Evaluation of lung ventilation distribution using electrical impedance tomography in standing sedated horses with capnoperitoneum.

OBJECTIVE: To determine changes in distribution of lung ventilation with increasing intra-abdominal pressure (IAP) from carbon dioxide (CO2) insufflation in standing sedated horses. STUDY DESIGN: Prospective experimental study. ANIMALS: A group of six healthy adult horses. METHODS: Each horse was sedated with acepromazine, detomidine and butorphanol and sedation maintained with a detomidine infusion. The horse was restrained in a stocks system and a 32 electrode electrical impedance tomography (EIT) belt was wrapped around the thorax at the fifth-sixth intercostal space. EIT images and arterial blood samples for PaO2 and PaCO2, pH and lactate concentration were obtained during capnoperitoneum at 0 (baseline A), 5, 8 and 12 mmHg as IAP increased and at 8, 5, 0 (baseline B) mmHg as IAP decreased. At each IAP, after a 2 minute stabilization period, EIT images were recorded for ≥ 2 minutes to obtain five consecutive breaths. Statistical analysis was performed using anova for repeated measures with Geisser-Greenhouse correction and a Tukey's multiple comparison test for parametric data. The relationship between PaO2 and the center of ventilation in the ventral-dorsal (CoV-VD) and right-left (CoV-RL) directions or total impedance change as a surrogate for tidal volume (ΔZVT) were tested using linear regression analysis. Significance was assumed when p ≤ 0.05. RESULTS: There were no significant changes in CoV-VD, CoV-RL, PaO2, PaCO2, lactate concentration, pH, heart rate and respiratory rate with targeted IAP. There was a significant decrease in ΔZVT compared with baseline A at 5 mmHg IAP as IAP was increased. CONCLUSIONS AND CLINICAL RELEVANCE: Capnoperitoneum causes a significant decrease in ΔZVT in standing sedated horses with increasing IAP.

Sinocutaneous fistula repair with a masseter muscle transposition flap combined with wound matrix and cancellous bone graft in a horse: A new technique.

OBJECTIVE: To describe a new technique to repair a sinocutaneous fistula with a masseter muscle transposition flap. STUDY DESIGN: Case report. ANIMAL: One 13-year-old thoroughbred stallion. METHODS: One 13-year-old stallion with a 3.5 × 6-cm sinocutaneous fistula over the right caudal maxillary sinus was treated with a transpositional masseter muscle flap. This repair consisted of a commercial wound matrix dressing placed directly over the hole in the maxilla and secured with suture material; a cancellous bone graft collected from the right tuber coxa placed on the dressing; and a portion of the superficial layer of the masseter muscle, with its pedicle at the facial crest, transposed dorsally over the bone graft, followed by a rotational skin flap with skin rostral to the fistula to close the defect. RESULTS: Seroma formation and dehiscence of the skin flap occurred, but the transposed muscle flap survived, and the technique resulted in successful closure of the sinocutaneous fistula with excellent cosmetic and functional outcome. CONCLUSION: A chronic maxillary sinocutaneous fistula was successfully treated by using a transposition flap of the masseter muscle and a rotational skin flap with minor complications. CLINICAL IMPACT: Transposition of the superficial layer of the masseter muscle should be considered for a repair of large maxillary sinocutaneous fistulas in horses.

In vitro mechanical evaluation of three transfixation pin-cast constructs applied to equine forelimbs.

OBJECTIVE To compare strain at the bone-pin and cast-pin interfaces among 3 transfixation pin-cast constructs applied to equine forelimbs. ANIMALS 15 forelimbs from 15 adult horses. PROCEDURES Limbs were randomly assigned to 1 of 3 constructs. Centrally threaded positive-profile pins were used for all constructs, and the most distal pin was placed just proximal to the epicondyles of the third metacarpal bone. Construct 1 consisted of two 6.3-mm-diameter pins spaced 4 cm apart at 30° to each other. Construct 2 was the same as construct 1 except the pins were placed 5 cm apart. Construct 3 consisted of four 4.8-mm-diameter pins spaced 2 cm apart and at 10° to one another. An osteotomy was created in the proximal phalanx. Strain gauges were attached to the cast and bone proximal to the pins and adjacent to the osteotomy. Limbs underwent compressive loading until failure. Simplified finite element models of constructs 1 and 3 were created to further evaluate strain and load transfer between the bone and cast. RESULTS Strain did not differ between constructs 1 and 2. Compared with the 2-pin constructs, construct 3 had less strain at the bone-pin interface and more strain at the cast-pin interface, which indicated a greater amount of load was transferred to the cast of the 4-pin construct than the cast of the 2-pin constructs. Finite element modeling supported those findings. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that the 4-pin construct was more effective in unloading the fractured bone than either 2-pin construct.

Comparison of hand-sewn and oversewn stapled jejunojejunal anastomoses in horses.

