The experiment evaluated the effects of intravenous administration of polymyxin B on experimental endotoxaemia in sheep. Twenty clinically healthy fat-tailed sheep were randomly divided into: a group treated with 6,000 U/kg of polymyxin B, a group at 12,000 U/kg, and positive and negative controls. Endotoxaemia was induced by intravenous administration of lipopolysaccharide (LPS) from E. coli serotype O55:B5 at 0.5 μg/kg. polymyxin was infused intravenously along with 2.5 L of isotonic intravenous fluids at 20 mL/kg/h. The positive control group received LPS and 2.5 L of isotonic fluids, the negatives receiving just 2.5 L of isotonic fluids. Clinical signs were evaluated before and at 1.5, 3, 4.5, 6, 24, and 48 h after LPS administration. Blood was also sampled at the denoted hours and serum haptoglobin, tumour necrosis factor-α (TNF-α), and plasma lactate concentrations were assayed. The serum concentration of TNF-α in the positive control group increased significantly up to 48 h after LPS administration. The concentration of TNF-α was significantly different from those of the polymyxin B and positive control groups from 3 to 48 h; also, the concentrations of haptoglobin at different times in the polymyxin groups were lower than those of the positive control group and were significant at hours 3 to 48 (P < 0.05). Following the LPS administration, haptoglobin and TNF-α concentrations changed without significant difference between the two polymyxin B groups. Polymyxin B (6,000 U/kg) restrained blood lactate concentrations. Furthermore, it significantly improved the clinical signs in endotoxaemic animals, including rectal temperature and heart and respiratory rates. Polymyxin B may be an antiendotoxic in fat-tailed sheep.

While the current tools to assess canine postoperative pain using physiological and behavioural parameters are reliable, an objective method such as the parasympathetic tone activity (PTA) index could improve postoperative care. The aim of the study was to determine the utility of the PTA index in assessing postoperative analgaesia. Thirty healthy bitches of different breeds were randomly allocated into three groups for analgaesic treatment: the paracetamol group (GPARAC, n = 10) received 15 mg/kg b.w., the carprofen group (GCARP, n = 10) 4 mg/kg b.w., and the meloxicam group (GMELOX, n = 10) 0.2 mg/kg b.w. for 48 h after surgery. GPARAC was medicated orally every 8 h, while GCARP and GMELOX were medicated intravenously every 24 h. The PTA index was used to measure the analgaesia–nociception balance 1 h before surgery (baseline), and at 1, 2, 4, 6, 8, 12, 16, 20, 24, 36, and 48 h after, at which times evaluation on the University of Melbourne Pain Scale (UMPS) was made. The baseline PTA index was 65 ± 8 for GPARAC, 65 ± 7 for GCARP, and 62 ± 5 for GMELOX. Postoperatively, it was 65 ± 9 for GPARAC, 63 ± 8 for GCARP, and 65 ± 8 for GMELOX. No statistically significant difference existed between baseline values or between values directly after treatments (P = 0.99 and P = 0.97, respectively). The PTA index showed a sensitivity of 40%, specificity of 98.46% and a negative predictive value of 99.07%. Our findings suggest that the PTA index measures comfort and postoperative analgaesia objectively, since it showed a clinical relationship with the UMPS.

Introduction: The aim of this study was to investigate fluorescein use in the diagnosis of bladder ruptures in rabbits as an experimental model.Material and Methods: The study was conducted on male New Zealand rabbits divided into a retrograde fluorescein group (n = 8) and an intravenous (IV) fluorescein group (n = 8). Following general anaesthesia, 10 mL of 10% fluorescein dye (sodium fluoresceine powder) was administered via ureterorenoscope to the bladder of the first group, and 0.5 mL of 10% fluorescein was administered intravenously to the second group. Then, the bladder was viewed through the cystoscope by urethral aspect. After experimental bladder perforation, groups were comparatively evaluated by paracentesis and laparotomy.Results: Following IV injection of fluorescein dye, the bladder veins were stained green within 10 s and then fluorescein mixed with urine flowed into bladder lumen. The green fluid flow was observed in the abdominal cavity after the perforation of the bladder in both groups.Conclusion: Fluorescein can be used as a marker in diagnosis of bladder ruptures. If there is no bleeding or intestinal content in the abdominal cavity, although a smoky yellow-green image is observed, bladder rupture can be suspected.

