Pharmacokinetics of oral clonazepam in growing commercial pigs (Sus scrofa domestica).

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.

Evaluation of the analgesic efficacy of grapiprant compared with robenacoxib in cats undergoing elective ovariohysterectomy in a prospective, randomized, masked, non-inferiority clinical trial.

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.

Single center retrospective clinical audit and comparison of outcome between epicardial and transvenous endocardial permanent pacemaker implantations in dogs.

The aim of this retrospective cohort study was to provide a single-center clinical audit of complications for single chamber permanent pacemaker implantation (PPI) techniques and determine if the clinical parameters, PPI technique or complications were associated with outcome. The electronic medical records were searched for dogs treated for bradyarrhythmia with PPI. Data related to presenting complaint, signalment of the dog, ECG diagnosis, echocardiographic findings, PPI technique, and programing of the pacemaker were recorded. Survival length (days) was recorded as the last veterinary visit; if the dog was dead the reason was documented. Cumulative survival of each pacemaker was examined by a Kaplan-Meier survival curve and the two techniques compared with a logrank test. Chi-square was used to determine the association between major complications and death. A total of 66 dogs with 52 transvenous and 30 epicardial PPIs were included. All epicardial pacemakers were implanted via transdiaphragmatic approach. A total of 31 life-threatening complications were reported. There were nine deaths related to major complications (13.6% of the study sample). The median follow-up period was 366 days, with a median survival of 255 days, and a significant difference in cumulative survival of each pacemaker (P = 0.01) between epicardial (93 days, range 0-1882 days) and transvenous (334 days, range 0-2745) PPIs but no significant difference in cumulative survival between the two techniques when only the first pacemaker was considered (p = 0.07). The presence of a major complications had a significant association with death due to pacemaker complications (P<0.001). The decision to perform epicardial PPI in failed transvenous PPI patients may have skewed the cumulative survival as was evident in the lack of significant difference in survival when only first PPI were examined. Major complication rates between the two techniques were similar and the authors consider both techniques equally reliable to manage symptomatic bradycardia in dogs.

Pharmacokinetics of intramuscular maropitant in pigs (Sus scrofa domesticus).

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.

EVALUATION OF AGREEMENT BETWEEN OSCILLOMETRIC AND DIRECT BLOOD PRESSURE MEASUREMENTS IN ANESTHETIZED TIGERS (PANTHERA TIGRIS).

Noninvasive blood pressure measurement is commonly performed with oscillometry; however, this technique provides clinically helpful information only if it is representative of the gold standard. Agreement between direct and oscillometric blood pressure measurements were performed in 14 anesthetized, captive tigers (Panthera tigris). A cuff, placed around the tail base and connected to a multiparameter monitor, was used to measure arterial blood pressure oscillometrically and provided systolic, mean, and diastolic pressures. At the same time, direct blood pressures were obtained from a dorsal pedal arterial catheter, and the oscillometric and direct readings were considered paired data points. Agreement between the two methods was evaluated by Bland-Altman plots. All animals completed the study and provided 196 paired data points. The bias (mm Hg) for systolic, mean, and diastolic arterial pressures was -3.7, -0.8, and -1.6, respectively. Limits of agreement (mm Hg) for systolic, mean, and diastolic arterial pressures were -31 to 24, -29 to 27, and -29 to 26, respectively. Oscillometry provided an acceptable amount of readings within 10 and 20 mm Hg of the gold standard. The oscillometric technique provided reasonable agreement with direct measurements. Therefore, in the conditions used in this study, oscillometric blood pressure measured via the ventral coccygeal artery provided reasonable estimates of invasive blood pressure in anesthetized tigers.

Retrospective evaluation of acute hyperkalemia of unknown origin during general anesthesia in dogs.

