Comparison of different applications of the sonographic contrast medium Levovist

The influence of the application modes (bolus injection, infusion) of the sonographic signal enhancers Levovist was investigated in a total of 24 dogs. The animals in the bolus group were given 0.2 ml/kg body mass Levovist at a concentration of 300 mg/ml while in the other group the same amount was continuously injected over a time of two minutes. Signal enhancement was measured by an audiodoppler. Contrast duration above six, twelve, 18 and 24 dB and maximum signal enhancement were determined for each application mode. The comparison of these parameters showed that a statistically significant longer contrast duration (significance level p less than 0,05) at 0 and 6 dB can be achieved by continuous injection. Bolus application, on the other hand, resulted in significantly higher maximum contrast enhancement. With time consuming investigations (perfusiondiagnostic, shuntdiagnostic) the contrast effect can be partly extended with continuous injection but the technical requirements are higher and there is the risk that the acoustic properties of the microbubbles are negatively influenced.     

PULMONARY ANGIOGRAPHY USING 16 SLICE MULTIDETECTOR COMPUTED TOMOGRAPHY IN NORMAL DOGS

We report a canine computed tomography (CT) pulmonary angiography technique using multidetector CT (MDCT). CT pulmonary angiography using a 16 slice MDCT was performed on five healthy, anesthetized beagles. A helical acquisition with pitch of 1.4 was used. The time delay for the angiographic study was determined using a bolus‐tracking program. A dose of 400 mg I/kg of nonionic contrast medium (Iohexol 300 mg I/ml) was administered to each dog via a cephalic catheter using an angiographic power injector at a rate of 5 ml/s. In two dogs a second study, using a contrast medium dose of 200 and 600 mg I/kg was performed. Arterial enhancement of transverse and reformatted images was classified subjectively as excellent, good, or poor, and assessed objectively by measuring Hounsfield units at the right main pulmonary artery. Angiographic studies were evaluated by two radiologists to determine the number of subsegmental arterial branches visualized. The median number of subsegmental arterial branches identified was five (range: 2–7). Based on the time attenuation curve obtained by the bolus‐tracking program, there was consistent enhancement of the right main pulmonary artery beginning at 6 s and peaking at 8 s in 4/5 dogs. The contrast medium dose of 400 mg I/kg produced good to excellent vascular enhancement in the same 4/5 dogs. A dose of 200 mg I/kg resulted in poor enhancement. CT pulmonary angiography using MDCT and an automated bolus‐tracking program allows rapid, consistent evaluation of the pulmonary vasculature using a single dose of 400 mg I/kg of contrast medium.     

The use of propofol for induction of anaesthesia in dogs premedicated with acepromazine, butorphanol and acepromazine-butorphanol

Cardiovascular, pulmonary and anaesthetic-analgesic responses were evaluated in 18 male and female dogs to determine the effect of the injectable anaesthetic propofol used in conjuction with acepromazine and butorphanol. The dogs were randomly divided into three groups. Dogs in Group A were premeditated with 0.1 mg/kg of intramuscular acepromazine followed by an induction dose of 4.4 mg/kg of intravenous propofol; Group B received 0.2 mg/kg of intramuscular butorphanol and 4.4 mg/kg of intravenous propofol; dogs in Group AB were administered a premeditation combination of 0.1 mg/kg of intramuscular acepromazine and 0.2 mg/kg of intramuscular butorphanol, followed by induction with 3.3 mg/kg of intravenous propofol. The induction dose of propofol was given over a period of 30-60 seconds to determine responses and duration of anaesthesia. Observations recorded in the dogs included heart and respiratory rates, indirect arterial blood pressures (systolic, diastolic and mean), cardiac rhythm, end-tidal CO, tension, oxygen saturation, induction time, duration of anaesthesia, recovery time and adverse reactions. The depth of anaesthesia was assessed by the response to mechanical noxious stimuli (tail clamping), the degree of muscle relaxation and the strength of reflexes. Significant respiratory depression was seen after propofol induction in both groups receiving butorphanol with or without acepromazine. The incidence of apnea was 4/6 dogs in Group B, and 5/6 dogs in Group AB. The incidence of apnea was also correlated to the rate of propofol administration. Propofol-mediated decreases in arterial blood pressure were observed in all three groups. Moderate bradycardia (minimum value > 55 beats/min) was observed in both Groups B and AB. There were no cardiac dysrhythmias noted in any of the 18 dogs. The anaesthetic duration and recovery times were longer in dogs premeditated with acepromazine/butorphanol.     

