An evaluation of fresh gas flow rates for spontaneously breathing cats and small dogs on the Humphrey ADE semi‐closed breathing system

ObjectiveTo evaluate the fresh gas flow (FGF) rate requirements for the Humphrey ADE semi-closed breathing system in the Mapleson A mode; to determine the FGF at which rebreathing occurs, and compare the efficiency of this system to the Bain (Mapleson D) system in spontaneously breathing cats and small dogs.Study DesignProspective clinical study.AnimalsTwenty-five healthy (ASA score I or II) client-owned cats and dogs (mean ± SD age 4.7 ± 5.0 years, and body weight 5.64 ± 3.26 kg) undergoing elective surgery or minor procedures.MethodsAnaesthesia was maintained with isoflurane delivered via the Humphrey ADE system in the A mode using an oxygen FGF of 100 mL kg⁻¹ minute⁻¹. The FGF was then reduced incrementally by 5–10 mL kg⁻¹minute⁻¹ at approximately five-minute intervals, until rebreathing (inspired CO₂ >5 mmHg (0.7 kPa)) was observed, after which flow rates were increased. In six animals, once the minimum FGF at which rebreathing occurred was found, the breathing system was changed to the Bain, and the effects of this FGF delivery examined, before FGF was increased.ResultsRebreathing did not occur at the FGF recommended by the manufacturer for the ADE. The mean ± SD FGF that resulted in rebreathing was 60 ± 20 mL kg⁻¹minute⁻¹. The mean minimum FGF at which rebreathing did not occur with the ADE was 87 ± 39 mL kg⁻¹minute⁻¹. This FGF resulted in significant rebreathing (inspired CO₂ 8.8 ± 2.6 mmHg (1.2 ± 0.3 kPa)) on the Bain system.ConclusionsThe FGF rates recommended for the Humphrey ADE are adequate to prevent rebreathing in spontaneously breathing cats and dogs <15 kg.Clinical relevanceThe Humphrey ADE system used in the A mode is a more efficient alternative to the Bain system, for maintenance of gaseous anaesthesia in spontaneously breathing cats and small dogs.     

A comparison of the 'Maxima' and the modified Ayre's T-piece breathing systems in spontaneously breathing cats

Objective To compare the fresh gas flow requirements of the ‘Maxima’ and Jackson‐Rees modified Ayre's T‐piece (JRMATP) in spontaneously breathing anaesthetized in cats. Study design Prospective randomized clinical study. Animals or sample population Fifteen adult cats (6 male, 9 female, 3.1 ± 0.4 kg [x? ± SD]). Materials & methods After pre‐anaesthetic medication with acepromazine and pethidine, anaesthesia was induced using thiopentone and the trachea was intubated with a cuffed endotracheal tube. This was attached to either a ‘Maxima’ or a JRMATP breathing system; allocation was randomized. Anaesthesia was maintained with halothane delivered in a 1 : 1 oxygen : nitrous oxide mixture. Initial total fresh gas flow (FGF) was set at 600 mL kg^?1 min^?1. After 20 minutes, FGF was reduced in increments of 200 mL min^?1 until rebreathing (inspired CO₂ concentration >0.2%) occurred. At this point, FGF was increased to 600 mL kg^?1 and the process was repeated with the other breathing system. The respiratory rate and airway pressure at the endotracheal tube connector were monitored throughout anaesthesia. Results The mean fresh gas flow that prevented rebreathing with the Maxima system (164 ± 39 mL kg^?1) was significantly less (p < 0.0001) than that required in the modified T‐piece (455 ± 0.77 mL kg^?1). Respiratory rates and airway pressures at the endotracheal tube connector were not significantly affected by breathing system employed. Conclusions In terms of the gas flow requirements that prevent rebreathing, the ‘Maxima’ breathing system is more efficient than the modified Ayre's T‐piece in spontaneously breathing cats anaesthetised with halothane.     

