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Abstract
OBJECTIVE To determine whether stored (cooled or frozen-thawed) jejunal segments can be used to obtain dependable leak pressure data after enterotomy closure.
SAMPLE 36 jejunal segments from 3 juvenile pigs.
PROCEDURES Jejunal segments were harvested from euthanized pigs and assigned to 1 of 3 treatment groups (n = 12 segments/group) as follows: fresh (used within 4 hours after collection), cooled (stored overnight at 5°C before use), and frozen-thawed (frozen at −12°C for 8 days and thawed at room temperature [23°C] for 1 hour before use). Jejunal segments were suspended and 2-cm enterotomy incisions were made on the antimesenteric border. Enterotomies were closed with a simple continuous suture pattern. Lactated Ringer solution was infused into each segment until failure at the suture line was detected. Leak pressure was measured by use of a digital transducer.
RESULTS Mean ± SD leak pressure for fresh, cooled, and frozen-thawed segments was 68.3 ± 23.7 mm Hg, 55.3 ± 28.1 mm Hg, and 14.4 ± 14.8 mm Hg, respectively. Overall, there were no significant differences in mean leak pressure among pigs, but a significant difference in mean leak pressure was detected among treatment groups. Mean leak pressure was significantly lower for frozen-thawed segments than for fresh or cooled segments, but mean leak pressure did not differ significantly between fresh and cooled segments.
CONCLUSIONS AND CLINICAL RELEVANCE Fresh porcine jejunal segments or segments cooled overnight may be used for determining intestinal leak pressure, but frozen-thawed segments should not be used.
Abstract
OBJECTIVE To biomechanically compare modified and standard laryngoplasty constructs in monotonic load to failure and cyclic loading.
SAMPLES 41 equine cadaveric larynges.
PROCEDURES Laryngoplasty constructs were created by use of a standard technique on one side and a modified technique (with a toggle to anchor suture to the arytenoid cartilage) on the other side. For monotonic loading, laryngoplasty constructs were prepared and suture ends attached to a load frame; constructs then were loaded until mechanical failure. Mean load at failure and failure modes were compared between constructs. For cyclic loading, arytenoid cartilages were maximally abducted and constructs were circumferentially loaded for 10,000 cycles. Loss of arytenoid abduction was evaluated every 500 cycles with a subjective grading scale and objective change in rima glottidis cross-sectional area.
RESULTS In monotonic loading, modified laryngoplasty constructs failed at a significantly higher mean ± SD load (191 ± 29 N) than did standard laryngoplasty constructs (91 ± 44 N). None of the modified laryngoplasty constructs failed by suture pull-through of the muscular process of the arytenoid cartilage, whereas most of the standard laryngoplasty constructs failed in that manner. In cyclic testing, 11 of 20 standard laryngoplasty constructs failed or achieved Dixon grade 3 abduction, whereas 0 of 20 modified laryngoplasty constructs failed. Modified laryngoplasty constructs lost significantly less rima glottidis cross-sectional area in circumferential testing, compared with loss for standard laryngoplasty constructs.
CONCLUSIONS AND CLINICAL RELEVANCE The modified laryngoplasty technique was biomechanically superior to the standard laryngoplasty technique in this ex vivo study.
Abstract
OBJECTIVE To compare tensile strength and time to completion of body wall closure among 3 suture patterns.
SAMPLE Eighteen 5 × 5-cm leather specimens and sixty-eight 5 × 5-cm full-thickness tissue specimens from the ventral portion of the abdominal body wall of 17 canine cadavers.
PROCEDURES During experiment 1 of a 2-experiment study, each leather specimen was cut in half and sutured with a simple interrupted or simple continuous pattern or continuous pattern with intermittent Aberdeen knots (intermittent Aberdeen pattern). During experiment 2, 4 tissue specimens were obtained from each cadaver; the linea alba of 3 specimens was incised and closed with 1 of the 3 suture patterns evaluated in experiment 1, and the fourth specimen was left intact as a control. All leather and tissue specimens underwent mechanical testing. Time to completion, mode of failure, and maximum force at failure (Fmax) were compared among the suture patterns.
RESULTS In experiment 1, the mean Fmax for the simple continuous and intermittent Aberdeen patterns was significantly greater than that for the simple interrupted pattern. In experiment 2, the mean Fmax for specimens obtained cranial to the umbilicus was greater than that for specimens obtained caudal to the umbilicus, and the mean time to completion for both continuous suture patterns was significantly less than that for the simple interrupted pattern. Most (34/51) sutured tissue specimens failed because the suture cut through the tissue at the suture-tissue interface.
CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that the intermittent Aberdeen pattern may be an alternative for body wall closure in dogs.
Abstract
OBJECTIVE To determine whether cellophane banding secured with locking polymer clips on cadaveric splenic veins would cause less CT imaging artifact and achieve equivalent mechanical strength, compared with cellophane banding secured with metal vascular clips.
ANIMALS 10 canine cadavers.
