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Scintigraphy and Positron Emission Tomography (PET) are both nuclear medicine imaging techniques, providing functional information of the imaged areas. Scintigraphy is a two-dimensional projected imaging technique that was introduced in equine imaging in the late 1970s. Scintigraphy allows imaging of large body parts and can cover multiple areas, remaining the only technique commonly used in horses for whole body imaging. PET is a cross-sectional imaging technique, first used in horses in 2015, allowing higher resolution three-dimensional functional imaging of the equine distal limb. This manuscript will cover current use and values of these two modalities in equine lameness diagnosis.

BACKGROUND: The pleiotropic effects of the melanocortin system show promise in overcoming limitations associated with large variations in opioid analgesic effectiveness observed in equine practice. Of particular interest is variation in the melanocortin-1-receptor (MC1R) gene, which dictates pigment type expression through its epistatic interaction with the agouti signalling protein (ASIP) gene. MC1R has previously been implicated in opioid efficacy in other species; however, this relationship is yet to be explored in horses. In this study, analgesic effectiveness was scored (1-3) based on noted response to dura penetration during the performance of cerebrospinal fluid centisis after sedation and tested for association with known genetic regions responsible for pigmentation variation in horses. RESULTS: The chestnut phenotype was statistically significant (P < 0.05) in lowering analgesic effectiveness when compared to the bay base coat colour. The 11bp indel in ASIP known to cause the black base coat colour was not significant (P>0.05); however, six single nucleotide polymorphisms (SNPs) within the genomic region encoding the ASIP gene and one within MC1R were identified as being nominally significant (P

Equine assisted services (EAS) consist of a complex system of horse, human, and environmental factors which ultimately impact program effectiveness. Despite recognition in the literature that organizational affiliation with spirituality or religion impacts values, practices, and culture, connection between faith, spirituality, and specific religious belief, when combined with EAS is a nascent field of inquiry. Despite preliminary observations that suggest many organizations offering EAS are affiliated with religious institutions or claim their practices are informed by a particular faith, the extent of these non-secular affiliations is unknown in current literature. To explore this, we surveyed 113 EAS organizations to determine the extent and type of non-secular (i.e., faith-based) affiliations and whether these affiliations were professed publicly, to all internal staff and participants, to staff only, or not at all (i.e., level of “transparency”). We collected data on a range of horse characteristics and program practices. We used chi-square analyses to assess associations between secular/non-secular status and characteristics of practices. Of 93 organizations, 71% claimed a non-secular affiliation. Of non-secular organizations, 61% were fully transparent, and 36% were open about their belief system only internally with staff and participants. More non-secular organizations emphasized horses that were sensitive to humans and the environment (p = 0.0063). Non-secular organizations placed more importance on partnering with horses with a history of abuse or neglect (p = 0.0461). Transparency of faith or religious affiliation was associated with selection of horses based on girth, bone, and sturdiness (p = 0.0004). This is the first study to explore how a proxy for organizational-level values is associated with EAS practice differences. Further research is needed to determine if program-level differences in faith affiliation impact outcomes for participants in EAS.

Horses and cattle have shown low susceptibility to SARS-CoV-2, and there is no evidence of experimental intraspecies transmission. Nonetheless, seropositive horses in the US and seropositive cattle in Germany and Italy have been reported. The current study investigated the prevalence of antibodies against SARS-CoV-2 in horses and cattle in Switzerland. In total, 1940 serum and plasma samples from 1110 horses and 830 cattle were screened with a species-specific ELISA based on the SARS-CoV-2 receptor-binding domain (RBD) and, in the case of suspect positive results, a surrogate virus neutralization test (sVNT) was used to demonstrate the neutralizing activity of the antibodies. Further confirmation of suspect positive samples was performed using either a pseudotype-based virus neutralization assay (PVNA; horses) or an indirect immunofluorescence test (IFA; cattle). The animals were sampled between February 2020 and December 2022. Additionally, in total, 486 bronchoalveolar lavage (BAL), oropharyngeal, nasal and rectal swab samples from horses and cattle were analyzed for the presence of SARS-CoV-2 RNA via reverse transcriptase quantitative polymerase chain reaction (RT-qPCR). Six horses (0.5%; 95% CI: 0.2-1.2%) were suspect positive via RBD-ELISA, and neutralizing antibodies were detected in two of them via confirmatory sVNT and PVNA tests. In the PVNA, the highest titers were measured against the Alpha and Delta SARS-CoV-2 variants. Fifteen cattle (1.8%; 95% CI: 1.0-3.0%) were suspect positive in RBD-ELISA; 3 of them had SARS-CoV-2-specific neutralizing antibodies in sVNT and 4 of the 15 were confirmed to be positive via IFA. All tested samples were RT-qPCR-negative. The results support the hypotheses that the prevalence of SARS-CoV-2 infections in horses and cattle in Switzerland was low up to the end of 2022.

