The efficacy of alfaxalone for immersion anesthesia in koi carp (Cyprinus carpio)

ObjectiveTo characterize the physiologic and behavioral effects of a single induction dose and two maintenance doses of alfaxalone delivered by water immersion in the anesthesia of koi (Cyprinus carpio).Study designProspective, within-subject complete crossover design.AnimalsSix adult koi (Cyprinus carpio) with a median body weight of 344.5 g (range 292.0–405.0 g).MethodsKoi were immersed in water containing 10 mg L^?1 alfaxalone until immobile and then maintained with alfaxalone at either 1 or 2.5 mg L^?1 via a recirculating water system. Times for anesthetic induction and recovery periods were recorded. Physiologic and blood gas parameters were evaluated before, during and after the anesthetic trial. Response to noxious stimuli was also assessed.ResultsMedian anesthesia induction time for all fish was 5.4 minutes. Median recovery time was 11.8 and 26.4 minutes in the 1.0 and 2.5 mg L^?1 doses, respectively, which were significantly different (p = 0.04). Cessation of opercular movement occurred in 0/6 and 4/6 fish exposed to 1.0 and 2.5 mg L^?1 dose respectively. No difference was observed in median heart rate over the duration of the anesthetic events. Response to noxious stimulation was 4/6 and 0/6 in the 1.0 and 2.5 mg L^?1 doses respectively. Oxygenation and ventilation did not change during the experiment, but there was a significant decrease in blood pH along with an increase in blood lactate concentration.Conclusion and clinical relevanceAdministration of alfaxalone, via water immersion, as an induction and maintenance anesthesia agent provided rapid and reliable anesthesia of koi with no mortality. The maintenance dose of 2.5 mg L^?1 was sufficient to prevent response to noxious stimuli but was associated with a clinically relevant depression in opercular rate.     

Analysis of Short-Term Cortisol Stress Response in Channel Catfish by Anesthetization with Metomidate Hydrochloride and Tricaine Methanesulfonate

The ability of the anesthetics metomidate hydrochloride and tricaine methanesulfonate (MS-222) to mitigate the cortisol stress response of Channel Catfish Ictalurus punctatus was evaluated during a 10-min confinement stress. The cortisol concentrations of Channel Catfish anesthetized in metomidate hydrochloride remained consistent throughout the 10-min exposure; however, for fish anesthetized with MS-222 and nonanesthetized fish, cortisol concentrations were approximately 7- and 22-fold higher, respectively, than the baseline concentrations. While both anesthetics reduced cortisol concentrations relative to those of nonanesthetized fish, these results suggest that MS-222 is an appropriate anesthetic to use during the initial 5 min of sedation and that metomidate hydrochloride is appropriate for longer periods of sedation.

Received November 18, 2014; accepted April 9, 2015     

A COMPARISON OF ALFAXALONE AND TRICAINE METHANESULPHONATE (MS-222) IN TWO FISH SPECIES

The purpose of this study was to evaluate the effectiveness of the alfaxalone formulation Alfaxan? as an immersion anesthetic in tropical fish species compared to that of tricaine methanesulfonate (MS-222). 22 black spot barbs (Puntius filamentosis) measuring (mean±SD) 11.4 ±1.4 cm in body length and 22 peacock cichlids (Aulonocara spp.) (measuring 8.4 ± 1.6cm were anesthetized in water baths containing 100 mg/L of MS-222 buffered with 200 mg/L of bicarbonate or 5 mg/L of alfaxalone following a 2-week washout period. Time to maximum effect, recovery periods, self-righting, spontaneous swimming movements, opercular movements, and response to noxious stimuli were recorded. The following results are for the black spot barbs following MS-222 and alfaxalone anesthesia, respectively: mean times (±SD) to surgical anesthesia were 5.5 ± 2.11 and 3.27 ± 1.72 minutes and mean recovery times were 2.95 ± 0.9 and 9.14 ± 3.15 minutes. The peacock cichlid anesthetic protocols for MS-222 (20 of 22 cichlids) and alfaxalone (20 of 21 cichlids) produced the following results, respectively: mean times (±SD) to surgical anesthesia were 14.75 ±5.43 and 11.1 ± 9.84 minutes and mean recovery times were 3.6 ±0.82 and 22.4 ±11.3 minutes. Median recovery time from 5 mg/L alfaxalone was significantly longer (P < 0.001) in both species, by 5 minutes for black spot barbs and by 17 minutes for peacock cichlids. Variation in induction and recovery times between species was observed, with black spot barbs having significantly (P < 0.0001) faster induction times when treated with both drugs, and a faster recovery time from 5 mg/L alfaxalone.     