Comparison of mainstream (Capnostat 5) and two low-flow sidestream capnometers (VM-2500-S and Capnostream) in spontaneously breathing rabbits anesthetized with a Bain coaxial breathing system

ObjectiveTo evaluate agreement with PaCO₂ of two low sampling rate sidestream capnometers and a mainstream capnometer in rabbits and the effect of using high fresh gas flow from a Bain coaxial breathing system.Study designProspective, crossover study.AnimalsA total of 10 New Zealand White rabbits weighing 3.4 ± 0.3 kg [mean ± standard deviation (SD)].MethodsTwo sidestream analyzers (Viamed VM-2500-S and Capnostream 35) with a sampling rate of 50 mL minute^–1 and a mainstream capnometer (Capnostat 5) were tested. All capnometers used infrared spectroscopy and advanced microprocessor technology. Rabbits were anesthetized and intubated with noncuffed endotracheal tubes of 3 mm internal diameter and adequate seal. A sidestream sampling adapter or the mainstream capnometer was attached to the endotracheal tube and connected to a Bain coaxial breathing system. Oxygen (1.5 L minute^–1) delivered sevoflurane to maintain anesthesia. An auricular artery catheter allowed blood sampling for PaCO₂ analysis corrected to rectal temperature. Inspired and end-tidal carbon dioxide (Pe′CO₂) measurements were recorded during blood sample withdrawal. From each rabbit, 10 paired PaCO₂/Pe′CO₂ measurements were obtained. Each rabbit was recovered from anesthesia and was anesthetized again with an alternate capnometer after 1 week. Data were analyzed using Bland–Altman and two-way anova for repeated measures.ResultsAnalysis included 100 paired samples. Negative bias reflects underestimation of PaCO₂. Bland–Altman mean (±1.95 SD) was –16.7 (–35.2 to 1.8) mmHg for Capnostat 5, –27.9 (–48.6 to –7.2) mmHg for Viamed, and –18.1 (–34.3 to –1.9) mmHg for Capnostream. Viamed PaCO₂–Pe′CO₂ gradient was greater than other two capnometers.ConclusionsAll three capnometers underestimated PaCO₂. Capnostat 5 and Capnostream performed similarly.Clinical relevanceThese capnometers underestimated PaCO₂ in spontaneously breathing rabbits anesthetized using a Bain coaxial breathing system with high fresh gas flows.     

A clinical evaluation of the 'mini parallel Lack' breathing system in cats and comparison with a modified Ayre's T-piece

OBJECTIVE: To evaluate the suitability of a 'mini parallel Lack' (MPL) breathing system for use in spontaneously breathing cats and to compare the fresh gas flow requirement with that of a modified Ayre's T-piece (MATP). ANIMALS: Twenty client-owned cats, ASA I and II, presented for elective procedures requiring anaesthesia. MATERIALS AND METHODS: Pre-anaesthetic medication and induction of anaesthesia were carried out using several techniques commonly used in our teaching hospital. Anaesthesia was maintained with halothane or isoflurane vaporized in either oxygen or with a mixture of oxygen and nitrous oxide. Both breathing systems were evaluated in each cat, with the order of use randomized. Initial fresh gas flows were 300 mL kg(-1) minute(-1) for the MPL and 500 mL kg(- 1) minute(-1) for the MATP. After a 20-minute stabilization period, fresh gas flow was reduced by 200 mL minute(-1) every 5 minutes until re-breathing--defined as an increase in the inspired partial pressure of carbon dioxide to 0.3 kPa (2 mm Hg)--was detected. The fresh gas flow was then increased in 100 mL minute(-1) increments until re-breathing was no longer detectable, and this value was recorded as the minimum fresh gas flow requirement for the breathing system in use. The procedure was then repeated for the second breathing system. Minimum fresh gas flow requirements were compared using a paired Students t-test. Cardiopulmonary variables were compared using anova. Valve opening pressure was measured in the MPL using a manometer. RESULTS: The mean (+/-SD) fresh gas flow that prevented re-breathing with the MPL (510 +/- 170 mL minute(-1); equivalent to 142 +/- 47 mL kg(-1) minute(-1)) was significantly lower than that required for the MATP (1430 +/- 560 mL minute(-1); equivalent to 397 +/-155 mL kg(-1) minute(-1)). There were no significant differences in cardiopulmonary variables attributable to the use of the two breathing systems. The MPL valve opening pressure was 1.1 cm H2O. CONCLUSIONS: The MPL breathing system used lower gas flows than the MATP without affecting cardiovascular or respiratory function. Clinical relevance In spontaneously breathing cats, the MPL offers the advantages of a reduction in cost and atmospheric pollution because less volatile agent is vaporized.     

