The effect of the inspired oxygen fraction on arterial blood oxygenation in spontaneously breathing,isoflurane anaesthetized horses: a retrospective study

ObjectivesTo investigate the influence of two inspired oxygen fractions (FIO₂) on the arterial oxygenation in horses anaesthetized with isoflurane.Study DesignRetrospective, case-control clinical study.AnimalsTwo hundred equine patients undergoing non-abdominal surgery (ASA class 1–2), using a standardized anaesthetic protocol and selected from anaesthetic records of a period of three years, based on pre-defined inclusion criteria.MethodsIn group O (n = 100), medical oxygen acted as carrier gas, while in group M (n = 100), a medical mixture of oxygen and air (FIO₂ 0.60) was used. Demographic data, FIO₂, arterial oxygen tension (PaO₂) and routinely monitored physiologic data were recorded. The alveolar-arterial oxygen tension difference [P(A-a)O₂] and PaO₂/FIO₂ ratio were calculated. The area under the curve, standardized to the anaesthetic duration, was calculated and statistically compared between groups using t-tests or Mann–Whitney tests as appropriate. Categorical data were compared using Chi-square tests.ResultsNo significant differences in age, body weight, sex, breed, surgical procedure, position, anaesthetic duration or arterial carbon dioxide tension were found. Mean FIO₂ was 0.78 in group O and 0.60 in group M. Compared to group O, significantly lower values for PaO₂ and for P(A-a)O₂ were found in group M. In contrast, the PaO₂/FIO₂ ratio and the percentage of horses with a PaO₂ <100 mmHg (13.33 kPa) were comparable in both groups.ConclusionsAlthough a reduction of the inspired oxygen fraction resulted in a lower PaO₂, the P(A-a)O₂ was also lower and the number of horses with PaO₂ values <100 mmHg was comparable.Clinical relevanceIn healthy isoflurane anaesthetized horses, the use of a mixture of oxygen and air as carrier gas seems acceptable, but further, prospective studies are needed to confirm whether it results in a lower degree of ventilation/perfusion mismatching.     

RESEARCH PAPER: Romifidine as a constant rate infusion in isoflurane anaesthetized horses: a clinical study

Objective To evaluate the effects of a constant rate infusion (CRI) of romifidine on the requirement of isoflurane, cardiovascular performance and recovery in anaesthetized horses undergoing arthroscopic surgery. Study design Randomized blinded prospective clinical trial. Animals Thirty horses scheduled for routine arthroscopy. Methods After premedication (acepromazine 0.02 mg kg^?1, romifidine 80 μg kg^?1, methadone 0.1 mg kg^?1) and induction (midazolam 0.06 mg kg^?1 ketamine 2.2 mg kg^?1), anaesthesia was maintained with isoflurane in oxygen. Horses were assigned randomly to receive a CRI of saline (group S) or 40 μg kg^?1 hour^?1 romifidine (group R). The influences of time and treatment on anaesthetic and cardiovascular parameters were evaluated using an analysis of variance. Body weight (t‐test), duration of anaesthesia (t‐test) and recovery score (Wilcoxon Rank Sum Test) were compared between groups. Significance was set at p < 0.05. Results All but one horse were positioned in the dorsal recumbent position and ventilated from the start of anaesthesia. End tidal isoflurane concentrations were similar in both groups at similar time points and over the whole anaesthetic period. Cardiac output was significantly lower in horses of the R group, but there were no significant differences between groups in cardiac index, body weight or age. All other cardiovascular parameters were similar in both groups. Quality of recovery did not differ significantly between groups, but more horses in group R stood without ataxia at the first attempt. One horse from group S had a problematic recovery. Conclusions and clinical relevance No inhalation anaesthetic sparing effect or side effects were observed by using a 40 μg kg^?1 hour^?1 romifidine CRI in isoflurane anaesthetized horses under clinical conditions. Cardiovascular performance remained acceptable. Further studies are needed to identify the effective dose of romifidine that will induce an inhalation anaesthetic sparing effect in anaesthetized horses.     

Genetic variation in leaf and stem glucosinolates in resynthesized lines of winter rapeseed (<Emphasis Type="Italic">Brassica napus</Emphasis> L.)

Glucosinolates are secondary components characteristic for the Brassicaceae with complex biological functions. Glucosinolates in the seeds are anti-nutritive when feeding animals and their inheritance have been extensively investigated. Much less is known about the genetics of glucosinolates in leaves and stems, which may attract some insects, while repelling others. They may also inhibit bacterial processes of importance when using green biomass for the production of biogas. The objective of this study was to analyse the genetic variation of total and individual glucosinolates in the green material of rapeseed. For this 28 resynthesized winter rapeseed lines were tested at two locations. There was a large variation in leaf glucosinolate content between 0.10 and 4.75 μmol/g dry matter. The predominant leaf glucosinolates are the alkenyle glucosinolates progoitrin, gluconapin and glucobrassicanapin. The line R53 is exceptional, while combining a relative high content of the indole glucosinolate glucobrassicin with low alkenyle glucosinolates in the leaves. The total glucosinolate concentration in the stems and leaves is not correlated with the seed glucosinolate concentrations. Heritabilities are above h2 = 0.60 for progoitrin, h2 = 0.65 for gluconapin, h2 = 0.30 for glucobrassicanapin and h2 = 0.52 for total glucosinolate content in the leaves. In conclusion, resynthesized rapeseed is an important genetic resource to modify the leaf glucosinolate content and composition of rapeseed.     