Effects of isoflurane,sevoflurane and methoxyflurane on the electroencephalogram of the chicken

ObjectiveAnaesthetics have differing effects on mammalian electroencephalogram (EEG) but little is known about the effects on avian EEG. This study explored how inhalant anaesthetics affect chicken EEG.Study designExperimental study.AnimalsTwelve female Hyline Brown chickens aged 6–11 weeks.MethodsEach chicken was anaesthetized with isoflurane, sevoflurane, and methoxyflurane. For each, anaesthesia was adjusted to 1, 1.5 and 2 times Minimum Anaesthetic Concentration (MAC). Total Power (Ptot), Median Frequency (F50), Spectral Edge Frequency (F95) and Burst Suppression Ratio (BSR) were calculated at each volume concentration. BSR data were analyzed using doubly repeated measures anova. Neither isoflurane nor sevoflurane could be included in analysis of F50, F95 and Ptot because of extensive burst suppression; Methoxyflurane data were analyzed using RM anova.ResultsThere was a significant interaction between anaesthetic and concentration on BSR [F(4,22) = 10.65, p < 0.0001]. For both isoflurane and sevoflurane, BSR increased with concentration. Isoflurane caused less suppression than sevoflurane at 1.5 MAC and at final 1 MAC while methoxyflurane caused virtually no burst suppression. Methoxyflurane concentration had a significant effect on F50 [F(2,20) = 3.83, p = 0.04], F95 [F(2,20) = 4.03, p = 0.03] and Ptot [F(2,20) = 5.22, p = 0.02]. Decreasing methoxyflurane from 2 to 1 MAC increased F50 and F95. Ptot increased when concentration decreased from 1.5 to 1 MAC and tended to be higher at 1 MAC than at 2 MAC.Conclusions and Clinical relevanceIsoflurane and sevoflurane suppressed chicken EEG in a dose-dependent manner. Higher concentrations of methoxyflurane caused an increasing degree of synchronization of EEG. Isoflurane and sevoflurane suppressed EEG activity to a greater extent than did methoxyflurane at equivalent MAC multiples. Isoflurane caused less suppression than sevoflurane at intermediate concentrations. These results indicate the similarity between avian and mammalian EEG responses to inhalant anaesthetics and reinforce the difference between MAC and anaesthetic effects on brain activity in birds.     

Effects of continuous intravenous infusion of morphine and morphine‐tramadol on the minimum alveolar concentration of sevoflurane and electroencephalographic entropy indices in dogs

ObjectiveTo compare the effects of continuous rate infusions (CRIs) of intravenous (IV) morphine and morphine-tramadol on the minimum alveolar concentration (MAC) of sevoflurane, and on electroencephalographic entropy indices in dogs.DesignProspective study.AnimalsEight young, healthy German shepherds, weighing 26.3 ± 3.1 kg (mean ± SD).MethodsAnaesthesia was induced and maintained with sevoflurane. A standard tail-clamp technique was used for MAC determination. Within one anaesthetic period, MAC was first determined during sevoflurane anaesthesia alone (MAC_B); then during morphine infusion (MAC_M), (loading dose 0.5 mg kg⁻¹IM; CRI, 0.2 mg kg⁻¹hour⁻¹⁾ then finally during morphine-tramadol infusion (tramadol loading dose 1.5 mg kg⁻¹IV; CRI, 2.6 mg kg⁻¹ hour⁻¹) (MAC_MT). At each change, periods of 45 minutes were allowed for equilibration. Stated entropy (SE), response entropy (RE), and RE-SE differences were measured five minutes prior to and during tail clamping.ResultsThe MAC_B was 2.1 ± 0.3vol%. The morphine and morphine-tramadol infusions reduced MAC to 1.6 ± 0.3vol% and 1.3 ± 0.3vol%, respectively. MAC was decreased below baseline more during morphine-tramadol than during morphine alone (39 ± 9% versus 25 ± 6%, respectively; p = 0.003). All SE and RE and most RE-SE differences were increased significantly (p < 0.05) over pre-stimulation in all groups when the dogs responded purposefully to noxious stimulation. When no response to noxious stimulation occurred, the entropy indices did not change.Conclusion and clinical relevanceIn dogs, combined morphine-tramadol CRI decreased sevoflurane MAC more than morphine CRI alone. Entropy indices changed during nociceptive responses in anaesthetized animals, suggesting that entropy measurements may be useful in determining anaesthetic depth in dogs.     

