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Summary: The most widely used method of assessing the physical status of humans presented for anaesthesia is the American Society of Anaesthesiologists Physical Status Classification System (ASA‐PS). The ASA‐PS has been applied to animals including horses, but its use is problematic. The authors virtually convened a group of internationally recognised equine veterinary anaesthesiologists with the goal of developing a risk assessment tool for the evaluation of healthy and diseased horses presented for anaesthesia. With this survey and analysis, the authors aim to develop a simple rubric system to assess equine anaesthetic risk that augments the ASA‐PS system. The goal is to identify both diseased and healthy horses at increased anaesthetic risk prior to induction of anaesthesia so that measures might be implemented to potentially reduce morbidity and mortality. [ABSTRACT FROM AUTHOR]

Summary: The inability to control pain is the most common reason for cessation of treatment and euthanasia in cases of laminitis, yet pain also serves a unique protective function in these cases, particularly in the acute phase when lamellar integrity is weakened. Successful analgesia requires an understanding of the disease pathophysiology, the sources of pain in laminitis, methods of serial pain evaluation, and methods of analgesia including systemic and regional techniques. This review discusses the approach to analgesia including detail of traditional and novel analgesic medications and techniques with specific reference to the laminitis case. [ABSTRACT FROM AUTHOR]

Summary: Background: The use of pulse oximetry in horses is limited due to inadequate readings with conventional transmission sensor probes. Objectives: The objectives of this study were to 1) develop an improved sensor design for horses to be used at an appropriate anatomical site, and 2) evaluate this design in an experimental study. Study design: In vivo experiment. Methods: A new sensor design for reflectance pulse oximetry at the buccal mucosa was developed. A conventional Nonin 2000SL sensor for transmission pulse oximetry was included into this design. Three different prototypes (N1, N2a, N2b) were constructed and used with the Nonin 2500A Vet pulse oximetry monitor. Thirteen anaesthetised warmblood horses were included into a desaturation protocol (100–70% SaO2). SpO2 and pulse frequency values were recorded, using SaO2 calculated from blood gas analysis and invasive pulse frequency measurements as reference methods. Bias and precision were evaluated by calculations of the root mean square deviation (Arms). The agreement of the methods was tested with Bland‐Altman analysis. Results: The quality of the pulse frequency readings determined the quality of the SpO2‐readings. Good pulse signal strength resulted in a SpO2‐accuracy comparable to that of the original sensor (Nonin 2000SL: Arms = 3%; N1: Arms = 3.60%; N2b: Arms = 3.46%). Especially at heart rates ≤30 bpm, pulse rate readings that were about twice as high as the reference value occurred. Their exclusion from the dataset resulted in a pulse rate accuracy similar to that of the original sensor. Bland‐Altman plots showed limits of agreement typical of pulse oximeters. Main limitations: The pulse frequency accuracy requires further improvement. The usability in clinical cases needs to be tested. Conclusions: The new sensor design has been shown to be suitable for buccal pulse oximetry in horses. [ABSTRACT FROM AUTHOR]

