Effect of lidocaine on the minimum alveolar concentration of sevoflurane in dogs

Objective  To investigate the effects of a low-dose constant rate infusion (LCRI; 50 μg kg⁻¹ minute⁻¹) and high-dose CRI (HCRI; 200 μg kg⁻¹ minute⁻¹) lidocaine on arterial blood pressure and on the minimum alveolar concentration (MAC) of sevoflurane (Sevo), in dogs.
Study design  Prospective, randomized experimental design.
Animals  Eight healthy adult spayed female dogs, weighing 16.0 ± 2.1 kg.
Methods  Each dog was anesthetized with sevoflurane in oxygen and mechanically ventilated, on three separate occasions 7 days apart. Following a 40-minute equilibration period, a 0.1-mL kg⁻¹ saline loading dose or lidocaine (2 mg kg⁻¹ intravenously) was administered over 3 minutes, followed by saline CRI or lidocaine LCRI or HCRI. The sevoflurane MAC was determined using a tail clamp. Heart rate (HR), blood pressure and plasma concentration of lidocaine were measured. All values are expressed as mean ± SD.
Results  The MAC of Sevo was 2.30 ± 0.19%. The LCRI reduced MAC by 15% to 1.95 ± 0.23% and HCRI by 37% to 1.45 ± 0.21%. Diastolic and mean pressure increased with HCRI. Lidocaine plasma concentration was 0.84 ± 0.18 for LCRI and 1.89 ± 0.37 μg mL⁻¹ for HCRI. Seventy-five percent of HCRI dogs vomited during recovery.
Conclusion and clinical relevance  Lidocaine infusions dose dependently decreased the MAC of Sevo, did not induce clinically significant changes in HR or arterial blood pressure, but vomiting was common during recovery in HCRI.     

Evaluation of analgesic and sedative effects of continuous infusion of dexmedetomidine by measuring somatosensory- and auditory-evoked potentials in the rat

Objective  To study, the analgesic and sedative effects of different constant rate infusions (CRI) of dexmedetomidine, in the rat, by measurement of specific electroencephalographic parameters. The recorded parameters were somatosensory-evoked potentials (SEPs) and auditory-evoked potentials (AEPs), which have been shown to be related to analgesia and sedation respectively.
Animals  Nine male Wistar rats (HsdCpb:Wu, Harlan Netherlands BV, body weight 300–350 g).
Methods  Somatosensory-evoked potentials were recorded from the primary somatosensory cortex and the vertex location (SI/Vx-SEPs). Auditory-evoked potentials were recorded from the primary auditory cortex and vertex location (AI/Vx-AEPs). Primary somatosensory cortex and vertex location recorded SEPs and AI/Vx-AEPs were recorded alternately, during CRI of dexmedetomidine (4.0, 10.0, 20.0 μg kg⁻¹ hour⁻¹) and a control (saline).
Results  The primary somatosensory cortex-evoked potentials were not affected by the dexmedetomidine CRI, but the other three parameters were significantly affected; although the AI-SEP to a lesser extent than the Vx-SEP and Vx-AEP. A maximum effect on the Vx-AEP was reached at lower doses than on the Vx-SEP.
Conclusions  Based on the present findings, it is suggested that CRI of dexmedetomidine provided profound sedation at low doses, whereas higher doses are needed to provide concurrent analgesia.
Clinical relevance  A constant rate infusion of dexmedetomidine can be a valuable adjunct in the provision of sedation and/or analgesia. However, analgesia cannot be produced without sedation, and sedation is not necessarily accompanied by comparative degrees of analgesia.     

Comparative study on the sedative effects of morphine, methadone, butorphanol or tramadol, in combination with acepromazine, in dogs

