Search Results

Abstract

Objective—To evaluate cardiopulmonary effects of anesthetic induction with diazepam and ketamine or xylazine and ketamine, with subsequent maintenance of anesthesia with isoflurane, in foals undergoing abdominal surgery.

Animals—17 pony foals.

Procedures—Foals underwent laparotomy at 7 to 15 days of age and laparoscopy 7 to 10 days later. Foals were randomly assigned to receive diazepam, ketamine, and isoflurane (D/K/Iso; n = 8) or xylazine, ketamine, and isoflurane (X/K/Iso; 9) for both procedures.

Results—During anesthesia for laparotomy, cardiac index, and mean arterial blood pressure ranged from 110 to 180 mL/kg/min and 57 to 81 mm Hg, respectively, in the D/K/Iso group and 98 to 171 mL/kg/min and 50 to 66 mm Hg, respectively, in the X/K/Iso group. Cardiac index, heart rate, and arterial blood pressures were significantly higher in the D/K/Iso group, compared with the X/K/Iso group. During anesthesia for laparoscopy, cardiac index and mean arterial blood pressure ranged from 85 to 165 mL/kg/min and 67 to 83 mm Hg, respectively, in the D/K/Iso group, and 98 to 171 mL/kg/min and 48 to 67 mm Hg, respectively, in the X/K/Iso group. Heart rates and arterial blood pressures were significantly higher in the D/K/Iso group, compared with the X/K/Iso group. There were no significant differences between groups during either experimental period for percentage end-tidal isoflurane, arterial blood gas partial pressures, or pH values.

Conclusions and Clinical Relevance—Anesthesia of foals for abdominal surgery with D/K/Iso was associated with less hemodynamic depression than with X/K/Iso.

Abstract

Objective—To determine the cardiovascular effects of 60 minutes of abdominal insufflation with CO₂ to an intra-abdominal pressure of 15 mm Hg in standing horses receiving a constant rate infusion of detomidine.

Animals—5 horses.

Procedure—Horses were randomly allocated into treatment or control groups. A washout period of a minimum of 7 days separated the 2 experimental periods of the crossover study. Catheters were placed into the right atrium, pulmonary artery, jugular vein, and right transverse facial artery after lidocaine infiltration. All horses were sedated with detomidine (8.54 µg/kg/h, IV). Horses in the treatment group received abdominal insufflation with CO₂ via a laparoscopic cannula to a final and constant intraabdominal pressure of 15 mm Hg for 60 minutes. Systemic arterial pressure, right atrial pressure, heart rate, cardiac output, core body temperature, and the pH and gas tensions of arterial and mixed venous blood were obtained. Cardiac index and systemic vascular resistance were calculated. Data were collected in 3 stages: preinsufflation (–10 and –5 minutes), insufflation (0, 15, 30, 45, and 60 minutes), and postinsufflation (70 and 80 minutes). The quality of sedation and level of analgesia were determined.

Results—The PaO₂ of horses in the treatment group was significantly higher after 60 minutes of pneumoperitoneum than in the control group. Core body temperature decreased significantly from baseline in both groups.

Conclusions and Clinical Relevance—A 60-minute period of abdominal insufflation to an intra-abdominal pressure of 15 mm Hg did not induce significant cardiovascular abnormalities in healthy horses. ( Am J Vet Res 2004;65:357–362)

Abstract

Objective—To compare the cardiopulmonary effects of administration of a solution of xylazine, guaifenesin, and ketamine (XGK) or inhaled isoflurane in mechanically ventilated calves undergoing surgery.

Animals—13 male calves 2 to 26 days of age.

Procedures—In calves in the XGK group, anesthesia was induced (0.5 mL/kg) and maintained (2.5 mL/kg/h) with a combination solution of xylazine (0.1 mg/mL), guaifenesin (50 mg/mL), and ketamine (1.0 mg/mL). For calves in the isoflurane group, anesthesia was induced and maintained with isoflurane in oxygen. The rates of XGK infusion and isoflurane administration were adjusted to achieve suitable anesthetic depth. All calves received 100% oxygen and were mechanically ventilated to maintain end-tidal carbon dioxide concentrations from 35 to 40 mm Hg and underwent laparoscopic bladder surgery through an abdominal approach. Cardiopulmonary variables were measured before induction and at intervals up to 90 minutes after anesthetic induction.

Results—The quality of induction was excellent in all calves. The XGK requirements were 0.57 ± 0.18 mL/kg and 2.70 ± 0.40 mL/kg/h to induce and maintain anesthesia, respectively. Heart rate was significantly lower than baseline throughout the anesthetic period in the XGK group. Systolic arterial blood pressure was significantly higher in the XGK group, compared with the isoflurane group, from 5 to 90 minutes. Cardiac index was lower than baseline in both groups. Differences between groups in cardiac index and arterial blood gas values were not significant.

