Development of an atrial transseptal puncture procedure in horses to access the left heart: An ultrasound-guided jugular vein and transhepatic approach.

BACKGROUND: Radiofrequency ablation has been successfully applied to treat right atrial arrhythmias in horses. Ablation of left-sided arrhythmias requires a retrograde transarterial approach which is complicated. In human medicine, the left atrium is accessed through transseptal puncture (TSP) of the fossa ovalis (FO) using a caudal approach via the femoral vein. OBJECTIVES: To develop a zero fluoroscopy TSP technique for horses using a jugular vein (cranial) and transhepatic (caudal) approach. STUDY DESIGN: In vivo experimental study. METHODS: Transseptal puncture was performed in 18 horses admitted for euthanasia and donated for scientific research under general anaesthesia: using a jugular vein approach (10 horses), a transhepatic approach (2 horses) or both (6 horses). Radiofrequency energy was applied on a guidewire to perforate the FO and allow sheath advancement under intracardiac and transthoracic echocardiographic guidance. Puncture lesions were inspected post-mortem. RESULTS: Transseptal puncture was successful in 17/18 horses, of which 15/16 jugular vein approaches and 5/8 transhepatic approaches. Failure was due to technical malfunction, inability to advance the guidewire toward the heart and inability to advance the sheath through the FO. Intracardiac echocardiography was essential to safely guide the puncture process. Atrial arrhythmias caused by the TSP occurred in 13/18 horses. Puncture lesions were found in the right atrium in the FO region, and left atrium ventral to pulmonary vein ostium III. MAIN LIMITATIONS: Because in several horses two approaches were tested consecutively, it cannot be excluded that the second TSP was performed at the previous puncture site. Due to the developmental nature of the study the approaches were not randomised and did not allow comparison. CONCLUSION: Transseptal puncture is feasible in horses using ultrasound guidance and allows for electrophysiological exploration of the left heart. Further studies are needed to evaluate post-operative follow-up.

ANESTHESIA IN CAPTIVE GIANT PANDAS (AILUROPODA MELANOLEUCA) WITH MEDETOMIDINE-KETAMINE.

One male and one female giant panda (Ailuropoda melanoleuca) from a Belgian zoo were anesthetized on eight different occasions over a course of 4 yr for electro-ejaculation (n = 3) or artificial insemination (n = 5). Medetomidine (0.03-0.04 mg/kg) and ketamine (2.5-3 mg/kg) were administered by intramuscular remote injection. Animals gained sternal recumbency with the loss of response to external stimuli after 4.9 ± 1.6 min (mean ± SD). The trachea was intubated with a 14-mm-internal diameter endotracheal tube; anesthesia was maintained with isoflurane in oxygen adjusted according to the required depth of anesthesia with a small-animal circle system. Physiological variables (heart rate, respiratory rate, oxygenation, end tidal carbon dioxide partial pressure and non-invasive blood pressure) were measured and remained within an acceptable range throughout anesthesia. Atipamezole (0.17-0.25 mg/kg) was administered intramuscularly after anesthesia. Recoveries were rapid and uneventful. Medetomidine 0.03 mg/kg and ketamine 2.5 mg/kg IM appeared to be the preferred doses for giant pandas.

Pharmacokinetics of gamma-hydroxybutyric acid in 6-week-old swine (Sus scrofa domesticus) after intravenous and oral administration.

Sedative as well as protective effects during hypoxia have been described for gamma-hydroxybutyric acid (GHB). Six swine (Sus scrofa domesticus) of 6 weeks old were administered NaGHB at a dose of 500 mg/kg intravenously (IV) and 500 and 750 mg/kg orally (PO) in a triple cross-over design. Repeated blood sampling was performed to allow pharmacokinetic analysis of GHB. Whole blood concentration at time point 0 after IV administration was 1727.21 ± 280.73 µg/mL, with a volume of distribution of 339.45 ± 51.41 mL/kg and clearance of 164.94 ± 47.05 mL/(kg h). The mean peak plasma concentrations after PO administration were 326.57 ± 36.70 and 488.01 ± 154.62 µg/mL for 500 mg/kg and 750 mg/kg, respectively. These were recorded at 1.42 ± 0.72 and 1.58 ± 0.58 h after PO dose for GHB 500 mg/kg and 750 mg/kg, respectively. The elimination half-life for IV and PO 500 mg/kg and PO 750 mg/kg dose was respectively 1.33 ± 0.30, 1.16 ± 0.31 and 1.11 ± 0.33 h. The bioavailability (F) for PO administration was 45%. No clinical adverse effects were observed after PO administration. Deep sleep was seen in one animal after IV administration, other animals showed head pressing and ataxia.