Efficacy of benzocaine as an anaesthetic for Crucian carp (Carassius carassius)

ObjectiveTo investigate the anaesthetic induction time and concentrations of stress markers in Crucian carp (Carassius carassius) subjected to different concentrations of benzocaine.Study designProspective experimental study.AnimalsThirty-six Crucian carp [body weight 368.3 ± 22.7 g and length 28.1 ± 1.9 cm (mean ± SD)].MethodsFish were divided into four groups, initially with nine fish per group. Each group was subjected to one of four final concentrations [0, 25, 50 and 100 parts per million (p.p.m.)] of benzocaine. The times to induction of sedation, to pre-anaesthesia and to anaesthesia were recorded according to the behavioural events observed after exposing the fish to benzocaine. At each stage, blood was collected from the caudal vein of three fish of the group, and these three fish were then euthanized. Plasma cortisol and glucose concentrations in the blood samples were measured as indices of stress response.ResultsInduction times for all stages of anaesthesia decreased significantly with increasing concentrations of benzocaine (1678 ± 103, 475 ± 73 and 251 ± 2 seconds for anaesthesia in 25, 50 and 100 p.p.m., respectively). Plasma cortisol and glucose concentrations were significantly lower in the anaesthetized groups than the control group (p < 0.05), and tended to decrease with an increasing dose of benzocaine. The cortisol concentrations (36.1 ± 5.8 ng dL^?1) at the anaesthetic stage for the 100 p.p.m. group were significantly decreased compared with the other groups (67.3 ± 14.9 ng dL^?1 in 25 p.p.m. and 47.6 ± 2.6 ng dL^?1 in 50 p.p.m.). Differences in glucose concentrations between benzocaine-treated groups were not significant.Conclusions and clinical relevanceIn this study, the fish group exposed to 100 p.p.m. benzocaine had a fast induction time for all monitored stages, low circulating cortisol and glucose concentrations and no immediate mortality.     

Surgical removal of an ovarian tumour in a koi carp (Cyprinus carpio)

Ultrasonography, radiography and exploratory coeliotomy were used to diagnose and treat a large intracoelomic neoplasm from a female koi carp (Cyprinus carpio) presented for abdominal enlargement of several months duration. Feed was withheld for 1 week immediately prior to surgery and the fish was sedated with isoeugenol (AQUI-S) at a dose rate of 10 mL/L to facilitate diagnostic imaging techniques. Surgical anaesthesia was induced by adding tricaine (MS-222) 50 mg/L to the water and an exploratory coeliotomy and tumour removal was performed. The fish was allowed to recover in fresh water at 18 degrees C and salt was added slowly to the water over a period of 1 hour to a concentration of 5 g/L This concentration was maintained in a recovery pond for 1 week postoperatively. Enrofloxacin was administered intramuscularly (10 mg/kg) immediately, 3 days and 1 week postoperatively. A diagnosis of undifferentiated ovarian carcinoma was made on the basis of the histological appearance of the neoplasm and immunohistochemical staining.     

Development of a minimum-anesthetic-concentration depression model to study the effects of various analgesics in goldfish (Carassius auratus)

Teleost fish demonstrate the neurophysiologic capacity to experience pain and analgesia. A common model for assessing analgesic effect is the reduction of minimum anesthetic concentration (MAC). The present study adapted the model of MAC depression to evaluate the analgesic effects of morphine, butorphanol, medetomidine, and ketoprofen in goldfish (Carassius auratus). MAC was determined by an up-down method of sequential population sampling, anesthetizing fish with tricaine methanesulfonate (MS-222) in concentration increments of 10 parts per million (ppm), and using intramuscular needle insertion as a supramaximal noxious stimulus. Baseline MAC was determined in triplicate at the beginning (MACi) and conclusion (MACe) of the experiment (approximately 60 days). For drug trials, MAC was redetermined 1 hr after administration of morphine (10, 20, 40 mg/kg i.m.), butorphanol (0.1, 0.2, 0.4 mg/kg i.m.), medetomidine (0.01, 0.015, 0.025 mg/kg i.m.), ketoprofen (0.5, 1.0, 2.0 mg/kg i.m.), or saline control. Each drug/dose was tested in random order with a > 6-day washout period. MACi and MACf were 163 and 182 ppm, respectively, and were significantly different from each other (P = 0.02). All doses of morphine and ketoprofen decreased MAC below MACi. The highest dose of medetomidine decreased MAC below MACi. The lowest dose of butorphanol decreased MAC below MACi, but higher doses increased MAC above MACf. The authors conclude that MAC determination in fish using MS-222 was feasible and reproducible in the short term. The fact that MAC increased over time and/or exposure may limit the usefulness of MS-222 in MAC depression studies. Morphine and ketoprofen decrease anesthetic needs in goldfish and may provide analgesia.     