PROCEDURES Clips of each material were applied to each cadaver in a crossover design study. Triple-layer cellophane bands secured with 4 medium-large or large polymer or metal clips were placed on cadaveric splenic veins and evaluated by use of CT. Beam-hardening artifact was assessed by artifact length, attenuation, and a subjective grading scale ranging from 1 to 3 for mild to severe imaging artifacts. Secured cellophane bands were mechanically tested to determine force-deformation curves and yield forces. Findings for clip methods were compared with a 1-way ANOVA with a Tukey post-test.
RESULTS For metal clips, beam-hardening artifact lengths and subjective artifact grades were significantly higher, whereas attenuation values were significantly lower, than findings for polymer clips. Polymer clips were significantly lower in strength than metal clips with mean ± SD yield loads of 1.9 ± 0.6 N (medium-large polymer clips), 2.8 ± 1.3 N (large polymer clips), 6.0 ± 1.9 N (medium-large metal clips), and 8.4 ± 2.7 N (large metal clips).
CONCLUSIONS AND CLINICAL RELEVANCE Use of locking polymer clips to secure cellophane banding resulted in less CT imaging artifact and mechanical strength, compared with use of metal vascular clips. Use of locking polymer clips may allow improved assessment of postoperative CT imaging in dogs with extrahepatic portosystemic shunts, which warrants in vivo clinical evaluation.
Abstract
OBJECTIVE To compare heat generation and mechanical bone damage for tapered and cylindrical transfixation pins during drilling, tapping, and pin insertion in equine third metacarpal bones.
SAMPLE 16 pairs of cadaveric equine third metacarpal bones.
PROCEDURES For cylindrical pin insertion, a 6.2-mm hole was drilled and tapped with a cylindrical tap, and then a standard 6.3-mm pin was inserted. For tapered pin insertion, a 6.0-mm hole was drilled, reamed with a tapered reamer, and tapped with a tapered tap, and then a 6.3-mm tapered pin was inserted. Paired t tests and 1-way ANOVAs were used to compare heat generation (measured by use of thermocouples and thermography), macrodamage (assessed by use of stereomicroscopy), and microdamage (assessed by examination of basic fuchsin–stained histologic specimens) between cylindrical and tapered pins and between tapered pins inserted to various insertion torques.
RESULTS Tapered pin insertion generated less heat but resulted in more bone damage than did cylindrical pin insertion when pins were inserted to the same insertion torque. Insertion of tapered pins to increasing insertion torques up to 16 N•m resulted in increased heat generation and bone damage.
CONCLUSIONS AND CLINICAL RELEVANCE Tapered pin insertion resulted in lower heat production than did cylindrical pin insertion. However, tapered pin insertion resulted in greater bone damage, which likely was attributable to differences in the tapered and cylindrical taps. A tapered pin may be preferable to a cylindrical pin for insertion in equine cortical bone provided that improvements in tap design can reduce bone damage during insertion.
Abstract
OBJECTIVE To examine effects of continuous rate infusion of lidocaine on transmural neutrophil infiltration in equine intestine subjected to manipulation only and remote to ischemic intestine.
ANIMALS 14 healthy horses.
PROCEDURES Ventral midline celiotomy was performed (time 0). Mild ischemia was induced in segments of jejunum and large colon. A 1-m segment of jejunum was manipulated by massaging the jejunal wall 10 times. Horses received lidocaine (n = 7) or saline (0.9% NaCl) solution (7) throughout anesthesia. Biopsy specimens were collected and used to assess tissue injury, neutrophil influx, cyclooxygenase expression, and hypoxia-inducible factor 1α (HIF-1α) expression at 0, 1, and 4 hours after manipulation and ischemia. Transepithelial resistance (TER) and mannitol flux were measured by use of Ussing chambers.
RESULTS Lidocaine did not consistently decrease neutrophil infiltration in ischemic, manipulated, or control tissues at 4 hours. Lidocaine significantly reduced circular muscle and overall scores for cyclooxygenase-2 expression in manipulated tissues. Manipulated tissues had significantly less HIF-1α expression at 4 hours than did control tissues. Mucosa from manipulated and control segments obtained at 4 hours had lower TER and greater mannitol flux than did control tissues at 0 hours. Lidocaine did not significantly decrease calprotectin expression. Severity of neutrophil infiltration was similar in control, ischemic, and manipulated tissues at 4 hours.
CONCLUSIONS AND CLINICAL RELEVANCE Manipulated jejunum did not have a significantly greater increase in neutrophil infiltration, compared with 4-hour control (nonmanipulated) jejunum remote to sites of manipulation, ischemia, and reperfusion. Lidocaine did not consistently reduce neutrophil infiltration in jejunum.
Abstract
OBJECTIVE To evaluate the pressure-volume relationship during capnoperitoneum in dogs and effects of body weight and body conformation.
ANIMALS 86 dogs scheduled for routine laparoscopy.
PROCEDURES Dogs were allocated into 3 groups on the basis of body weight. Body measurements, body condition score, and body conformation indices were calculated. Carbon dioxide was insufflated into the abdomen with a syringe, and pressure was measured at the laparoscopic cannula. Volume and pressure data were processed, and the yield point, defined by use of a cutoff volume (COV) and cutoff pressure (COP), was calculated.
