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1.
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2.
Intravenous alfaxalone, administered at a dose of 5 mg/kg in the jugular vein, was evaluated in 20 leopard geckos (Eublepharis macularius) to ascertain its ability to provide anesthesia. The induction time, time to loss of mandibular tone, interval of deep anesthesia, and full recovery time were 27.5 ± 30.7 seconds (10 to 56 seconds), 1.3 ± 1.4 minutes (11 seconds to 4 minutes), 12.5 ± 2.2 minutes (11.11 to 15.39 minutes), and 18.8 ± 12.1 minutes (10.4 to 52.31 minutes), respectively. A significant reduction in heart rate (74 ± 12.9 beats/minute) was recorded between 2 and 24 minutes after alfaxalone administration. A significant decrease in respiratory rate (26.8 ± 10.1 breaths/minute) was recorded 2 minutes after alfaxalone administration, and respiratory rate remained lower than the basal rate (31.4 ± 3.1 breaths/minute) for 24 minutes but without statistical significance. The intravenous administration of alfaxalone in leopard geckos achieved a rapid onset of anesthesia and a suitable recovery time. Based on this investigation, an afaxalone dose of 5 mg/kg intravenously proved to be suitable for sedation before tracheal intubation. Moreover, the administration route via the jugular vein, was acceptable in leopard geckos; a species in which other venipuncture sites can be challenging or inaccessible.  相似文献   

3.
A 3-year-old spayed female rabbit developed chronic coughing and gagging after removal of a nasogastric tube placed for medical management of gastrointestinal stasis.  Radiographs revealed a tubular structure that appeared to be located in the proximal trachea.  The foreign body was removed using rigid tracheoscopy and determined to be the distal 15 cm of the nasogastric tube.  The rabbit was discharged the same day and the owner reported that its clinical signs completely resolved after removal of the foreign body.  相似文献   

4.

Objective

To assess the degree and duration of corneal anaesthesia provided by topical application of a non-ophthalmic 2% lidocaine gel in horses.

Study design

Experimental, ‘blinded’, randomized prospective study.

Animals

Twelve adult horses without relevant ocular abnormalities.

Methods

Baseline corneal touch threshold (CTT) measurements were obtained bilaterally by use of a Cochet–Bonnet aesthesiometer just prior to topical treatment. A volume of 0.2 mL of 2% lidocaine gel was administered in one randomly selected eye and the same volume of a viscous lubricant in the other eye to serve as control. The CTT value was measured on both eyes 5, 10, 20, 30, 45, 60, 75 and 90 minutes after drug application. The potential for local adverse effects following lidocaine gel application was also evaluated.

Results

Mean CTT baseline measurements were not significantly different (p > 0.05) between the control eyes (3.41 ± 0.56 cm) and those subsequently treated with the lidocaine gel (3.50 ± 0.64 cm). In control eyes, no significant changes in corneal sensitivity (p > 0.05) occurred over time during the study period. By contrast, a marked reduction in corneal sensitivity was observed after lidocaine application, with mean CTT values significantly lower (p < 0.001) than those of the control eyes from 5 to 75 minutes. A steady-state maximal corneal anaesthesia was present from 10 to 45 minutes after lidocaine gel application with mean CTT values ranging from 0.21 to 0.45 cm. Corneal epithelial irregularities were detected in three lidocaine-treated eyes, but spontaneous resolution occurred within 24 hours.

Conclusions and clinical relevance

Deep and sustained corneal anaesthesia is achieved after application of 2% lidocaine gel to the equine eye, with minimal changes in the corneal epithelium. It might be useful for minor ophthalmic surgeries performed in the standing sedated horse.  相似文献   