An investigation of the bacterial contamination of small animal breathing systems during routine use

OBJECTIVE: To investigate the need for sterilization of anaesthetic breathing systems to prevent cross-infection between animals due to the re-use of anaesthetic circuit tubing. STUDY DESIGN: Prospective microbiological study. METHODS: Bacteriology samples were taken from 37 sterile breathing systems, each used for 1 day, at two sampling sites (one proximal and one distal to the animal). The number of patient connections, cumulative anaesthesia time, culture results, number of colony-forming units and the number of different species were recorded. Secondly, four sterile breathing systems were used for 2 months under routine conditions and sampled every 2 weeks and the same parameters recorded. Finally, the inner surfaces of four sterile breathing systems were inoculated with a known load of canine oropharyngeal bacteria. Bacteriology samples were taken at 1 minute, 1 hour and 1 day post-deposition. The number of colonies identified was compared with the initial load. RESULTS: Only a very small number of micro-organisms were isolated and these were generally organisms of low pathogenic potential. The proximal site was found to be significantly more colonized than the distal site (p < 0.001). Neither longer daily connection time (p = 0.54), nor a higher number of connections (p = 0.81) increased the incidence of proximal site colonization. Over the 2-month study period, the bacterial population did not increase. There was no correlation between cultures isolated from successive samples taken from the same tubing. There was rapid loss of viability of the micro-organisms deliberately inoculated onto the tubing surface: the number of colonies isolated from the breathing system after 1 minute was significantly lower than in the inoculum (p = 0.042). CONCLUSIONS AND CLINICAL RELEVANCE: Sterile anaesthesia breathing systems were colonized by environmental micro-organisms of low pathogenicity. Although long-term survival of recognized pathogens in a dry environment is still possible, the use of a bacterial filter or a sterilized breathing system for routine veterinary anaesthesia cannot be supported by current evidence.     

Bispectral index and the clinically evaluated anaesthetic depth in dogs

Objective This study investigated whether the bispectral index (BIS monitor) corresponded with the clinical assessment of anaesthetic depth in dogs. Study design Prospective clinical study. Animals Sixty‐five dogs undergoing anaesthesia for surgery. Methods Dogs were assigned to one of three different anaesthetic techniques. A three point scale was devised to determine the clinical depth of anaesthesia (CDA); CDA 1 represented light, CDA 2 surgical and CDA 3 excessive depth of anaesthesia. BIS values were recorded and CDA assessed at specific times and points throughout surgery. Data were statistically analysed using mixed model regression. Results Clinical depth of anaesthesia was assessed as CDA 1 on 68, 2 on 748 and 3 on four occasions. The BIS recorded for CDA 1 differed significantly from that for CDA 2 (p < 0.001). However, individual BIS values measured at light and surgical levels of anaesthesia overlapped considerably. The sensitivities and specificities calculated for BIS to diagnose CDA 1 compared to CDA 2 in the three anaesthetic protocols were 28–86% and 55–85%. The accompanying positive predictive value was 0.08–0.29 and the negative predictive value was 0.95–0.97. End‐tidal isoflurane concentrations (anaesthetic techniques 1 and 3) and propofol infusion (technique 2) at CDA 1 was significantly lower than those at CDA 2 (p = 0.001). Conclusions Although BIS values overall distinguished between CDA scores, the calculated specificities, sensitivities and predictive values were low, and there were anomalous results in individual cases. Clinical relevance The use of the BIS as the sole method to determine anaesthetic depth in dogs is imprudent.     