Background In the horse, effects of cardiovascular-active drugs on local perfusion of the gastrointestinal tract are poorly understood. Objectives To determine the effect of drugs commonly used to support blood pressure, on local intestinal blood flow and tissue oxygenation under isoflurane anaesthesia. Study design In vivo randomised crossover experiment. Methods Ten horses were anaesthetised with isoflurane. After 90 min of equilibration three doses (μg/kg bwt/min) of dobutamine ( DOB 0.5/1/3), dopamine ( DA 1/2/5), noradrenaline ( NA 0.1/0.2/0.5) and phenylephrine ( PHE 0.5/1/3) were infused for 15 min, in a randomised order, with a 45 min washout-period. Blood flow and tissue oxygenation ( sO2) of jejunum, colon and stomach were measured using white light remission spectrophotometry and laser doppler flowmetry; heart rate ( HR), mean arterial blood pressure ( MAP), cardiac output ( CO) were measured and systemic vascular resistance ( SVR) calculated. Results Compared to baseline high dose dobutamine significantly increased CO, HR, MAP (P<0.001) and blood flow to the jejunum (+47 ± 26%, P = 0.001) and colon (+29 ± 15%, P<0.001) (mean ± s.d.). Dopamine ( DA5) increased CO but decreased colonic blood flow (−39 ± 21% from baseline, P<0.001), as well as SVR and MAP compared to baseline (P<0.001). Noradrenaline had no significant influence on intestinal perfusion, but increased MAP and SVR from baseline (P<0.001). Phenylephrine ( PHE3) caused a significant decrease in blood flow and sO2, most profoundly at the colon compared to baseline (flow −44 ± 21%; sO2 −16 ± 3%, P<0.001), while MAP and SVR increased and CO and HR decreased (P<0.001). Main limitations The measurement technique only allows for flow measurements in arbitrary units, which can limit comparability to other techniques. Conclusion At the investigated doses dobutamine improved systemic and peripheral haemodynamics, while dopamine decreased MAP and peripheral perfusion. Noradrenaline increased MAP and SVR while peripheral blood flow was maintained, phenylephrine increased MAP, but reduced both local and systemic perfusion. [ABSTRACT FROM AUTHOR]

Reasons for performing study High airway pressures, necessary to keep equine lungs open, can have a detrimental impact on central and peripheral perfusion. Objective The aim of this study was to assess the effects of stepwise increasing airway pressure recruitment on central and intestinal perfusion and oxygenation during isoflurane anaesthesia in horses. Study design In vivo experimental study. Methods Ten anaesthetised horses were ventilated using intermittent positive pressure ventilation immediately after induction. After 90 min, end-expiratory pressure ( PEEP) was increased by steps of 5 cmH2O every 10 min up to a PEEP of 30 cmH2O and decreased back to zero maintaining a constant airway pressure difference of 20 cmH2O. Mean arterial blood pressure ( MAP), heart rate, central venous pressure, pulmonary artery pressure, expiratory isoflurane concentration and cardiac output (thermodilution method) were measured. Cardiac index ( CI) was calculated. Arterial blood gases were taken to measure arterial partial oxygen pressure (PaO2) and calculate arterial oxygen saturation (SaO2). Intestinal microperfusion and oxygenation were measured by laser Doppler flowmetry and white-light spectrophotometry. After ventral median laparotomy, a probe was placed on the stomach, jejunum and pelvic flexion of the colon. An ANOVA for repeated measurements and Tukey's post hoc test were used for statistical analysis (α = 5%). Results Recruitment of the lungs resulted in a significant increase in PaO2 from 201 ± 58 mmHg (baseline) to a maximum of 495 ± 75 mmHg. The CI and MAP decreased continuously with increasing airway pressures. When CI and MAP were 37 ± 9 ml/kg/min and 52 ± 8 mmHg (at PEEP of 25 cmH2O), respectively, a sudden decrease in intestinal perfusion followed by a delayed decrease in oxygenation occurred. Conclusions There was linear correlation between airway pressures and CI and MAP but not between central and gastrointestinal perfusion. Despite improvement of arterial oxygenation the decrease in CI and, therefore, in oxygen delivery PEEP resulted in a decrease in gastrointestinal oxygenation. [ABSTRACT FROM AUTHOR]