Objective  To compare the effects of morphine (MOR), methadone (MET), butorphanol (BUT) and tramadol (TRA), in combination with acepromazine, on sedation, cardiorespiratory variables, body temperature and incidence of emesis in dogs.
Study design  Prospective randomized, blinded, experimental trial.
Animals  Six adult mixed-breed male dogs weighing 12.0 ± 4.3 kg.
Methods  Dogs received intravenous administration (IV) of acepromazine (0.05 mg kg⁻¹) and 15 minutes later, one of four opioids was randomly administered IV in a cross-over design, with at least 1-week intervals. Dogs then received MOR 0.5 mg kg⁻¹; MET 0.5 mg kg⁻¹; BUT 0.15 mg kg⁻¹; or TRA 2.0 mg kg⁻¹. Indirect systolic arterial pressure (SAP), heart rate (HR), respiratory rate ( f _R), rectal temperature, pedal withdrawal reflex and sedation were evaluated at regular intervals for 90 minutes.
Results  Acepromazine administration decreased SAP, HR and temperature and produced mild sedation. All opioids further decreased temperature and MOR, BUT and TRA were associated with further decreases in HR. Tramadol decreased SAP whereas BUT decreased f _R compared with values before opioid administration. Retching was observed in five of six dogs and vomiting occurred in one dog in MOR, but not in any dog in the remaining treatments. Sedation scores were greater in MET followed by MOR and BUT. Tramadol was associated with minor changes in sedation produced by acepromazine alone.
Conclusions and clinical relevance  When used with acepromazine, MET appears to provide better sedation than MOR, BUT and TRA. If vomiting is to be avoided, MET, BUT and TRA may be better options than MOR.     

Sedative effects of propofol in horses

Objective  We hypothesized that propofol can produce rapidly-reversible, dose-dependent standing sedation in horses.
Study design  Prospective randomized, blinded, experimental trial.
Animals  Twelve healthy horses aged 12 ± 6 years (mean ± SD), weighing 565 ± 20 kg, and with an equal distribution of mares and geldings.
Methods  Propofol was administered as an intravenous bolus at one of three randomized doses (0.20, 0.35 and 0.50 mg kg⁻¹). Cardiovascular and behavioral measurements were made by a single investigator, who was blinded to treatment dose, at 3 minute intervals until subjective behavior scores returned to pre-sedation baseline values. Continuous data were analyzed over time using repeated-measures anova and noncontinuous data were analyzed using Friedman tests.
Results  There were no significant propofol dose or temporal effects on heart rate, respiratory rate, vertical head height, or jugular venous blood gases (pH_v, P_vO₂, P_vCO₂). The 0.35 mg kg⁻¹ dose caused mild sedation lasting up to 6 minutes. The 0.50 mg kg⁻¹ dose increased sedation depth and duration, but with increased ataxia and apparent muscle weakness.
Conclusions and clinical relevance  Intravenous 0.35 mg kg⁻¹ propofol provided brief, mild sedation in horses. Caution is warranted at higher doses due to increased risk of ataxia.     

The effects of L‐659,066, a peripheral α2‐adrenoceptor antagonist,and verapamil on the cardiovascular influences of dexmedetomidine in conscious sheep

Raekallio M. R., Honkavaara J. M., Vainio O. M. The effects of L‐659,066, a peripheral α₂‐adrenoceptor antagonist, and verapamil on the cardiovascular influences of dexmedetomidine in conscious sheep. J. vet. Pharmacol. Therap. 33 , 434–438. We investigated whether administration of L‐659,066, a peripheral α₂‐adrenoceptor antagonist, or verapamil, a calcium‐channel antagonist, would prevent the cardiovascular effects of dexmedetomidine. Eleven sheep received three intravenous treatments with a randomized, cross‐over design: dexmedetomidine (5 μg/kg, DEX); DEX with L‐659,066 (250 μg/kg, DEX + L); and verapamil (0.05 mg/kg) 10 min prior to DEX (Ver + DEX). Haemodynamics were recorded at intervals upto 40 min. Acute increases in mean arterial pressure (MAP) (106 ± 10.7 to 120.8 ± 11.7 mmHg), central venous pressure (CVP) (3.3 ± 3.2 to 14.7 ± 5.0 mmHg) and systemic vascular resistance (SVR) (1579 ± 338 to 2301 ± 523 dyne s/cm⁵), and decreases in cardiac output (CO) (5.36 ± 0.87 to 3.93 ± 1.30 L/min) and heart rate (HR) (88.6 ± 15.3 to 49.7 ± 5.5/min) were detected with DEX. The peak SVR remained lower after Ver + DEX (1835 ± 226 dyne s/cm⁵) than DEX alone, but the other parameters did not significantly differ between these treatments. 2 min after drug delivery, differences between DEX and DEX + L were statistically significant for all measured haemodynamic parameters. With DEX + L, an early decrease in MAP (99.9 ± 6.8 to 89.3 ± 6.6 mmHg) was detected, and DEX + L induced a slight but significant increase in CVP and a decrease in HR at the end of the observation period, while SVR and CO did not significantly change. All animals were assessed as deeply sedated from 2–20 min with no differences between treatments. L‐659,066 has great potential for clinical use to prevent the cardiovascular effects of dexmedetomidine mediated by peripheral α₂‐adrenoceptors, whereas the effects of verapamil were marginal.     