Dobutamine use in horses during romifidine and isoflurane anaesthesia.

This retrospective study aimed to assess the incidence of hypotension and the subsequent administration of dobutamine in horses anesthetized with isoflurane and romifidine during elective surgery. Time from induction of anaesthesia to administration of dobutamine was registered, as well as the time and dose needed to restore mean arterial pressure (MAP) ≥ 70 mmHg. Additionally, the influence of patient and anaesthesia related parameters on the need for dobutamine supplementation was evaluated. In total, 118 horses were included in this retrospective study. Dobutamine was administered to effect when MAP<70 mmHg. Data registered: patient weight, acepromazine premedication, body position, administration of intraoperative ketamine bolus, locoregional anaesthesia, mechanical ventilation, duration of anaesthesia, dose and duration of dobutamine administration, heart rate, MAP before dobutamine administration, MAP and time required to increase MAP≥70 mmHg. Dobutamine infusion was needed in 54.2% of the horses 30 ± 17 min after isoflurane-romifidine anaesthesia started. Dobutamine 0.55 ± 0.18 µg kg-1 min-1 achieved a MAP≥70 mmHg in 12 ± 8 min. Duration of dobutamine infusion was 56 ± 37 min. An univariable logistic regression showed a significant association between dobutamine and acepromazine administration (p = 0.01; OR = 3.43), anaesthesia time (p = 0.02; OR = 2.41) and dorsal recumbency (p < 0.001; OR = 8.40). In a multivariable logistic regression, only dorsal recumbency significantly increased the need for dobutamine supplementation (p < 0.001; OR = 7.70). There was no significant association between patient weight (p = 0.11; OR = 1), locoregional anaesthesia (p = 0.07; OR = 0.47), administration of a ketamine bolus (p = 0.95; OR = 0.98) or volume controlled ventilation (p = 0.94; OR = 1.04) and dobutamine administration. Low doses of dobutamine were suitable to restore MAP above 70 mmHg within a limited time period. Only dorsal recumbency increased the need of dobutamine administration.

Successful caudal vena cava and pulmonary vein isolation in healthy horses using 3D electro-anatomical mapping and a contact force-guided ablation system.

BACKGROUND: Recently, treatment of equine atrial tachycardia by three-dimensional electro-anatomical mapping (3D EAM) and radiofrequency catheter ablation (RFCA) has been described. Myocardial sleeves in the caudal vena cava and pulmonary veins are a potential trigger for initiation and perpetuation of atrial tachycardia and atrial fibrillation in the horse. Isolation of these myocardial sleeves by RFCA may be an effective treatment for these arrhythmias. OBJECTIVES: To describe the feasibility of 3D EAM and RFCA to isolate caudal vena cava and pulmonary veins in adult horses using 3D mapping and a contact force (CF)-guided ablation system. STUDY DESIGN: In vivo experiments. METHODS: 3D EAM and RFCA was performed in five horses without cardiovascular disease under general anaesthesia, using the CF-guided system CARTO®3. Point-by-point RFCA aimed for isolation of caudal vena cava and pulmonary veins. Radiofrequency energy was delivered in power-controlled mode with a target power of 45 W, CF between 10 and 15 g and 30 mL/min irrigation rate, until an ablation-index of 450-500 was reached. RESULTS: In the right atrium, myocardial sleeves of the caudal vena cava were isolated (n = 5). In the left atrium, isolation of ostium II (n = 3), ostium III (n = 1) and ostium I, II and III en bloc (n = 1) was performed. Successful isolation was confirmed by entrance and exit block. MAIN LIMITATIONS: Horses were euthanised at the end of the procedure, so long term effects such as potential reconnection of isolated veins could not be studied. CONCLUSIONS: This is the first description of 3D EAM and RFCA with CARTO®3 in horses, thereby showing the technical feasibility and successful caudal vena cava and pulmonary vein isolation. CF measurement allowed monitoring of catheter-tissue contact, resulting in efficient acute lesion creation as confirmed by entrance and exit block. This is a promising treatment for cardiac arrhythmias in horses.

