The difference between the tCCL with and without the quadriceps force was not significant (p=0.0597). The force required to cause CTT was greater in the TTA than the tCCL up to 6mm (p<0.0001). As axial load increased, the force required to advance the tibia increased in both treatment groups (p value for overall weight effect =0.0002). Conclusions- These data confirm that TTA does reduce CTT in tCCL stifles in this model. The addition of a simulated quadriceps force to a CCL deficient stifle prior to a TTA, by itself, may not significantly lessen CTT. Clinical Relevance- While this in vitro model demonstrated that TTA reduced CTT in canine stifles with CCL transected, the modular limitations preclude extrapolation to the effect of TTA on the live dog.
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    Effect of a single intra-articular injection of bupivacaine on synovial fluid prostaglandin E2 concentrations in normal canine stifles
    Giangarra, Jenna E.; Barry, Sabrina L.; Dahlgren, Linda A.; Lanz, Otto I.; Benitez, Marian E.; Werre, Stephen R. (2018-04-25)
    Objective: To identify if synovial fluid prostaglandin E2 increases in response to a single intra-articular dose of bupivacaine in the normal canine stifle. Results: There were no significant differences in synovial fluid prostaglandin E2 (PGE2) concentrations between treatment groups or over time within bupivacaine or saline groups. Samples requiring ≥ 3 arthrocentesis attempts had significantly higher PGE2 concentrations compared to samples requiring 1 or 2 attempts. Following correction for number of arthrocentesis attempts, PGE2 concentrations were significantly higher than baseline at 24 and 48 h in the bupivacaine group; however there were no significant differences between the bupivacaine and saline groups. In normal dogs, a single bupivacaine injection did not cause significant synovial inflammation, as measured by PGE2 concentrations, compared to saline controls. Future research should minimize aspiration attempts and include evaluation of the synovial response to bupivacaine in clinical cases with joint disease.
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    Effect of a single intra-articular injection of bupivacaine on synovial fluid prostaglandin E2 concentrations in normal canine stifles
    Giangarra, Jenna Elizabeth (Virginia Tech, 2018-06-19)
    Intra-articular bupivacaine is a common analgesic used in dogs with orthopedic disease. Bupivacaine has been linked to chondrotoxicity. The mechanism for bupivacaine's chondrotoxicity is unknown, but may involve inflammation. Prostaglandin E2 (PGE2) is an inflammatory mediator and a marker of joint inflammation. The aim of this study was to compare synovial fluid PGE2 concentrations after a single intra-articular injection of bupivacaine with a saline control in normal canine stifles. We hypothesized that bupivacaine stifles would have a significantly elevated PGE2 concentration compared to controls. Stifles from eight healthy, adult Beagles were randomly selected as the treated stifle and infused with bupivacaine. The contralateral stifle was injected with saline. Synovial fluid was collected before and after injection. PGE2 was quantified using a commercial ELISA. Data were transformed and mixed model ANOVA was performed with significance set at p<0.05. There were no significant differences in PGE2 concentration between treatment groups or times. Samples acquired with one or two aspiration attempts had significantly lower PGE2 concentrations than samples with =3 aspiration attempts (p=0.001). When adjusted for number of attempts, PGE2 concentrations were significantly higher 24 (p=0.003) and 48 (p=0.041) hours after injection compared to baseline in the bupivacaine group, but not in the saline group. Intra-articular bupivacaine injection did not result in increased synovial fluid PGE2 concentrations compared to controls; however, multiple aspiration attempts did, suggesting that synovial fluid PGE2 concentration is sensitive to multiple fluid collection attempts. Future studies investigating synovial fluid inflammatory mediators should consider methods to minimize aspiration attempts.
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    The Effect of Stifle Angle on Stifle Kinematics following TPLO: An in vitro Experimental Analysis
    Johnson, Kelly Ann (Virginia Tech, 2010-04-19)
    Objective: To determine the ability of the Tibial Plateau Leveling Osteotomy (TPLO) to restore normal joint kinematics in a cranial cruciate ligament (CrCL)-deficient stifle through a loaded range of motion. Methods: Paired pelvic limbs from 12 dogs were compared in an in vitro biomechanical study. Each limb was placed in a custom designed jig at 120° of stifle extension under an axial load of 20% body weight. Electromagnetic motion tracking sensors were placed on the distal femur and proximal tibia. A force was applied at approximately 10 N/sec to mimic the action of the quadriceps muscle. Force application allowed the limb to move from 120° to maximal extension. Positional data was acquired at 60 points/second. Each limb was tested under normal, CrCL-deficient, and TPLO-treated conditions. Results: The TPLO failed to normalize CTT within the CrCL-deficient stifle; however, values trended towards intact values throughout the range of motion. No significant differences were noted in internal rotation in any of the three conditions from 120° – 137°. Hyperextension values did not differ significantly between conditions. Conclusion: Data from this biomechanical model suggests that the TPLO fails to neutralize CTT throughout a loaded range of motion. Internal rotation and hyperextension values were not found to differ significantly between intact, CrCL-deficient and TPLO repaired stifles. The effectiveness of the TPLO in restoring normal biomechanics is more significant at greater angles of flexion.