Objective—To assess a technique for laparoscopic collection of serial full-thickness small intestinal biopsy specimens in horses.
Animals—13 healthy adult horses.
Procedures—In the ex vivo portion of the study, sections of duodenum and jejunum obtained from 6 horses immediately after euthanasia were divided into 3 segments. Each segment was randomly assigned to the control group, the double-layer hand-sewn closure group, or the endoscopic linear stapler (ELS) group. Bursting strength and bursting wall tension were measured and compared among groups; luminal diameter reduction at the biopsy site was compared between the biopsy groups. In the in vivo portion of the study, serial full-thickness small intestinal biopsy specimens were laparoscopically collected with an ELS from the descending duodenum and distal portion of the jejunum at monthly intervals in 7 sedated, standing horses. Biopsy specimens were evaluated for suitability for histologic examination.
Results—Mean bursting strength and bursting wall tension were significantly lower in the ELS group than in the hand-sewn and control groups in both the duodenal and jejunal segments. Use of the hand-sewn closure technique at the biopsy site reduced luminal diameter significantly more than use of the stapling technique. In the in vivo part of the study, all 52 biopsy specimens collected during 26 laparoscopic procedures were suitable for histologic examination and no clinically important perioperative complications developed.
Conclusions and Clinical Relevance—Laparoscopic collection of serial full-thickness small intestinal biopsy specimens with a 45-mm ELS may be an effective and safe technique for use in healthy adult experimental horses.
Objective—To evaluate changes in pH of peritoneal fluid associated with CO2 insufflation during laparoscopy in dogs.
Animals—13 client-owned dogs and 10 purpose-bred teaching dogs.
Procedures—Laparotomy was performed on control dogs; peritoneal fluid pH was mea-sured at time of incision of the abdominal cavity (time 0) and 30 minutes later. Laparoscopic insufflation with CO2 was performed and routine laparoscopic procedures conducted on the teaching dogs. Insufflation pressure was limited to 12 mm Hg. Intraperitoneal fluid pH was measured by use of pH indicator paper at 4 time points. Arterial blood gas analysis was performed at the same time points.
Results—Peritoneal fluid pH did not change significantly between 0 and 30 minutes in the control dogs. For dogs with CO2 insufflation, measurements obtained were a mean of 8.5, 24.5, 44.5, and 72.0 minutes after insufflation. The pH of peritoneal fluid decreased signifi-cantly between the first (7.825 ± 0.350) and second (7.672 ± 0.366) time point. Blood pH decreased significantly between the first (7.343 ± 0.078), third (7.235 ± 0.042), and fourth (7.225 ± 0.038) time points. The PaCO2 increased significantly between the first (39.9 ± 9.8 mm Hg) and fourth (54.6 ± 4.4 mm Hg) time points. Base excess decreased significantly between the first and all subsequent time points.
Conclusions and Clinical Relevance—Pneumoperitoneum attributable to CO2 insufflation caused a mild and transient decrease in peritoneal fluid pH in dogs. Changes in peritoneal fluid associated with CO2 insufflation in dogs were similar to those in other animals.
Objective—To compare castration of dogs by use of intratesticular injection of zinc gluconate with traditional surgical procedures in terms of acceptance by pet owners, ease of use, and short-term outcomes on Isabela Island of the Galápagos Islands.
Animals—161 privately owned male dogs admitted to a neuter program.
Procedures—Medical records of male dogs neutered during a 4-week animal control campaign were reviewed to collect information regarding signalment, method of castration, complication rate, and treatment outcomes.
Results—Of the 161 dogs admitted for castration, 58 were surgically castrated and 103 were treated with zinc gluconate. Dogs were returned to their owners for observation following castration. Wound dehiscence occurred in 2 skin incisions, representing 3.4% of the 58 dogs that underwent bilateral orchiectomy. Necrotizing zinc-gluconate injection-site reactions occurred in 4 dogs receiving injection volumes near the maximum label dose (0.8 to 1.0 mL), representing 3.9% of the zinc-gluconate procedures. Surgical wound complications were treated by superficial wound debridement and resuturing, in contrast to zinc-gluconate injection-site reactions, which all required orchiectomy and extensive surgical debridement, including scrotal ablation in 2 dogs.
Conclusions and Clinical Relevance—Low cost, ease of use, and cultural acceptance of a castration technique that does not require removal of the testes make zinc gluconate a valuable option for large-scale use in dogs, particularly in remote locations lacking sophisticated clinical facilities or skilled surgeons and staff. Further investigation is needed to identify risk factors in dogs for adverse reactions to zinc gluconate and to develop strategies for avoidance.
Objective—To determine the microchemical and surface composition of tibial plateau leveling osteotomy (TPLO) plates before and after explantation.
Sample Population—7 TPLO plates surgically removed from host dogs 6 to 54 months after implantation; 2 raw unpolished-and-unpassivated 316L TPLO plates; and 2 heat-treated, polished-and-passivated, and cleaned 316L TPLO plates.