5.
Plant litter decomposition is one of the most important links connecting plants to the soil through the carbon (C) and nitrogen (N) cycles. Climate change scenarios predict changes in precipitation and N deposition, and previous studies have demonstrated that increases in the availability of water and N affect the litter decomposition rate and nutrient release. We studied the effects of increased N deposition and precipitation on changes in the remaining mass and the C and N contents of shoot litter after decomposition in a typical steppe in Inner Mongolia, China. The treatments included the addition of NH4NO3 at rates equivalent to 0, 25, 50, and 100 kg ? N ? ha? 2yr? 1 with and without added water. The addition of water proved to be a more effective practice than amendment with NH4NO3 for improving the litter decomposition rate; the addition of water significantly increased the rate of litter decomposition (P < 0.001), whereas the addition of N alone had no apparent effect on litter mass loss. However, a repeated measures analysis of variance (ANOVA) showed that the interaction of water and N significantly affected both mass loss and litter N content (P < 0.05), and a linear relationship was identified between litter mass loss and litter decomposition time (P < 0.001). No correlation was found between litter mass loss and organic C content, but a significant positive correlation was found between residual litter mass and N content (P < 0.01). Although the study was conducted over a relatively short period, our results indicate that increased precipitation could potentially promote litter decomposition, whereas increased N input has little effect. The effects of time on litter mass loss and residual C and N concentrations indicate the need for long-term trials that measure the complete process of litter decomposition and the peaks of C and N release.  相似文献   

6.
The objective of this study was to establish the clinical pharmacokinetic profile of 4 different opioid drugs (buprenorphine, butorphanol, hydromorphone, and morphine) in the domestic ferret (Mustela putorius furo). Twenty-four, approximately 1-year-old, male neutered purpose-bred domestic ferrets were used for this study. The ferrets were divided into 4 groups of 6, with a different opioid drug used for each group. A preopioid venous blood sample was obtained via cranial vena cava venipuncture. Following the initial blood collection, a single injection of opioid (hydromorphone 0.1 mg/kg, buprenorphine 0.04 mg/kg, butorphanol 0.3 mg/kg, and morphine 1 mg/kg) was given to each ferret, dependent on assigned drug group, intramuscularly (buprenorphine) or subcutaneously (hydromorphone, butorphanol, and morphine). Intramuscular injections were administered in the semimembranosis and semitendinosis muscles, whereas the subcutaneous injections were delivered in the intrascapular subcutaneous space. A venous blood sample was obtained at 5, 15, 30, 60, 120, 240, 360, 480, and 720 minutes postinjection from the ferrets in the buprenorphine, butorphanol, and hydromorphone groups. Mass spectrometry and liquid chromatography was performed to obtain plasma concentrations of the administered drugs. The mean maximum concentration of buprenorphine was 6.96 ng/mL, butorphanol was 48.6 ng/mL, and hydromorphone was 17.3 ng/mL. Maximum concentrations were achieved at a mean of 9 minutes after administration for buprenorphine, 13.3 minutes for butorphanol, and 8.33 minutes for hydromorphone. The mean half-life of buprenorphine was 219.1 minutes, butorphanol was 91.1 minutes, and hydromorphone was 24.7 minutes. Owing to severe complications arising within the morphine group, including hypersalivation and vomiting, the morphine study was discontinued prior to blood sample collection. Intramuscular injections of buprenorphine and subcutaneous injections of butorphanol or hydromorphone appeared to be well tolerated by all ferrets. The pharmacokinetics of buprenorphine, butorphanol, and hydromorphone of a single equipotent dose of each drug have been established through this research investigation and may be useful for further studies.  相似文献   

7.

Objective

To assess the efficacy of psoas compartment and sacral plexus block for pelvic limb amputation in dogs.

Study design

Prospective clinical study.

Animals

A total of 16 dogs aged 8 ± 3 years and weighing 35 ± 14 kg (mean ± standard deviation).

Methods

Dogs were administered morphine (0.5 mg kg?1) and atropine (0.02 mg kg?1); anesthesia was induced with propofol and maintained with isoflurane. Regional blocks were performed before surgery in eight dogs with bupivacaine (2.2 mg kg?1) and eight dogs were administered an equivalent volume of saline. The lumbar plexus within the psoas compartment was identified using electrolocation lateral to the lumbar vertebrae at the fourth–fifth, fifth–sixth and sixth–seventh vertebral interspaces. The sacral plexus, ventrolateral to the sacrum, was identified using electrolocation. Anesthesia was monitored using heart rate (HR), invasive blood pressure, electrocardiography, expired gases, respiratory frequency and esophageal temperature by an investigator unaware of the group allocation. Pelvic limb amputation by coxofemoral disarticulation was performed. Dogs that responded to surgical stimulation (>10% increase in HR or arterial pressure) were administered fentanyl (2 μg kg?1) intravenously for rescue analgesia. Postoperative pain was assessed at extubation; 30, 60 and 120 minutes; and the morning after surgery using a visual analog scale (VAS).