Studies on immunological, biochemical, hematological and growth regulation by Scomber scombrus fish protein extract supplementation in young pigs

Several trials with young pigs were conducted during an experimental period of 6 weeks to evaluate the effects on growth and immune responses of dietary supplementation with 10, 25 and 50 g/kg of E‐CAB‐94011, a fish extract rich in proteins, unsaturated fatty acids and endogenous anti‐oxidants. This extract was obtained using a lyophilization process consisting of three phases: freezing, primary drying and secondary drying. Conditions in the dryer were varied through the cycle to ensure that the resulting product had the desired physical and chemical properties, and that the required stability was achieved. A total of 360 pigs were randomly allocated according to initial bodyweight and divided into four groups of 90 pigs. The control diet contained hard red spring wheat, spray‐dried whey and soybean meal. The treatment diets were the control plus 10 g/kg, 25 g/kg and 50 g/kg of E‐CAB‐94011. Growth performance, plasma biochemical values, hematological values and humoral and cellular immune responses were measured. Results indicated that supplementation with E‐CAB‐94011 affects both growth and immune response. When the growth parameters of pigs were compared, the largest percentage improvement in growth was observed from weaning to 8–10 weeks of age. These experiments confirm that the use of E‐CAB‐94011 results in significant improvements, even when the herd of origin has a relatively high health status.     

不同CO2气腹压对小型猪循环系统的影响

选择30只健康小型猪随机分为A、B、C、D、E等5组。分别以0、0．8、1．06、1．33、1．6kPa的气腹压进行充气腹试验,以探讨不同CO2气腹压对小型猪循环系统的影响。结果显示,A组试验猪血压和心率持续降低。B、C、D、E组试验猪会引起血压和心率的升高。本试验确定了不同气腹压对小型猪循环系统的影响程度是E组〉D组〉C组〉B组。因此,在小型猪腹腔镜手术充气腹时,选用1.33kPa气腹压值对循环系统的影响较小,同时能保证小型猪腹腔的充分膨胀隆起,便于手术操作,从而为今后开展小型猪腹腔镜手术奠定了理论基础。     

Comparison of arterial and central venous cannulations using ultrasound guidance in pigs

OBJECTIVE: To evaluate the feasibility of ultrasound guided vascular access in pigs by comparing central venous and arterial cannulation techniques. ANIMALS: Twenty-two healthy female Pietrain pigs, 14-18 weeks old and weighing 51.1 +/- 4.3 kg (mean +/- SD). STUDY DESIGN: Comparative animal trial. MATERIALS AND METHODS: After induction of general anaesthesia, cannulation of the external jugular vein and internal carotid artery was attempted using real-time ultrasound guidance. The quality of the ultrasound picture was assessed on an analogue scale from 1 (excellent) to 5 (insufficient). Vessel size, cannulation success rate, number of puncture attempts and time from first puncture attempt until insertion of the Seldinger wire were recorded. RESULTS: Cannulation was successful in all but one animal in which a cut-down technique was performed. The arteries were significantly smaller than the veins (p < 0.001) resulting in a significantly prolonged cannulation time (p = 0.032) for insertion of arterial catheters without differences in success rate. In 89% of attempted cannulations, the Seldinger wire was inserted within 5 minutes. CONCLUSIONS AND CLINICAL RELEVANCE: In anaesthetized pigs undergoing instrumentation for biomedical research, ultrasound-guided vascular access is a simple and rapid alternative to surgical cut-down. In veterinary anaesthesia, the technique might be useful in sedated or anesthetized pigs in which arterial or central venous access is required.     

Proper theoretical analysis of the oxygen wash-in kinetics of circle breathing systems

Objective To correctly define the theoretical treatment of oxygen wash‐in kinetics in circle breathing systems and reevaluate previously published results for the rate of change of oxygen concentration in a large animal circle breathing system. Study design Theoretical analysis of previously published data. Animals None. Methods Previously published data for the rate of change of oxygen concentration in a large animal circle breathing system with two reservoir bag sizes (40 and 20 L) at three different flow rates (3, 6, and 10 L minute^?1) were obtained from the original publication, via digital extraction, and analyzed to determine system time constants. The results of this analysis were compared to those originally reported and the level of mathematical agreement between experiment and theory was quantified. Results Theoretical time constants for the system with 40 L reservoir bag with flow rates of 3, 6, and 10 L minute^?1 were 16.4, 8.2, and 4.9 minutes, respectively. Experimentally derived time constants for this system with flow rates of 3, 6, and 10 L minute^?1 were 18.1, 9.2, and 5.4 minutes, respectively. Percent differences between experimental and theoretical time constants for this system with flow rates of 3, 6, and 10 L minute^?1 were 10.4, 12.2, and 10.2%, respectively. For the system with a 20 L reservoir bag and 6 L minute^?1 flow rate, the theoretical and experimentally derived time constants were 5.5 and 5.6 minutes, respectively, with a 1.8% difference. The average relative deviations between theory and experiment for the system at 6 L minute^?1 flow with a 40 or 20 L reservoir bag were 1.3% and 3.0%, respectively. Conclusions and clinical relevance Proper theoretical analysis of experimentally obtained data for the wash‐in kinetics of oxygen into a large animal circle breathing system leads to improved mathematical agreement between theory and experiment when compared to the originally published results. Application of this method should allow more accurate prediction of the rate of change of oxygen concentration in anesthetic circuits.     