OBJECTIVE: To report and characterize cases of acute hyperkalemia of unknown origin in dogs under anesthesia. STUDY DESIGN: Multicentric retrospective clinical study. ANIMALS: Medical records of 19 client-owned dogs that developed acute hyperkalemia during anesthesia. METHODS: Anesthetic records of dogs developing acute hyperkalemia from January 2015 to December 2022 were evaluated. Data collected included demographics, duration of anesthesia until the episode, electrolytes and blood gas measurements, electrocardiogram (ECG) abnormalities, drugs used as part of the anesthetic protocol, hyperkalemia treatment and outcome. RESULTS: A total of 13 cases met the inclusion criteria with documented acute hyperkalemia with no apparent underlying cause during anesthesia. Dogs were [mean ± standard deviation (range)] 6.5 ± 5.0 (3-10) years old and weighed 18.0 ± 14.3 (5.1-40.0) kg. All dogs were administered dexmedetomidine and an opioid as part of the premedication. All dogs had inhalation anesthesia of >60 minutes' duration. The first clinical sign was bradycardia that was minimally responsive to anticholinergic administration and was often accompanied by moderate/severe hypotension. These signs were rapidly followed by ECG changes compatible with hyperkalemia and/or cardiac arrest. Rapid identification and treatment for hyperkalemia, with or without dexmedetomidine reversal, resulted in survival of 12 dogs and one fatality. CONCLUSIONS AND CLINICAL RELEVANCE: Unknown origin hyperkalemia is a life-threatening complication that can occur during general anesthesia. In healthy dogs, preanesthetic administration of dexmedetomidine in association with an opioid and followed by inhalation anesthesia of more than 1 hour duration may predispose to this complication. A sudden decrease in heart rate >90 minutes after dexmedetomidine administration, or ECG changes, may warrant measurement of blood potassium concentrations.

Evaluation of the perioperative analgesic effects of grapiprant compared with carprofen in dogs undergoing elective ovariohysterectomy.

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 ≥ 5/24. The noninferiority limit (NI) for the GCPS-SF was Δ = 3. The NI for vF was Δ = -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 CI for GCPS-SF was below the NI of 3 and the lower CI 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.

Effects of intravenous acepromazine and butorphanol on propofol dosage for induction of anesthesia in healthy Beagle dogs.

OBJECTIVE: To determine the effects of intravenous (IV) premedication with acepromazine, butorphanol or their combination, on the propofol anesthetic induction dosage in dogs. STUDY DESIGN: Prospective, blinded, Latin square design. ANIMALS: A total of three male and three female, healthy Beagle dogs, aged 3.79 ± 0.02 years, weighing 10.6 ± 1.1 kg, mean ± standard deviation. METHODS: Each dog was assigned to one of six IV treatments weekly: 0.9% saline (treatment SAL), low-dose acepromazine (0.02 mg kg-1; treatment LDA), high-dose acepromazine (0.04 mg kg-1; treatment HDA), low-dose butorphanol (0.2 mg kg-1; treatment LDB), high-dose butorphanol (0.4 mg kg-1; treatment HDB); and a combination of acepromazine (0.02 mg kg-1) with butorphanol (0.2 mg kg-1; treatment ABC). Physiologic variables and sedation scores were collected at baseline and 10 minutes after premedication. Then propofol was administered at 1 mg kg-1 IV over 15 seconds, followed by boluses (0.5 mg kg-1 over 5 seconds) every 15 seconds until intubation. Propofol dose, physiologic variables, recovery time, recovery score and adverse effects were monitored and recorded. Data were analyzed using mixed-effects anova (p < 0.05). RESULTS: Propofol dosage was lower in all treatments than in treatment SAL (4.4 ± 0.5 mg kg-1); the largest decrease was recorded in treatment ABC (1.7 ± 0.3 mg kg-1). Post induction mean arterial pressures (MAPs) were lower than baseline values of treatments LDA, HDA and ABC. Apnea and hypotension (MAP < 60 mmHg) developed in some dogs in all treatments with the greatest incidence of hypotension in treatment ABC (4/6 dogs). CONCLUSIONS AND CLINICAL RELEVANCE: Although the largest decrease in propofol dosage required for intubation was after IV premedication with acepromazine and butorphanol, hypotension and apnea still occurred.

Advanced Vascular Access in Small Animal Emergency and Critical Care.

In canine and feline patients presenting in a state of hemodynamic collapse, obtaining vascular access can be challenging. Delays in achieving vascular access interfere with delivery of patient care. In human medicine, definitions of difficult vascular access are variable and include the need for multiple placement attempts or involvement of specialized teams and equipment. Incidence and risk factors for difficult vascular access have not been well studied in veterinary patients, which limits understanding of how best to address this issue. Alternatives to percutaneous peripheral or central intravenous catheterization in dogs and cats include venous cutdowns, umbilical access in newborns, corpus cavernosum access in males, ultrasound-guided catheterization, and intraosseous catheterization. In recent years, advances in ultrasonography and intraosseous access techniques have made these more accessible to veterinary practitioners. These vascular access techniques are reviewed here, along with advantages, limitations, and areas for future study of each technique.