Conclusions and Clinical Relevance—Administration of XGK resulted in excellent anesthetic induction and maintenance with cardiopulmonary alterations similar to those associated with isoflurane in mechanically ventilated calves.

Abstract

Objective—To evaluate 2 plate designs for pancarpal arthrodesis and their effects on load transfer to the respective bones as well as to develop a computational model with directed input from the biomechanical testing of the 2 constructs.

Sample—Both forelimbs from the cadaver of an adult castrated male Golden Retriever.

Procedures—CT imaging was performed on the forelimb pair. Each forelimb was subsequently instrumented with a hybrid dynamic compression plate or a castless pancarpal arthrodesis plate. Biomechanical testing was performed. The forelimbs were statically loaded in the elastic range and then cyclically loaded to failure. Finite element (FE) modeling was used to compare the 2 plate designs with respect to bone and implant stress distribution and magnitude when loaded.

Results—Cyclic loading to failure elicited failure patterns similar to those observed clinically. The mean ± SD error between computational and experimental strain was < 15% ± 13% at the maximum loads applied during static elastic loading. The highest bone stresses were at the distal extent of the metacarpal bones at the level of the screw holes with both plates; however, the compression plate resulted in slightly greater stresses than did the arthrodesis plate. Both models also revealed an increase in bone stress at the proximal screw position in the radius. The highest plate stress was identified at the level of the radiocarpal bone, and an increased screw stress (junction of screw head with shaft) was identified at both the most proximal and distal ends of the plates.

Conclusions and Clinical Relevance—The FE model successfully approximated the biomechanical characteristics of an ex vivo pancarpal plate construct for comparison of the effects of application of different plate designs.

Abstract

Objective—To compare laparoscopic dissection withlaparoscopic dissection combined with abdominal instillation of ferric hyaluronate gel for the treatment of experimentally induced adhesions in pony foals.

Animals—12 healthy pony foals.

Procedure—A serosal abrasion method was used to create adhesions at 4 sites on the jejunum (day 0). At day 7, laparoscopy was performed and the adhesions observed in each foal were recorded. In group-1 foals (n = 6), the adhesions were separated laparoscopically (treatment 1). In group-2 foals (n = 6), 300 mL of 0.5% ferric hyaluronate gel was infused into the abdomen after the adhesions were separated laparoscopically (treatment 2). At day 24, terminal laparoscopy was performed and the adhesions observed were recorded. Total number of adhesions within each group was compared between day 7 and 24. Data were analyzed to determine whether an association existed between the number of adhesions on day 24 and treatment type.

Results—At day 24, the number of adhesions was significantly decreased within each group, compared with the number of adhesions at day 7 (group-1 foals, 10 vs 22 adhesions; group-2 foals, 3 vs 20 adhesions). Treatment 1 was associated with a significantly higher number of adhesions at day 24, compared with treatment 2 (odds ratio, 4.54; 95% confidence interval, 1.03 to 23.02).

Conclusions and Clinical Relevance—Abdominal instillation of 0.5% ferric hyaluronate gel after laparoscopic dissection was a more effective technique than laparoscopic dissection alone to treat experimentally induced adhesions in pony foals. Laparoscopic adhesiolysis following abdominal surgery in foals is a safe and effective technique. ( Am J Vet Res 2004;65:681–686)

Abstract

Objective—To describe and compare the distribution of technetium Tc 99m (^99mTc) pertechnate following intraosseous or IV injection (with or without use of a tourniquet) in the distal portion of the forelimb in standing horses.

Animals—4 horses.

Procedure—Each horse received 4 forelimb treatments in random sequence: intraosseous infusion with tourniquet application (IOT), intraosseous infusion without tourniquet application, IV infusion with tourniquet application (IVT), and IV infusion without tourniquet application. Dynamic nuclear scintigraphic imaging of the third metacarpal bone, proximal and middle phalanges, and distal phalanx was performed from the start of each treatment until 1 hour after infusion was completed. Radionuclide activity was compared within and between treatment groups.

Results—Tourniquet application was necessary to maintain high levels of radionuclide activity in the distal portion of the forelimb after intraosseous or IV infusion with ^99mTc pertechnate; IVT and IOT treatments resulted in similar radionuclide activity in the proximal and middle phalanges and distal phalanx. Of the 4 treatments, there was significantly higher radionuclide activity in the distal aspect of the third metacarpal bone after the IOT treatment.