Pharmacokinetics of hexobarbital, sulphadimidine and chloramphencoliin neonatal and young pigs.

Half-life and apparent specific volume of distribution of hexobarbital, sulphadimidine and chloramphenicol were investigated in newborn, 1, 3, 5 and 8 weeks old pigs. Hexobarbital sleeping time and plasma concentration of hexobarbital at recovery were measured in the same age groups. The half-life of hexobarbital and chloramphenicol was long in newborn pigs but decreased fast during the first week after birth. From 1 to 8 weeks after birth the decrease was less pronounced. The half-life of sulphadimidine increased during the first 3 weeks of life, but in 1 and 3 weeks old pigs the amount of N⁴-acetylated sulphadimidine in plasma at 200 min. after the injection was higher than in the newborn pigs.The apparent specific volume of distribution of hexobarbital, sulphadimidine and chloramphenicol was changed in different ways from birth to 8 weeks of age.The hexobarbital sleeping time was very long in the newborn pigs and decreased until 3 weeks of age. The concentration of hexobarbital in plasma at recovery was unchanged from birth to 8 weeks of age.The concentration of chloramphenicol metabolites in plasma 100 min. after the injection increased very fast during the 8 weeks of observation. The concentration of N⁴-acetylated sulphadimidine in plasma at 200 min. after the injection increased from birth to 1 week of age, then it decreased.The data are stressing that the neonatal pig is a convenient model for pharmacokinetic testing of drugs used as pharmacotherapeutics in neonatal life.     

The pharmacokinetics and pharmacodynamics of the injectable anaesthetic alfaxalone in the horse

ObjectiveTo determine the pharmacokinetics and pharmacodynamics of the neurosteroidal anaesthetic, alfaxalone, in horses after a single intravenous (IV) injection of alfaxalone, following premedication with acepromazine, xylazine and guaiphenesin.Study designProspective experimental study.AnimalsTen (five male and five female), adult, healthy, Standardbred horses.MethodsHorses were premedicated with acepromazine (0.03 mg kg^?1 IV). Twenty minutes later they received xylazine (1 mg kg^?1 IV), then after 5 minutes, guaiphenesin (35 mg kg^?1 IV) followed immediately by IV induction of anaesthesia with alfaxalone (1 mg kg^?1). Cardiorespiratory variables (pulse rate, respiratory rate, pulse oximetry) and clinical signs of anaesthetic depth were evaluated throughout anaesthesia. Venous blood samples were collected at strategic time points and plasma concentrations of alfaxalone were assayed using liquid chromatography-mass spectrometry (LC/MS) and analysed by noncompartmental pharmacokinetic analysis. The quality of anaesthetic induction and recovery was scored on a scale of 1–5 (1 very poor, 5 excellent).ResultsThe median (range) induction and recovery scores were 4 (3–5) (good: horse slowly and moderately gently attained recumbency with minimal or no rigidity or paddling) and 4 (1–5) (good: horse stood on first attempt with some knuckling and ataxia) respectively. The monitored cardiopulmonary variables were within the range expected for clinical equine anaesthesia. The mean ± SD durations of anaesthesia from induction to sternal recumbency and from induction to standing were 42.7 ± 8.4 and 47 ± 9.6 minutes, respectively. The mean ± SD plasma elimination half life (t_1/2), plasma clearance (Clp) and volume of distribution (V_d) for alfaxalone were 33.4 minutes, 37.1 ± 11.1 mL minute^?1 kg^?1 and 1.6 ± 0.4 L kg^?1, respectively.Conclusions and clinical relevanceAlfaxalone, in a 2-hydroxypropyl-beta-cyclodextrin formulation, provides anaesthesia with a short duration of recumbency that is characterised by a smooth induction and satisfactory recovery in the horse. As in other species, alfaxalone is rapidly cleared from the plasma in the horse.     