Transient unilateral Horner's syndrome after epidural ropivacaine in a dog

Observations  A left sided Horner's syndrome (ptosis, prolapse of the nictitating membrane and miosis) was observed in a 4-year-old female, neutered Beagle dog after epidural injection of 0.22 mL kg⁻¹ ropivacaine (0.75%) in 0.01 mL kg⁻¹ of saline during isoflurane anaesthesia. Clinical signs disappeared gradually and resolved completely 4 hours and 10 minutes after injection.
Conclusions  The epidural injection of 0.22 mL kg⁻¹ ropivacaine (0.75%) in 0.01 mL kg⁻¹ of saline during isoflurane anaesthesia caused unilateral (left) Horner's syndrome in a 4-year-old female, neutered Beagle dog.     

Prothrombotic and Inflammatory Effects of Intravenous Administration of Human Immunoglobulin G in Dogs

Background: Intravenous administration of human immunoglobulin G (hIVIgG) has been suggested to potentiate thromboembolism in dogs, but supportive scientific reports are lacking.
Objectives: To determine if hIVIgG therapy promotes hypercoagulability and inflammation in dogs.
Animals: Twelve healthy Beagle dogs.
Methods: Prospective, experimental trial. An hIVIgG/saline solution was infused IV at 1 g/kg BW over 8 hours to 6 dogs, and physiological saline was infused to the other 6 dogs. Blood samples were drawn before, during, and after infusion for serial measurement of indicators of coagulation and inflammation. Data were analyzed by 2-way repeated measures analysis of variance.
Results: Dogs administered hIVIgG developed mildly decreased blood platelet concentrations without thrombocytopenia (median, 200 × 10³/μL; range, 150–302 × 10³/μL; P < .01), leukopenia (median, 3.5 × 10³/μL; range, 20–62 × 10³/μL; P < .001), and mildly increased plasma total protein concentrations (median, 6.3 g/dL; range, 5.6–6.7 g/dL; P < .001). Administration of hIVIgG was also associated with increases in fibrin/fibrinogen degradation products in all dogs (either 5 μg/mL or 10 μg/dL), thrombin-antithrombin III complexes (median, 7.2 ng/mL; range, 4.9–14.2 ng/mL; P < .001), and C-reactive protein concentrations (median, 2.5 mg/dL; range, 0.5–4.3 mg/dL; P < .01).
Conclusion and Clinical Importance: Administration of hIVIgG to dogs promotes hypercoagulability and an inflammatory state. This should be further evaluated and considered when using hIVIgG in dogs with IMHA or other prothrombotic conditions.     

Comparison of three doses of dexmedetomidine with medetomidine in cats following intramuscular administration

Cats ( n  = 6) were administered dexmedetomidine (DEX) and medetomidine (MED) at three different dose levels in a randomized, blinded, cross-over study. DEX was administered at 25, 50 and 75 μg/kg (D25, D50 and D75), corresponding to MED 50, 100 and 150 μg/kg (M50, M100 and M150). Sedation, analgesia and muscular relaxation were scored subjectively. Heart and respiratory rates and rectal temperature were measured. Corresponding doses of DEX and MED were compared. Effects were also compared between dose levels for each compound. At dose level 2 (D50-M100), the duration of effective clinical sedation was significantly shorter after DEX (202.5±16.0 min) than after MED (230.0±41.2 min). Proceeding from D50-M100 to D75-M150, the duration of effective clinical sedation was increased more after DEX (by 57.5±38.4 min) than after MED (by 14.2±41.9 min) Increasing from D50-M100 to D75-M150, heart rate was further decreased after DEX (by 8.1±13.4%) but not after MED. There was no statistically significant difference between corresponding doses of DEX and MED for any of the other parameters studied. Changes in sedation, analgesia and muscular relaxation were dose-dependent. It was concluded that anaesthetic effects of medetomidine in cats are probably due entirely to its d-isomer and that dexmedetomidine at 25, 50 and 75 μg/kg induces dose-dependent sedation, analgesia and muscular relaxation of clinical significance in cats.     

