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Two healthy research cats involved in a randomized, blinded prospective pharmacodynamics study evaluating midazolam continuous-rate infusion as a means to decrease sevoflurane concentrations experienced unexpectedly prolonged recoveries. Midazolam loading doses, infusion rates, and the targeted plasma midazolam concentrations at steady-state were determined by pharmacokinetic modeling based on the results of a preliminary pharmacokinetic study using a single dose of midazolam. In the pharmacodynamics study, cats remained oversedated after recovery from anesthesia, and plasma concentrations of midazolam and its primary metabolite (1-hydroxymidazolam) remained elevated. The use of flumazenil was unsuccessful in timely treatment of oversedation. Administration of intravenous lipid emulsion was used in one of the cats to facilitate recovery and appeared to be effective in both reducing the depth of midazolam-induced oversedation and significantly reducing the plasma concentration of 1-hydroxymidazolam. The effects after the administration of both treatment modalities on clinical signs and plasma drug concentrations in cats are discussed. The observations suggest that cats may eliminate 1-hydroxymidazolam more slowly than expected; consequently dose adjustments may be required when continuous infusion of midazolam is intended. In addition, intravenous lipid emulsion may facilitate recovery from midazolam oversedation, particularly in cases unresponsive to traditional treatment modalities. However, further investigations are warranted to delineate the efficacy of this modality in the treatment of midazolam oversedation.

Clonazepam causes sedation and psychomotor impairment in people. Due to similarities between people and swine in response to benzodiazepines, clonazepam may represent a viable option to produce mild‐to‐moderate tranquillization in pigs. The objective of this study was to determine the pharmacokinetic profile of a single oral dose (0.5 mg/kg) of clonazepam in eight healthy, growing commercial cross pigs. Serial plasma samples were collected at baseline and up to 96 h after administration. Plasma concentrations were quantified using reverse‐phase high‐performance liquid chromatography, and compartment models were fit to time–concentration data. A one‐compartment first‐order model best fits the data. Maximum plasma concentration was 99.5 ng/mL, and time to maximum concentration was 3.4 h. Elimination half‐life was 7.3 h, mean residence time 7.4 h, and apparent volume of distribution 5.7 L/kg. Achieved plasma concentrations exceeded those associated with psychomotor impairment in people although pharmacodynamic effects have not been investigated in pigs. A simulated oral regimen consisting of 0.35 mg/kg administered every 8 h to pigs would achieve plasma concentrations above 32 ng/mL which are shown to produce psychomotor impairment in people. Further studies to test the clinical efficacy of these dosages in commercial and miniature pigs are warranted. [ABSTRACT FROM AUTHOR]

Objectives: The main objective of this study was to compare the postoperative analgesic effects of grapiprant with those of robenacoxib in cats undergoing ovariohysterectomy (OVH). Methods: In total, 37 female cats (age range 4 months–10 years, weighing ⩾2.5 kg) were enrolled in a prospective, randomized, masked, non-inferiority (NI) clinical trial. Cats received oral robenacoxib (1 mg/kg) or grapiprant (2 mg/kg) 2 h before OVH. Analgesia was assessed via the Feline Grimace Scale (FGS), the Glasgow Composite Measure Pain Scale-Feline (CMPS-F), von Frey monofilaments (vFFs) and pressure algometry (ALG) 2 h before treatment administration, at extubation, and 2, 4, 6, 8, 18 and 24 hours after extubation. Hydromorphone (<8 h postoperatively) or buprenorphine (>18 h postoperatively) were administered to cats with scores of ⩾5/20 on CMPS-F and/or ⩾4/10 on FGS. NI margins for CMPS-F and vFFs were set at 3 and −0.2, respectively. A mixed-effect ANOVA was used for FGS scores (P <0.05). Data are reported as mean ± SEM. Results: The data from 33 cats were analyzed. The upper limit of the 95% confidence interval (CI) (0.35) was less than the NI margin of 3 for CMPS-F, and the lower limit of the 95% CI (0.055) was greater than the NI margin of −0.2 for vFFs, indicating NI of grapiprant. The FGS scores were greater than baseline at extubation for both treatments (1.65 ± 0.63; P = 0.001); however, there was no difference between treatments. There was no difference between treatments, nor treatment by time interaction, for vFFs (P <0.001). The CMPS-F scores for both treatments were higher at extubation but returned to baseline after 4 h (P <0.001). For ALG, there was no difference in treatment or treatment by time interaction. The robenacoxib group had lower pressure readings at extubation and 6 h compared with baseline. Conclusions and relevance: These results indicate that grapiprant was non-inferior to robenacoxib for mitigating postsurgical pain in cats after OVH performed via ventral celiotomy. The impact of grapiprant for analgesia in OVH via the flank is unknown. [ABSTRACT FROM AUTHOR]