Agreement between oscillometric and direct blood pressure measurements in anesthetized captive chimpanzees (Pan troglodytes).

OBJECTIVE: To evaluate the level of agreement (LOA) between direct and oscillometric blood pressure (BP) measurements and the ability of oscillometric measurements to accurately detect hypotension in anesthetized chimpanzees (Pan troglodytes). ANIMALS: 8 captive, adult chimpanzees. PROCEDURES: During prescheduled annual examinations, each chimpanzee underwent general anesthesia and patient monitoring for their examination, echocardiography for a concurrent study, and measurement of direct BP with the use of tibial artery catheterization and oscillometry with the use of a cuff placed around a brachium and a cuff placed around the second digit of the contralateral forelimb for the present study. Bland-Altman plots were generated to compare results for direct and oscillometric BP measurements. Mean bias and 95% LOAs were calculated for oscillometric measurements of systolic arterial pressure (SAP), diastolic arterial pressure (DAP), and mean arterial pressure (MAP) for each cuff site. Sensitivity and specificity in detecting hypotension were also determined for each cuff site. RESULTS: There were 74 paired direct and brachial oscillometric measurements of each, SAP, MAP, and DAP and 66 paired direct and digit oscillometric measurements of each, SAP, MAP, and DAP. Only brachial oscillometric measurements of MAP had adequate sensitivity (78%) and specificity (95%) to accurately detect hypotension, and this technique also had the least mean bias (0.8 mm Hg; 95% LOA, -29 to 31 mm Hg). CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that brachial oscillometric measurement of MAP provided reasonable agreement with tibial arterial direct MAP measurement and performed well in diagnosing hypotension in anesthetized chimpanzees.

ECHOCARDIOGRAPHY AND DIRECT ARTERIAL BLOOD PRESSURE MEASUREMENT IN CAPTIVE CHIMPANZEES (PAN TROGLODYTES) DURING TWO PHASES OF AN ANESTHETIC PROTOCOL.

The effects of α-2 agonists on echocardiographic findings in great apes are not well documented, and knowledge of these effects would expand the understanding of cardiac examinations of chimpanzees under anesthesia with protocols using these drugs. Ten adult chimpanzees (Pan troglodytes), four males and six females, underwent echocardiographic examinations after anesthesia with dexmedetomidine, midazolam, and ketamine (phase 1). Four animals required isoflurane to achieve an adequate plane of anesthesia. Atipamezole was used to antagonize dexmedetomidine, and all remaining animals were placed on isoflurane (phase 2), and then a second echocardiogram was performed. Direct arterial blood pressure was monitored during the anesthetic event. Measurements and recordings were assessed for statistically significant differences between the two phases and sex. There were no significant differences between phases or sex for any two-dimensional echocardiographic measurement of systolic function, although interventricular septum thickness at end systole approached a significant decrease from phase 1 to phase 2 (P = 0.058) when sex was considered a between-subject factor. Left ventricular outflow tract (P = 0.017) and pulmonary artery (P = 0.028) velocities increased after reversal of the dexmedetomidine. Diastolic transmitral flow was consistent with grade 3 diastolic dysfunction (median early to late ventricular filling velocities (E/A) of 2.02, interquartile range [IQR], 1.53-2.13) with a nonsignificant decrease of E velocity and increase in A velocity and decreased E/A after reversal. Trace mitral and tricuspid regurgitation were common findings in the sample population. Arterial blood pressure significantly decreased between phase 1 and phase 2 (P < 0.01). All chimpanzees entered a hypotensive state (mean arterial pressure < 60 mm Hg) during phase 2. Although limited by the small number of chimpanzees, this study showed an increase in afterload, potential diastolic dysfunction, and a decrease in blood pressure after the antagonism of dexmedetomidine. Additional studies to further assess the effects of α-2 agonists in chimpanzees are warranted.

Influence of a novel scaffold composed of polyurethane, hydroxyapatite, and decellularized bone particles on the healing of fourth metacarpal defects in mares.