Effects of metaraminol bitartrate on intraocular pressure in dogs under halothane anesthesia

The effects of metaraminol bitartrate on intraocular pressure (IOP) were studied in dogs anesthetized with halothane. Forty-five healthy, adult, mixed-breed dogs, of both sexes, were divided into three groups of 15 dogs each (GI, GII and GIII) and maintained under general anesthesia with halothane after tranquilization with levomepromazine and induction with thiopental. Saline (0.9%) was administered intravenously (IV) to GI through continuous infusion, at a velocity of 0.125 mL kg⁻¹ min⁻¹. GII and GIII received metaraminol 0.004% IV, at a dose of 5 μg kg⁻¹ min⁻¹, at 0.125 mL kg⁻¹ min⁻¹ and at a dose of 2 μg kg⁻¹ min⁻¹, at 0.06 mL kg⁻¹ min⁻¹, respectively. IOP was measured by applanation tonometry (Tono-Pen) before and during anesthesia. Results showed that IOP decreased in GI, increased in GII, and remained at basal levels in GIII. Continuous infusion of metaraminol at 2 μg kg min⁻¹ maintained IOP at pretest levels, while infusion at 5 μg kg⁻¹ min⁻¹ produced an elevation of IOP.     

Effects of different doses of L-659'066 on the bispectral index and clinical sedation in dogs treated with dexmedetomidine

ObjectiveTo evaluate the effects of three doses of L-659’066 (MK-467) on the bispectral index (BIS) and clinical sedation in dexmedetomidine-sedated Beagles.Study designRandomized, experimental cross over study.AnimalsEight purpose-bred healthy laboratory Beagles.MethodsDexmedetomidine (10 μg kg^?1 IV [DEX]) was administered alone or in combination with three doses of L-659’066 (250 μg kg^?1 [DL250]; 500 μg kg^?1 [DL500] and 750 μg kg^?1 [DL750] IV) in the same syringe in a randomized crossover manner. The bispectral index (BIS), electromyography (EMG) and sedation score were recorded at baseline and 5, 10, 20, 30, 45 and 60 minutes after treatment.ResultsWhen compared to DEX, BIS and EMG were significantly higher and the sedation score significantly lower with DL500 and DL750. With DEX, BIS was significantly decreased at times 20, 30 and 60 minutes whereas the sedation scores were significantly increased at all time points after drug administration in all groups. Bioequivalence for clinical sedation was detected between DEX and all doses of L-659’066, reaching European Medicines Agency (EMA) standards.Conclusions and clinical relevanceAlthough L-659’066 interfered with dexmedetomidine induced sedation, the degree of the reduction was not clinically relevant. Despite performing better when dexmedetomidine was used alone, BIS did not reflect the clinical sedative status when the antagonist was added.     

The effect of pre-anaesthetic medication on the incidence of cardiac arrhythmias during halothane anaesthesia in cats

Objective To compare the incidence of arrhythmias in cats receiving either acepromazine or diazepam for pre-anaesthetic medication prior to halothane anaesthesia.
Study design A blinded, randomized clinical study.
Animals Forty-six healthy cats undergoing surgery.
Methods Animals were allocated to one of two groups for pre-anaesthetic medication. Group 1 received diazepam (0.2 mg kg⁻¹). Group 2 received acepromazine (0.02 mg kg⁻¹). The trial drug was administered intramuscularly in combination with buprenorphine (0.01 mg kg⁻¹) 30 minutes prior to induction of anaesthesia with propofol (approximately 5 mg kg⁻¹). Anaesthesia was maintained using halothane: delivered concentration was 1–2% carried in oxygen and nitrous oxide via an endotracheal tube attached to an Ayre's T-piece (with Jackson-Rees modification) breathing system. The incidence of cardiac arrhythmias was determined by continuously monitoring the electrocardiogram from the time of induction until recovery occurred. Demographical group characteristics were compared using analysis of variance. The incidence of cardiac arrhythmias was compared by the Chi squared test. Statistical significance was set at the 5% level.
Results The two groups were similar in weight, age, length and type of procedure undertaken. The incidence of arrhythmias was the same in each group (3/23 cases) ( p = 1.0).
Conclusions The incidence of cardiac arrhythmias in this study did not appear to be influenced by the nature of pre-anaesthetic medication.
Clinical relevance The incidence of cardiac arrhythmias under halothane anaesthesia was 13% in this study. Acepromazine did not appear to exert an anti-arrhythmic effect. This may not be the case in a larger scale study.     