Evaluation of Emamectin Benzoate for the Control of Experimentally Induced Infestations of Argulus sp. in Goldfish and Koi Carp

Abstract

The effect of 0.2% emamectin benzoate (SLICE; Intervet/ Schering-Plough Animal Health, Roseland, New Jersey) administered in top-dressed, pelleted commercial fish feed was evaluated for control of freshwater Argulus sp. in goldfish Carassius auratus and koi carp, a variant of common carp Cyprinus carpio, in freshwater aquaria at 24–25°C. Sixteen individually housed goldfish were each exposed to 37 Argulus. The number of fish lice attached to each fish at the start of the experiment was not determined; however, the total number of motile fish lice in each aquarium (on fish and in the water) was determined at the start and end of each experiment. Eight goldfish were fed the control diet (0 μg · kg fish biomass^?1 · d^?1) and eight were fed the medicated diet (50 μg · kg fish biomass^?1 · d^?1) for seven consecutive days. After treatment, fish louse infestation in controls was 20.5 ± 1.5 (mean ± SE) lice per fish. No Argulus were found on fish in the treated group. In a separate experiment, 10 individually housed koi were each exposed to 128 Argulus. Five koi were fed the control diet and five were fed a low-dose medicated diet (5 μg · kg fish biomass^?1 · d^?1) for 7 d. After treatment, fish louse infestation among the controls was 14.6 ± 3.8 lice per koi. No Argulus were found on koi in the treated group. Hence, a 7-d regimen of oral emamectin benzoate controlled experimental infestation of Argulus when administered to goldfish at 50 μg · kg fish biomass^?1 · d^?1 and to koi at 5 μg · kg fish biomass^?1 · d^?1.

Received March 24, 2010; accepted January 17, 2011     

Retrospective study of the perioperative management and complications of ureteral obstruction in 37 cats

ObjectivesTo describe perioperative management and complications, risk factors and mortality rates in cats anaesthetized for treatment of ureteral obstruction.Study designRetrospective, clinical, cohort study.AnimalsThirty-seven client-owned cats anaesthetized for ureteral surgery.MethodsRecords with sufficient data for cats treated between March 2010 and March 2013 were examined for breed, age, gender, history, concurrent diseases, pre- and post-anaesthetic biochemical and haematological parameters, American Society of Anesthesiologists classification, anaesthetic protocol, surgical technique, surgeon, perioperative complications and mortality within 48 hours after extubation. Associations between risk factors and outcome variables were evaluated using univariable analysis. Odds ratios and 95% confidence intervals were calculated for significant parameters. Sensitivity and specificity using receiving operator characteristic curve analysis were calculated for creatinine, potassium level and standard base excess (SBE) to denote survival or non-survival.ResultsPreoperatively, all cats were azotaemic: mean ± SD urea was 31.6 ± 26.9 mmol L⁻¹ and median (range) creatinine was 562 μmol L⁻¹ (95 μmol L⁻¹ to off scale). Thirteen cats were hyperkalaemic (K⁺ > 6.5 mmol L⁻¹). Anaesthesia-related complications included bradycardia (n = 8, 21.6%), hypotension (n = 15, 40.5%) and hypothermia (n = 32, 86.5%). Seven cats (18.9%) died postoperatively. Non-survivors were significantly (p = 0.011) older (9.8 ± 1.9 years) than survivors (6.4 ± 3.1 years) and had higher potassium concentrations (p = 0.040). Risk factors associated with mortality were ASA classes IV and V (p = 0.022), emergency procedures (p = 0.045) and bicarbonate administration (p = 0.002). Non-survivors had higher creatinine concentrations (p = 0.021) and lower SBE (p = 0.030).Conclusion and clinical relevanceIntraoperative anaesthetic complications were common; increased age, poor health status, preoperative bicarbonate administration, hyperkalaemia and increased creatinine were associated with increased risk for death and can be used to predict risk for complications.     

Pharmacokinetics and pharmacodynamic effects in koi carp (Cyprinus carpio) following immersion in propofol

Objective

To test the hypothesis that plasma propofol concentration (PPC) is associated with anesthetic effect in koi carp administered propofol by immersion.