The use of a medetomidine,butorphanol and atropine combination to enable blood sampling in young pigs

AIM: To determine the suitability of a reversible, injectable anaesthetic combination including medetomidine, butorphanol and atropine to produce the degree of immobilisation required to allow blood sampling in young pigs.

METHODS: Twenty 6-week-old crossbred, intact male pigs were sedated with an intramuscular (I/M) injection of 80 µ'g/kg medetomidine, 200 µ'g/kg butorphanol and 25 µ'g/kg atropine. Heart and respiratory rates and rectal temperatures were monitored. Excessive salivation, gagging, laryngeal reflex, presence of pedal reflex and deep and surface analgesia were noted. Time of injection and the time when pigs reached mild and full sedation were also recorded.

RESULTS: Mild sedation was produced in 90% of pigs after 5.6 (SEM 0.96) min (n=18; median 5, range 2–16 min), and full sedation (lateral recumbency and loss of jaw tone) in 60% of pigs after 12.5 (SEM 2.14) min (n=12; median 10, range 5-28 min). The depth and duration of sedation were very variable and most animals were easily aroused. Ninety percent of the animals required the administration of halothane by mask to allow blood sampling, but the amount of halothane required was small. Heart and respiratory rates decreased (p<0.001) but remained within the normal range. Rectal temperature was above normal at the time of sedation and at the time of blood sampling when the ambient temperature was 29° C but not when the ambient temperature was reduced to 25°C.

CONCLUSIONS: The combination of medetomidine, butorphanol and atropine at these doses produced sedation of variable depth and duration that was insufficient on its own to allow blood sampling in the majority of pigs. Hyperthermia can occur in temperature-controlled environments when using medetomidine, butorphanol and atropine in pigs. Reduction of stress and a quieter environment may improve the effects of the anaesthetic combination.     

The combination of deoxynivalenol and zearalenone at permitted feed concentrations causes serious physiological effects in young pigs

This study was to investigate the effects of the combination of deoxynivalenol (DON) and zearalenone (ZON) on pigs. Twenty-four weaning piglets were divided into a control group fed a diet free of mycotoxins and a toxin group fed a diet containing 1 mg/kg DON and 250 µg/kg ZON. The results showed that supplementation of DON and ZON in diets had extensive effects on pigs. More specifically, DON and ZON caused levels of total protein, albumin, and globulin in sera to decrease (p < 0.05) by 14.5%, 6.5% and 11.3%, respectively, and at the same time increased (p < 0.05) the serum enzyme activities of γ-glutamyltransferase, aspartate aminotransferase and alanine aminotransferase by 72.0%, 32.6% and 36.6%, respectively. In addition, DON and ZON decreased (p < 0.05) the level of anti-classical swine fever antibody titers by 14.8%. Real-time PCR showed that DON and ZON caused the mRNA expression levels of IFN-γ, TNF-α, IL-2, to decrease (p < 0.05) by 36.0%, 29.0% and 35.4%, respectively. Histopathological studies demonstrated that DON and ZON caused abnormalities in the liver, spleen, lymph nodes, uterus, and kidney. The concentrations of DON and ZON used in this study are in line with the published critical values permitted by BML. Our study clearly put the standard and adequacy of safety measures for these toxins into question. The authors suggest that with the increasing availability of cellular and molecular technologies, it is time to revisit the safety standards for toxins in feeds so as to make feeds safer, providing consumers with safer products.     