Recombinant bovine interferon alpha (rBoIFN-α) has been demonstrated to have antiviral activity. However, no conduct of acute or chronic toxicity tests has been reported. Specific pathogen-free Sprague Dawley rats were administered doses at different concentrations through intraperitoneal or intravenous injection. After the administration (single for an acute toxicity test over 14 days or daily for a sub-chronic toxicity test over 30 days), the rats’ behaviour and other indicators and the degree of toxic reaction were continuously monitored. Blood was collected for haematological and serum biochemical examinations. At the end of the experiments, the rats were sacrificed for necropsy and histopathological tissue analysis. The external performance, behaviour characteristics, and changes in body temperature and body weight of the rats in each subgroup were comparable to the normal control subgroup. Except for a few cases, there were no lesions in the viscera’s pathological structures, and the blood parameters and biochemical indicators were not noticeably different from those of the control subgroup. This study suggests that rBoIFN-α seems to be safe for rats, and its use may foster the development of the cattle industry in China by protecting livestock health.

OBJECTIVE To evaluate the effects of using ropivacaine combined with dexmedetomidine for sciatic and saphenous nerve blocks in dogs. ANIMALS 7 healthy adult Beagles. PROCEDURES In phase 1, dogs received each of the following 3 treatments in random order: perineural sciatic and saphenous nerve injections of 0.5% ropivacaine (0.4 mL/kg) mixed with saline (0.9% NaCl) solution (0.04 mL/kg; DEX0PN), 0.5% ropivacaine mixed with dexmedetomidine (1 μg/kg; DEX1PN), and 0.5% ropivacaine mixed with dexmedetomidine (2 μg/kg; DEX2PN). In phase 2, dogs received perineural sciatic and saphenous nerve injections of 0.5% ropivacaine and an IV injection of diluted dexmedetomidine (1 μg/kg; DEX1IV). For perineural injections, the dose was divided equally between the 2 sites. Duration of sensory blockade was evaluated, and plasma dexmedetomidine concentrations were measured. RESULTS Duration of sensory blockade was significantly longer with DEX1PN and DEX2PN, compared with DEX0PN; DEX1IV did not prolong duration of sensory blockade, compared with DEX0PN. Peak plasma dexmedetomidine concentrations were reached after 15 minutes with DEX1PN (mean ± SD, 348 ± 200 pg/mL) and after 30 minutes DEX2PN (816 ± 607 pg/mL), and bioavailability was 54 ± 40% and 73 ± 43%, respectively. The highest plasma dexmedetomidine concentration was measured with DEX1IV (1,032 ± 415 pg/mL) 5 minutes after injection. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that perineural injection of 0.5% ropivacaine in combination with dexmedetomidine (1 μg/kg) for locoregional anesthesia in dogs seemed to balance the benefit of prolonging sensory nerve blockade while minimizing adverse effects.