Xylazine Infusion during Equine Colic Anesthesia with Isoflurane and Lidocaine: A Retrospective Study.

This retrospective study investigated the effect of a xylazine infusion on heart rate; mean arterial pressure; blood gases; anesthetic and dobutamine requirements; recovery quality and duration; percentage of death/survival; and days to die/discharge in horses after colic surgery under partial intravenous anesthesia with isoflurane and lidocaine infusion. Anesthetic records of equine colic surgery were reviewed from similar periods in 2020-2021 and 2021-2022. In both groups, after sedation with xylazine 0.7 mg/kg intravenously (IV) and induction with ketamine 2.2 mg/kg and midazolam 0.06 mg/kg IV, anesthesia was maintained with isoflurane and lidocaine (bolus 1.5 mg/kg IV, infusion 2 mg/kg/h). Group L (2020-2021, n = 45) received xylazine 0.2 mg/kg IV before recovery, group XL (2021-2022, n = 44) received xylazine 0.5 mg/kg/h IV intraoperatively. In group XL, minimal (p = 0.04) and average (p = 0.04) heart rate, intraoperative hematocrit (p = 0.001), minimal (p = 0.002) and maximal (p = 0.04) dobutamine administration rate, animals requiring ketamine top-ups (p = 0.04), and the number of days to discharge (p = 0.02), were significantly lower compared to group L. During recovery in group XL, the time to sternal recumbency (p = 0.03) and time to first attempt (p = 0.04) were significantly longer. This retrospective study suggests that a xylazine infusion may have beneficial effects on horses undergoing colic surgery. Further prospective studies are necessary.

Three-dimensional electro-anatomical mapping and radiofrequency ablation as a novel treatment for atrioventricular accessory pathway in a horse: A case report.

We describe the diagnosis and treatment of an atrioventricular accessory pathway (AP) in a horse using 3-dimensional electro-anatomical mapping (3D EAM) and radiofrequency catheter ablation (RFCA). During routine evaluation of the horse, intermittent ventricular pre-excitation was identified on the ECG, characterized by a short PQ interval and abnormal QRS morphology. A right cranial location of the AP was suspected from the 12-lead ECG and vectorcardiography. After precise localization of the AP using 3D EAM, ablation was performed and AP conduction was eliminated. Immediately after recovery from anesthesia an occasional pre-excited complex still was observed, but a 24-hour ECG and an ECG during exercise 1 and 6 weeks after the procedure showed complete disappearance of pre-excitation. This case shows the feasibility of 3D EAM and RFCA to identify and treat an AP in horses.

The Antinociceptive Effect of Magnesium Sulphate Administered in the Epidural Space in Standing Horses.

To study the antinociceptive properties of epidural magnesium sulphate (MgSO4) in standing horses Experimental, placebo-controlled, masked, cross-over A group of six healthy horses Through an epidural catheter, 1 mg kg -1 MgSO4 (treatment Mg) diluted to a volume of 15 mL or the same volume of saline (treatment S) was administered over 15 minutes. Electrical, thermal and mechanical nociceptive thresholds were determined on the pelvic limb before and 20, 40, 60, 80, 100, 120, 140, 160 and 180 minutes after the start of the injection. Heart rate (HR) and respiratory frequency (fR) were recorded every 10 minutes. Blood samples were collected before treatment and every 30 minutes throughout the study period. Data were assessed for normality using a Shapiro-Wilk test. A linear mixed model with horse as random effect and time, treatment and their interaction as fixed effects was used. Treatments were compared at 20, 60, 120 and 180 minutes using the Wilcoxon rank sum test stratified for horse (global α = 0.05, with Bonferroni correction α = 0.0125). Epidural MgSO4 caused a significant increase in the electrical threshold (mA) (P = .0001), but no significant differences in thermal and mechanical nociceptive thresholds. During the injection of MgSO4, two horses collapsed. One stood up within 20 minutes and was able to continue the study, the second one was excluded. A significant difference was found for HR at T180 (Mg 44 ± 23 beats minute-1; S 32 ± 9 beats minute-1) (P = .0090). Epidural administration of MgSO4 caused an increase in the electrical threshold of the pelvic limbs of horses. Caution is warranted however, as with the current dose, 2 horses collapsed.