The effect of three anaesthetic protocols on the stress response in cane toads (Rhinella marina)

ObjectiveThree anaesthetics (MS222, clove oil and a mixture of ketamine/diazepam) were administered to cane toads to determine their effect on the hypothalamic-pituitary-adrenal (HPA) axis. Time to induction and recovery and any adverse events were also evaluated.Study designProspective randomized experimental trial.AnimalsThirty adult male cane toads (Rhinella marina) with body mass ranging between 130 and 250 g were captured from the field.MethodsThree groups of 10 toads were anaesthetized with ketamine (200 mg kg^?1) and diazepam (0.2 mg kg^?1) by intramuscular injection, MS222 (3 g L^?1) or clove-oil (0.3 mL L^?1) both by immersion. Blood samples were collected to determine plasma corticosterone concentrations. Induction and recovery time were recorded in each treatment. After full recovery animals were euthanized and a complete post-mortem examination was performed.ResultsSignificant differences were found in the activation of the HPA axis and in the times of induction and recovery between treatments (p < 0.001). Animals anaesthetized with clove-oil had the highest levels of corticosterone in plasma (42.5 ± 21.6 ng mL^?1). No differences were found between ketamine/diazepam (15.0 ± 13.3 ng mL^?1) and MS222 (22.0 ± 13.6 ng mL^?1) groups. The mean ± SD induction (minutes) and recovery (hours) times respectively were; ketamine/diazepam 66.5 ± 11 and 8 ± 3, clove oil 39 ± 12 and 7.6 ± 3, and MS222 42.5 ± 11 and 1.5 ± 0.5. Clove oil exposure had 30% mortality. Death followed a period of respiratory distress with changes consistent with non-cardiogenic oedema observed at post-mortem examination.Conclusions and Clinical relevanceBased on shorter induction and recovery times and minimal activation of HPA, MS222 is the anaesthetic of choice in cane toads. If it is not possible to use immersion methods of anaesthesia, ketamine/diazepam can be used but induction and recovery times are prolonged. Clove oil had unacceptable mortality in this study and should be used with extreme caution.     

Sedative and analgesic effects of romifidine in camels (Camelus dromedarius)

ObjectiveTo evaluate the clinical effectiveness and the sedative and analgesic effects of intravenous (IV) romifidine in camels.Study designRandomized prospective study.AnimalsEighteen healthy adult Dromedary camels.MethodsRomifidine was administered IV to camels (n = 6) at three different doses (40, 80 or 120 μg kg^?1). Time of onset, degree and duration of sedation and analgesia were recorded immediately after drug administration. Heart rate, respiratory rate, ruminal contractions, muscle relaxation, response to auditory and tactile stimulation, distance between ears, distance from lower lip to the ground, and degree of ataxia were also recorded pre-administration and at 5, 15, 30, 45, 60, 90, 120 and 180 minutes post-administration. Plasma glucose, blood urea nitrogen and creatinine were measured.ResultsRomifidine produced dose dependent sedation and analgesia. Significant decreases in heart rate (p < 0.001), ruminal contractions (p < 0.05), distance from lower lip to the ground (p < 0.001), response to auditory and tactile stimuli (p < 0.01), and significant increases in the degree of ataxia (p < 0.01), distance between the ear tips (p < 0.001) and blood glucose (p < 0.01) concentration were recorded after administration of romifidine until recovery. However, no significant changes in rectal temperature and respiratory rate were recorded.Conclusions and clinical relevanceIntravenous administration of romifidine at three different doses appeared to be an effective sedative and analgesic agent for camels. Bradycardia, ruminal atony, and hyperglycemia were the most important adverse effects after IV administration of romifidine. The IV administration of romifidine at a dose rate of 120 μg kg^?1 caused profound sedation and analgesia. Romifidine could be used for chemical restraint for a variety of diagnostic and minor surgical procedures in camels.     

A comparison of the pharmacodynamic effects of intravenous ketamine–xylazine with alfaxalone in mute swans (Cygnus olor) presenting at a wildlife veterinary hospital