Alfaxalone in cyclodextrin for induction and maintenance of anaesthesia in ponies undergoing field castration

Objective  To evaluate the induction and maintenance of anaesthesia using alfaxalone following pre-anaesthetic medication with romifidine and butorphanol in ponies undergoing castration in the field.
Study design  Prospective clinical study.
Animals  Seventeen male ponies weighing 169 ± 29 kg.
Methods  The ponies were sedated with romifidine and butorphanol intravenously (IV). Induction time was recorded following administration of alfaxalone 1 mg kg⁻¹ and diazepam 0.02 mg kg⁻¹ IV. If movement during surgery occurred, alfaxalone 0.2 mg kg⁻¹ was administered IV. The quality of anaesthetic induction, and recovery were scored on a subjective scale of 1 (good) to 5 (poor). The number of attempts to attain sternal recumbency and standing, quality of recovery and times from induction to end of surgery, first head lift, sternal recumbency and standing were recorded.
Results  Induction quality was good [median score (range) 1 (1–3)] with a mean ± SD time of 29 ± 6 seconds taken to achieve lateral recumbency. Ten ponies required incremental doses of alfaxalone during surgery. Mean times to the end of surgery, first head lift, sternal recumbency and standing were 26 ± 9 minutes, 31 ± 9 minutes, 33 ± 9 minutes and 34 ± 9 minutes respectively. The number of attempts to attain sternal recumbency was 1(1–1) and to attain standing was 1(1–2). Quality of recovery was good, with a recovery score of 1(1–2).
Conclusions and clinical relevance  Alfaxalone provided smooth induction and recovery characteristics and was considered suitable for maintenance of anaesthesia for castration in ponies.     

In vivo confocal microscopy of the normal equine cornea and limbus

Objective  To describe morphologic features, pachymetry and endothelial cell density of the normal equine cornea and limbus by in vivo confocal microscopy.
Animals studied  Ten horses without ocular disease.
Procedure  The central and peripheral corneas were examined with a modified Heidelberg Retina Tomograph II and Rostock Cornea Module using a combination of automated and manual image acquisition modes. Thickness measurements of various corneal layers were performed and endothelial cell density determined.
Results  Images of the constituent cellular and noncellular elements of the corneal epithelium, stroma, endothelium, and limbus were acquired in all horses. Corneal stromal nerves, the subepithelial nerve plexus, and the sub-basal nerve plexus were visualized. Cells with an appearance characteristic of Langerhans cells and corneal stromal dendritic cells were consistently detected in the corneal basal epithelium and anterior stroma, respectively. Median central total corneal thickness was 835 μm (range 725–920 μm) and median central corneal epithelial thickness was 131 μm (range 115–141 μm). Median central endothelial cell density was 3002 cells per mm² (range 2473–3581 cells per mm²).
Conclusions  In vivo corneal confocal microscopy provides a noninvasive method of assessing normal equine corneal structure at the cellular level and is a precise technique for corneal sublayer pachymetry and cell density measurements. A resident population of presumed Langerhans cells and corneal stromal dendritic cells was detected in the normal equine cornea. The described techniques can be applied to diagnostic evaluation of corneal alternations associated with disease and have broad clinical and research applications in the horse.     

Fluticasone Propionate Aerosol is More Effective for Prevention than Treatment of Recurrent Airway Obstruction

Background: Efficacy of inhaled fluticasone propionate (FP) for management of recurrent airway obstruction (RAO) has only been evaluated after several weeks' treatment.
Objectives: To compare efficacy of (1) 3-day treatments with FP to dexamethasone (DEX) for management of RAO; and (2) FP and DEX to no treatment in prevention of acute RAO exacerbations.
Animals: Nine RAO affected horses.
Methods: Crossover studies in RAO-affected horses compared (a) 3-day treatment of RAO exacerbation with FP (3 and 6 mg q12h) and DEX (0.1 mg/kg q24h) and (b) FP (6 mg q12h) and DEX (0.1 mg/kg q24h) to no treatment for prevention of acute exacerbations of RAO. Treatment efficacy and unwanted effects were judged from maximal change in pleural pressure (ΔPpl_max), serum cortisol (COR), bronchoalveolar lavage (BAL) cytology, and subjective scores for respiratory distress and lameness.
Results: In treatment trial, DEX and FP (6 mg) significantly decreased ΔPpl_max by 48 and 72 hours, respectively; FP (3 mg) had no significant effect. DEX decreased COR more than did FP. In prevention trial, both DEX and FP (6 mg) prevented the increase in ΔPpl_max that occurred in untreated horses. Both treatments decreased COR to the same degree. FP and DEX had no effects on bronchoalveolar lavage fluid (BALF) cytology and there was no evidence of laminitis.
Conclusions and Clinical Importance: FP (6 mg q12h) is as effective as DEX for prevention of acute exacerbations of RAO and lower doses should be evaluated. High-dose FP is not as effective as DEX for treatment of RAO exacerbations.     