Effects of detomidine or romifidine during maintenance and recovery from isoflurane anaesthesia in horses.

OBJECTIVE: To evaluate the effects of detomidine or romifidine on cardiovascular function, isoflurane requirements and recovery quality in horses undergoing isoflurane anaesthesia. STUDY DESIGN: Prospective, randomized, blinded, clinical study. ANIMALS: A total of 63 healthy horses undergoing elective surgery during general anaesthesia. METHODS: Horses were randomly allocated to three groups of 21 animals each. In group R, horses were given romifidine intravenously (IV) for premedication (80 µg kg-1), maintenance (40 µg kg-1 hour-1) and before recovery (20 µg kg-1). In group D2.5, horses were given detomidine IV for premedication (15 µg kg-1), maintenance (5 µg kg-1 hour-1) and before recovery (2.5 µg kg-1). In group D5, horses were given the same doses of detomidine IV for premedication and maintenance but 5 µg kg-1 prior to recovery. Premedication was combined with morphine IV (0.1 mg kg-1) in all groups. Cardiovascular and blood gas variables, expired fraction of isoflurane (Fe'Iso), dobutamine or ketamine requirements, recovery times, recovery events scores (from sternal to standing position) and visual analogue scale (VAS) were compared between groups using either anova followed by Tukey, Kruskal-Wallis followed by Bonferroni or chi-square tests, as appropriate (p < 0.05). RESULTS: No significant differences were observed between groups for Fe'Iso, dobutamine or ketamine requirements and recovery times. Cardiovascular and blood gas measurements remained within physiological ranges for all groups. Group D5 horses had significantly worse scores for balance and coordination (p = 0.002), overall impression (p = 0.021) and final score (p = 0.008) than group R horses and significantly worse mean scores for VAS than the other groups (p = 0.002). CONCLUSIONS AND CLINICAL RELEVANCE: Detomidine or romifidine constant rate infusion provided similar conditions for maintenance of anaesthesia. Higher doses of detomidine at the end of anaesthesia might decrease the recovery quality.

Intravenous Magnesium Sulphate in Standing Horses: Effects on Physiological Parameters, Plasma Concentration of Magnesium and Nociceptive Threshold Tests☆.

A bolus of 50 mg kg -1 MgSO4 (treatment Mg) or the same volume of saline (treatment S) was infused over 15 minutes in 5 adult healthy horses. T0 was the end of the infusion. Physiological parameters were recorded throughout the study period. Measurements of electrical, thermal, and mechanical nociceptive thresholds were performed at the pelvic limbs at baseline (before T0), and at specific timepoints. Blood samples were taken at fixed timepoints before, during and until 12 hours after the infusion. For statistical analysis, the 95% confidence intervals (CI's) for the differences in nociceptive thresholds between treatments were calculated. Physiological parameters were compared using a linear mixed model (global α = 0.05, with Bonferroni correction α = 0.0125). The concentrations of ions were also compared with the baseline values at specific timepoints, using a linear mixed model. The Pearson's correlation coefficient was derived between the ion concentrations. The 95% CI's of thermal, mechanical and electrical thresholds were [-1; +2]°C, [0; +3] N and [-1; +1] mA (positive differences indicate higher thresholds for treatment Mg), respectively. Heart rate was significantly higher (P < .0001) and non-invasive systolic arterial pressure (P < .0001) and respiratory rate (P = .0002) significantly lower after treatment Mg compared to treatment S. Additionally, non-invasive systolic arterial pressure was significantly different at T45 (P < .001). Although mild changes in cardiovascular parameters and plasma concentrations were seen with intravenous administration of MgSO4, no changes in nociceptive thresholds were detected in standing non-sedated horses.

Flexor tendon repair using a reinforced tubular, medicated electrospun construct.