ObjectiveTo compare effects of intravenous (IV) alfaxalone with ketamine–xylazine combination on anaesthetic induction, recovery and cardiopulmonary variables in mute swans.Study designRandomized, controlled, clinical study.AnimalsA group of 58 mute swans.MethodsSwans were given either alfaxalone (10 mg kg^–1; group A) or a combination of ketamine (12.5 mg kg^–1) and xylazine (0.28 mg kg^–1) (group KX) IV. Heart and respiratory rates, end-tidal carbon dioxide and peripheral haemoglobin oxygen saturation were recorded at 5 minute intervals during anaesthesia. Time from anaesthetic induction to intubation, from cessation of isoflurane to extubation, to lifting head, sternal recumbency and absence of head/neck ataxia were recorded. Anaesthetic and recovery quality were scored (1 = very poor; 5 = excellent). Data are presented as median (interquartile range). Significance was set at p < 0.05.ResultsIn group A, 44% (12/27) of swans required mechanical ventilation for 2–14 minutes versus 3.2% (1/31) of swans in group KX (p = 0.0002). Heart rate was higher in group A than in group KX [146 (127–168) versus 65.5 (56–78) beats minute^–1, respectively; p < 0.0001]. The isoflurane concentration required to maintain anaesthesia was higher in group A than in group KX [2.5% (2.0–3.0%) versus 1.5% (1.0–2.0%), respectively; p = 0.0001]. Time from cessation of isoflurane administration to lifting head was significantly longer in group A than in group KX [12 (9–17) versus 6 (4–7.75) minutes, respectively; p < 0.0001]. Anaesthesia quality scores were significantly better in group KX than in group A [4 (4–5) versus 4 (3–4), respectively; p = 0.0011], as were recovery scores [4 (3–5) versus 2 (2–3), respectively; p = 0.0005].Conclusions and clinical relevanceAlfaxalone is a suitable anaesthetic induction agent for use in mute swans. There is a greater incidence of postinduction apnoea and a higher incidence of agitation on recovery with alfaxalone than with ketamine–xylazine.     

Effects of propofol on isoflurane minimum alveolar concentration and cardiovascular function in mechanically ventilated goats

ObjectiveTo evaluate the effects of propofol, on isoflurane minimum alveolar concentration (MAC) and cardiovascular function in mechanically ventilated goats.Study designProspective, randomized, crossover experimental study.AnimalsSix goats, three does and three wethers.MethodsGeneral anaesthesia was induced with isoflurane in oxygen. Following endotracheal intubation, anaesthesia was maintained with isoflurane in oxygen. Intermittent positive pressure ventilation was applied. Baseline isoflurane MAC was determined, the noxious stimulus used being clamping a claw. The goats then received, on separate occasions, three propofol treatments intravenously: bolus of 0.5 mg kg^?1 followed by a constant rate infusion (CRI) of 0.05 mg kg^?1 minute^?1 (treatment LPROP); bolus of 1.0 mg kg^?1 followed by a CRI of 0.1 mg kg^?1 minute^?1 (treatment MPROP), bolus of 2.0 mg kg^?1 followed by a CRI of 0.2 mg kg^?1 minute^?1 (treatment HPROP). Isoflurane MAC was re-determined following propofol treatments. Plasma propofol concentrations at the time of MAC confirmation were measured. Cardiopulmonary parameters were monitored throughout the anaesthetic period. Quality of recovery was scored. The Friedman test was used to test for differences between isoflurane MACs. Medians of repeatedly measured cardiovascular parameters were tested for differences between and within treatments using repeated anova by ranks (p < 0.05 for statistical significance).ResultsIsoflurane MAC [median (interquartile range)] was 1.37 (1.36–1.37) vol%. Propofol CRI significantly reduced the isoflurane MAC, to 1.15 (1.08–1.15), 0.90 (0.87–0.93) and 0.55 (0.49–0.58) vol% following LPROP, MPROP and HPROP treatment, respectively. Increasing plasma propofol concentrations strongly correlated (Spearman rank correlation) with decrease in MAC (Rho = 0.91). Cardiovascular function was not affected significantly by propofol treatment. Quality of recovery was satisfactory.Conclusions and clinical relevanceIn goats, propofol reduces isoflurane MAC in a dose-dependent manner with minimal cardiovascular effects.     

Effect of anaesthesia on cell-mediated immunity in dogs undergoing mastectomy for mammary cancer

ObjectiveTo investigate if anaesthesia for canine cancer mastectomy further influences host cell-mediated immunity (CMI) promoting cancer progression.Study designA randomized, controlled, blinded clinical study.AnimalsA total of 20 bitches with malignant mammary tumours of clinical stage II or III undergoing the same type of mastectomy (regional mastectomy).MethodsDogs were randomly allocated to one of two anaesthetic groups (10 per group). The anaesthetic protocol of group A used minimally immunosuppressive drugs (tramadol, robenacoxib, propofol), whereas that of group B (control) used more immunosuppressive drugs (morphine, fentanyl, thiopental, isoflurane). For each animal, measurements of white blood cells (WBCs), neutrophils and lymphocytes, and flow cytometric assessment of T cells (CD3⁺), helper T cells (CD4⁺), cytotoxic T cells (CD8⁺) and CD5^low+ T cells were performed prior to anaesthesia (day 0) and on days 3 and 10 postsurgery. Data were analysed using a General Linear Model for repeated measures and presented as mean ± standard deviation, p ≤ 0.05.ResultsIn all animals, on day 3, WBCs and neutrophils were significantly increased (p < 0.0005), while flow cytometry revealed significantly decreased relative percentages of T cells (CD3⁺) (p = 0.003) and their subpopulations CD4⁺ (p = 0.006), CD8⁺ (p = 0.029) and CD5^low+ (p = 0.031). Specifically, on day 3, the cytotoxic T cells (CD8⁺) were significantly decreased (p = 0.05) only in group B, whereas the CD4⁺ (p = 0.006) and CD5^low+ (p = 0.008) T cells in group A. The only significant difference between groups was found preoperatively in the CD4⁺/CD8⁺ ratio, which was higher in group A (p = 0.006).Conclusions and clinical relevanceIn dogs with mammary cancer undergoing regional mastectomy, a significant decrease in components of CMI was observed on day 3 postsurgery in both anaesthetic groups. Some indication, however, for better preserved cellular immunity by less immunosuppressive anaesthetic/analgesic drugs was detected, rendering their use advisable.     