Both pet and research pigs can suffer from some degree of pain from surgery, injuries, or osteoarthritis (OA). Despite this, there is a paucity of data on safe and effective analgesia agents in pigs. Grapiprant is an EP4 antagonist that blocks the action of the pro‐inflammatory prostanoid, PGE2. It has shown efficacy in attenuating pain associated with ovariohysterectomy and OA in dogs. However, there are no data regarding grapiprant in pigs. Therefore, the pharmacokinetic profile of orally administered grapiprant to juvenile pigs (Sus scrofa domestica) was evaluated in this study. Seven juvenile pigs received 12 mg/kg grapiprant orally. Blood was collected from an indwelling jugular catheter using the push–pull method at set timepoints up to 48 hours. Sample analysis was performed with high‐performance liquid chromatography. Mean grapiprant plasma concentration was 164.3 ± 104.7 ng/mL which occurred at 0.8 ± 0.3 h. This study demonstrated that grapiprant concentrations consistent with analgesia in dogs were reached at this dosage in pigs. Further studies are needed to evaluate the efficacy of grapiprant in pigs. [ABSTRACT FROM AUTHOR]

Pigs are at risk of vomiting from medical conditions as well as the emetic side effects of drugs administered for peri‐operative manipulations, but there is a lack of pharmacokinetic data for potential anti‐emetic therapies, such as maropitant, in this species. The main objective of this study was to estimate plasma pharmacokinetic parameters for maropitant in pigs after a single intramuscular (IM) administration dosed at 1.0 mg/kg. A secondary objective was to estimate pilot pharmacokinetic parameters in pigs after oral (PO) administration at 2.0 mg/kg. Maropitant was administered to six commercial pigs at a dose of 1.0 mg/kg IM. Plasma samples were collected over 72 h. After a 7‐day washout period, two pigs were administered maropitant at a dose of 2.0 mg/kg PO. Maropitant concentrations were measured via liquid chromatography/mass spectrometry (LC–MS/MS). A non‐compartmental analysis was used to derive pharmacokinetics parameters. No adverse events were noted in any of the study pigs after administration. Following single IM administration, maximum plasma concentration was estimated at 412.7 ± 132.0 ng/mL and time to maximum concentration ranged from 0.083 to 1.0 h. Elimination half‐life was estimated at 6.7 ± 1.28 h, and mean residence time was 6.1 ± 1.2 h. Volume of distribution after IM administration was 15.9 L/kg. Area under the curve was 1336 ± 132.0 h*ng/mL. The relative bioavailability of PO administration was noted to be 15.5% and 27.2% in the two pilot pigs. The maximum systemic concentration observed in the study pigs after IM administration was higher than what was observed after subcutaneous administration in dogs, cats, or rabbits. The achieved maximum concentration exceeded the concentrations for anti‐emetic purposes in dogs and cats; however, a specific anti‐emetic concentration is currently not known for pigs. Further research is needed into the pharmacodynamics of maropitant in pigs to determine specific therapeutic strategies for this drug. [ABSTRACT FROM AUTHOR]