Thiamylal-and halothane-sparing effect of diazepam in dogs

The thiamylal- and halothane-sparing effect of diazepam was studied in two experiments using 32 conditioned dogs. Twenty-four dogs received 0.05, 0.1 or 0.2 ml/kg diazepam or 0.9% saline (placebo) prior to the administration of thiamylal sodium i.v. Eight dogs received 0.1 or 0.2 mg/kg diazepam i.v. or placebo prior to or during halothane anesthesia. All three doses of diazepam significantly decreased the amount of thiamylal required to allow orotracheal intubation. The 0.2 mg/kg i.v. dose of diazepam produced the most significant effects. Premedication of dogs with diazepam did not reduce the concentration of halothane required to maintain anesthesia. The administration of 0.1 and 0.2 mg/kg diazepam i.v. during halothane anesthesia decreased the concentration of halothane required to maintain anesthesia. These studies demonstrate that diazepam reduces the amount of thiamylal required for orotracheal intubation, and when given intra-operatively reduces the concentration of halothane required to maintain anesthesia.     

Xylazine premedication does not modify the onset and duration of cisatracurium blockade in anaesthetized dogs

The purpose of this study was to evaluate the effect of xylazine as premedication on the onset time and duration of cisatracurium neuromuscular blockade in anaesthetized dogs. This study was carried out on 12 healthy dogs aged 0.5-6 years and weighing 9-26 kg undergoing various elective surgical procedures. The dogs were randomly divided into two groups of t (test) and c (control), with six dogs each. In group t, premedication was conducted using acepromazine maleate 0.3 mg kg(-1) and xylazine 0.3 mg kg(-1) and in group c only acepromazine (same dose) was injected intramuscularly 20 min before general anaesthesia. After induction with thiopental, anaesthesia was maintained with halothane in oxygen to deliver an end-tidal halothane concentration of 1.1%. Neuromuscular blockade was induced with cisatracurium 0.2 mg kg(-1) and monitored using the train-of-four (TOF) stimulation pattern applied at the ulnar nerve. The onset time of cisatracurium blockade was 195 +/- 85.44 s in test and 153.3 +/- 38.16 s in control group. The duration of neuromuscular blockade was 24.8 +/- 4.79 min in t and 28.3 +/- 5.46 min in the c group. Statistical analysis of the data showed no significant difference between groups in terms of onset and duration of neuromuscular blockade.     

Serum disposition of exogenous progesterone after intramuscular administration in bitches

Progesterone was administered IM to 6 adult anestrous bitches at a dosage of 2 mg/kg of body weight. Serum progesterone concentrations were measured prior to progesterone administration and for 72 hours thereafter. The serum progesterone concentration time data were analyzed by use of a pharmacokinetics modeling computer program. The mean (+/- SD) peak serum progesterone concentration (34.3 +/- 7.8 ng/ml) was reached at 1.8 +/- 0.2 hours after progesterone administration. The mean serum progesterone concentration was 6.9 +/- 1.4 ng/ml at 24 hours and 2.0 +/- 0.4 ng/ml at 48 hours after progesterone administration. By 72 hours after administration, mean serum progesterone concentration was 0.9 +/- 0.2 ng/ml, which was comparable to serum progesterone concentrations prior to injection. The mean half-life of the absorption phase was 0.5 hours (range, 0.3 to 0.7 hours). The mean half-life of elimination was 12.1 hours (range, 9.5 to 13.8 hours). By analysis of the data, it was established that a dosage of 3 mg/kg, when the hormone was given IM to dogs once a day, would maintain serum progesterone concentration greater than 10 ng/ml.     