Evaluation of an extended‐release formulation of ceftiofur crystalline‐free acid in koi (Cyprinus carpio)

The use of an extended release ceftiofur crystalline‐free acid formulation (CCFA, Excede For Swine^®, Pfizer Animal Health) in koi was evaluated after administration of single intramuscular (i.m.) or intracoelomic (i.c.) doses. Twenty koi were divided randomly into a control group and four treatment groups (20 mg/kg i.m., 60 mg/kg i.m., 30 mg/kg i.c., and 60 mg/kg i.c.). Serum ceftiofur‐free acid equivalents (CFAE) concentrations were quantified. The pharmacokinetic data were analyzed using a nonlinear mixed‐effects approach. Following a CCFA injection of 60 mg/kg i.m., time durations that serum CFAE concentrations were above the target concentration of 4 μg/mL ranged from 0.4 to 2.5 weeks in 3 of 4 fish, while serum CFAE concentrations remained below 4 μg/mL for lower doses evaluated. Substantial inter‐individual variations and intra‐individual fluctuations of CFAE concentrations were observed for all treatment groups. Histological findings following euthanasia included aseptic granulomatous reactions, but no systemic adverse effects were detected. Given the unpredictable time vs. CFAE concentration profiles for treated koi, the authors would not recommend this product for therapeutic use in koi at this time. Further research would be necessary to correlate serum and tissue concentrations and to better establish MIC data for Aeromonas spp. isolated from naturally infected koi.     

The effect of maropitant on intraoperative isoflurane requirements and postoperative nausea and vomiting in dogs: a randomized clinical trial

ObjectiveTo establish if preoperative maropitant significantly reduced intraoperative isoflurane requirements and reduced clinical signs associated with postoperative nausea and vomiting (PONV) in dogs.Study designRandomized clinical trial.AnimalsTwenty-four healthy, client-owned dogs undergoing routine ovariohysterectomy.MethodsPremedication involved acepromazine (0.03 mg kg⁻¹) combined with methadone (0.3 mg kg⁻¹) intramuscularly 45 minutes before anaesthetic induction with intravenous (IV) propofol, dosed to effect. Meloxicam (0.2 mg kg⁻¹) was administered intravenously. Dogs were randomly assigned to administration of saline (group S; 0.1 mL kg⁻¹, n = 12) or maropitant (group M; 1 mg kg⁻¹, n = 12) subcutaneously at time of premedication. Methadone (0.1 mg kg⁻¹ IV) was repeated 4 hours later. Anaesthesia was maintained with isoflurane in oxygen, dosed to effect by an observer unaware of group allocation. The dogs were assessed hourly, starting 1 hour postoperatively, using the short form of the Glasgow Composite Pain Score (GCPS), and for ptyalism and signs attributable to PONV [score from 0 (none) to 3 (severe)] by blinded observers. Owners completed a questionnaire at the postoperative recheck.ResultsOverall mean ± standard deviation end-tidal isoflurane percentage was lower in group M (1.19 ± 0.26%) than group S (1.44 ± 0.23%) (p = 0.022), but was not significantly different between groups at specific noxious events (skin incision, ovarian pedicle clamp application, cervical clamp application, wound closure). Cardiorespiratory variables and postoperative GCPS were not significantly different between groups. Overall, 50% of dogs displayed signs attributable to PONV, with no difference in PONV scores between groups (p = 0.198). No difference in anaesthetic recovery was noted by owners between groups.ConclusionsMaropitant reduced overall intraoperative isoflurane requirements but did not affect the incidence of PONV.Clinical relevanceMaropitant provided no significant benefits to dogs undergoing ovariohysterectomy with this anaesthetic and analgesic protocol, although clinically significant reductions in isoflurane requirements were noted.     