OBJECTIVE To determine effects of fentanyl, lidocaine, and a fentanyl-lidocaine combination on the minimum alveolar concentration of sevoflurane preventing motor movement (MACNM) in dogs. ANIMALS 6 adult Beagles. PROCEDURES Dogs were anesthetized with sevoflurane in oxygen 3 times (1-week intervals). Baseline MACNM (MACNM-B) was determined starting 45 minutes after induction of anesthesia. Dogs then received 1 of 3 treatments IV: fentanyl (loading dose, 15 µg/kg; constant rate infusion [CRI], 6 µg/kg/h), lidocaine (loading dose, 2 mg/kg; CRI, 6 mg/kg/h), and the fentanyl-lidocaine combination at the same doses. Determination of treatment MACNM (MACNM-T) was initiated 90 minutes after start of the CRI. Venous blood samples were collected at the time of each treatment MACNM measurement for determination of plasma concentrations of fentanyl and lidocaine. RESULTS Mean ± SEM overall MACNM-B for the 3 treatments was 2.70 ± 0.27 vol%. The MACNM decreased from MACNM-B to MACNM-T by 39%, 21%, and 55% for fentanyl, lidocaine, and the fentanyl-lidocaine combination, respectively. This decrease differed significantly among treatments. Plasma fentanyl concentration was 3.25 and 2.94 ng/mL for fentanyl and the fentanyl-lidocaine combination, respectively. Plasma lidocaine concentration was 2,570 and 2,417 ng/mL for lidocaine and the fentanyl-lidocaine combination, respectively. Plasma fentanyl and lidocaine concentrations did not differ significantly between fentanyl and the fentanyl-lidocaine combination or between lidocaine and the fentanyl-lidocaine combination. CONCLUSIONS AND CLINICAL RELEVANCE CRIs of fentanyl, lidocaine, and the fentanyl-lidocaine combination at the doses used were associated with clinically important and significant decreases in the MACNM of sevoflurane in dogs. [ABSTRACT FROM AUTHOR]

OBJECTIVE To evaluate the effect of IM administration of a tiletamine hydrochloridezolazepam hydrochloride (TZ) combination with either dexmedetomidine hydrochloride or saline (0.9% NaCI) solution (SS) on the motor response to claw clamping, selected cardiorespiratory variables, and quality of recovery from anesthesia in alpacas. ANIMALS 5 adult sexually intact male alpacas. PROCEDURES Each alpaca was given the T Z combination (2 mg/kg) with dexmedetomidine (5 [D5], 10 [DIO], 15 [DI5 ], or 20 [D20] pg/kg) or SSIM at l-week intervals (5 experiments); motor response to claw clamping was assessed, and characteristics of anesthesia, recovery from anesthesia, and selected cardiorespiratory variables were recorded. RESU LTS Mean ± SEM duration of lack of motor response to claw clamping was longest when alpacas received treatments DI5 (30.9 ± 5.9 minutes) and D20 (40.8 ± 5.9 minutes). Duration of lateral recumbency was significantly longer with dexmedetomidine administration. The longest time (81.3 ± 10.4 minutes) to standing was observed when alpacas received treatment D20. Following treatment SS, 4 alpacas moved in response to claw clamping at the 5-minute time point. Heart rate decreased from pretreatment values in all alpacas when dexmedetomidine was administered. Treatments DIO, D15, and D20 decreased Pao2, compared with treatment SS, during the first 15 minutes. During recovery, muscle stiffness and multiple efforts to regain a sternal position were observed in 3 SS-treated and I D5-treated alpacas; all other recoveries were graded as excellent. CONCLUSIONS AND CLINICAL RELEVANCE In TZ-anesthetized alpacas, dexmedetomidine (10, 15, and 20 pg/kg) administered IM increased the duration of lack of motor response to claw clamping, compared with the effect of SS. [ABSTRACT FROM AUTHOR]

OBJECTIVE To evaluate the effect of MgSO4, alone and in combination with propofol, on the minimum alveolar concentration preventing motor movement (MACNM) in sevoflurane-anesthetized dogs. ANIMALS 6 healthy purpose-bred adult male Beagles (least squares mean ± SEM body weight, 12.0 ± 1.1 kg). PROCEDURES Dogs were anesthetized 3 times at weekly intervals. The MACNM was measured 45 minutes after induction of anesthesia (baseline; MACNM-B) and was determined each time by use of a noxious electrical stimulus. Treatments were administered as a loading dose and constant rate infusion (CRI) as follows: treatment 1, MgSO4 loading dose of 45 mg/kg and CRI of 15 mg/kg/h; treatment 2, propofol loading dose of 4 mg/kg and CRI of 9 mg/kg/h; and treatment 3, MgSO4 and propofol combination (same doses used previously for each drug). A mixed-model ANOVA and Tukey-Kramer tests were used to determine effects of each treatment on the percentage decrease from MACNM-B. Data were reported as least squares mean ± SEM values. RESULTS Decrease from MACNM-B was 3.4 ± 3.1%, 48.3 ± 3.1%, and 50.3 ± 3.1%, for treatments 1, 2, and 3, respectively. The decrease for treatments 2 and 3 was significantly different from that for treatment 1; however, no significant difference existed between results for treatments 2 and 3. CONCLUSIONS AND CLINICAL RELEVANCE MgSO4 did not affect MACNM, nor did it potentiate the effects of propofol on MACNM. Administration of MgSO4 in this study appeared to provide no clinical advantage as an anesthetic adjuvant. [ABSTRACT FROM AUTHOR]