OBJECTIVE: To determine the effect of a novel scaffold, designed for use in bone regeneration, on healing of splint bone segmental defects in mares. STUDY DESIGN: In vivo experimental study. SAMPLE POPULATION: Five adult mares (4-10 years old; mean weight, 437.7 kg ± 29 kg). METHODS: Bilateral 2-cm full-thickness defects were created in the fourth metacarpal bones (MCIV) of each horse. Each defect was randomly assigned to either a novel scaffold treatment (n = 5) or an untreated control (n = 5). The scaffold was composed of polyurethane, hydroxyapatite, and decellularized bone particles. Bone healing was assessed for a period of 60 days by thermography, ultrasonography, radiography, and computed tomography (CT). Biopsies of each defect were performed 60 days after surgery for histological evaluation. RESULTS: On the basis of radiographic analysis, scaffold-treated defects had greater filling (67.42% ± 26.7%) compared with untreated defects (35.88% ± 32.7%; P = .006). After 60 days, CT revealed that the density of the defects treated with the scaffolds (807.80 ± 129.6 Hounsfield units [HU]) was greater than density of the untreated defects (464.80 ± 81.3 HU; P = .004). Evaluation of histology slides provided evidence of bone formation within an average of 9.43% ± 3.7% of the cross-sectional area of scaffolds in contrast to unfilled defects in which connective tissue was predominant throughout the biopsy specimens. CONCLUSION: The novel scaffold was biocompatible and supported bone formation within the MCIV segmental defects. CLINICAL SIGNIFICANCE: This novel scaffold offers an effective option for filling bone voids in horses when support of bone healing is indicated.

TRANSCUTANEOUS OXYGEN MONITORING IN LOUISIANA PINE SNAKES (PITUOPHIS RUTHVENI).

Hypoxic physiological states may occur during anesthetic events of snakes but accurate monitoring of oxygenation is challenging. Oxygenation levels of nine Louisiana pine snakes (Pituophis ruthveni) were assessed using transcutaneous regional oxygen saturation (rSO2) at the level of the liver (rSO2Liver) and at the halfway point of the body (rSO2Half ). Reflectance pulse oximetry measured SpO2, with a sensor overlying the heart. Values were compared with the venous partial pressure of oxygen (PvO2). Measurements were taken during four phases, simulating an anesthetic event: phase 1, breathing room air; phase 2, while supplied with supplemental oxygen via face mask; phase 3, during ketamine and dexmedetomidine sedation; and phase 4, after receiving atipamezole. There were no significant changes in any oxygenation parameters between concurrent phases, but respiratory rate significantly decreased (P = 0.02) between phases 1 and 2. Strong positive associations were found between both rSO2Liver and rSO2Half when compared with PvO2 irrespective of phase (r = 0.72, r = 0.63 respectively), but not with SpO2 (r = 0.3). Strength of correlation varied with each phase but was uniformly strongest for rSO2Liver. The measurement of rSO2 appears superior compared with traditional pulse oximetry for assessing oxygenation levels of snakes.

POTENTIAL FOR ELECTROENCEPHALOGRAPHIC MONITORING OF ANESTHETIC DEPTH IN CAPTIVE CHIMPANZEES (PAN TROGLODYTES) USING A NOVEL BRAIN FUNCTION MONITOR.

The electroencephalogram (EEG) waveform can predictably change with depth of anesthesia, and algorithms such as the Patient State index (PSi) have been developed to convert the waveform into a user-friendly objective reading of anesthetic depth. In this study, PSi values were measured in 10 captive chimpanzees (Pan troglodytes) during three phases of an anesthetic event. Phase 1 included sedation with dexmedetomidine, midazolam, and ketamine. Phase 2 started with administration of an α-2 antagonist and isoflurane. Phase 3 started with discontinuing isoflurane and ended with spontaneous movement and extubation. Initial PSi readings for phase 1 were high at 74.5 ± 12.2 (mean ± SD), before declining to 24.1 ± 5.3 for the remainder of the phase. Phase 2 PSi values were recorded as 21.4 ± 5.4 and then climbed during phase 3. Spontaneous movement was recorded at PSi values of 72 to 79. Electroencephalographic monitoring via PSi was successfully performed during three phases of anesthesia in the chimpanzees and was consistent with human values reported during general anesthesia. This paper serves as a preliminary investigation into EEG monitoring of chimpanzees, and further work is needed for its validation.

ECHOCARDIOGRAPHIC PARAMETERS IN EIGHT ADULT TIGERS ( PANTHERA TIGRIS) DURING TWO PHASES OF AN ANESTHETIC PROTOCOL.