Pharmacokinetics of intramuscularly administered pethidine in dogs and the influence of anaesthesia and surgery

The plasma concentration of pethidine was measured after it had been administered intramuscularly to fully conscious dogs, and to dogs in the postoperative period and during general anaesthesia. The absorption of the drug was erratic except in the anaesthetised animals and the plasma concentrations of the drug were also higher in this group. Correlation of plasma concentrations of the drug with its analgesic activity revealed a 'critical' concentration of pethidine of 0.4 micrograms/ml for complete analgesia; useful though not complete analgesia was achieved with concentrations above 0.2 micrograms/ml. These concentrations were maintained for 90 minutes after the administration of the drug at a dose of 2.0 mg/kg and for 120 minutes after a dose of 3.5 mg/kg.     

Medetomidine, levo-methadone and diazepam as premedication for lumbosacral epidural anaesthesia in dogs

The effect of medetomidine (40 μg/ kg) together with levo-methadone (0.5 mg/kg) was evaluated in dogs as a sedative and analgesic premedication followed by a lumbosacral epidural block with mepivacaine 2% or bupi-vacaine 0.5% (0.3–0.5 ml/10cm crown-rump length). When sedation became insufficient in the course of surgery, additional diazepam (0.1–0.2 mg/kg) was administered. Only in 43% of the dogs could surgery be performed without additional sedation. Medetomidine and levo-methadone influenced the cardio-respiratory system markedly. Hypoxaemia as well as hypercarbia were evident. Diazepam had no additional effect on these respiratory changes. After surgery 19 dogs were given atipamezole, 18 received atipamezole and naloxone while 17 received no antagonists. In 10 out of the 19 dogs receiving only atipamezole, fits of excitability were seen, but those receiving atipamezole and naloxone had a quiet recovery.     

Dose-sparing effects of romifidine premedication for thiopentone and halothane anaesthesia in the dog

Two intravenous doses of romifldine (40 and 80 μg/kg) and a placebo were compared as premedicants for anaesthesia induced with thiopentone and maintained using halothane in oxygen. Romifldine significantly and linearly reduced the induction dose of thiopentone; placebo-treated dogs required 15.1 ± 3.6 mg/kg, while dogs treated with 40 μg/kg and 80 μg/kg romifldine required 6.5 ± 1.6 and 3.9 ± 0.3 mg/kg thiopentone, respectively.
Romlfldine also significantly and linearly reduced the end tidal halothane concentration necessary to maintain a predetermined level of anaesthesia; piacebetreated dogs required 1.6 ± 0.3 per cent halothane, while dogs treated with 40 μg/kg and 80 μg/kg romifldine required 1.3 ± 0.4 and 0–8 ± 0.2 per cent, respectively.
Romifldine produced a significant shortening In the recovery from anaesthesia, and the higher dose of romlfldine significantly improved the overall quality of anaesthesia.     

Comparison of intra-operative analgesia provided by intravenous regional anesthesia or brachial plexus block for pancarpal arthrodesis in dogs

The aim of this study was to compare intravenous regional anesthesia (IVRA) and brachial plexus block (BPB) for intra-operative analgesia in dogs undergoing pancarpal arthrodesis (PA). Twenty dogs scheduled for PA were intramuscularly sedated with acepromazine (0.03mg/kg), general anesthesia was intravenously (IV) induced with thiopental (10mg/kg) and, after intubation, maintained with isoflurane in oxygen. In 10 dogs (GIVRA) IVRA was performed on the injured limb administering 0.6ml/kg of 0.5% lidocaine. In 10 dogs (GBPB) the BPB was performed at the axillary level with the help of a nerve stimulator and 0.3ml/kg of a 1:1 solution of 2% lidocaine and 1% ropivacaine was injected. During surgery fentanyl (0.002mg/kg IV) was administered if there was a 15% increase of HR and/or MAP compared to the values before surgical stimulation. All the standard cardiovascular and respiratory parameters were continuously monitored during surgery. The duration of surgery and the time of extubation were recorded. Data were compared with a 1-way ANOVA test (P<0.05). No patients required fentanyl administration during surgery. All the recorded parameters were similar in the two groups. The two techniques were similar in providing intra-operative analgesia in dogs undergoing orthopaedic surgery.     