Thermal antinociception after dexmedetomidine administration in cats: a dose-finding study

The optimum dose of dexmedetomidine for antinociception to a thermal stimulus was determined in a crossover study of 12 cats. In five treatment groups ( n  = 10 per group), dexmedetomidine was administered intramuscularly (i.m.) at 2, 5, 10, 20 and 40 μg/kg; positive and negative controls were administered buprenorphine (20 μg/kg, i.m.) and 0.9% saline (0.006 mL/kg, i.m.) respectively. Baseline thermal thresholds and visual analogue scale (VAS) sedation scores were obtained prior to drug treatment and then at regular intervals until 24 h after administration. The summary measures of overall mean thresholds and overall mean VAS scores were investigated using a univariate general linear model for multiple factors with post hoc Tukey's tests ( P  < 0.05). Only dexmedetomidine at 40 μg/kg displayed an analgesic effect (less than that of buprenorphine). The VAS for sedation did not significantly affect the thresholds obtained and treatment was the only significant factor to influence VAS. Dexmedetomidine resulted in higher VAS for sedation than saline and buprenorphine. Dexmedetomidine at 40 μg/kg significantly increased nociceptive thresholds compared with saline control, but less than buprenorphine. Dexmedetomidine produced dose-dependent sedation, but only the highest dose produced analgesia, suggesting that induction of analgesia requires the highest dose (or an additional analgesic) in the clinical setting.     

Plasma and ear tissue concentrations of enrofloxacin and its metabolite ciprofloxacin in dogs with chronic end-stage otitis externa after intravenous administration of enrofloxacin

The purpose of this study was to measure the concentrations of enrofloxacin and its metabolite ciprofloxacin following intravenous administration of enrofloxacin in the plasma and ear tissue of dogs with chronic end-stage otitis undergoing a total ear canal ablation and lateral bulla osteotomy. The goals were to determine the relationship between the dose of enrofloxacin and the concentrations of enrofloxacin and ciprofloxacin, and determine appropriate doses of enrofloxacin for treatment of chronic otitis externa and media. Thirty dogs were randomized to an enrofloxacin-treatment group (5, 10, 15 or 20 mg kg⁻¹) or control group (no enrofloxacin). After surgical removal, ear tissue samples (skin, vertical ear canal, horizontal ear canal, middle ear) and a blood sample were collected. Concentrations of enrofloxacin and ciprofloxacin in the plasma and ear tissue were measured by high performance liquid chromatography. Repeated measures models were applied to log-transformed data to assess dosing trends and Pearson correlations were calculated to assess concentration associations. Ear tissue concentrations of enrofloxacin and ciprofloxacin were significantly ( P  < 0.05) higher than plasma concentrations. Each 5 mg kg⁻¹ increase in the dose of enrofloxacin resulted in a 72% and 37% increase in enrofloxacin and ciprofloxacin concentrations, respectively. For bacteria with an minimal inhibitory concentration of 0.12–0.15 or less, 0.19–0.24, 0.31–0.39 and 0.51–0.64 µg mL⁻¹, enrofloxacin should be dosed at 5, 10, 15 and 20 mg kg⁻¹, respectively. Treatment with enrofloxacin would not be recommended for a bacterial organism intermediate or resistant in susceptibility to enrofloxacin since appropriate levels of enrofloxacin would not be attained.     