Reasons for performing study: Dexmedetomidine has been administered in the equine as a constant-rate infusion (CRI) during inhalation anaesthesia, preserving optimal cardiopulmonary function with calm and coordinated recoveries. Inhalant anaesthetic sparing effects have been demonstrated in other species, but not in horses. Objectives: To determine the effects of a CRI of dexmedetomidine on the minimal alveolar concentration (MAC) of sevoflurane in ponies. Methods: Six healthy adult ponies were involved in this prospective, randomised, crossover, blinded, experimental study. Each pony was anaesthetised twice (3 weeks washout period). After induction with sevoflurane in oxygen (via nasotracheal tube), the ponies were positioned on a surgical table (T0), and anaesthesia was maintained with sevoflurane (expired sevoflurane fraction 2.5%) in 55% oxygen. The ponies were randomly allocated to treatment D (dexmedetomidine 3.5 µg/kg bwt i.v. [T10-T15] followed by a CRI of dexmedetomidine at 1.75 µg/kg bwt/h) or treatment S (bolus and CRI of saline at the same volume and rate as treatment D). After T60, MAC determination, using a classic bracketing technique, was initiated. Stimuli consisted of constant-current electrical stimuli at the skin of the lateral pastern region. Triplicate MAC estimations were obtained and averaged in each pony. Monitoring included pulse oximetry, electrocardiography, anaesthetic gas monitoring, arterial blood pressure measurement and arterial blood gases. Normocapnia was maintained by mechanical ventilation. Analysis of variance (treatment and period as fixed factors) was used to detect differences between treatments (α= 0.05). Results: An intravenous (i.v.) dexmedetomidine CRI decreased mean ± s.d. sevoflurane MAC from 2.42 ± 0.55 to 1.07 ± 0.21% (mean MAC reduction 53 ± 15%). Conclusions and potential relevance: A dexmedetomidine CRI at the reported dose significantly reduces the MAC of sevoflurane. [ABSTRACT FROM AUTHOR]

Abstract Background The aim of the study was to evaluate the performance of contact heat thermal stimulation in horses at different body sites and under different environmental conditions and different test situations. Five warm-blood horses were equipped with the thermal probe located on the skin of nostril (N), withers (W) or coronary band (C). Skin temperature and reaction temperature (thermal threshold) at each location were measured and percent thermal excursion (% TE = 100 * (threshold temperature - skin temperature)/(cut-out temperature - skin temperature) was calculated. Environmental conditions were changed in partial random order for all locations, so each horse was tested in its familiar box stall and stocks, in the morning and evening and at warm and cold ambient temperatures. Type of reaction to the stimulus and horse’s general behaviour during stimulation were recorded. The stimulation sites were examined for the occurrence of possible skin lesions. Results Skin temperatures were significantly different during warm and cold ambient temperatures at all three locations, but remained constant over repeated stimulation. An obvious response to stimulation before reaching cut-out temperature could be detected most frequently at N and W in boxes during warm ambient temperatures. The most frequent type of reaction to thermal stimulation at the nostril was headshaking (64.6%), skin twitching at the withers (82.9%) and hoof withdrawal at the coronary band (79.2%). Conclusion The outcome of thermal threshold testing depended on ambient temperature, stimulation site and environment. Best results with the WTT2 in horses were obtained at the nostrils or withers in a familiar environment at warm ambient temperatures.

Background: Orotracheal intubation is commonly performed for inhalation anaesthesia in horses to ensure safe and reliable administration of volatile anaesthetics and to secure the airways. In human and equine medicine, the occurrence of intubation-associated complications has been described, which can range from mild mucosal irritation to severe necrosis. However, there are only sparse descriptions of mucosal alterations and the course of healing after elective surgery in horses., Objective: To investigate the prevalence and severity of tracheal lesions following endotracheal intubation associated with general anaesthesia in equine patients., Study Design: Prospective, clinical study., Methods: Forty adult Warmblood horses, weighing 400-600 kg, presented for elective surgery under general anaesthesia were included. For orotracheal intubation, a silicone tube was used and inflated until a cuff pressure of 40 cmH 2 O was confirmed. In all horses, endoscopic examination of the trachea with video documentation was performed prior to intubation and immediately after extubation, as well as 1, 3, 5 and 7 days after general anaesthesia. The type (redness, secretion, bleeding, erosions) and degree (0 = non-existent to 4 = severe) of corresponding lesions were assessed and scored. The occurrences of clinical signs were recorded. Statistical evaluation was performed using Friedman's test and Pearson correlation., Results: The median score immediately after recovery from anaesthesia was 6 (2-12) and increased significantly to 11 (4-15) after 1 day (p = 0.021). At day 7, the median score was 0 (0-2) with only four horses showing signs of mild tracheitis, and clinical signs were not observed throughout this time period. The duration of intubation correlated with the degree of tracheal damage (r 2  = 0.67, p < 0.001)., Main Limitations: Clinical, non-randomised study without a control group., Conclusion: Although orotracheal intubation was accompanied by focal inflammation of the trachea, in the present study no horses showed clinical signs and lesions healed within a week., (© 2025 The Author(s). Equine Veterinary Journal published by John Wiley & Sons Ltd on behalf of EVJ Ltd.)