Effects of medetomidine-midazolam,midazolambutorphanol, or acepromazine-butorphanol as premedicants for mask induction of anesthesia with sevoflurane in dogs

OBJECTIVE: To characterize the effects of medetomidine-midazolam, midazolam-butorphanol, or acepromazine-butorphanol as premedicants for mask induction of anesthesia with sevoflurane in dogs. ANIMALS: 10 healthy Beagles. PROCEDURE: The following premedicants were administered intramuscularly: medetomidine-midazolam (20 microg/kg and 0.3 mg/kg, respectively), midazolam-butorphanol (0.1 and 0.2 mg/kg, respectively), and acepromazine-butorphanol (0.05 and 0.2 mg/kg, respectively). Saline (0.9% NaCI) solution (0.1 ml/kg) was administered intramuscularly as a control. Anesthesia was induced in each dog with sevoflurane in a 100% O2 at a flow rate of 4 L/min developed by a facemask. Vaporizer settings were increased by 0.8% at 15-second intervals until the value corresponding to 4.8% sevoflurane was achieved. Time to onset and cessation of involuntary movements, loss of the palpebral reflex, negative response to tail-clamp stimulation, and endotracheal intubation were recorded, and the cardiopulmonary variables were measured. RESULTS: Mask induction with sevoflurane in dogs that received each premedicant resulted in a shorter induction time and milder changes in heart rate, mean arterial blood pressure, cardiac output, and respiratory rate, compared with mask induction without premedicants. Treatment with medetomidine-midazolam resulted in a shorter and smoother induction, compared with acepromazine-butorphanol or midazolam-butorphanol treatment, whereas the cardiovascular changes were greater. Cardiopulmonary variables of dogs during induction following treatment with acepromazine-butorphanol or midazolam-butorphanol were maintained close to the anesthetic maintenance values for sevoflurane, with the exception of mild hypotension that was observed in dogs following acepromazine-butorphanol treatment. CONCLUSION AND CLINICAL RELEVANCE: In dogs use of premedicants provides a smoother and better quality mask induction with sevoflurane.     

Gabapentin as an adjuvant for postoperative pain management in dogs undergoing mastectomy

This study aimed to evaluate the analgesic efficacy of gabapentin as an adjuvant for postoperative pain management in dogs. Twenty dogs undergoing mastectomy were randomized to receive perioperative oral placebo or gabapentin (10 mg/kg). All dogs were premedicated with intramuscular acepromazine (0.03 mg/kg) and morphine (0.3 mg/ kg). Anesthesia was induced with propofol (4 mg/kg) intravenously and maintained with isoflurane. Intravenous meloxicam (0.2 mg/kg) was administered preoperatively. Postoperative analgesia was evaluated for 72 hr. Rescue analgesia was provided with intramuscular morphine (0.5 mg/kg). Dogs in the Placebo group received significantly more morphine doses than the Gabapentin group (P=0.021), despite no significant differences in pain scores. Perioperative gabapentin reduced the postoperative morphine requirements in dogs after mastectomy.     

Pharmacokinetics of tinidazole in dogs and cats

Pharmacokinetics of tinidazole in dogs and cats after single intravenous (15 mg/kg) and oral doses (15 mg/kg or 30 mg/kg) were studied in a randomized crossover study. Tinidazole was completely absorbed at both oral dose levels in cats and dogs. Peak tinidazole concentration in plasma was 17.8 micrograms/ml in dogs and 22.5 micrograms/ml in cats after 15 mg/kg p.o. The oral dose of 30 mg/kg resulted in peak levels of 37.9 micrograms/ml in dogs and 33.6 micrograms/ml in cats. The apparent total plasma clearance of the drug was about twofold higher in dogs than in cats, resulting in an elimination half-life that was twice as long in cats (8.4 h) as in dogs (4.4 h). The apparent volume of distribution was 663 ml/kg in dogs and 536 ml/kg in cats. Therapeutic plasma drug concentrations higher than the MIC values of most tinidazole-sensitive bacteria were achieved for 24 h in cats and for 12 h in dogs after a single oral dose of 15 mg/kg. From the pharmacokinetic standpoint tinidazole seems to be well-suited to clinical use in small animal practice.     