Evaluation of the Perkins® handheld applanation tonometer in the measurement of intraocular pressure in dogs and cats

Objective  To evaluate and to validate the accuracy of the Perkins^® handheld applanation tonometer in the measurement of IOP in dogs and cats.
Animals  Twenty eyes from 10 dogs and 10 cats immediately after sacrifice were used for the postmortem study and 20 eyes from 10 clinically normal and anesthetized dogs and cats were used for the in vivo study. Both eyes of 20 conscious dogs and cats were also evaluated.
Procedure  Readings of IOP postmortem and in vivo were taken using manometry (measured with a mercury column manometer) and tonometry (measured with a Perkins^® handheld applanation tonometer). The IOP measurement with Perkins^® tonometer in anesthetized and conscious dogs and cats was accomplished by instillation of proxymetacaine 0.5% and of 1% fluorescein eye drops.
Results  The correlation coefficient ( r ²) between the manometry and the Perkins^® tonometer were 0.982 (dogs) and 0.988 (cats), and the corresponding linear regression equation were y  = 0.0893 x  + 0.1105 (dogs) and y  = 0.0899 x  + 0.1145 (cats) in the postmortem study. The mean IOP readings with the Perkins^® tonometer after calibration curve correction were 14.9 ± 1.6 mmHg (range 12.2–17.2 mmHg) in conscious dogs, and were 15.1 ± 1.7 mmHg (range 12.1–18.7 mmHg) in conscious cats.
Conclusion  There was an excellent correlation between the IOP values obtained from direct ocular manometry and the Perkins^® tonometer in dogs and cats. The Perkins^® handheld tonometer could be in the future a new alternative for the diagnosis of glaucoma in veterinary ophthalmology.     

Effect of oral administration of 3,3',4,4',5-pentachlorobiphyenl on the intestinal microbiota of Sprague–Dawley rats

The effect of the endocrine-disrupting chemical 3,3',4,4',5-pentachlorobiphyenl (PCB 126) on intestinal microbiota after oral administration, and the improvement of intestinal microbiota and feces quantity by the subsequent administration of Lactobacillus acidophilus or Lactobacillus reuteri was investigated. All the rats were given 100 μg/kg bodyweight of PCB 126. The changes in bacterial counts were confirmed using a culture method. The administration of PCB 126 tended to decrease the bacterial counts of lactobacilli (10^9.6−10^10.2 to 10^8.8−10^9.2) and bifidobacteria (10^5.3−10^6.1 to 10^3.6−10^4.2), and to increase those of Enterobacteriaceae (10^8.2−10^9.1 to 10^9.4−10^10.3) and staphylococci (10^6.6−10^7.4 to 10^7.2−10^8.4) compared to no PCB 126 administration. After administration of PCB 126, L. acidophilus or L. reuteri orally administered to rats caused Enterobacteriaceae and staphylococci counts to decrease, suggesting that the intestinal microbiota was improved by the lactobacilli. The administration of L. acidophilus and L. reuteri improved the balance of intestinal microbiota, and defecation volume returned to its normal level. L. acidophilus and L. reuteri have a remedial effect on intestinal microbiota affected by PCB 126 and can function to lessen accumulated PCB 126 volume.     

Analgesic and motor-blocking action of epidurally administered levobupivacaine or bupivacaine in the conscious dog

Objective  To compare the analgesic and motor-blocking effects of epidurally administered levobupivacaine and bupivacaine in the conscious dog.
Study design  Prospective, randomized, cross-over study.
Animals  Six adult female Beagle dogs.
Methods  Each animal received three doses of levobupivacaine or bupivacaine (0.5, 1.0 and 1.5 mg kg⁻¹; concentrations 0.25%, 0.50%, and 0.75%, respectively) in a total volume of 0.2 mL kg⁻¹ by means of a chronically implanted epidural catheter. Onset, duration (through pinch response in the sacral, lumbar and toe areas) and degree of analgesia and motor-blocking status was determined with a scoring system and at regular intervals over 8.5 hours before (baseline) and after drug administration.
Results  Epidurally administered levobupivacaine and bupivacaine had a similar dose-dependent analgesic action with no significant differences in onset (range: 5–8 minutes), duration (bupivacaine: 42 ± 28, 135 ± 68 and 265 ± 68 minutes, and levobupivacaine: 28 ± 33, 79 ± 55 and 292 ± 133 minutes; 0.25%, 0.50%, and 0.75%, respectively) or maximum degree of analgesia. However, levobupivacaine tended to produce a shorter duration of motor block than bupivacaine and the difference in the motor to nociceptive blockade times was significant at the highest dose.
Conclusion  Epidural levobupivacaine produced an analgesic action similar to that of bupivacaine.
Clinical relevance  Epidural levobupivacaine is suitable for clinical use in dogs, mostly at the highest dose if a high degree of analgesia is required.