Reactions to Gudair® vaccination identified in sheep used for biomedical research.

CASE REPORT: We report Gudair® vaccination (against ovine Johne's disease, Mycobacterium avium subsp. paratuberculosis) site reactions in sheep used as a surgical model in biomedical research and discuss the actual and potential impact these lesions may have on surgical procedures, particularly in otology. Nine female Merino-cross sheep (Ovis aries) were enrolled in a project designed to investigate the healing capabilities of the malleus bone in the middle ear. The sheep were 12-18 months of age. Eight sheep had lesions near the base of the right ear that were discovered when surgery was performed. The size of the lesions varied and all lesions had a thick capsule containing various amount of caseous material. Two lesions had a draining tract where purulent material was apparent at the lowest point. The prescapular lymph nodes were not palpable in any of the sheep. Aerobic growth of various organisms was reported from four sheep lesions when the purulent material was transferred to a broth media. Histopathological examination revealed intralesional Mycobacteria and focal caseous necrosis or granulomatous dermatitis and cellulitis in seven of the eight lesions. Mild necrotising to granulomatous dermatitis and cellulitis was described in the lesion where organisms were not found. CONCLUSIONS: The lesions were confirmed at the end of the study to be associated with the vaccination and did not cause any known adverse effects on the research. However, it is important to acknowledge the risk of contamination these lesions could have on a sterile surgical site.

Maternal and fetal arterial blood gas data during general anaesthesia for caesarean delivery of preterm twin lambs.

Much remains to be understood with regards the effects of prolonged anaesthesia on maternal and fetal haemodynamics and oxygenation. With the aim of improving anaesthetic management of pregnant sheep undergoing recovery surgery under anaesthesia, paired maternal and fetal arterial blood samples were collected during caesarean delivery of twin preterm lambs to document the blood gas status of the ewe and fetus. Twenty-one Merino twin pregnant ewes at 126 (±1) days of gestation were anaesthetized for caesarean delivery of their fetuses. Arterial blood samples were collected from the radial artery of the ewe and umbilical artery of the fetus at the point of delivery. There was a significant difference between maternal PaCO2 and end-tidal CO2 and alveolar and arterial PaO2, indicating ventilation perfusion mismatch. Interestingly, the ewes were anaemic but the fetuses were not. These data underscore the need to undertake further work to determine the optimal anaesthetic regimen for twin pregnant ewes at different gestational ages in a biomedical research setting.

Body temperature measurements in pigs during general anaesthesia.

The aim was to compare rectal, pharyngeal and oesophageal temperature measurements in anaesthetized pigs. Data were compared using the Bland-Altman method, and correlation coefficients and error measures were calculated. Sixty-six sets of data were collected from 16 pigs weighing 16.2 ± 4.2 kg. The bias (and 95% limit of agreement) for rectal and pharyngeal compared with oesophageal temperature were 0.69 (-1.18 to 2.57) ℃ and 0.22 (-0.84 to 1.28) ℃, respectively. The correlation coefficients for rectal and pharyngeal compared with oesophageal temperature were 0.47 and 0.87, respectively. The absolute error for rectal and pharyngeal compared with oesophageal temperature was 0.7 ± 0.9℃ and 0.2 ± 0.5℃, respectively. Pharyngeal temperature measurement may be more suitable than rectal temperature measurement for estimation of oesophageal temperature during general anaesthesia of pigs.

Catheterization of the urethra in female pigs.

Female pigs are commonly utilized as an animal model for biomedical research and require urethral catheterization. Sixteen pigs were anaesthetized for research purposes and required the placement of a urethral catheter. Post-mortem examination of the vaginas revealed the urethral opening to be consistently halfway from the mucocutaneous junction of the vulva to the cervix. A shallow diverticulum was also observed on the ventral floor of the urethral opening. To optimize conditions for success the pig should be carefully positioned supine, a vaginal speculum and light source should be used, the pig should be adequately anaesthetized, and the anatomy of the vagina should be reviewed.