A reinforced tubular, medicated electrospun construct was developed for deep flexor tendon repair. This construct combines mechanical strength with the release of anti-inflammatory and anti-adhesion drugs. In this study, the reinforced construct was evaluated using a rabbit model. It was compared to its components (a tubular, medicated electrospun polymer without reinforcement and a tubular braid as such) on the one hand to a modified Kessler suture as a control group. Forty New Zealand rabbits were randomly divided into two groups. Surgery was performed in the second and fourth deep flexor tendons of one hind paw of the rabbits in the two groups using four repair techniques. Biomechanical tensile testing and macroscopic and histological evaluations were performed at 3 and 8 weeks postoperatively. A two-way analysis of variance with pairwise comparisons revealed that the three experimental surgical techniques (a reinforced tubular medicated electrospun construct, tubular-medicated construct, and tubular braid as such) showed similar strength as that of a modified Kessler suture repair, which was characterized by a mean load at ultimate failure of 19.85 N (standard deviation [SD] 5.29 N) at 3 weeks and 18.15 N (SD 8.01 N) at 8 weeks. Macroscopically, a significantly different adhesion pattern was observed at the suture knots, either centrally or peripherally, depending on the technique. Histologically, a qualitative assessment showed good to excellent repair at the tendon repair site, irrespective of the applied technique. This study demonstrates that mechanical and biological repair strategies for flexor tendon repair can be successfully combined.

Accuracy and trending capability of haemoglobin measurement by noninvasive pulse co-oximetry in anaesthetized horses.

OBJECTIVE: To assess the accuracy and trending capability of continuous measurement of haemoglobin concentration [Hb], haemoglobin oxygen saturation (SaO2) and oxygen content (CaO2) measured by the Masimo Radical-7 pulse co-oximeter in horses undergoing inhalational anaesthesia. STUDY DESIGN: Prospective observational clinical study. ANIMALS: A group of 23 anaesthetized adult horses. METHODS: In 23 healthy adult horses undergoing elective surgical procedures, paired measurements of pulse co-oximetry-based haemoglobin concentration (SpHb), SaO2 (SpO2), and CaO2 (SpOC) and simultaneous arterial blood samples were collected at multiple time points throughout anaesthesia. The arterial samples were analysed by a laboratory co-oximeter for total haemoglobin (tHb), SaO2 and manually calculated CaO2. Bland-Altman plots, linear regression analysis, error grid analysis, four-quadrant plot and Critchley polar plot were used to assess the accuracy and trending capability of the pulse co-oximeter. Data are presented as mean differences and 95% limits of agreement (LoA). RESULTS: In 101 data pairs analysed, the pulse co-oximeter slightly underestimated tHb (bias 0.06 g dL-1; LoA -1.0 to 1.2 g dL-1), SaO2 (bias 1.4%; LoA -2.0% to 4.8%), and CaO2 (bias 0.3 mL dL-1; LoA -2.1 to 2.7 mL dL-1). Zone A of the error grid encompassed 99% of data pairs for SpHb. Perfusion index (PI) ≥ 1% was recorded in 58/101 and PI < 1% in 43/101. The concordance rate for consecutive changes in SpHb and tHb with PI ≥ 1% and < 1% was 80% and 91% with four-quadrant plot, and 45.8% and 66.6% with Critchley polar plot. CONCLUSIONS: Pulse co-oximetry has acceptable accuracy for the values measured, even with low PI, whereas its trending ability requires further investigation in those horses with a higher [Hb] variation during anaesthesia.

A critical evaluation for validation of composite and unidimensional postoperative pain scales in horses.