Influence of three anesthetic protocols on glomerular filtration rate in dogs

OBJECTIVE: To investigate renal function in clinically normal dogs when awake and during anesthesia with medetomidine; xylazine, ketamine, and halothane (XKH) combination; or propofol. ANIMALS: 10 adult female Beagles. PROCEDURES: At intervals of 15 days, dogs were administered medetomidine (0.05 mg/kg, IV); XKH combination (xylazine [1 mg/kg, IV], ketamine [5 mg/kg, IV], and halothane [1% end-tidal concentration]); or propofol (6 mg/kg, IV) to induce anesthesia or no treatment. Glomerular filtration rate was assessed on the basis of renal uptake (RU; determined via renal scintigraphy) and plasma clearance (CL) of technetium 99m-labeled diethylenetriamine pentaacetic acid ((99m)Tc-DTPA). RESULTS: In awake dogs, mean +/- SEM RU was 9.7 +/- 0.4% and CL was 3.86 +/- 0.23 mL/min/ kg. Renal uptake and CL of (99m)Tc-DTPA were not significantly modified by administration of XKH (RU, 11.4 +/- 0.9%; CL, 4.6 +/- 0.32 mL/min/kg) or propofol (RU, 9.7 +/- 0.3%; CL, 3.78 +/- 0.37 mL/min/kg). Half-life elimination time of plasma (99m)Tc-DTPA decreased significantly in XKH-anesthetized dogs, compared with the value in awake dogs (14.4 minutes and 28.9 minutes, respectively). However, glomerular filtration rate was significantly decreased by administration of medetomidine (RU, 3.9 +/- 0.1%), and the time to maximum kidney activity was significantly increased (867 +/- 56 seconds vs 181 +/- 11 seconds without anesthesia). CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that anesthesia with propofol or an XKH combination did not alter renal function in healthy Beagles, but anesthesia with medetomidine decreased early RU of (99m)Tc-DTPA.     

Evaluation of the analgesic effect of lidocaine and bupivacaine used to provide a brachial plexus block for forelimb surgery in 10 dogs

Twenty adult dogs weighing between 1.4 and 53.5 kg and aged between six months and nine years were anaesthetised and the brachial plexus was localised with the aid of a nerve stimulator. In 10 of the dogs a brachial plexus block was induced with a mixture of lidocaine and bupivacaine and the other 10 each received 0.25 ml/kg saline as a control. The end-tidal isoflurane concentration was maintained between 1.3 and 1.4 per cent during surgery for carpal arthrodesis or a fracture of the radius or ulna. Acute heart rate or blood pressure increases of 20 per cent or more were treated with 1 microg/kg fentanyl intravenously. Postoperatively, signs of pain were scored by a single blinded observer at hourly intervals until eight hours after the block had been induced, on a scale from 0 to 18. Dogs with pain scores above 5 received 0.1 to 0.2 mg/kg methadone intravenously, repeated as necessary. During surgery the control dogs received significantly more fentanyl (median 0.05 microg/kg/minute, range 0.02 to 0.20 microg/kg/minute) than the group given local anaesthetic (median 0 microg/kg/minute, range 0 to 0.02 microg/kg/minute). Postoperatively, the control group required significantly more methadone (median 0.2 mg/kg, range 0.1 to 1 mg/kg) than the treated group (median 0 mg/kg, range 0 to 0.13 mg/kg).     