Conclusions and Clinical Relevance—By use of a tourniquet, radionuclide administration via the intraosseous or IV routes resulted in effective perfusion of the distal portion of the forelimb and similar distribution of the agent in the phalanges of horses. Further studies are required to ascertain whether these findings apply to delivery of therapeutic agents in infected tissues via IOT or IVT. (Am J Vet Res 2005;66:1267–1272)

Abstract

Objective—To determine the relationship between epidural cranial migration and injectate volume of an isotonic solution containing dye in laterally recumbent foal cadavers and evaluate the cranial migration and dermatome analgesia of an epidural dye solution during conditions of laparoscopy in foals.

Animals—19 foal cadavers and 8 pony foals.

Procedure—Foal cadavers received an epidural injection of dye solution (0.05, 0.1, 0.15, or 0.2 mL/kg) containing 1.2 mg of new methylene blue (NMB)/mL of saline (0.9% NaCl) solution. Length of the dye column and number of intervertebral spaces cranial and caudal to the injection site were measured. Anesthetized foals received an epidural injection of dye solution (0.2 mL/kg) containing saline solution or 2% mepivacaine. Foals were placed in a 10o headdown position, and pneumoperitoneum was induced. Dermatome analgesia was determined by use of a described electrical stimulus technique. Foals were euthanatized, and length of the dye column was measured.

Results—Epidural cranial migration of dye solution in foal cadavers increased with increasing volume injected. No significant difference was found in epidural cranial migration of a dye solution (0.2 mL/kg) between anesthetized foals undergoing conditions of laparoscopy and foal cadavers in lateral recumbency. Further craniad migration of the dye column occurred than indicated by dermatome analgesia.

Conclusions and Clinical Relevance—Epidural cranial migration increases with volume of injectate. On the basis of dermatome analgesia, an epidural injection of 2% mepivacaine (0.2 mL/kg) alone provides analgesia up to at least the caudal thoracic dermatome and could permit caudal laparoscopic surgical procedures in foals. ( Am J Vet Res 2005; 66:1324–1329)

Abstract

Objective—To use magnetic resonance (MR) imaging to describe and compare the anatomic distribution of a lipid contrast medium injected via the retrobulbar and Peterson nerve block techniques in heads of bovine cadavers.

Design—Original study.

Sample—5 grossly normal heads obtained from cattle at necropsy.

Procedure—Standardized techniques for the modified retrobulbar and Peterson nerve blocks were established. Each cadaver had 1 treatment performed on a randomly selected side of the head; the second treatment was performed on the alternate side of the head. Injections were performed with canola oil, which is an MR-positive contrast medium. Images of heads in the transverse and dorsal planes were obtained with a 3.0 Tesla short-bore MR system.

Results—The retrobulbar technique was characterized by widespread distribution of the contrast medium around the periorbital structures; further distribution of the medium was detected along the optic nerve and in the ethmoid turbinates and nasopharynx. After the Peterson nerve block technique, contrast medium was repeatedly located in the pterygopalatine fossa, but distribution to surrounding structures was minimal.

Conclusions and Clinical Relevance—Results indicate that the retrobulbar injection technique results in a greater distribution of contrast medium to the target nerves and surrounding structures, compared with that achieved via the Peterson nerve block technique. This may explain the previously reported clinical impression that the retrobulbar block is more reliable than the Peterson nerve block but is associated with a greater risk of complications. (J Am Vet Med Assoc 2003;223:852–855)

Abstract

Objective—To determine reasons for epidural catheter placement among horses examined at a veterinary teaching hospital, efficacy of epidural administration of analgesics, duration of catheter placement, reasons for catheter removal, and complications encountered.

Design—Retrospective study.

Animals—43 horses.

Procedure—Medical records were reviewed.

Results—A total of 50 epidural catheters were placed in the 43 horses. Underlying conditions included fractures, lacerations, septic arthritis, myositis, perineal injuries, and cellulitis. Horses ranged from 2 to 21 years old and weighed between 365 and 795 kg (803 and 1,749 lb). Median duration of catheter placement was 96 hours (range, 1.5 to 480 hours). The response to epidural drug administration was reported as positive in 34 horses and negative in 4. There was no apparent response in 2 horses, and response could not be determined in 3. Three temporary patient-related complications associated with epidural catheter administration were observed. Technical problems associated with the epidural catheters included dislodgement of the catheter itself (7 catheters) or of the adapter or filter (5), obstruction (5), and leakage (5). Twenty-two catheters were removed because of resolution of the underlying condition, and 10 were removed because of complications. For 6 catheters, the reason for catheter removal was not recorded. The remaining 12 catheters were in place when the horses were euthanatized .

Conclusions and Clinical Relevance—Results suggest that epidural catheterization can be used successfully for repeated epidural delivery of analgesics and anesthetics in horses with various clinical conditions. Complications associated with epidural catheters or epidural drug administration were infrequent and transient. (J Am Vet Med Assoc 2003;222:1394–1398)