Proper pain therapy requires adequate pain assessment. This study evaluated the reliability and validity of the Unesp-Botucatu horse acute pain scale (UHAPS), the Orthopedic Composite Pain Scale (CPS) and unidimensional scales in horses admitted for orthopedic and soft tissue surgery. Forty-two horses were assessed and videotaped before surgery, up to 4 hours postoperatively, up to 3 hours after analgesic treatment, and 24 hours postoperatively (168 video clips). After six evaluators viewing each edited video clip twice in random order at a 20-day interval, they chose whether analgesia would be indicated and applied the Simple Descriptive, Numeric and Visual Analog scales, CPS, and UHAPS. For all evaluators, intra-observer reliability of UHAPS and CPS ranged from 0.70 to 0.97. Reproducibility was variable among the evaluators and ranged from poor to very good for all scales. Principal component analysis showed a weak association among 50% and 62% of the UHAPS and CPS items, respectively. Criterion validity based on Spearman correlation among all scales was above 0.67. Internal consistency was minimally acceptable (0.51-0.64). Item-total correlation was acceptable (0.3-0.7) for 50% and 38% of UHAPS and CPS items, respectively. UHAPS and CPS were specific (90% and 79% respectively), but both were not sensitive (43 and 38%, respectively). Construct validity (responsiveness) was confirmed for all scales because pain scores increased after surgery. The cut-off point for rescue analgesia was ≥ 5 and ≥ 7 for the UHAPS and CPS, respectively. All scales presented adequate repeatability, criterion validity, and partial responsiveness. Both composite scales showed poor association among items, minimally acceptable internal consistency, and weak sensitivity, indicating that they are suboptimal instruments for assessing postoperative pain. Both composite scales require further refinement with the exclusion of redundant or needless items and reduction of their maximum score applied to each item or should be replaced by other tools.

Evaluation of the Effect of the Inspired Oxygen Fraction on Blood Oxygenation during Inhalant Anaesthesia in Horses: A Systematic Review with Meta-Analysis.

In anaesthetized horses, pronounced ventilation/perfusion mismatching often occurs. Several authors have investigated the effect of lower inspired oxygen fractions (FiO2) to reduce formation of absorption atelectasis. This systematic review compared the effects of low (<0.6) and high (>0.8) FiO2 on the arterial oxygen tension (PaO2), the alveolar-to-arterial oxygen tension difference (P(A-a)O2), and the PaO2/FiO2 ratio in horses during inhalation anaesthesia. Using the Systematic Review Protocol for Animal Intervention Studies, four experimental and one clinical investigations were deemed suitable for inclusion. A meta-analysis was performed on the four experimental studies. The PaO2 was significantly lower (p = 0.0007, mean difference -23.54 kPa, 95% CI -37.18, -9.90) with a lower FiO2. However, the P(A-a)O2 was also significantly lower (p < 0.00001, mean difference -20.80 kPa, 95% CI -26.28, -15.32) when using a low FiO2. For the PaO2/FiO2 ratio, only one study fitted the inclusion criteria, so no meta-analysis was performed. It is concluded that, while only a limited number of studies are available, the use of a higher FiO2 in horses during inhalation anaesthesia will result in higher levels of PaO2, but also a larger P(A-a)O2 difference. Further studies are needed to increase the level of evidence on this subject.

Development and validation of the facial scale (FaceSed) to evaluate sedation in horses.

Although facial characteristics are used to estimate horse sedation, there are no studies measuring their reliability and validity. This randomised controlled, prospective, horizontal study aimed to validate a facial sedation scale for horses (FaceSed). Seven horses received detomidine infusion i.v. in low or high doses/rates alone (DL 2.5 µg/kg+6.25 µg/kg/h; DH 5 µg/kg+12.5 µg/kg/h) or combined with methadone (DLM and DHM, 0.2 mg/kg+0.05 mg/kg/h) for 120 min, or acepromazine boli i.v. in low (ACPL 0.02 mg/kg) or high doses (ACPH 0.09 mg/kg). Horses' faces were photographed at i) baseline, ii) peak, iii) intermediate, and iv) end of sedation. After randomisation of moments and treatments, photos were sent to four evaluators to assess the FaceSed items (ear position, orbital opening, relaxation of the lower and upper lip) twice, within a one-month interval. The intraclass correlation coefficient of intra- and interobserver reliability of FaceSed scores were good to very good (0.74-0.94) and moderate to very good (0.57-0.87), respectively. Criterion validity based on Spearman correlation between the FaceSed versus the numerical rating scale and head height above the ground were 0.92 and -0.75, respectively. All items and the FaceSed total score showed responsiveness (construct validity). According to the principal component analysis all FaceSed items had load factors >0.50 at the first dimension. The high internal consistency (Cronbach´s α = 0.83) indicated good intercorrelation among items. Item-total Spearman correlation was adequate (rho 0.3-0.73), indicating homogeneity of the scale. All items showed sensitivity (0.82-0.97) to detect sedation, however only orbital opening (0.79) and upper lip relaxation (0.82) were specific to detect absence of sedation. The limitations were that the facial expression was performed using photos, which do not represent the facial movement and the horses were docile, which may have reduced specificity. The FaceSed is a valid and reliable tool to assess tranquilisation and sedation in horses.