Eight adult tigers ( Panthera tigris) underwent a complete echocardiographic examination following sedation with medetomidine, midazolam, and induction of general anesthesia using ketamine and isoflurane (phase 1). Atipamezole was used to antagonize medetomidine (phase 2) and a second echocardiographic examination was performed. Physiologic tricuspid and pulmonic regurgitations were common findings in the sample population and one tiger was excluded from final analyses due to the finding of a ventricular septal defect. Measurements and mean arterial pressure were assessed for statistically significant differences between the two examination phases as well as gender and weight. There was a statistically significant difference between interventricular septum thickness at end systole, ejection fraction, and mean arterial pressure between anesthetic phases while fractional shortening and left ventricular internal dimension at end-systole approached, but did not reach, statistical significance between phases. Weight was found to be a statistically significant predictor of stroke volume and left ventricular internal dimension at end-diastole. The echocardiographic measurements obtained during this study can be used as guidelines for future examinations in adult tigers. The effects of medetomidine on these measurements and systolic function should be taken into account when performing echocardiograms and monitoring anesthetic events.

Use of plethysmographic variability index and perfusion index to evaluate changes in arterial blood pressure in anesthetized tigers (Panthera tigris).

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 for 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.

Effect of dexmedetomidine on the minimum infusion rate of propofol preventing movement in dogs.

OBJECTIVE: To determine the effect of dexmedetomidine on induction dose and minimum infusion rate of propofol preventing movement (MIRNM). STUDY DESIGN: Randomized crossover, unmasked, experimental design. ANIMALS: Three male and three female healthy Beagle dogs weighing 10.2 ± 2.8 kg. METHODS: Dogs were studied on three occasions at weekly intervals. Premedications were 0.9% saline (treatment P) or dexmedetomidine (1 µg kg-1, treatment PLD; 2 µg kg-1, treatment PHD) intravenously. Anesthesia was induced with propofol (2 mg kg-1 and then 1 mg kg-1 every 15 seconds) until intubation. Anesthesia was maintained for 90 minutes in P with propofol (0.5 mg kg-1 minute-1) and saline, in PLD with propofol (0.35 mg kg-1 minute-1) and dexmedetomidine (1 µg kg-1 hour-1), and in PHD with propofol (0.3 mg kg-1 minute-1) and dexmedetomidine (2 µg kg-1 hour-1). The stimulus (50 V, 50 Hz, 10 ms) was applied to the antebrachium, and propofol infusion was increased or decreased by 0.025 mg kg-1 minute-1 based on a positive or negative response, respectively. Data were analyzed using a mixed-model anova and presented as mean ± standard error. RESULTS: Propofol induction doses were 8.68 ± 0.57 (P), 6.13 ± 0.67 (PLD) and 4.78 ± 0.39 (PHD) mg kg-1 and differed among treatments (p < 0.05). Propofol MIRNM values were 0.68 ± 0.13, 0.49 ± 0.16 and 0.26 ± 0.05 mg kg-1 minute-1 for P, PLD and PHD, respectively. Propofol MIRNM decreased 59% in PHD (p < 0.05). Plasma propofol concentrations were 14.04 ± 2.30 (P), 11.30 ± 4.30 (PLD) and 7.96 ± 0.72 (PHD) µg mL-1 and dexmedetomidine concentrations were 0.68 ± 0.12 (PLD) and 0.89 ± 0.08 (PHD) ng mL-1 at MIRNM determination. CONCLUSIONS AND CLINICAL RELEVANCE: Dexmedetomidine (1 and 2 µg kg-1) decreased propofol induction dose. Dexmedetomidine (2 µg kg-1 hour-1) resulted in a significant decrease in propofol MIRNM.

Campylobacter colonization of the chicken induces a proinflammatory response in mucosal tissues.

Campylobacter jejuni is a major cause of human inflammatory enteritis, but colonizes the gastrointestinal tract of poultry to a high level in a commensal manner. In vitro, C. jejuni induces the production of cytokines from both human and avian-model epithelial cell and macrophage infections. This suggests that, in vivo, Campylobacter could induce proinflammatory signals in both hosts. We investigated whether a proinflammatory cytokine response can be measured in both day-of-hatch and 2-week-old Light Sussex chickens during infection with C. jejuni. A significant induction of proinflammatory chemokine transcript was observed in birds of both ages, compared with levels in mock-infected controls. This correlated with an influx of heterophils but was not associated with any pathology. These results suggest that in poultry there may be a controlled inflammatory process during colonization.