Pharmacodynamic properties of succinylcholine in greyhounds

Succinylcholine is a depolarizing neuromuscular blocking drug, which is rapidly hydrolyzed by the enzyme pseudocholinesterase. In Greyhounds, the metabolism of certain drugs is atypical relative to other breeds, and it has been suggested that Greyhounds may be an atypical population, with lower pseudocholinesterase activity, slower hydrolysis of the drug succinylcholine, and a prolonged duration of action of the drug, compared with a mixed-breed control population. Six healthy adult Greyhounds and 6 healthy adult mixed-breed dogs were studied. Blood was drawn from each dog and analyzed for serum cholinesterase activity, and a biochemical profile was done to verify normal liver function. The dogs were anesthetized with methohexital (10 mg/kg) and isoflurane (1.25 minimal alveolar concentration) in 100% oxygen. Ventilation was controlled, fluids were administered IV (lactated Ringer solution, 10 ml/kg/h), and blood gases, blood pressure, and heart rate were monitored. The right hind limb was immobilized and a force transducer was used to monitor twitch strength of the interosseous muscle with supramaximal stimulation of the tibial nerve. Succinylcholine was administered to each dog 3 times at a dosage of 0.3 mg/kg. After drug administration, the time to 50% recovery of twitch strength (single twitch, 1/s), and 50% recovery of train-of-4 was determined. Subsequent doses were administered after complete recovery. The time to 50% recovery after succinylcholine administration in Greyhounds (38 minutes, dose 1, single twitch) was not significantly different than the time to 50% recovery in mixed-breed dogs (29 minutes, dose 1, single twitch), using either monitoring technique. Pseudocholinesterase activity was also not significantly different between the Greyhounds (1,685 mU/ml) and the mixed-breed dogs (1,588 mU/ml).(ABSTRACT TRUNCATED AT 250 WORDS)     

Antagonism of xylazine sedation with yohimbine, 4-aminopyridine, and doxapram in dogs

Groups of atropinized dogs (6 dogs/group) were sedated with xylazine (2.2 mg/kg of body weight, IM). At recumbency, the dogs were given IV saline solution (control groups), yohimbine (0.05, 0.1, and 0.2 mg/kg), 4-aminopyridine (4-AP; 0.3, 0.6, and 0.9 mg/kg), doxapram (0.5, 1.0, 2.0, and 4.0 mg/kg), or the smallest dose of these antagonists in dual combinations or in triple combination. Two additional groups were sedated with an overdose of xylazine (11 mg/kg, IM). At recumbency, 1 of these groups was given saline solution IV and the other group was given yohimbine IV (0.4 mg/kg) as the antagonist. With the 2.2 mg/kg dose of xylazine, control mean arousal time (MAT) and mean walk time (MWT) were 15.5 minutes and 24.8 minutes, respectively. These values were decreased by the individual antagonists to 0.5 to 2.5 minutes and 0.9 to 7.4 minutes, respectively. Approximate equipotent doses of antagonists (mg/kg) were: yohimbine, 0.2; 4-AP, 0.6; and doxapram, 0.5. Relapses did not occur after yohimbine or 4-AP. With doxapram, muscle tremors and spasms, abnormal postures, or aggressive behavior occurred in several dogs and several dogs had partial or complete relapses. The small doses of individual antagonists were synergistic with regard to MAT, MWT, and duration of residual sedation, but the various combinations of antagonists were not more effective in these regards than were larger doses of the single antagonists. With the overdose of xylazine, control MAT and MWT were 41.5 minutes and 144.5 minutes, respectively. Yohimbine decreased these values to 2.2 minutes and 2.5 minutes, respectively. Relapses did not occur.(ABSTRACT TRUNCATED AT 250 WORDS)     

Serum and tissue fluid norfloxacin concentrations after oral administration of the drug to healthy dogs

Norfloxacin, a 4-quinolone antibiotic, was administered orally to 4 healthy dogs at dosages of 11 and 22 mg/kg of body weight, every 12 hours for 4 days, with a 4-week interval between dosing regimens. Serum and tissue cage fluid (TCF) norfloxacin concentrations were measured at 0, 0.5, 1, 1.5, 2, 3, 4, 5, 6, 8, 10, and 12 hours after the first and seventh dose of each dosing regimen. When administered at a dosage of 11 mg/kg, the mean peak serum concentration (Cmax) was 1.0 microgram/ml at 1 hour, the time of mean peak concentration (Tmax) after the first dose. After the seventh dose, the Cmax was 1.4 micrograms/ml at Tmax of 1.5 hours. The Tmax for the TCF concentration was 5 hours, with Cmax of 0.3 microgram/ml and 0.7 microgram/ml after the first and seventh dose, respectively. When administered at a dosage of 22 mg/kg, the serum Tmax was 2 hours after the first dose, with Cmax of 2.8 micrograms/ml. After the seventh dose, the serum Tmax was 1.5 hours, with Cmax of 2.8 micrograms/ml. The Tmax for the TCF concentration was 5 hours after the first and seventh doses, with Cmax of 1.2 micrograms/ml and 1.6 micrograms/ml, respectively. After the seventh dose, the serum elimination half-life was 6.3 hours for a dosage of 11 mg/kg and was 6.7 hours for a dosage of 22 mg/kg. For serum concentration, the area under the curve from 0 to 12 hours (AUC0----12) was 8.77 micrograms.h/ml and 18.27 micrograms.h/ml for dosages of 11 mg/kg and 22 mg/kg, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)     