Results

The number of intraoperative fentanyl doses was fewer in the bupivacaine group (2.7 ± 1.1 versus 6.0 ± 2.2; p < 0.01). Differences in physiologic variables were not clinically significant. VAS scores were lower in bupivacaine dogs at extubation (0.8 ± 1.9 versus 3.8 ± 2.5) and at 30 minutes (1.0 ± 1.4 versus 4.3 ± 2.1; p < 0.05).

Conclusions and clinical relevance

Psoas compartment (lumbar plexus) and sacral plexus block provided analgesia during pelvic limb amputation in dogs.  相似文献   

8.
Beavers (Castor canadensis) disappeared from drainages north of Yellowstone National Park in the mid-1900s because of trapping, a potential tularemia outbreak, and willow (Salix spp.) stand degradation by ungulates. Beavers were reintroduced in 1986 after a 40–yr absence with inventories of active-beaver structures completed each fall after reintroduction for 24 consecutive yr. We used this inventory to evaluate the expansion of beaver populations in a riparian environment recovering from past overuse by ungulates. Specifically, we investigated the density of active-beaver colonies and dams, the change in willow cover, and habitats associated with beaver expansion since reintroduction. Successful establishment and expansion of beavers indicate that sufficient resources were available to the population despite the suboptimal condition of riparian vegetation. Carrying capacity on third-order streams was reached approximately 14 yr after reintroduction (2000) with an average annual density of 1.33 (95th percentile = 1.23 ? 1.44 active colonies/stream km) between 2000 and 2010. The average annual density of beaver dams during this time was 2.37 (2.04 ? 2.71 active dams/stream km). Despite the beaver population being at carrying capacity in meadows since 2000, willow cover increased by 16% between 1981 and 2011. We speculate that beaver activities, together with reduced ungulate browsing from predation and habitat loss, combined to increase willow cover. Willow cover and height were positively associated with colony longevity, but numerous other influencing variables included secondary channels, sinuosity, stream depth, and sandbar width. Our results provide evidence that beaver reintroduction can be successful in riparian areas where willow stand condition is less than optimal and that beavers might ultimately improve willow condition. We suggest that reducing ungulate use of overgrazed riparian environments will facilitate the reestablishment of beaver populations. We also provide managers with habitats that should be identified in an environment targeted for reintroduction.  相似文献   