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Objective---To evaluate antinociceptive and selected effects associated with IM administration of xylazine hydrochloride in combination with tiletamine-zolazepam in llamas. Animals--8 adult male llamas. Procedures--Each llama received tiletamine-zolazepam (2 mg/kg) combined with either xylazine (0.1,0.2, or 0.4 mg/kg) or saline (0.9% NaCl) solution IM (treatments designated as TZ-Xy0.1, TZ-Xy0.2, TZ-Xy0.4, and TZ-Sal, respectively) at 1-week intervals. Selected cardiorespiratory variables were assessed during lateral recumbency and anesthesia, and recovery characteristics were recorded. Duration of antinociception was evaluated by clamping a claw every 5 minutes. Results--Interval between treatment administration and lateral recumbency for TZ-Xy0.4 was shorter than that forTZ-Xy0.1 or TZ-Sal. Mean ± SEM duration of antinociception was longer for TZ-Xy0.4 (51.3 ± 7.0 minutes), compared with findings for TZ-Xy0.2 (31.9 ± 6.0 minutes), TZ-Xy0.1 (8.1 ± 4.0 minutes), and TZ-Sal (0.6 ± 0.6 minutes). Interval between treatment administration and standing was longer forTZ-Xy0.4 (112 ± 9 minutes) than it was for TZ-Xy0.2 (77 ± 9 minutes) or TZ-Sal (68 ± 9 minutes). Mean heart and respiratory rates during the first 30 minutes for TZ-Sal exceeded values for the other treatments. Administration of TZ-Xy0.2 andTZ-Xy0.4 resulted in Pao2 <60 mm Hg at 5 minutes after llamas attained lateral recumbency, and values differed from TZ-Sal findings at 5, 10, and 15 minutes; Paco2 was greater for TZ-Xy0.2 andTZ-Xy0.4 than for TZ-Sal at 5, 10, 15, and 20 minutes. Conclusions and Clinical Relevance--Xylazine (0.2 and 0.4 mg/kg) increased the duration of antinociception in llamas anesthetized with tiletamine-zolazepam. [ABSTRACT FROM AUTHOR]

Objective--To investigate the effects of the concurrent administration of 70% N2O on the minimum alveolar concentration (MAC) for sevoflurane in dogs, the MAC derivative that blocks motor movement (MACNM), and the MAC derivative that blocks autonomic responses (MACBAR). Animals--7 adult sexually intact male mixed-breed dogs. Procedures--For each dog, anesthesia was induced with sevoflurane delivered via a face mask. Initially, the baseline MAC, MACNM, and MACBAR for sevoflurane were determined by use of a noxious stimulus (50 V, 50 Hz, and 10 milliseconds) applied subcutaneously over a midulnar region. Nitrous oxide (70%) was added to the breathing circuit, and MAC, MACNM, and MACBAR were determined again. Percentage changes from the respective baseline concentrations for MAC, MACNM, and MACBAR were calculated after the administration of N2O. Results--Baseline median values for the MAC, MACNM, and MACBAR for sevoflurane were 1.75%, 2.00%, and 2.50%, respectively. Addition of 70% N2O significantly decreased MAC, MACNM, and MACBAR by 24.4%, 25.0%, and 35.2%, respectively, and these values did not differ significantly from each other. Conclusions and Clinical Relevance--Supplementation with 70% N2O caused a clinically important and significant decrease in the MAC, MACNM, and MACBAR for sevoflurane in dogs. [ABSTRACT FROM AUTHOR]