Procedures—Samples were removed by use of standard techniques to ensure the plate surface was not damaged. Sample pieces were dissolved and analyzed by inductively coupled plasma–mass spectrometry (ICP-MS) to determine bulk elemental composition. Other sample pieces were investigated by use of scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and x-ray photoelectron spectroscopy (XPS) for determination of sample morphology, near-surface elemental composition, and surface elemental composition, respectively. To investigate the possibility of corrosion in situ, some samples were chemically corroded and analyzed.
Results—ICP-MS confirmed that elemental composition of samples was consistent with 316L stainless steel. The SEM and EDS analyses revealed trace amounts of polishing materials and a nonuniform carbonaceous biofilm on < 1% of the surface area of samples removed from the host dogs. The XPS analysis indicated an increase in the chromium-to-iron ratio on passivated surfaces, with no difference between passivated samples before implantation and after explantation.
Conclusions and Clinical Relevance—Composition of the TPLO plates was consistent with 316L stainless steel. No chemical or topographic changes were detected in TPLO plates that had been implanted in dogs for up to 54 months. A small amount of biofilm was evident on the surface of 2 plates.
Objective—To determine in vitro effects of PBSS, milk, and bacteria-contaminated milk (BCM; contaminated by Streptococcus agalactiae) on properties of 3 synthetic absorbable suture materials.
Sample Population—3 types of synthetic absorbable suture materials (poliglecaprone 25, polyglycolic acid, and polydioxanone).
Procedures—Suture materials were tested to determine breaking strength and elasticity before (day 0) and after incubation in 3 media (PBSS, milk, and BCM) for 7, 14, and 21 days. A loop of suture material was elongated at a rate of 60 mm/min until it reached the breaking point. Tensile properties were statistically analyzed among media and incubation times.
Results—Incubation in milk and BCM significantly decreased breaking strength and elasticity of poliglecaprone 25, compared with results for incubation in PBSS. Incubation in BCM significantly decreased tensile properties of polyglycolic acid suture, compared with results for incubation in PBSS and milk. After incubation for 21 days, tensile properties of polydioxanone did not differ significantly among the media but were significantly decreased from values on day 0.
Conclusions and Clinical Relevance—On the basis of this study, poliglecaprone 25 is an inappropriate suture material for use in teat surgery. Polyglycolic acid suture should be avoided in teats of cattle with mastitis. Of the suture materials tested, polydioxanone was best suited for use in teat surgery, as determined on the basis of material testing after incubation in milk, even when the milk was contaminated with bacteria.
Objective—To evaluate manufacturing variability, diffusion of filling solutions, and maintenance of occlusion over time in 3 sizes of silicone hydraulic occluders (HOs).
Sample Population—2-, 5-, and 20-mm HOs (HO2, HO5, and HO20, respectively).
Procedures—Manufacturing variability was analyzed by comparing variation in internal luminal areas and filling volumes within each size group. Occluders were filled to 100% occlusion with air (n = 4), saline (0.9% NaCl) solution (4), or sodium hyaluronate (4) and submerged in simulated body fluid. Changes in luminal area and weight were recorded for 133 days to evaluate maintenance of occlusion.
Results—Considerable variability in uninflated luminal area and fill volumes was observed among the 3 sizes of HOs. Loss of occlusion developed in the first 12 hours in all air-filled HOs. Fluid-filled occluders were reliable in maintenance of occlusion after 133 days (99.99% for HO20, 99.59% for HO5, and 90.40% for HO2), although diffusion of saline solution and hyaluronate from all HOs was confirmed by detection of significant decreases in weight over time. There was no significant difference in weight loss between HOs filled with saline solution and HOs filled with sodium hyaluronate.
Conclusions and Clinical Relevance—Saline solution or sodium hyaluronate may be used as a filling solution in the HOs tested. Maintenance of occlusion was best in the larger sizes. Saline solution or sodium hyaluronate should be used in future clinical investigations of HOs. Retrograde filling to remove air should be used when filling HOs with fluid.
Objective—To determine the material properties of Slocum TPLO plates and assess the soft tissue reaction adjacent to these plates in dogs that had undergone tibial plateau leveling osteotomy (TPLO).
Sample Population—3 new TPLO plates, 8 retrieved TPLO plates, and 1 new Synthes dynamic compression plate.
Procedures—Metallurgic analyses were performed. Tissue samples were obtained from areas adjacent to retrieved plates and submitted for histologic examination.
Results—All of the TPLO plates had a 2-phase microstructure consisting of austenite and ferrite in various amounts. Residua, inclusions, and cavities were seen during microscopic examination of the plate surface. The major differences between new and retrieved TPLO plates were the presence of small gaps separating many inclusions from the surrounding matrix and the presence of various-sized pits on the surface of the retrieved plates. The dynamic compression plate had a nearly pure austenitic structure and was largely free from residua, inclusions, and cavities. Histologic examination of tissue samples obtained from areas adjacent to retrieved TPLO plates revealed intra- and extracellular particulate debris. Two types of particles (one consisting of chromium, nickel, molybdenum, and iron and the other consisting of aluminum and silicon) were seen.