9.
Land managers across the western United States are faced with selecting and applying tree-removal treatments on pinyon (Pinus spp.) and juniper (Juniperus spp.) woodland-encroached sagebrush (Artemisia spp.) rangelands, but current understanding of long-term vegetation and hydrological responses of sagebrush sites to tree removal is inadequate for guiding management. This study applied a suite of vegetation and soil measures (0.5 ? 990 m2), small-plot rainfall simulations (0.5 m2), and overland flow experiments (9 m2) to quantify the effects of mechanical tree removal (tree cutting and mastication) on vegetation, runoff, and erosion at two mid- to late-succession woodland-encroached sagebrush sites in the Great Basin, United States, 9 yr after treatment. Low amounts of hillslope-scale shrub (3 ? 15%) and grass (7 ? 12%) canopy cover and extensive intercanopy (area between tree canopies) bare ground (69 ? 88% bare, 75% of area) in untreated areas at both sites facilitated high levels of runoff and sediment from high-intensity (102 mm ? h? 1, 45 min) rainfall simulations in interspaces (~ 45 mm runoff, 59 ? 381 g ? m? 2 sediment) between trees and shrubs and from concentrated overland flow experiments (15, 30, and 45 L ? min? 1, 8 min each) in the intercanopy (371 ? 501 L runoff, 2 342 ? 3 015 g sediment). Tree cutting increased hillslope-scale density of sagebrush by 5% and perennial grass cover by twofold at one site while tree cutting and mastication increased hillslope-scale sagebrush density by 36% and 16%, respectively, and perennial grass cover by threefold at a second more-degraded (initially more sparsely vegetated) site over nine growing seasons. Cover of cheatgrass (Bromus tectorum L.) was < 1% at the sites pretreatment and 1 ? 7% 9 yr after treatment. Bare ground remained high across both sites 9 yr after tree removal and was reduced by treatments solely at the more degraded site. Increases in hillslope-scale vegetation following tree removal had limited impact on runoff and erosion for rainfall simulations and concentrated flow experiments at both sites due to persistent high bare ground. The one exception was reduced runoff and erosion within the cut treatments for intercanopy plots with cut-downed-trees. The cut-downed-trees provided ample litter cover and tree debris at the ground surface to reduce the amount and erosive energy of concentrated overland flow. Trends in hillslope-scale vegetation responses to tree removal in this study demonstrate the effectiveness of mechanical treatments to reestablish sagebrush steppe vegetation without increasing cheatgrass for mid- to late-succession woodland-encroached sites along the warm-dry to cool-moist soil temperature ? moisture threshold in the Great Basin. Our results indicate improved hydrologic function through sagebrush steppe vegetation recruitment after mechanical tree removal on mid- to late-succession woodlands can require more than 9 yr. We anticipate intercanopy runoff and erosion rates will decrease over time at both sites as shrub and grass cover continue to increase, but follow-up tree removal will be needed to prevent pinyon and juniper recolonization. The low intercanopy runoff and erosion measured underneath isolated cut-downed-trees in this study clearly demonstrate that tree debris following mechanical treatments can effectively limit microsite-scale runoff and erosion over time where tree debris settles in good contact with the soil surface.  相似文献   

10.

Objective

To compare the duration of action of atracurium in diabetic and nondiabetic dogs.

Study design

Prospective, blinded, clinical study.

Animals

A total of 26 diabetic and 29 nondiabetic dogs.

Methods

Following preanaesthetic medication and intravenous (IV) propofol induction, anaesthesia was maintained with isoflurane in oxygen. Atracurium 0.2 mg kg?1 IV was administered to provide neuromuscular blockade (NMB) and the responses (twitches; T) to train-of-four nerve stimulation were recorded by palpation and electromyography (EMG). Time to onset of NMB (from atracurium administration to loss of T4 by EMG), duration of NMB (to return of T1 by EMG) and also times to loss and return of T2–T4 were recorded. Heart rate (HR), mean arterial pressure, end-tidal isoflurane (Fe′Iso), end-tidal CO2 concentrations and oesophageal temperature were recorded at onset of NMB and when T1EMG returned. Groups were compared using t tests and Mann–Whitney U tests (p < 0.05).

Results

Diabetic dogs were older (9.9 ± 0.3 compared with 6.8 ± 0.7 years, p = 0.0003). Group parameters were similar at onset and offset of NMB apart from HR at offset, which was higher for diabetics compared to nondiabetics (114 ± 4 compared with 100 ± 3 beats minute?1, respectively, p = 0.004), Fe′Iso was higher in the diabetic group at onset (1.3 ± 0.03% compared with 1.2 ± 0.04%, p = 0.026) and offset (1.4 ± 0.03% compared with 1.3 ± 0.03%, p = 0.007), and temperature was higher for diabetics at onset (37.5 ± 0.1 °C compared with 37.0 ± 0.2 °C, p = 0.012) and offset (37.5 ± 0.1 °C compared with 36.9 ± 0.2 °C, p = 0.004). The duration of action of atracurium(tactile) and atracurium(EMG) were similar for both groups.

Conclusions and clinical relevance

The duration of action of atracurium was similar in diabetic and nondiabetic dogs as indicated by tactile and EMG monitoring.  相似文献   

11.

Objective

To evaluate the effect of pulsed inhaled nitric oxide (INO) on arterial oxygenation in horses during abdominal surgery.

Study design

Prospective, randomized, clinical trial.

Animals

Thirty horses that underwent abdominal surgery at the University Animal Hospital in Uppsala, Sweden.