Maxillary nerve blocks (MNBs) commonly facilitate dental surgeries in standing horses. The goal of this prospective, blinded, cross-over design trial including 15 client-owned horses was to evaluate 3 methods of sensory function testing for confirming a successful MNB. Testing was performed bilaterally before sedation, 5 min after sedation, and 15 and 30 min after MNB with 0.5% bupivacaine and involved a needle prick dorsal to each naris, hemostat clamping of each nostril, and gingival algometry (measuring sensitivity to pain). Responses to stimulation were numerically scored and scores were summed up to a total score. Total score increases on the blocked side by ≥ 2 between baseline and 30 min Post MNB recordings signified a successful MNB. Sedation in the preceding 6 h, presence of sino-nasal disease, side of dental pathology, age, butorphanol administration, and detomidine dosing (µg/kg/min) throughout the tooth extraction procedure were recorded. In 73% of horses, MNB was successful. Sedation in the preceding 6 h ( P  = .732), age ( P  = .936), side of pathology ( P  = .516), and sino-nasal disease ( P  = .769) were not associated with total scores. Detomidine dosage and butorphanol use did not differ between horses in which the MNB was considered successful and for those in which it was not ( P  = .967 and P  = .538, respectively). Scores obtained with gingival algometry were less closely associated with total scores (rho = .649) than those obtained with needle prick and nostril clamping (rho = .819 and .892, respectively). Therefore, needle prick and nostril clamping are considered the more reliable methods for use in clinical practice to determine the success of an MNB., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Objective: Data were extracted from preexisting published studies and evaluated retrospectively to compare lactate and base deficit values at baseline and posthemorrhage with changes in corresponding hemoglobin (Hb) and Hct measurements to assess any association of such changes with severity of hemorrhage over time. To understand the goal, the objective of this study was to demonstrate statistical changes in laboratory values as described above., Methods: Previous prospectively designed experiments on 120 mixed-breed dogs were conducted. Various parameters, including Hb and Hct, lactate concentration, and base deficit, were extracted from the previously mentioned experiments. To validate this retrospective study, subset data on heart rate and arterial pressure were compared. In a subset analysis, 60 experiments were extracted to compare baseline mean arterial pressure to posthemorrhagic values to prove the validity of this model. Published studies were evaluated retrospectively to compare lactate and base deficit values at baseline and posthemorrhage., Results: Arterial pressure is lowest posthemorrhage, increases, then stabilizes. Baseline Hb averaged 15.1 g/dL and Hct 43.4%, and posthemorrhage values averaged 12.1 g/dL (Hb) and 35.3% (Hct). Significant differences were observed for both Hb (3.0 g/dL difference; P < .001) and Hct (8.3% difference; P < .001) posthemorrhage. Lactate significantly increased (2.1; P < .001), and base deficit significantly decreased (5.2; P < .001)., Conclusions: The data collected retrospectively validated the model for significant hypotension. It was then possible to evaluate whether Hb and Hct may accurately predict the degree of hemorrhage. In this model, both Hb and Hct decreased posthemorrhage significantly, although the actual change in Hb and Hct posthemorrhage was modest. Lactate concentration increased, and base deficit decreased., Clinical Relevance: The data suggest that Hb, Hct, lactate, and base deficit should be studied to see if they may have a potential role in guiding resuscitation decisions.