Conclusions and Clinical Relevance—Results determined that new and retrieved TPLO plates were manufactured from 316L stainless steel and produced by a casting process, but not all plates met specifications for chemical composition of cast surgical implants (American Society for Testing Materials standard F745); tissues surrounding retrieved plates had evidence of adverse reactions, probably as a result of plate corrosion.
Objective—To compare variables for screw insertion, pushout strength, and failure modes for a headless tapered compression screw inserted in standard and oversize holes in a simulated lateral condylar fracture model.
Sample Population—6 pairs of third metacarpal bones from horse cadavers.
Procedure—Simulated lateral condylar fractures were created, reduced, and stabilized with a headless tapered compression screw by use of a standard or oversize hole. Torque, work, and time for drilling, tapping, and screw insertion were measured during site preparation and screw implantation. Axial load and displacement were measured during screw pushout. Effects of drill hole size on variables for screw insertion and screw pushout were assessed by use of Wilcoxon tests.
Results—Drill time was 59% greater for oversize holes than for standard holes. Variables for tapping (mean maximum torque, total work, positive work, and time) were 42%, 70%, 73%, and 58% less, respectively, for oversize holes, compared with standard holes. Variables for screw pushout testing (mean yield load, failure load, failure displacement, and failure energy) were 40%, 40%, 47%, and 71% less, respectively, for oversize holes, compared with standard holes. Screws could not be completely inserted in 1 standard and 2 oversize holes.
Conclusions and Clinical Relevance—Enlarging the diameter of the drill hole facilitated tapping but decreased overall holding strength of screws. Therefore, holes with a standard diameter are recommended for implantation of variable pitch screws whenever possible. During implantation, care should be taken to ensure that screw threads follow tapped bone threads.
Objective—To biomechanically and histologically compare single-layer continuous Cushing and simple continuous appositional cystotomy closure in rats with xylene-induced cystitis.
Animals—40 female Sprague-Dawley rats.
Procedure—Rats were anesthetized, their urinary bladders catheterized and evacuated, and xylene instilled in each bladder for 5 minutes and then aspirated. Forty-eight hours later, ventral midline celiotomy and cystotomy (8 mm) were performed. Cystotomies were closed with 6-0 poliglecaprone 25 by use of a single-layer continuous Cushing or simple continuous appositional pattern (20 rats/group), and cystotomy times were recorded. Rats were allocated to healing durations (5 rats/group) of 0, 3, 7, and 14 days. Celiotomies were closed in a routine manner. After the allotted healing interval, another celiotomy was performed, the urethra cannulated, and ureters ligated. The cannula was secured to the urethra, and the bladder infused at 0.1 mL/min. Leak pressure volume, leak pressure, peak pressure volume, and peak pressure were recorded via a pressure transducer. Bladders were harvested and histologically assessed.
Results—Cystotomy time, biomechanical testing values, and overall inflammation scores did not differ between closure methods for any healing duration. Both methods had significantly greater leak pressures, with the appositional method also having significantly greater peak pressures on day 7, compared to day 0. Biomechanical testing values decreased from day 7 to 14 as a result of juxtaincisional weakening of the bladder and xylene-induced changes in collagen.
Conclusions and Clinical Relevance—Simple continuous appositional was equal biomechanically and histologically to continuous Cushing for all comparison variables. Poliglecaprone 25 was acceptable for cystotomy closure.
Objective—To compare application time, accuracy of tibial plateau slope (TPS) correction, presence and magnitude of rotational and angular deformities, and mechanical properties of 5 canine tibial plateau leveling methods.
Sample Population—27 canine tibial replicas created by rapid prototyping methods.
Procedure—The application time, accuracy of TPS correction, presence and magnitude of rotational and angular deformation, and construct axial stiffness of 3 internal fixation methods (tibial plateau leveling osteotomy, tibial wedge osteotomy, and chevron wedge osteotomy [CWO]) and 2 external skeletal fixation (ESF) methods (hinged hybrid circular external fixation and wedge osteotomy linear fixation [WOLF]) were assessed.
Results—Mean bone model axial stiffness did not differ among methods. Mean application time was more rapid for WOLF than for other methods. Mean TPSs did not differ from our 5° target and were lower for ESF methods, compared with internal fixation methods. Mean postoperative rotational malalignment did not differ from our target or among groups. Mean postoperative medio-lateral angulation did not differ from our target, except for CWO. Internal fixation methods lead to axially stiffer constructs than ESF methods. Reuse of ESF frames did not lead to a decrease in axial stiffness.
Conclusions and Clinical Relevance—The 5 tibial plateau leveling methods had acceptable geometric and mechanical properties. External skeletal fixation methods were more accurate as a result of precise data available for determining the exact magnitude of correction required to achieve a 5° TPS.