Use of rocuronium administered by continuous infusion in dogs

OBJECTIVE: A clinical trial to determine whether continuous infusion administration technique was suitable for maintaining neuromuscular blockade with rocuronium bromide in dogs. ANIMALS: Twenty-two dogs, 10 males and 12 females, median age 2 years 4 months, median weight 32 kg undergoing elective surgical procedures under general anaesthesia: ASA classification I or II. MATERIALS AND METHODS: After induction of anaesthesia, neuromuscular function was evaluated using train-of-four (TOF) stimulation of the dorsal buccal branch of the facial nerve. A bolus dose of 0.5 mg kg(-1) rocuronium was administered intravenously and an infusion of 0.2 mg kg(-1) hour(-1) was started immediately. Neuromuscular blockade was assessed visually by counting the number of twitches observed during TOF stimulation repeated at 10-second intervals. RESULTS: The bolus dose of rocuronium abolished the response to TOF stimulation in 21 of the 22 dogs. The median onset time of neuromuscular blockade (complete loss of all four twitches) was 82 seconds (range 38-184 seconds). Median infusion duration was 76 minutes (range 20.3-146 minutes). CONCLUSIONS AND CLINICAL RELEVANCE: This protocol of rocuronium administration was considered to be effective in dogs. Constant infusion of rocuronium is easily applicable to clinical practice and further work is required on infusion titration.     

Pharmacokinetics of norfloxacin in dogs after single intravenous and single and multiple oral administrations of the drug

Norfloxacin was given to 6 healthy dogs at a dosage of 5 mg/kg of body weight IV and orally in a complete crossover study, and orally at dosages of 5, 10, and 20 mg/kg to 6 healthy dogs in a 3-way crossover study. For 24 hours, serum concentration was monitored serially after each administration. Another 6 dogs were given 5 mg of norfloxacin/kg orally every 12 hours for 14 days, and serum concentration was determined serially for 12 hours after the first and last administration of the drug. Complete blood count and serum biochemical analysis were performed before and after 14 days of oral norfloxacin administration, and clinical signs of drug toxicosis were monitored twice daily during norfloxacin administration. Urine concentration of norfloxacin was determined periodically during serum acquisition periods. Norfloxacin concentration was determined, using high-performance liquid chromatography with a limit of detection of 25 ng of norfloxacin/ml of serum or urine. Serum norfloxacin pharmacokinetic values after single IV dosing in dogs were best modeled, using a 2-compartment open model, with distribution and elimination half-lives of 0.467 and 3.56 hours (harmonic means), respectively. Area-derived volume of distribution (Vd area) was 1.77 +/- 0.69 L/kg (arithmetic mean +/- SD), and serum clearance (Cls) was 0.332 +/- 0.115 L/h/kg. Mean residence time was 4.32 +/- 0.98 hour. Comparison of the area under the curve (AUC; derived, using model-independent calculations) after iv administration (5 mg/kg) with AUC after oral administration (5 mg/kg) in the same dogs indicated bioavailability of 35.0 +/- 46.1%, with a mean residence time after oral administration of 5.71 +/-2.24 hours. Urine concentration was 33.8 +/- 15.3 micrograms/ml at 4 hours after a single dose of 5 mg/kg given orally, whereas concentration after 20 mg/kg was given orally was 56.8 +/- 18.0 micrograms/ml at 6 hours after dosing. Twelve hours after drug administration, urine concentration was 47.4 +/- 20.6 micrograms/ml after the 5-mg/kg dose and 80.6 +/- 37.7 micrograms/ml after the 20/mg/kg dose.(ABSTRACT TRUNCATED AT 250 WORDS)