Preoperative factors associated with hypotension in young anaesthetised dogs undergoing elective desexing.

OBJECTIVES: Document the proportion of dogs with perioperative hypotension and explore the association of sex, age and body mass and indices of hydration with mean arterial blood pressure (MAP) in two cohorts of young, healthy anaesthetised dogs. METHODS: Dogs were anaesthetised with a standardised protocol. The proportion of dogs with invasively measured MAP <60 mmHg for ≥10 min was recorded. The area under the MAP*time curve (MAP-AUC) was calculated for a standard perioperative period. The association of explanatory variables, including sex, age, body mass and indices of hydration (urine specific gravity (USG), packed cell volume and total solids) measured prior to surgery, with the MAP-AUC was explored using regression analysis in the first cohort (n = 71) and externally validated in the second cohort (n = 24). RESULTS: In cohort 1, 35 of 71 dogs (0.49, 95% confidence interval (CI) 0.37-0.61) dogs and 17/24 dogs in cohort 2 (0.71, 95% CI 0.53-0.89) developed hypotension. Regression analysis showed that age and USG were significantly associated with MAP-AUC for cohort 1 (P = 0.0138). There was a positive association of MAP-AUC with age and a negative association with USG. The association of MAP-AUC with USG was supported in cohort 2, with a significant negative association (P = 0.014, r = -0.54) CONCLUSION: The high frequency of hypotension in both cohorts supports blood pressure monitoring during anaesthesia of young, healthy dogs. USG, an index of hydration, appears negatively associated with MAP during anaesthesia, suggesting that subclinical dehydration may contribute to lower MAP during surgical anaesthesia.

Pressure and volume controlled mechanical ventilation in anaesthetized pregnant sheep.

Optimal mechanical ventilation of the pregnant ewe during anaesthesia is of vital importance for maintaining fetal viability. This study aimed to compare peak inspiratory pressure (PIP), oxygenation and cardiovascular parameters with pressure-control (PCV) or volume-control (VCV) mechanical ventilation of anaesthetized pregnant sheep. Twenty ewes at 110 days gestation underwent general anaesthesia in dorsal recumbency for fetal surgery in a research setting. All the sheep were mechanically ventilated; one group with PCV (n = 10) and another with VCV (n = 10) to maintain normocapnia. PIP, direct arterial blood pressure, heart rate, arterial pH and arterial oxygen tension were recorded. PIP was lower in the PCV group (P < 0.001). Arterial oxygen tension was higher in the PCV group (P = 0.013). Mean and diastolic pressures were lower in the PCV group (P = 0.029 and P = 0.047, respectively). Both VCV and PCV provide adequate oxygenation of pregnant sheep anaesthetized in dorsal recumbency, though PCV may provide superior oxygenation at a lower PIP.

Laparoscopic kidney orthotopic transplant: preclinical study in the pig model.

BACKGROUND: Laparoscopic surgery has rapidly expanded in clinical practice replacing conventional open surgery over the last three decades. Laparoscopic donor nephrectomy has been favored due to its multiple benefits. The aim of this study was to explore the safety and feasibility of kidney transplantation by a laparoscopic technique in a pig model. MATERIALS AND METHODS: The study was approved by the university animal ethics committee. Eight female pigs (Sus Scrofra, weighing 45-50 kg) were divided into 2 groups: group I included 4 animals that underwent laparoscopic kidney orthotopic transplantation on the left side. The right kidney was remained functional in situ. The pigs recovered and were observed for 1 week. In the 4 hosts group II pigs underwent a laparoscopic kidney transplantation on the left side. With simultaneous clipping of the right ureter. After recovery, the pigs were observed for 4 weeks. A laparotomy for examination was performed prior to euthanasia. RESULTS: All 4 group I pigs survived for 1 week. The laparotomy showed normal graft perfusion with wall patent renal artery and vein as well as satisfactory urine output upon transection of ureter in 3 hosts. Renal artery stenosis occurred in one pig. In The Immediate kidney graft function was achieved in 3 group II pigs. The fourth died following extubation due to laryngospasm despite a functional graft. The average creatinine levels were 195.5 µmol/L on day 3; 224.5 µmol/L at week 1; 127 µmol/L at week 2; 182.7 umol/L at week 3; and 154.7 umol/L at week 4. CONCLUSION: Laparoscopic kidney transplantation was feasible and safe in a pig model with immediate graft function. This study will provide further evidence to support application of laparoscopic technique to human kidney transplant.