RESULTS 20 dogs were excluded because of recording errors, air leakage attributable to surgical flaws, or trocar defects. For the remaining 66 dogs, the pressure-volume curve was linear-like until the yield point was reached, and then it became visibly exponential. Mean ± SD COP was 5.99 ± 0.805 mm Hg. No correlation was detected between yield point, body variables, or body weight. Mean COV was 1,196.2 ± 697.9 mL (65.15 ± 20.83 mL of CO2/kg), and COV was correlated significantly with body weight and one of the body condition indices but not with other variables.
CONCLUSION AND CLINICAL RELEVANCE In this study, there was a similar COP for all dogs of all sizes. In addition, results suggested that increasing the abdominal pressure after the yield point was reached did not contribute to a substantial increase in working space in the abdomen. No correlation was found between yield point, body variables, and body weight.
Abstract
OBJECTIVE To assess use of a new radiographic method to determine the distance by which the tibial tuberosity should be advanced to reduce the patellar tendon-tibial plateau angle (PTA) to 90° by means of the modified Maquet technique (MMT) in dogs.
SAMPLE 24 pelvic limbs from 12 adult medium-sized to large-breed canine cadavers.
PROCEDURES Radiographs of stifle joints at 135° extension in true lateral position were used to determine tibial tuberosity advancement distances for use in the MMT. A method was devised to incorporate the planned osteotomy axis; distal patellar translations of 0, 3, 5, or 10 mm; and advancement cage implant application level along the osteotomy site in advancement planning measurements. Concordance correlation coefficients (CCCs) were calculated to compare these adjusted advancement measurements with true advancement measurements obtained for the same joints in another study after treatment by MMT. Intraobserver, interobserver, and total agreement for selected measurements were determined by assessment of CCCs for results obtained by 3 blinded observers.
RESULTS Agreement between true advancement measurements and measurements obtained with osteotomy axis and cage position method calculations that incorporated a 5-mm distal patellar translation distance was excellent (CCC, 0.96). Intraobserver and interobserver agreements for the planning measurements evaluated were good to excellent (CCC, 0.83 to 0.96).
CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that the osteotomy axis and cage position method incorporating a 5-mm distal patellar translation distance has the potential to improve success rates for achieving a PTA of 90° in medium-sized to large-breed dogs undergoing MMT for treatment of cranial cruciate ligament rupture. Further research is warranted.
Abstract
OBJECTIVE
To evaluate effects of laparoscopic-assisted incisional gastropexy (LAIG) on gastric motility in dogs by use of a wireless motility device (WMD).
ANIMALS
10 healthy client-owned large or giant-breed dogs.
PROCEDURES
10 dogs owned by clients interested in prophylactic LAIG were enrolled. To determine effects of LAIG on gastrointestinal motility in dogs during the nonfed state, each dog was evaluated by use of a noninvasive WMD before and > 4 weeks after LAIG. All dogs underwent LAIG, with or without concurrent elective gonadectomy. Data obtained before and after LAIG were analyzed by use of proprietary software to determine the gastric emptying time, small bowel transit time, large bowel transit time, whole bowel transit time, and motility index.
RESULTS
No changes in variables were detected between measurements obtained before and after prophylactic LAIG.
CONCLUSIONS AND CLINICAL RELEVANCE
In this study, prophylactic LAIG did not have an effect on gastrointestinal motility. The WMD was tolerated well by all dogs and appeared to be a safe and effective method for evaluating gastrointestinal motility in this population of dogs.
Abstract
OBJECTIVE To evaluate the validity of 2 radiographic methods for measurement of the tibial tuberosity advancement distance required to achieve a reduction in patellar tendon–tibial plateau angle (PTA) to the ideal 90° in dogs by use of the modified Maquet technique (MMT).
SAMPLE 24 stifle joints harvested from 12 canine cadavers.
PROCEDURES Radiographs of stifle joints placed at 135° in the true lateral position were used to measure the required tibial tuberosity advancement distance with the conventional (AM) and correction (AE) methods. The MMT was used to successively advance the tibial crest to AM and AE. Postoperative PTA was measured on a mediolateral radiograph for each advancement measurement method. If none of the measurements were close to 90°, the advancement distance was modified until the PTA was equal to 90° within 0.1°, and the true advancement distance (TA) was measured. Results were used to determine the optimal commercially available size of cage implant that would be used in a clinical situation.
RESULTS Median AM and AE were 10.6 mm and 11.5 mm, respectively. Mean PTAs for the conventional and correction methods were 93.4° and 92.3°, respectively, and differed significantly from 90°. Median TA was 13.5 mm. The AM and AE led to the same cage size recommendations as for TA for only 1 and 4 stifle joints, respectively.
CONCLUSIONS AND CLINICAL RELEVANCE Both radiographic methods of measuring the distance required to advance the tibial tuberosity in dogs led to an under-reduction in postoperative PTA when the MMT was used. A new, more accurate radiographic method needs to be developed.