OBJECTIVE To characterize the pharmacokinetics of mycophenolate mofetil (MMF) following single-dose IV or PO administration, characterize the pharmacokinetics of MMF following long-term PO administration, and describe the clinicopathologic effects of long-term MMF administration in horses. ANIMALS 12 healthy adult horses. PROCEDURES In phase 1, 6 horses received a single IV (2.5 mg/kg) or PO (5 mg/kg) dose of MMF in a randomized balanced crossover assessment (≥ 2-week interval between administrations). In phase 2, 6 other horses received MMF for 60 days (5 mg/kg, PO, q 24 h for 30 days and then 5 mg/kg, PO, q 48 h for an additional 30 days). RESULTS Following IV (single-dose) or PO (single- or multiple-dose) administration, MMF was rapidly converted to mycophenolic acid. For single-dose PO administration, mean ± SD maximum plasma mycophenolic acid concentration was 1,778.3 ± 441.5 ng/mL at 0.71 ± 0.29 hours. For single-dose IV administration, mean systemic clearance and volume of distribution at steady state were 0.689 ± 0.194 L/h/kg and 1.57 ± 0.626 L/kg, respectively. Following single doses, mean terminal half-life was 3.99 ± 0.865 hours for IV administration and 4.02 ± 1.01 hours for PO administration. The accumulation index following long-term PO administration was 1.0 ± 0.002, and the terminal half-life was 4.59 ± 1.25 hours following the final dose on day 60. None of the horses developed abnormal clinical signs or had any consistently abnormal clinicopathologic findings. CONCLUSIONS AND CLINICAL RELEVANCE Further investigation of the clinical efficacy of long-term MMF treatment of horses with autoimmune diseases is warranted.

OBJECTIVE To determine the median time to maximum concentration (tmax) of amikacin in the synovial fluid of the tarsocrural joint following IV regional limb perfusion (IVRLP) of the drug in a saphenous vein of horses. ANIMALS 7 healthy adult horses. PROCEDURES With each horse sedated and restrained in a standing position, a 10-cm-wide Esmarch tourniquet was applied to a randomly selected hind limb 10 cm proximal to the point of the tarsus. Amikacin sulfate (2 g diluted with saline [0.9% NaCl] solution to a volume of 60 mL) was instilled in the saphenous vein over 3 minutes with a peristaltic pump. Tarsocrural synovial fluid samples were collected at 5, 10, 15, 20, 25, and 30 minutes after completion of IVRLP. The tourniquet was removed after collection of the last sample. Amikacin concentration was quantified by a fluorescence polarization immunoassay. Median maximum amikacin concentration and tmax were determined. RESULTS 1 horse was excluded from analysis because an insufficient volume of synovial fluid for evaluation was obtained at multiple times. The median maximum synovial fluid amikacin concentration was 450.5 μg/mL (range, 304.7 to 930.7 μg/mL), and median tmax was 25 minutes (range, 20 to 30 minutes). All horses had synovial fluid amikacin concentrations ≥ 160 μg/mL (therapeutic concentration for common equine pathogens) at 20 minutes after IVRLP. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that, in healthy horses, maintaining the tourniquet for 20 minutes after IVRLP of amikacin in a saphenous vein was sufficient to achieve therapeutic concentrations of amikacin in the tarsocrural joint.

OBJECTIVE To determine the cardiopulmonary effects of IV administration of fentanyl to cats anesthetized with isoflurane and during anesthetic recovery with concurrent administration of acepromazine or dexmedetomidine. ANIMALS 6 healthy adult cats. PROCEDURES Cats received an IV bolus (5 μg/kg) followed by an IV infusion (5 μg/kg/h) of fentanyl for 120 minutes during isoflurane anesthesia and for 30 minutes after discontinuing isoflurane. Cats were randomly assigned in a crossover study to receive acepromazine (0.05 mg/kg) or dexmedetomidine (2.5 μg/kg), IV, when isoflurane was discontinued. Cardiopulmonary data were obtained during anesthesia and for 30 minutes during the anesthetic recovery period. RESULTS The administration of fentanyl during isoflurane anesthesia resulted in a transient increase in arterial blood pressure, mean pulmonary artery pressure, and oxygen delivery. Compared with values during isoflurane anesthesia, administration of dexmedetomidine during anesthetic recovery resulted in significant decreases in cardiac index, stroke index, and oxygen delivery and significant increases in arterial, central venous, and mean pulmonary artery pressures; systemic vascular resistance index; and oxygen extraction ratio. Administration of acepromazine resulted in increases in heart rate, cardiac index, oxygen uptake, and oxygen extraction ratio. Oxygen extraction ratio did not differ between acepromazine and dexmedetomidine. CONCLUSIONS AND CLINICAL RELEVANCE Fentanyl transiently improved indices of cardiopulmonary performance when administered to healthy cats anesthetized with isoflurane. The cardiovascular effects of acepromazine and dexmedetomidine in healthy cats receiving fentanyl during recovery from isoflurane anesthesia differed, but measured cardiopulmonary parameters remained within acceptable limits.