Methods

Anaesthesia was induced according to a standard protocol – romifidine, butorphanol, diazepam and ketamine and maintained with isoflurane in oxygen. Fifteen horses were administered pulsed INO and 15 served as controls. After baseline data collection, pulsed INO delivery commenced. Arterial and venous blood were collected and analysed. Cardiorespiratory parameters were measured, and oxygen content and F-shunt were calculated.

Results

Arterial oxygen tension (PaO2) and arterial oxygen saturation (SaO2) increased from 10.9 ± 5.7 kPa (82 ± 43 mmHg) and 93 ± 6% to 17.3 ± 6.9 kPa (134 ± 52 mmHg) (p < 0.0001) and 98 ± 2% (p < 0.0001), respectively, in horses administered pulsed INO. In the control group, PaO2 and SaO2 decreased from 13.9 ± 9.1 kPa (104 ± 68 mmHg) and 93 ± 7% to 12.1 ± 8.6 kPa (91 ± 65 mmHg) (p = 0.0413) and 91 ± 8% (p = 0.0256), respectively. At the end of anaesthesia, the oxygen content was significantly higher in horses administered pulsed INO compared to controls (p = 0.0126). The calculated F-shunt decreased from 39 ± 10% to 27 ± 6% (p < 0.0001) in horses administered pulsed INO, and remained unchanged in controls, 40 ± 12% to 44 ± 12%. Blood lactate concentration decreased (–17 ± 21%) in horses administered pulsed INO (p = 0.0119), whereas no difference was measured in controls (2 ± 31%).

Conclusions and clinical relevance

The present study showed that it is possible to effectively reduce the F-shunt and improve arterial oxygenation in horses during abdominal surgery by continuous delivery of pulsed INO.  相似文献   

12.

Objective

To determine the intubation dose and select physiologic effects of alfaxalone alone or in combination with midazolam or ketamine in dogs.

Study design

Prospective, clinical study.

Animals

Fifty-three healthy client-owned dogs [mean ± standard deviation (SD)] 5.1 ± 1.8 years, 27 ± 15.4 kg, scheduled for elective orthopedic surgery.

Methods

After premedication with acepromazine (0.02 mg kg–1) and hydromorphone (0.1 mg kg–1) intramuscularly, alfaxalone (0.25 mg kg–1) was administered intravenously over 15 seconds followed immediately by 0.9% saline (AS), midazolam (0.3 mg kg–1; AM), ketamine (1 mg kg–1; AK1), or ketamine (2 mg kg–1; AK2). Additional alfaxalone (0.25 mg kg–1 increments) was administered as required to permit endotracheal intubation. The incidence of apnea and the time from intubation until spontaneous movement were recorded. Heart rate (HR) and blood pressure were recorded 15 minutes after premedication, after intubation and 2, 5, 10 and 15 minutes thereafter. Blood was collected for measurement of serum glucose and insulin concentrations before induction, after intubation and at 2, 5, 10 and 50 minutes. Data were analyzed by split-plot anova with Bonferroni adjustment for the number of group comparisons.

Results

Mean ± SD alfaxalone mg kg–1 doses required for endotracheal intubation were AS (1.0 ± 0.4), AM (0.4 ± 0.2), AK1 (0.5 ± 0.3) and AK2 (0.5 ± 0.4) (p = 0.0005). Differences in cardiopulmonary variables among groups were minor; HR decreased in AS, while in other groups, HR increased transiently postintubation. Incidence of apnea in AS was 54% with no significant difference among groups. Midazolam significantly prolonged time from intubation until spontaneous movement (p < 0.002).

Conclusions and clinical relevance

Midazolam and ketamine reduced the alfaxalone dose required for endotracheal intubation. Serum glucose and insulin concentrations were not influenced by administration of alfaxalone alone or when administered with midazolam or ketamine.  相似文献   

13.

Objective

To compare airway management during induction of anaesthesia, spontaneous ventilation (SV) and controlled mechanical ventilation (CMV), using an endotracheal tube (ETT), laryngeal mask (LM), rabbit-specific supraglottic airway device (v-gel) or facemask (FM).

Study design

Prospective randomized crossover experiment.

Animals

Ten New Zealand White rabbits.