Evaluation of the anaesthetic effects of medetomidine and ketamine in rats and their reversal with atipamezole

ObjectivesTo compare the anaesthetic effects of varying doses of medetomidine (MED) combined with ketamine (KET) in rats, and to determine the efficacy of atipamezole (ATI) in the reversal of these effects using electroencephalogram (EEG) and assessment of clinical parameters.Study designProspective, randomized experimental trial.AnimalsTwenty-one male Sprague–Dawley rats weighing 300–398 g and aged 8–11 weeks old.MethodsThree groups received intraperitoneal injections of MED (0.2, 0.4 or 0.8 mg kg^?1) with KET (60 mg kg^?1) (MED-200, MED-400 and MED-800). Atipamezole, at doses five times higher than the previous dose of MED, was then administered intraperitoneally 70 minutes after MED-KET injection. The EEG band powers and spectral edge frequencies (SEFs), respiratory rates, reflex scores to toe-web clamping and behavioural changes were measured. Correlations between EEG parameters and reflex scores were also evaluated.ResultsThe duration of surgical anaesthesia was directly proportional to the dose of MED. Lower frequency bands (δ1 to α2) increased in all groups, and these changes were reversed by ATI. Minimal changes were observed in the higher frequency bands (β1 to γ), but their powers were increased by ATI. The SEFs were decreased in all groups, and they were reversed by ATI. While α1 band power and SEF95 showed strong correlations with the depth of anaesthesia, their changes appeared before the measured decreases in reflex score. Recovery from anaesthesia was extended by increasing the dose of MED.Conclusions and clinical relevanceSpectral EEG parameters may not accurately predict the depth of surgical anaesthesia because they had already changed during the induction of surgical anaesthesia. The ATI dose used in the present study may not be enough for complete reversal of anaesthesia induced by MED-KET.     

Electroencephalographic assessment of oral meloxicam,topical anaesthetic cream and cautery iron for mitigating acute pain in pigs (Sus scrofa) undergoing tail docking

Objective

To evaluate the efficacy of oral meloxicam, topical anaesthetic cream and cautery iron in mitigating acute nociceptive responses of pigs to tail docking.

Effect of high oral doses of nitrate on salivary recirculation of nitrates and nitrites and on bacterial diversity in the saliva of young pigs

Ingested nitrate is absorbed in the small intestine, recirculated into the saliva and reduced to nitrite by oral bacteria. In pigs receiving a moderate dietary addition of nitrate, the recirculation into the saliva is modest, so we aimed to assess the effect of higher nitrate doses to find out how the animal reacts to this new situation and to evaluate if a higher nitrate level could enhance the nitrate reduction process, improving the nitrite production Trial 1. Six piglets received 100 g of a commercial diet with 2.45% KNO₃. In relation to baseline values, nitrate in blood serum and saliva increased 15 times, and declined after 6 h vs. 2 h. Salivary nitrite increased seven times after the addition and declined after 6 h vs. 2 h. Trial 2. Six piglets were fed a diet with or without 1.22% KNO₃ for 2 weeks. Salivary nitrate and nitrite increased with the addition of KNO3: nitrate increased from d0 to the end of the trial, nitrite increased 15 times after 1 week, but decreased after 2 weeks to 4.5‐fold the control. After 2 weeks, nitrate reduced Shan diversity index of salivary microbiota. The present results indicate that the long exposure to high quantities of nitrates impairs the oral reduction of nitrate to nitrite and engenders a reduction of the mouth’s microbiota diversity.     

Dietary protein level affects in vitro peristaltic reflex in the small intestine of young pigs

The aim of the study was to investigate the effect of dietary protein level on contractility of the small intestine in young pigs. Animals (about 15 kg BW initially) were fed during 40 days with isoenergetic diets containing 16, 18, or 20% of crude protein. Higher protein levels in the diets as well as similar concentration of essential amino acids were attained by substitution of corn starch with wheat gluten and crystalline amino acids. At about 40 kg BW, the animals were sacrificed and the longitudinal strips of duodenum and mid-jejunum were taken for analysis of smooth muscle mechanical activity in vitro. Spontaneous activity, responses to electrical field stimulation (EFS), and responses to acetylcholine (ACh) were recorded. Frequency and amplitude of spontaneous contractions were similar in all groups, both in the duodenum and the mid-jejunum. In the duodenum, responses to EFS and ACh were the same irrespective of the dietary protein level. Responses to EFS in the mid-jejunum were significantly enhanced in the animals receiving the diet with 20% protein; however, the response to ACh was not changed. The mechanism of neuronal response may involve primary afferent pathways “sensing” contents in the lumen of the intestine through enterochromaffin cells. The enteric neuronal pathways may also be activated by a higher level of free amino acid(s) or by dietary peptides and proteins.