Influence of calcium chloride on the cardio‐respiratory effects of a bolus of enoximone in isoflurane anaesthetized ponies

ObejctiveTo investigate the influence of calcium chloride (CaCl₂) on the cardio–respiratory effects of enoximone in isoflurane anaesthetized ponies.Study designProspective consecutive experimental trial.AnimalsSix healthy ponies, weighing 287 ± 55 kg were included in this study.MethodsAfter sedation (romifidine, 80 μg kg^?1), anaesthesia was induced with midazolam (0.06 mg kg^?1) and ketamine (2.2 mg kg^?1) and maintained with isoflurane in oxygen. The ponies’ lungs were ventilated to maintain normocapnia. After 90 minutes, a bolus of enoximone (0.5 mg kg^?1) was administered, followed by a CaCl₂ infusion (0.5 mg kg^?1 minute^?1 over 10 minutes) (treatment EC). Sodium, potassium, ionized and total calcium concentrations, cardiovascular variables and blood–gases were measured in the 120 minutes after treatment. Using a mixed model anova, the results were compared to those of a previous report [Vet Anaesth Analg, 34 (2007) 416], evaluating the effects of 0.5 mg kg^?1 enoximone in the same ponies and under identical circumstances (treatment E). Both an overall comparison and comparisons at specific time points after treatment were performed (α = 0.05).ResultsAlthough ionized and total calcium concentrations were higher during treatment EC, the cardio–respiratory effects of enoximone were comparable for both treatments. A small but significant difference in packed cell volume was detected.Conclusions and clinical relevanceCalcium chloride did not enhance the effects of enoximone in normocalcaemic anaesthetized ponies.     

Cardiovascular responses to transvenous electrical cardioversion of atrial fibrillation in anaesthetized horses

ObjectiveTo examine the influence of direct current shock application in anaesthetized horses with atrial fibrillation (AF) and to study the effects of cardioversion to sinus rhythm (SR).Study designProspective clinical study.AnimalsEight horses successfully treated for AF (transvenous electrical cardioversion after amiodarone pre-treatment).MethodsCardioversion catheters and a pacing catheter were placed under sedation [detomidine 10 μg kg^?1 intravenously (IV)]. After additional sedation (5–10 μg kg^?1 detomidine, 0.1 mg kg^?1 methadone IV), anaesthesia was induced with ketamine, 2.2 mg kg^?1 and midazolam, 0.06 mg kg^?1 (IV) in a sling and maintained with isoflurane in oxygen. Flunixin meglumine, 1.1 mg kg^?1, was administered IV. Shocks were delivered as biphasic truncated exponential waves, synchronized with the R-wave of the electrocardiogram. Monitoring included pulse oximetry, electrocardiography, capnography, inhalational anaesthetic agent concentration, arterial blood pressure, LiDCO and PulseCO cardiac index (CI) and arterial blood gases. Values before and after the first unsuccessful shock and before and after cardioversion to SR were compared.ResultsValues before the first shock were comparable to reported values in healthy, isoflurane anaesthetized horses. Reliable CI measurements could not be obtained using the PulseCO technique. Intermittent positive pressure ventilation was required in most horses (bradypnea and/or PaCO₂ >8 kPa, 60 mmHg), while dobutamine was administered in two horses (0.3–0.5 μg kg^?1 minute^?1). After the 1st unsuccessful shock application, systolic arterial pressure (SAP) was decreased (p = 0.025), other recorded values were not influenced (CI measurements not available for this analysis). SR was associated with increases in CI (p = 0.039) and stroke index (p = 0.002) and a decrease in SAP (p = 0.030).Conclusions and clinical relevanceDespite the presence of AF, cardiovascular function was well maintained during anaesthesia and was not affected by shock application. Cardiac index and stroke index increased and SAP decreased after cardioversion.     

Mixed Giardia duodenalis assemblage A, B, C and E infections in pet chinchillas (Chinchilla lanigera) in Flanders (Belgium)

Fourteen isolates of Toxoplasma gondii were isolated from cats from 4 different geographic provinces (Anhui, Hubei, Shanxi and Guangdong) in China and their genetic diversity with 8 nuclear loci SAG2, SAG3, BTUB, GRA6, L358, PK1, c22-8, c29-2, and an apicoplast locus Apico, was analysed by restriction fragment length polymorphisms (RFLPs). Two genotypes from these 14 isolates were identified but none of them belongs to the typical genetic types (types I, II and III). It is unexpected that such high similarity was observed in these 14 isolates although their original regions are significantly distant. Our results strongly indicate that the three traditional clonal lineages of types I, II and III of this parasite may not be preponderant in China. In addition, our results show that the genotypes of T. gondii in China may be highly clonal with atypical genotypes and higher virulence.