Methods

After premedication, rabbits were randomly allocated to four groups: 1) ETT; 2) LM; 3) v-gel or 4) FM. The required dose of propofol, duration and number of attempts to place an airway device and leakage during SV and CMV at different peak inspiratory pressures (6, 10, 12, 14 and 16 cmH2O) were recorded. Computed tomography (CT) of the head, neck and abdomen were performed before and after CMV.

Results

Significantly less propofol and time [2.0 ± 0.5 mg kg?1, 82 ± 34 seconds, p < 0.001] were needed to place the FM compared to the three other groups [v-gel 5.1 ± 2.1 mg kg?1, 302 ± 124 seconds; LM 4.8 ± 1.2 mg kg?1, 275 ± 89 seconds; ETT 5.5 ± 1.4 mg kg?1, 315 ± 147 seconds]. A leak > 25% of the tidal volume occurred at the lowest pressure in FM [median (range), 6 (6–8) cmH2O], which was significantly lower than with v-gel [16 (6–no leak at 16) cmH2O], LM [>16 (6–no leak at 16)] or ETT [>16 (no leak at 16) cmH2O] (p < 0.001). On CT images, the height and width of the larynx were significantly smaller with v-gel in comparison to FM and LM (p = 0.004). A significant increase in the amount of gas in the stomach (p = 0.007), but not gastric volume, was detected in FM and LM.

Conclusions and clinical relevance

The v-gel is a practical alternative to LM and ETT for airway management and CMV, but can compress the larynx. The FM is easily placed, but significant leakage occurs during CMV.  相似文献   

14.
Runoff from grazing pasture lands can impact water quality in receiving streams if not well managed. Management consists of conservation practices to reduce runoff and pollutants transport. Simulation models have been effectively used to design and implement these conservation practices. The Agricultural Policy Environmental Extender (APEX), a process-based hydrologic model, was used in this study to simulate the management impacts on surface runoff from three small grazed pasture watersheds located at the North Appalachian Experimental Watersheds near Coshocton, Ohio. Specific objectives of this study were to 1) calibrate the APEX model and test runoff predictions against measured runoff and 2) simulate the long-term impacts of different management scenarios on surface runoff. Results show that the APEX model simulated surface runoff reasonably well with the coefficient of determination (R2) and Nash-Sutcliffe efficiency values varying from 0.49 to 0.72 and from 0.25 to 0.60 for calibration and validation, respectively. After validation, the APEX model was run for 37 yr (1975 ? 2011) for long-term scenarios to analyze the impacts of soil properties and management on surface runoff. Data from this study indicated that keeping the watershed land use as a hay meadow instead of grazing significantly reduced cumulative runoff by 58 ? 67%. Buffer strips of perennial grasses resulted in decreased simulated runoff. To simulate the impacts of soils on runoff, the surface (0 ? 5 cm) soil properties of the toe position were applied to the entire grazed watershed. Subsequently, the increase in soil richness resulted in reduction (≤ 5%) in surface runoff. The simulation results from the present study demonstrate the benefits of hayed meadow over grazed pasture and further predict the decreased trend of runoff due to soil properties change and buffer strips.  相似文献   

15.

Objective

To compare postanesthetic xylazine and dexmedetomidine on recovery characteristics from sevoflurane anesthesia in horses.

Study design

Randomized, crossover study.

Animals

Six geldings, mean ± standard deviation (SD) (range), 17 ± 4 (11–24) years and 527 ± 80 (420–660) kg.

Methods

Horses were anesthetized with sevoflurane for 60 minutes under standardized conditions for a regional limb perfusion study. In recovery, horses were administered either xylazine (200 μg kg?1) or dexmedetomidine (0.875 μg kg?1) intravenously. Recoveries were unassisted and were video-recorded for later evaluation of recovery events and quality by two individuals unaware of treatment allocation. Recovery quality was assessed using a 100 mm visual analog scale (VAS) (0 = poor recovery, 100 = excellent recovery), the Edinburgh Scoring System (ESS) (0–100; 100 = excellent recovery) and the mean attempt interval (MAI) (longer = better). Data are mean ± SD.