Description of different ultrasound guided transversus abdominis plane block in pig cadavers - A pilot study.

OBJECTIVE: To develop an ultrasound (US)-guided transversus abdominis plane (TAP) block in pigs. STUDY DESIGN: Prospective, descriptive, experimental study. ANIMALS: A total of 26 hemi-abdomens belonging to 13 Seghers Hybrid cadavers. METHODS: The study consisted of two parts. In part 1, a preliminary anatomical understanding of the abdominal wall innervation in pigs was established (two hemi-abdomens of one pig). Part 2 was divided into three phases, and a US-guided TAP technique using methylene blue dye (0.3 mL kg-1 for each hemi-abdomen) was developed. In chronological order, a pilot study (phase I) was conducted to establish good injection points (four hemi-abdomens). In phase II a two-point injection technique (10 hemi-abdomens) was performed. A cranial injection was made at two-thirds of the distance between the xyphoid process and the iliac crest, immediately ventral to the rib arch. A caudal injection was performed ventral to the last rib. In phase III a three-point injection technique was performed (10 hemi-abdomens) with an extra injection point halfway between the cranial and caudal injection point. Staining of the different nerves was recorded during dissection. RESULTS: In part 1 the nerves innervating the pig's abdominal wall, thoracic vertebrae 12-16 (T12-16) and lumbar vertebrae 1-3 (L1-3), were identified. In part 2, data from the pilot study, adequate nerve staining with the two- or three-point injection technique, were obtained in T12 (29 versus 45% respectively), T13 (29 versus 100%), T14 (73 versus 45%), T15 (75 versus 78%), T16 (58 versus 78%), L1 (100 versus 75%), L2 (88 versus 84%) and L3 (23 versus 0%). CONCLUSIONS AND CLINICAL RELEVANCE: US-guided TAP block can be used in swine but only a moderate success rate for adequate nerve staining was achieved in this study. Further studies are necessary to determine a correct injection volume and assess clinical intra- and postoperative efficacy.

Development, Validation, and Reliability of a Sedation Scale in Horses (EquiSed).

The lack of standardization of sedation scales in horses limits the reproducibility between different studies. This prospective, randomized, blinded, horizontal and controlled trial aimed to validate a scale for sedation in horses (EquiSed). Seven horses were treated with intravenous detomidine in low/high doses alone (DL 2.5 µg/kg + 6.25 µg/kg/h; DH 5 µg/kg +12.5 µg/kg/h) or associated with methadone (DLM and DHM, 0.2 mg/kg + 0.05 mg/kg/h) and with low (ACPL 0.02 mg/kg) or high (ACPH 0.09 mg/kg) doses of acepromazine alone. Horses were filmed at (i) baseline (ii) peak, (iii) intermediate, and (iv) end of sedation immediately before auditory, visual and pressure stimuli were applied and postural instability evaluated for another study. Videos were randomized and blindly evaluated by four evaluators in two phases with 1-month interval. Intra- and interobserver reliability of the sum of EquiSed (Intraclass correlation coefficient) ranged between 0.84-0.94 and 0.45-0.88, respectively. The criterion validity was endorsed by the high Spearman correlation between the EquiSed and visual analog (0.77), numerical rating (0.76), and simple descriptive scales (0.70), and average correlation with head height above the ground (HHAG) (-0.52). The Friedman test confirmed the EquiSed responsiveness over time. The principal component analysis showed that all items of the scale had a load factor ≥ 0.50. The item-total Spearman correlation for all items ranged from 0.3 to 0.5, and the internal consistency was good (Cronbach's α = 0.73). The area under the curve of EquiSed HHAG as a predictive diagnostic measure was 0.88. The sensitivity of the EquiSed calculated according to the cut-off point (score 7 of the sum of the EquiSed) determined by the receiver operating characteristic curve, was 96% and specificity was 83%. EquiSed has good intra- and interobserver reliabilities and is valid to evaluate tranquilization and sedation in horses.

Recovery Quality After Romifidine Versus Detomidine Infusion During Isoflurane Anesthesia in Horses.