OBJECTIVE To evaluate and compare postoperative analgesic effects of grapiprant and carprofen in dogs undergoing ovariohysterectomy. ANIMALS 42 sexually intact female healthy dogs (< 35 kg and 0.5 to 7 years old) were enrolled. PROCEDURES In a masked, randomized, noninferiority clinical trial, dogs received either 2 mg/kg of grapiprant or 4.4 mg/kg of carprofen orally 2 hours prior to ovariohysterectomy. Postoperative pain was assessed using the Glasgow Composite Pain Scale-Short Form (GCPS-SF) at extubation and 2, 4, 6, 8, 18, and 24 hours postextubation and compared to baseline. After each pain scoring, mechanical nociceptive testing with von Frey monofilaments (vF) was performed to assess hyperalgesia. Hydromorphone (0.05 mg/kg, IM) was administered to any dog with a GCPS-SF of 2 5/24. The noninferiority limit (NI) for the GCPS-SF was 8 = 3. The NI for vF was & = -0.2. Following noninferiority, a mixed-effect ANOVA and post hoc comparisons were made with the Tukey correction method (P < .05). RESULTS 3 dogs required rescue analgesia and were excluded from statistical analysis, Of the remaining 39 dogs, the upper Cl for GCPS-SF was below the NI of 3 and the lower Cl for vF was greater than the NI of -0.2, indicating noninferiority of grapiprant as compared to carprofen. There was no difference between treatment (P = .89) nor treatment by time (P = .62) for GCPS-SF. There was no difference between groups at any time point or over time when vF were used. CLINICAL RELEVANCE Our study results support the use of grapiprant as an analgesic alternative to carprofen in dogs undergoing ovariohysterectomy. [ABSTRACT FROM AUTHOR]

OBJECTIVE To investigate use of the plethysmographic variability index (PVI) and perfusion index (PI) for evaluating changes in arterial blood pressure in anesthetized tigers (Panthera tigris). ANIMALS 8 adult tigers. PROCEDURES Each tiger was anesthetized once with a combination of ketamine, midazolam, medetomidine, and isoflurane. Anesthetic monitoring included assessment of PI, PVI, direct blood pressure measurements, anesthetic gas concentrations, esophageal temperature, and results of capnography and ECG. Mean arterial blood pressure (MAP) was maintained for at least 20 minutes at each of the following blood pressure conditions: hypotensive (MAP = 50 ± 5 mm Hg), normotensive (MAP = 70 ± 5 mm Hg), and hypertensive (MAP = 90 ± 5 mm Hg). Arterial blood gas analysis was performed at the beginning of anesthesia and at each blood pressure condition. RESULTS Mean ± SD PI values were 1.82 ± 2.38%, 1.17 ± 0.77%, and 1.71 ± 1.51% and mean PVI values were 16.00 ± 5.07%, 10.44 ± 3.55%, and 8.17 ± 3.49% for hypotensive, normotensive, and hypertensive conditions, respectively. The PI values did not differ significantly among blood pressure conditions. The PVI value for the hypotensive condition differed significantly from values for the normotensive and hypertensive conditions. The PVI values were significantly correlated with MAP (r = -0.657). The OR of hypotension to nonhypotension fo r PVI values > 18% was 43.6. CONCLUSIONS AND CLINICAL RELEVANCE PVI was a clinically applicable variable determined by use of noninvasive methods in anesthetized tigers. Values of PVI > 18% may indicate hypotension. [ABSTRACT FROM AUTHOR]

OBJECTIVE To evaluate agreement among diplomates of the American College of Veterinary Anesthesia and Analgesia for scores determined by use of a simple descriptive scale (SDS) or a composite grading scale (CGS) for quality of recovery of horses from anesthesia and to investigate use of 3-axis accelerometry (3AA) for objective evaluation of recovery. ANIMALS 12 healthy adult horses. PROCEDURES Horses were fitted with a 3AA device and then were anesthetized. Eight diplomates evaluated recovery by use of an SDS, and 7 other diplomates evaluated recovery by use of a CGS. Agreement was tested with κ and AC1 statistics for the SDS and an ANOVA for the CGS. A library of mathematical models was used to map 3AA data against CGS scores. RESULTS Agreement among diplomates using the SDS was slight (κ = 0.19; AC1 = 0.22). The CGS scores differed significantly among diplomates. Best fit of 3AA data against CGS scores yielded the following equation: RS = 9.998 × SG0.633 × ∑UG0.174, where RS is a horse's recovery score determined with 3AA, SG is acceleration of the successful attempt to stand, and ∑UG is the sum of accelerations of unsuccessful attempts to stand. CONCLUSIONS AND CLINICAL RELEVANCE Subjective scoring of recovery of horses from anesthesia resulted in poor agreement among diplomates. Subjective scoring may lead to differences in conclusions about recovery quality; thus, there is a need for an objective scoring method. The 3AA system removed subjective bias in evaluations of recovery of horses and warrants further study. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate changes in peak reverse torque (PRT) of the locking head screws that occur over time. A locking plate construct, consisting of an 8-hole locking plate and 8 locking screws, was used to stabilize a tibia segmental bone defect in a goat model. PRT was measured after periods of 3, 6, 9, and 12 months of ambulation. PRT for each screw was determined during plate removal. Statistical analysis revealed that after 6 months of loading, locking screws placed in position no. 4 had significantly less PRT as compared with screws placed in position no. 5 ( p < 0.05). There were no statistically significant differences in PRT between groups as a factor of time ( p > 0.05). Intracortical fractures occurred during the placement of 151 out of 664 screws (22.7%) and were significantly more common in the screw positions closest to the osteotomy (positions 4 and 5, p < 0.05). Periosteal and endosteal bone reactions and locking screw backout occurred significantly more often in the proximal bone segments ( p < 0.05). Screw backout significantly, negatively influenced the PRT of the screws placed in positions no. 3, 4, and 5 ( p < 0.05). The locking plate-screw constructs provided stable fixation of 2.5-cm segmental tibia defects in a goat animal model for up to 12 months., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Grzeskowiak, Rifkin, Croy, Steiner, Seddighi, Mulon, Adair and Anderson.)