Results

All recovery quality assessments (xylazine and dexmedetomidine, respectively: VAS: 71 ± 21 mm, 84 ± 13 mm; ESS: 65 ± 22, 67 ± 30; MAI: 52 ± 24 minutes, 60 ± 32 minutes) and events (first limb movement: 37 ± 8 minutes, 42 ± 10 minutes; first attempt to lift head: 44 ± 12 minutes, 48 ± 9 minutes; first attempt to sternal posture: 57 ± 28 minutes, 50 ± 7 minutes; number of head bangs: 2.0 ± 3.0, 0.5 ± 0.5; time to first attempt to stand: 72 ± 6 minutes, 78 ± 13 minutes; time to standing: 79 ± 14 minutes, 84 ± 13 minutes) did not differ significantly between treatments (p > 0.05).

Conclusions and clinical relevance

Recovery characteristics did not differ significantly between postanesthetic xylazine and dexmedetomidine following 1 hour of sevoflurane anesthesia in horses in this study. Further evaluations in more horses and in younger horses are required to confirm these results.  相似文献   

16.
We investigated the effectiveness of rotational and permanent grazing exclosure periods for improving topsoil quality in three commercial farms devoted to cattle breeding in sodic grassland (halophytic steppe) soils of the Flooding Pampa of Argentina. We compared two plots under continuous grazing (C1-C2) with two plots under more than 8 yr of rotational grazing management (R1-R2) and two adjacent plots under permanent grazing exclosure for more than 8 (E1) and 4 (E2) yr. Periodic and permanent grazing exclosure periods caused significant (P < 0.05) and progressive increases in topsoil organic carbon content and organic carbon stock (0 ? 20 cm; from 24 to 61 Mg ha? 1) as follows: (C1 = C2) < (R1 = R2 = E2) < E1 plots. Topsoil physical properties (bulk density, structural instability, and bearing capacity) and salinity were higher (P < 0.05) in C1 and C2 than in the other plots, while infiltration rate was higher in the oldest exclosure (E1) than in the other plots. Topsoil pH decreased from C1-C2 plots (9.5 ? 9.9) to R1-R2 plots (7.3 ? 8.2) to E1-E2 plots (6.5 ? 7.5), while SAR was highest in C1-C2 and lowest in E1 plots. We propose a conceptual model leading to soil recovery in this halophytic steppe community, triggered by organic carbon accumulation induced by grazing management. Short-time grazing exclusion periods (i.e., rotational grazing) are a plausible and low-cost management option to be recommended to the farmers in this highly restrictive environment.  相似文献   

17.

Objective

To determine the effects of low and high dose infusions of dexmedetomidine and a peripheral α2-adrenoceptor antagonist, MK-467, on sevoflurane minimum alveolar concentration (MAC) in dogs.

Study design

Crossover experimental study.

Animals

Six healthy, adult Beagle dogs weighing 12.6 ± 0.9 kg (mean ± standard deviation).

Methods

Dogs were anesthetized with sevoflurane in oxygen. After a 60-minute instrumentation and equilibration period, the MAC of sevoflurane was determined in triplicate using the tail clamp technique. PaCO2 and temperature were maintained at 40 ± 5 mmHg (5.3 ± 0.7 kPa) and 38 ± 0.5 ºC, respectively. After baseline MAC determination, dogs were administered two incremental loading and infusion doses of either dexmedetomidine (1.5 μg kg?1 then 1.5 μg kg?1 hour?1 and 4.5 μg kg?1 then 4.5 μg kg?1 hour?1) or MK-467 (90 μg kg?1 then 90 μg kg?1 hour?1 and 180 μg kg?1 then 180 μg kg?1 hour?1); loading doses were administered over 10 minutes. MAC was redetermined in duplicate starting 30 minutes after the start of drug administration at each dose. End-tidal sevoflurane concentrations were corrected for calibration and adjusted to sea level. A repeated-measures analysis was performed and comparisons between doses were conducted using Tukey's method. Statistical significance was considered at p < 0.05.

Results

Sevoflurane MAC decreased significantly from 1.86 ± 0.3% to 1.04 ± 0.1% and 0.57 ± 0.1% with incremental doses of dexmedetomidine. Sevoflurane MAC significantly increased with high dose MK-467, from 1.93 ± 0.3% to 2.29 ± 0.5%.