Intraperitoneal medetomidine: a novel analgesic strategy for postoperative pain management in pregnant sheep.

The absorption of medetomidine released by continuous infusion from an osmotic pump in the abdominal cavity was studied in pregnant sheep during the 24 h postoperative period. Additionally pain and sedation was assessed. Eleven sheep were studied: six were treated with a medetomidine loaded osmotic pump delivering 10 µL/h (3 µg/kg/h medetomidine); and five with a saline loaded osmotic pump (control). Serial blood samples were taken and analysed to determine plasma medetomidine levels. Medetomidine was absorbed from the peritoneal cavity and a steady plasma concentration was achieved within 10 h, mean (SD) peak concentration was 2.87 (0.22) ng/mL. Sheep receiving medetomidine analgesia had significantly lower pain scores at 10 h than controls. Four control sheep required rescue analgesia, compared with 0 in the treatment group. Delivery of 3 µg/kg/h medetomidine by an intraperitoneal osmotic pump to pregnant sheep in the 24 h postoperative period provides adequate plasma concentrations of medetomidine for analgesia without sedation.

Transplacental transfer of medetomidine and ketamine in pregnant ewes.

The extent of placental transfer of medetomidine and ketamine is unknown in pregnant ewes. Date-mated singleton (n = 8) and twin (n = 8) pregnant merino cross ewes were anaesthetized for Caesarean delivery of preterm lamb fetuses. A combination of medetomidine (20 µg/kg) and ketamine (10 mg/kg) was administered by intravenous injection and surgery performed immediately thereafter. Blood samples were collected from the ewe at one, five and 10 min after intravenous injection and from the umbilical vein of the fetus at delivery. Non-pregnant ewes were also anaesthetized (n = 8). There was no difference in the plasma concentration of medetomidine or ketamine when comparing singleton and twin ewes or pregnant and non-pregnant ewes for the short duration of the study. Fetal plasma concentrations of each drug were comparable to the maternal concentrations at the same time. We conclude that both drugs cross the placenta readily and provide anaesthesia and analgesia for the fetus when it is delivered.

Target-controlled infusion of propofol in dogs--evaluation of four targets for induction of anaesthesia.

Four groups of 20 dogs were anaesthetised by means of target-controlled infusions of propofol designed to achieve 2.5 microg/ml, 3.0 microg/ml, 3.5 microg/ml or 4.0 microg/ml of propofol in blood. The dogs' pulse rate and respiratory rate were recorded before premedication and induction, immediately after endotracheal intubation and three and five minutes later (times 0, 3 and 5, respectively), and their arterial blood pressure was recorded oscillometrically just before induction and at times 0, 3 and 5. The targets of 2.5, 3.0, 3.5 and 4.0 microg/ml resulted in the successful induction of anaesthesia in 13 (65 per cent), 16 (80 per cent), 20 (100 per cent) and 20 (100 per cent) of the dogs, respectively. The incidence of postinduction apnoea was 0 (0 per cent), one (5 per cent), two (10 per cent) and eight (40 per cent) at time 5 for groups 2.5, 3.0, 3.5 and 4.0 mug/ml, respectively, and its incidence at time 5 was significantly higher in the 4.0 microg/ml group (P<0.05) than in the other groups. In all the groups there was a significant (P<0.05) decrease in blood pressure between just before induction and the later measurements. Although there were no statistically significant differences between the groups in terms of inducing anaesthesia at a specific target, a target of 3.5 microg/ml appears to ensure a successful induction of anaesthesia without a significant increase in the incidence of apnoea.