To examine the influence of detomidine or romifidine on recovery quality from isoflurane anesthesia, 78 anesthetic records were reviewed, from horses that had received romifidine (group R) during premedication [80-120 µg kg-1 IV], anesthetic maintenance (40 µg kg-1 hour-1 IV), and recovery (20 µg kg-1 IV) or detomidine (group D), at doses of 10-20 µg kg-1 IV, 5 µg kg-1 hour-1 IV, and 2.5 µg kg-1 IV, respectively. Duration of the different recovery phases, the number of attempts to sternal and standing, scores for transition to standing (TrSta), balance and coordination once standing (BC), and final recovery score (FS) were compared between groups using a Mann-Whitney U-test, independent t-test, or chi-squared test, as appropriate (alpha 0.05). Parametric data are represented as the mean ± standard deviation, and nonparametric data as the median (interquartile range). Compared with group D (25 horses), horses in group R (53 horses) needed significantly fewer attempts to achieve sternal recumbency [R 1 (1-1) vs. D 1 (1-2)], remained significantly longer in sternal recumbency [R 10 (3-14,5) vs. D 5 (1-9,5) minutes], needed significantly less attempts to stand [R 1 (1-1) vs. D 2 (1-4)], and a significantly shorter time to stand after making their first attempt [R 0 (0-0) vs. D 3 (0-6) minutes], with significantly better scores for TrSta, BC, and FS in group R. The results suggest that, at the doses used, romifidine provides a better recovery quality.

Three dimensional ultra-high-density electro-anatomical cardiac mapping in horses: methodology.

BACKGROUND: Ultra-high-density cardiac mapping allows very accurate characterisation of atrial and ventricular electrophysiology and activation timing. OBJECTIVE: To describe the technique and evaluate the feasibility of magnetic electro-anatomical mapping of the equine heart. STUDY DESIGN: In vivo experimental method development. METHODS: A mapping system using an 8.5F bidirectional deflectable catheter with a deployable mini-basket (3-22 mm) containing 64 electrodes divided over eight splines was evaluated. Based upon predefined beat acceptance criteria, the system automatically acquires endocardial electrograms and catheter location information. Electro-anatomical maps were acquired from four horses in sinus rhythm under general anaesthesia. RESULTS: All endocardial areas within each chamber could be reached. Access to the left atrium required the use of a deflectable sheath. With the exception of the left atrial map of horse 1, all four chambers in all four horses could be mapped. Optimisation of the beat acceptance criteria led to a reduction in manual correction of the automatically accepted beats from 13.1% in the first horse to 0.4% of the beats in the last horse. MAIN LIMITATIONS: Only a limited number of horses were included in the study. CONCLUSION: Ultra-high-density 3D electro-anatomical mapping is feasible in adult horses and is a promising tool for electrophysiological research and characterisation of complex arrhythmias.

Gastrostomy tube placement via a laparotomic procedure in growing conventional piglets to perform multi-dose preclinical paediatric drug studies.

The use of juvenile conventional pigs as a preclinical animal model to perform pharmacokinetic (PK), pharmacodynamic (PD) and safety studies for the paediatric population is increasing. Repetitive oral administration of drugs to juvenile pigs is however challenging. A representative method which can be used from birth till adulthood is necessary. The current study presents the placement and use of a gastrostomy button in pigs with a weight ranging from 2.4 to 161 kg. The surgical placement was performed via a laparotomic procedure on, each time, 12 pigs (six male, six female) of 1 week, 4 weeks, 8 weeks and 6-7 months old. For every age category, eight pigs were part of a PK study with a non-steroidal anti-inflammatory drug (NSAID) and four pigs served as a control group. No severe complications were observed during surgery. The button remained functional for 10 days in 40 out of 48 pigs. No significant differences in body temperature or white blood cell count were observed during the trial. Three control pigs showed signs of inflammation indicating a NSAID might be warranted. Autopsy revealed minimal signs of major inflammation in the abdominal cavity or the stomach. A limited number of pigs showed mucosal inflammation, ulcers or abscesses in the stomach or around the fistula. These results indicate that the laparotomic placement of a gastrostomy button might be considered safe and easy in growing pigs to perform repetitive oral dosing preclinical studies. However, the method is not advised in pigs weighing more than 100 kg.