Background: Previous studies in human patients suggest depth of sedation may be affected by environmental noise or music; however, related data in domestic animals is limited. The objective of the current study was to investigate the effect of noise and music on dexmedetomidine-induced (DM- 10 µg/kg, IM) sedation in 10 dogs., Methods: In a crossover design, post-DM injection dogs were immediately subjected to recorded human voices at either 55-60 decibel (dB) (Noise 1) or 80-85 dB (Noise 2); classical music at 45-50 dB (Music); or background noise of 40-45 dB (Control+). Control- included IM saline injection and exposure to 40-45 dB background noise. Sedation was assessed via monitoring spontaneous behavior and accelerometry (delta-g) throughout three 20-min evaluation periods: baseline, noise exposure, and post-treatment. Sedation was further assessed during two restraint tests at 30 min (R1) and 40 min (R2) post-injection. A mixed model for crossover design was used to determine the effect of noise exposure and time on either spontaneous behavior scores or delta-g. The restraint scores were analyzed using a two-way repeated measures ANOVA., Results: Spontaneous behavior scores indicated less sedation during Noise 2 compared to Control+ ( P  = 0.05). R2 restraint scores for all DM treatments except Noise 2 indicated significantly higher sedation than Control- [C+ ( P  = 0.003), M ( P  = 0.014) and N1 ( P  = 0.044)]., Discussion: Results suggest that the quality of sedation is negatively impacted by high-intensity noise conditions (80-85 dB), but exposure to music did not improve sedation in this population of research dogs., Competing Interests: DJ Rezac is an employee of Veterinary & Biomedical Research, Inc., manufacturers and distributors of the HeyRex accelerometer devices. The company supplied accelerometers used in this study and provided technical assistance in data transformation. HeyRex did not contribute to statistical analysis or interpretation of results. Julia D. Albright holds the PetSafe endowed chair for small animal behavioral research at the University of Tennessee.

Propofol is an intravenous anesthetic commonly used due to its favorable pharmacokinetic and pharmacodynamic profile. There are discrepancies in the literature about the most appropriate sample for determining propofol concentrations. Although plasma has been used for determining propofol concentrations, whole blood has been the preferred sample. There is also a lack of consistency in the literature on the effect of storage time and temperature on propofol concentrations and this may lead to errors in the design of pharmacokinetic/pharmacodynamics studies. The purpose of this study was to determine the difference in propofol concentrations in whole blood versus plasma and to evaluate the influence of storage time (56 days) and temperature (4 °C, -20 °C, -80 °C) on the stability of propofol concentrations in blood and plasma samples. Results from the study indicate that whole blood and plasma samples containing propofol stored at -80 °C have concentrations as high as or higher than those stored at 4 °C or -20 °C for 56 days; thus, -80 °C is an appropriate temperature for propofol sample storage. Plasma propofol concentrations were consistently higher than whole blood for all three storage temperatures. Consequently, plasma is the most appropriate sample for propofol analysis due to its consistent determinations., Competing Interests: The authors declare there are no competing interests.