OBJECTIVE To describe the pharmacokinetics of morphine, lidocaine, and ketamine associated with IV administration of a constant rate infusion (CRI) of a morphine-lidocaine-ketamine (MLK) combination to calves undergoing umbilical herniorrhaphy. ANIMALS 20 weaned Holstein calves with umbilical hernias. PROCEDURES Calves were randomly assigned to receive a CRI of an MLK solution (0.11 mL/kg/h; morphine, 4.8 μg/kg/h; lidocaine, 2.1 mg/kg/h; and ketamine, 0.42 mg/kg/h) for 24 hours (MLK group) or 2 doses of flunixin meglumine (1.1 mg/kg, IV, q 24 h) and a CRI of saline (0.9% NaCl) solution (0.11 mL/kg/h) for 24 hours (control group). For all calves, the CRI was begun after anesthesia induction. Blood samples were obtained immediately before and at predetermined times for 120 hours after initiation of the assigned treatment. Noncompartmental analysis was used to estimate pharmacokinetic parameters for the MLK group. RESULTS During the CRI, steady-state serum concentrations were achieved for lidocaine and ketamine, but not morphine. Mean terminal half-life was 4.1, 0.98, and 1.55 hours and area under the concentration-time curve was 41, 14,494, and 7,426 h•μg/mL for morphine, lidocaine, and ketamine, respectively. After the CRI, the mean serum drug concentration at steady state was 6.3, 616.7, and 328 ng/mL for morphine, lidocaine, and ketamine, respectively. CONCLUSIONS AND CLINICAL RELEVANCE During the CRI of the MLK solution, steady-state serum concentrations were achieved for lidocaine and ketamine, but not morphine, likely owing to the fairly long half-life of morphine. Kinetic analyses of MLK infusions in cattle are necessary to establish optimal dosing protocols.

The aim of this study was to evaluate the respiratory and hemodynamic effects of a low-dose dexmedetomidine infusion [1mg/kg body weight (BW) per hour], with or without a loading dose (1 mg/kg BW), in dogs under isoflurane anesthesia. Thirty dogs were premedicated with methadone [0.3 mg/kg BW intramuscular (IM)], induced with propofol intravenous (IV) and maintained with isoflurane (1.3% to 1.4%) under mechanical ventilation. Animals were randomly assigned to 3 intravenous (IV) treatments (n = 10): 1 mg/kg BW dexmedetomidine, followed by 1 mg/kg BW per hour (group BI); or saline solution bolus, followed by either an infusion of 1 mg/kg BW per hour dexmedetomidine (group I) or saline solution (group C). The infusions were interrupted after 30 minutes. Respiratory system static compliance (Cstat) and respiratory system resistance (Rrs), partial pressure of oxygen/fractional inspired oxygen ratio (PaO(2)/FIO(2)), intrapulmonary shunt (Fshunt), and cardiac output (CO) were determined 5 minutes before the bolus (BASELINE), at the end of the bolus (BOLUS), and at 15 (T15), 30 (T3(0)), and 45 minutes (T45) intervals. In group BI, Cstat and PaO(2)/FiO(2) were higher at T15 and T3(0) than at BASELINE in the same group and than group C at the same times. In group I, the same parameters at T30 were higher than at BASELINE and than group C at the same time. In group BI, Rrs and Fshunt were lower than at BASELINE and than group C at the same time. In group I, the same parameters at T30 were lower than at BASELINE and those of group C at the same time. Cardiac output (CO) at T30 was higher in groups BI and I than in group C. The results of this study showed that low-dose dexmedetomidine infusion improves oxygenation and respiratory system mechanics and has a stabilizing hemodynamic effect in dogs anesthetized with isoflurane and mechanically ventilated.