Conclusions and clinical relevance

Dexmedetomidine caused a dose-dependent decrease in sevoflurane MAC, whereas MK-467 caused an increase in MAC at the higher infusion dose. Further studies evaluating the combined effects of dexmedetomidine and MK-467 on MAC and cardiovascular function may elucidate potential benefits of the addition of a peripheral α2-adrenergic antagonist to inhalation anesthesia in dogs.  相似文献   

18.
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19.

Objective

To determine the effect of fentanyl on the induction dose of propofol and minimum infusion rate required to prevent movement in response to noxious stimulation (MIRNM) in dogs.

Study design

Crossover experimental design.

Animals

Six healthy, adult intact male Beagle dogs, mean ± standard deviation 12.6 ± 0.4 kg.

Methods

Dogs were administered 0.9% saline (treatment P), fentanyl (5 μg kg?1) (treatment PLDF) or fentanyl (10 μg kg?1) (treatment PHDF) intravenously over 5 minutes. Five minutes later, anesthesia was induced with propofol (2 mg kg?1, followed by 1 mg kg?1 every 15 seconds to achieve intubation) and maintained for 90 minutes by constant rate infusions (CRIs) of propofol alone or with fentanyl: P, propofol (0.5 mg kg?1 minute?1); PLDF, propofol (0.35 mg kg?1 minute?1) and fentanyl (0.1 μg kg?1 minute?1); PHDF, propofol (0.3 mg kg?1 minute?1) and fentanyl (0.2 μg kg?1 minute?1). Propofol CRI was increased or decreased based on the response to stimulation (50 V, 50 Hz, 10 mA), with 20 minutes between adjustments. Data were analyzed using a mixed-model anova and presented as mean ± standard error.

Results

ropofol induction doses were 6.16 ± 0.31, 3.67 ± 0.21 and 3.33 ± 0.42 mg kg?1 for P, PLDF and PHDF, respectively. Doses for PLDF and PHDF were significantly decreased from P (p < 0.05) but not different between treatments. Propofol MIRNM was 0.60 ± 0.04, 0.29 ± 0.02 and 0.22 ± 0.02 mg kg?1 minute?1 for P, PLDF and PHDF, respectively. MIRNM in PLDF and PHDF was significantly decreased from P. MIRNM in PLDF and PHDF were not different, but their respective percent decreases of 51 ± 3 and 63 ± 2% differed (p = 0.035).

Conclusions and clinical relevance

Fentanyl, at the doses studied, caused statistically significant and clinically important decreases in the propofol induction dose and MIRNM.  相似文献   

20.
Despite the importance of vegetative reproduction in annual tiller replacement, little is known about the patterns and timing of tiller recruitment from the bud bank, especially regarding fire return intervals and seasons of fire. We examined aboveground plant density, temporal patterns of tiller production, and belowground bud bank dynamics for Bouteloua gracilis (Willd ex. Kunth) Lag. ex Griffiths), Pascopyrum smithii (Rydb.) A. Löve, and Hesperostipa comata (Trin. & Rupr.) Barkworth following summer, fall, and spring prescribed fires at 2-yr, 3-yr, and 6-yr fire return intervals, and their interactions. Fire treatments were initiated in 2006, and buds were assessed July 2011 through July 2013. Density and number of reproductive B. gracilis tillers increased in 2013 following drought during 2012, unlike H. comata, which decreased reproductive tiller production. Irrespective of fire treatments, B. gracilis produced the most buds (8 ? 10 buds ? tiller? 1) and H. comata produced the least (2 ? 3 buds ? tiller? 1), with P. smithii producing an intermediate amount (6 ? 8 buds ? tiller? 1). Immediate B. gracilis and P. smithii bud mortality did not occur for all season and fire return interval treatments. However, H. comata bud mortality increased immediately following summer and fall prescribed fires. Three-yr fire return intervals increased active buds throughout the 2013 winter and growing season for B. gracilis and P. smithii relative to control plots and 2- and 6-yr fire return intervals. Fire stimulated bud activity of B. gracilis and P. smithii relative to nonburned plots. The aboveground and belowground response of H. comata indicated meristem limitations following fire treatments, illustrating greater vulnerability to fire for that species than B. gracilis and P. smithii.  相似文献   

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