Many surgical procedures on ruminants can be performed humanely and safely using local or regional anesthesia and physical restraint, but sedation and general anesthesia are necessary in order to perform some procedures. Although anesthesia-associated risks are greater in ruminants than monogastrics, ruminants can be anesthetized relatively safely in a field setting if the risks are understood, and adequate planning and precautions are in place. This article discusses the important features impacting sedation and anesthesia of cattle and small ruminants, and describes some commonly used drug protocols., (Copyright © 2016 Elsevier Inc. All rights reserved.)

The objective of this study was to determine the effects of propofol on the minimum alveolar concentration of sevoflurane needed to prevent motor movement (MAC(NM)) in dogs subjected to a noxious stimulus using randomized crossover design. Six, healthy, adult beagles (9.2 ± 1.3 kg) were used. Dogs were anesthetized with sevoflurane on 3 occasions, at weekly intervals, and baseline MAC(NM) (MAC(NM-B)) was determined on each occasion. Propofol treatments were administered as loading dose (LD) and constant rate infusion (CRI) as follows: Treatment 1 (T1) was 2 mg/kg body weight (BW) and 4.5 mg/kg BW per hour; T2 was 4 mg/kg BW and 9 mg/kg BW per hour; T3 was 8 mg/kg BW and 18 mg/kg BW per hour, respectively. Treatment MAC(NM) (MAC(NM-T)) determination was initiated 60 min after the start of the CRI. Two venous blood samples were collected and combined at each MAC(NM-T) determination for measurement of blood propofol concentration using high-performance liquid chromatography method (HPLC). Data were analyzed using a mixed-model ANOVA and are presented as least square means (LSM) ± standard error of means (SEM). Propofol infusions in the range of 4.5 to 18 mg/kg BW per hour resulted in mean blood concentrations between 1.3 and 4.4 μg/mL, and decreased (P < 0.05) sevoflurane MAC(NM) in a concentration-dependent manner. The percentage decrease in MAC(NM) was 20.5%, 43.0%, and 68.3%, with corresponding blood propofol concentrations of 1.3 ± 0.3 μg/mL, 2.5 ± 0.3 μg/mL, and 4.4 ± 0.3 μg/mL, for T1, T2, and T3, respectively. Venous blood propofol concentrations were strongly correlated (r = 0.855, P < 0.0001) with the decrease in MAC(NM). In dogs, propofol decreased the sevoflurane MAC(NM) in a concentration-dependent manner.

The study objective was to determine the effects of 70% nitrous oxide (N2O) and fentanyl on the end-tidal concentration of sevoflurane necessary to prevent movement (MACNM) in response to noxious stimulation in dogs. Six healthy, adult, intact male, mixed-breed dogs were used on 3 occasions in a randomized crossover design. After induction of anesthesia with sevoflurane, each of the following treatments was randomly administered: fentanyl loading dose (Ld) of 15 μg/kg and infusion of 6 μg/kg per hour [treatment 1 (T1)], 70% N2O (T2), or fentanyl (Ld of 15 μg/kg and infusion of 6 μg/kg per hour) combined with 70% N2O (T3). Each dog received each of the 3 treatments once during the 3-week period. Determination of MACNM was initiated 90 min after the start of each treatment. The values were compared using the baseline MACNM, which had been determined in a previous study on the same group of dogs. Data were analyzed using a mixed-model analysis of variance (ANOVA) and Tukey-Kramer tests, and expressed as least squares mean ± SEM. The baseline MACNM decreased by 36.6 ± 4.0%, 15.0 ± 4.0%, and 46.0 ± 4.0% for T1, T2, and T3, respectively (P < 0.05), and differed (P < 0.05) among treatments. Mean fentanyl plasma concentrations did not differ (P ≥ 0.05) between T1 (3.70 ± 0.56 ng/mL) and T3 (3.50 ± 0.56 ng/mL). The combination of fentanyl and N2O resulted in a greater sevoflurane MACNM sparing effect than either treatment alone.

Advancements in veterinary medicine have resulted in an increased number of geriatric horses being presented for medical or surgical procedures that require general anesthesia. Due to the physiological changes associated with aging and the likelihood of concurrent disease conditions, the geriatric equine is at an increased risk during anesthesia. The main physiological changes associated with aging, and their impact on anesthesia, are discussed in this review., Competing Interests: Disclosure The authors report no conflicts of interest in this work.