Effects of different doses of dexmedetomidine on anaesthetic induction with alfaxalone – a clinical trial

ObjectiveTo document the effects of two doses of dexmedetomidine on the induction characteristics and dose requirements of alfaxalone.Study designRandomized controlled clinical trial.AnimalsSixty one client owned dogs, status ASA I-II.MethodsDogs were allocated randomly into three groups, receiving as pre-anaesthetic medication, no dexmedetomidine (D₀), 1 μg kg^?1 dexmedetomidine (D₁) intramuscularly (IM) or 3 μg kg^?1 dexmedetomidine IM (D₃). All dogs also received 0.2 mg kg^?1 methadone IM. Level of sedation was assessed prior to induction of anaesthesia. Induction of general anaesthesia was performed with alfaxalone administered intravenously to effect at a rate of 1 mg kg^?1 minute^?1; the required dose to achieve tracheal intubation was recorded. Anaesthesia was maintained with isoflurane in oxygen. Cardiopulmonary parameters were recorded throughout the anaesthetic period. Quality of intubation, induction and recovery of anaesthesia were recorded. Quantitative data were compared with one-way anova or Kruskal-Wallis test. Repeated measures were log-transformed and analysed with repeated measures anova (p < 0.05).ResultsTreatment groups were similar for categorical data, with exception of sedation level (p < 0.001). The doses (mean ± SD) of alfaxalone required for intubation were D₀ 1.68 ± 0.24, D₁ 1.60 ± 0.36 and D₃ 1.41 ± 0.43, the difference between D₀ and D₃ being statistically significant (p = 0.036). Heart and respiratory rates during the anaesthetic period were significantly different over time and between groups (p < 0.001); systolic arterial blood pressure was significantly different over time (p < 0.001) but not between groups (p = 0.833). Induction quality and recovery scores were similar between groups (p = 1.000 and p = 0.414, respectively).Conclusions and clinical relevanceThe administration of alfaxalone resulted in a good quality anaesthetic induction which was not affected by the dose of dexmedetomidine. Dexmedetomidine at 3 μg kg^?1 IM combined with methadone provides good sedation and enables a reduction of alfaxalone requirements.     

Effects of ketamine or midazolam continuous rate infusions on alfaxalone total intravenous anaesthesia requirements and recovery quality in healthy dogs: a randomized clinical trial

ObjectiveTo determine the alfaxalone dose reduction during total intravenous anaesthesia (TIVA) when combined with ketamine or midazolam constant rate infusions and to assess recovery quality in healthy dogs.Study designProspective, blinded clinical study.AnimalsA group of 33 healthy, client-owned dogs subjected to dental procedures.MethodsAfter premedication with intramuscular acepromazine 0.05 mg kg^-1 and methadone 0.3 mg kg^-1, anaesthetic induction started with intravenous alfaxalone 0.5 mg kg^-1 followed by either lactated Ringer’s solution (0.04 mL kg^-1, group A), ketamine (2 mg kg^-1, group AK) or midazolam (0.2 mg kg^-1, group AM) and completed with alfaxalone until endotracheal intubation was achieved. Anaesthesia was maintained with alfaxalone (6 mg kg^-1 hour^-1), adjusted (±20%) every 5 minutes to maintain a suitable level of anaesthesia. Ketamine (0.6 mg kg^-1 hour^-1) or midazolam (0.4 mg kg^-1 hour^-1) were employed for anaesthetic maintenance in groups AK and AM, respectively. Physiological variables were monitored during anaesthesia. Times from alfaxalone discontinuation to extubation, sternal recumbency and standing position were calculated. Recovery quality and incidence of adverse events were recorded. Groups were compared using parametric analysis of variance and nonparametric (Kruskal-Wallis, Chi-square, Fisher’s exact) tests as appropriate, p < 0.05.ResultsMidazolam significantly reduced alfaxalone induction and maintenance doses (46%; p = 0.034 and 32%, p = 0.012, respectively), whereas ketamine only reduced the alfaxalone induction dose (30%; p = 0.010). Recovery quality was unacceptable in nine dogs in group A, three dogs in group AK and three dogs in group AM.Conclusions and clinical relevanceMidazolam, but not ketamine, reduced the alfaxalone infusion rate, and both co-adjuvant drugs reduced the alfaxalone induction dose. Alfaxalone TIVA allowed anaesthetic maintenance for dental procedures in dogs, but the quality of anaesthetic recovery remained unacceptable irrespective of its combination with ketamine or midazolam.