The objective of this study was to compare the biomechanical properties of hand-sewn jejunojejunal anastomoses to those of oversewn stapled jejunojejunal anastomoses. Jejunojejunal anastomoses were constructed from harvested jejunal segments using a single-layer Lembert technique (1HS), double-layer simple continuous/Cushing technique (2HS), stapled side-to-side technique oversewn with Cushing pattern (SS), and closed 1-stage stapled functional end-to-end technique oversewn with Cushing pattern (FEE). Anastomosed segments were distended with fluid until the point of biomechanical failure. The 2HS had the longest construction time of all anastomoses. Bursting pressures were significantly higher for hand-sewn jejunojejunostomies than those for oversewn stapled jejunojejunostomies. No significant differences were found in bursting pressures between 1HS and 2HS or between SS and FEE. Hand-sewn jejunojejunostomies proved to be biomechanically stronger than oversewn stapled jejunojejunostomies when initially constructed. However, all anastomotic types would be secure techniques to be used clinically based on the supraphysiological pressures they are capable of withstanding.

Comparaison des anastomoses jéjuno-jéjunales cousues à la main et agrafées et cousues chez les chevaux. Cette étude avait pour objectif de comparer les propriétés biomécaniques des anastomoses jéjuno-jéjunales cousues à la main et celles des anastomoses jéjuno-jéjunales agrafées et cousues. Des anastomoses jéjuno-jéjunales ont été construites à partir de segments jéjunaux prélevés en utilisant la technique Lembert à couche unique (1HS), la technique Cushing à double couche simple continue (2HS), la technique agrafée côte à côte selon la méthode Cushing (SS) et la technique fonctionnelle de bout en bout fermée en 1 étape avec couture selon la méthode Cushing (FEE). Des segments anastomosés ont été dilatés avec du liquide jusqu'au point de défaillance biomécanique. La technique 2HS présentait le temps de construction le plus long de toutes les anastomoses. Les pressions de rupture étaient significativement supérieures pour les jéjuno-jéjunostomies cousues par rapport aux jéjuno-jéjunostomies agrafées et cousues. Aucune différence significative n'a été constatée au niveau des pressions de rupture entre 1HS et 2HS ou entre SS et FEE. Les jéjuno-jéjunostomies cousues à la main se sont avérées plus fortes sur le plan mécanique que les jéjuno-jéjunostomies agrafées et cousues lors de la construction initiale. Cependant, tous les types anastomotiques seraient des techniques sûres pour utilisation clinique en se basant sur les pressions supra-physiologiques qu'elles sont capables de supporter.(Traduit par Isabelle Vallières).

Laparoscopic cryptorchidectomy with a vessel-sealing device in dorsal recumbent horses: 43 cases.

OBJECTIVE: To document laparoscopic cryptorchidectomy with a vessel-sealing device in dorsal recumbent horses. STUDY DESIGN: Retrospective study. ANIMALS: Forty-three male horses. METHODS: Food was withheld for 36 hours before horses were placed under general anesthesia and positioned in dorsal recumbency. One laparoscopic portal and 2 instrument portals were placed for the laparoscopic procedure. A third instrument portal was created in bilateral cryptorchid horses. A vessel-sealing device was used for hemostasis and transection of retained testes. Descended testes were removed via closed castration with primary closure of the scrotal incision. Time required for removal of the retained testis and perioperative complications were recorded. Short-term (14, 30, 60 days) and long-term follow-up (>1.5 years) consisted of telephone interview with owners and referring veterinarians. RESULTS: Forty-three male horses underwent laparoscopic cryptorchidectomy. Thirteen horses were bilateral cryptorchids, 19 were unilateral cryptorchids with a descended testis, and 11 were unilateral cryptorchids with 1 testis previously removed. Inguinal testes, identified in 5 horses, were pulled into the abdomen prior to excision. The vaginal ring was apposed with endoscopic staples in 3 of 5 horses. Mean surgery time was 31.34 ± 7.41 minutes. No intraoperative or immediate postoperative complications were encountered. No short-term or long-term complications were reported. CONCLUSION: Laparoscopic cryptorchidectomy can be safely performed with a vessel sealing-device in dorsal recumbent horses. This method was effective and did not result in any complication in our case series.

Quality of Adhesions After Sutured Paramedian vs. Laparoscopic Toggle Abomasopexy in an Ovine Model.

OBJECTIVE: To evaluate adhesions created by abomasopexies using either chromic gut or polydioxanone suture through a right paramedian approach and determine whether a laparoscopic toggle technique is an acceptable alternative to open abomasopexy using an ovine model. STUDY DESIGN: Experimental study. ANIMALS: Mature ewes (n=30). METHODS: Ewes received 1 of 3 abomasopexy techniques (n=10): right paramedian approach using chromic gut or polydioxanone, or a laparoscopic toggle technique. After euthanasia 8 weeks postoperatively, adhesions were removed en bloc and adhesion cross-sectional area (width × length) and depth (distance from abdominal wall to abomasum) were measured and given a grade of 0-3 based on the quality of adhesion. Surgical time was recorded and compared for each technique. Significance was set at P≤.05. RESULTS: Abomasopexies performed with either suture material resulted in a significantly larger mean cross-sectional area and higher adhesion grades compared to those performed using the toggle. Width and length of adhesions formed using chromic gut or polydioxanone were not significantly different; however, both were significantly wider and longer than those formed using the toggle. The laparoscopic toggle technique required significantly less surgical time than the sutured techniques. CONCLUSION: Polydioxanone is as effective as chromic gut suture material in inducing abomasal adhesion formation in our sheep model. The clinical significance of the size and grade of adhesions formed is unknown and requires further investigation before the laparoscopic toggle technique can be recommended as a replacement for paramedian abomasopexy in cattle for the treatment of displaced abomasum.