INTRODUCTION: Morphine is an effective analgesic in horses, however, IV administration at therapeutic doses has been shown to produce dose-dependent neuroexcitation and unwanted gastrointestinal effects. The analgesic effects of morphine have, at least in part, been attributed to the morphine-6-glucuronide (M6G) metabolite. Oral administration to horses results in comparable M6G concentrations to that achieved following IV administration of a therapeutic dose without the adverse effects. The anti-nociceptive effects have not yet been reported. In the current study the thermal anti-nociceptive effects of single and multiple oral doses of morphine were assessed. METHODS: Six horses received a single 0.2 mg/kg IV dose of morphine and multiple oral doses of 0.8 mg/kg morphine every 12 h for 4.5 days. Blood samples were collected throughout administration, morphine, and metabolite concentrations determined and pharmacokinetic analysis performed. Drug related behavior and physiologic responses were recorded. Response to noxious stimuli was evaluated by determining thermal threshold latency in response to the application of heat. RESULTS: The maximum concentrations of M6G were higher following oral administration compared to IV and the combined morphine and M6G concentrations exceeded that of IV administration starting at 2 h. Oral administration of 0.8 mg/kg morphine provided and maintained comparable anti-nociception effects to IV morphine with less adverse effects, following single and multiple doses. Morphine was well tolerated following oral administration with less excitation and minimal effects on gastrointestinal borborygmi scores compared to IV administration. DISCUSSION: Results of the current study warrant further investigation of the anti-nociceptive effects of oral morphine administration to horses.

Steroid-associated laminitis remains a major concern with use of corticosteroids in horses. Individual case factors such as joint pathology, pre-existing endocrinopathies, or corticosteroid type, dose, and timing influencing steroid-induced laminitis risk have not been investigated. This study aimed to determine if systemic absorption of triamcinolone acetonide (TA) varies between intrasynovial (antebrachiocarpal) and extrasynovial (sacroiliac) injection sites, and to determine the effects of TA absorption on glucose, insulin, cortisol, and adrenocorticotropic hormone (ACTH). Twenty adult horses were randomized into antebrachiocarpal or sacroiliac joint injection groups, and each horse received bilateral injections with a total dose of 18 mg triamcinolone. Blood was collected prior to injection and at 1, 2, 4, 6, 8, 10, 12, 16, 20, 24, 36, 48, 60, and 72 h post-injection. Peak TA absorption occurred at 8 h in both groups, and was significantly higher in the intrasynovial group compared to the extrasynovial group (1.397 ng/mL, 0.672 ng/mL, p 20 μU/mL) from both groups experienced a more marked hyperinsulinemia, reaching a mean peak insulin of 197.5 μU/mL as compared to 90.06 μU/mL in those with normal baseline insulin. Cortisol and ACTH were significantly decreased from baseline at timepoints from 4-72 h post-injection in both groups. This study is the first to evaluate drug absorption from the sacroiliac site and demonstrates that drug absorption varies between intrasynovial and extrasynovial injection sites. TA absorption causes metabolic derangements, most notably a marked hyperinsulinemia that is more severe in horses with elevated baseline insulin values. The influence of baseline endocrinopathies on response to corticosteroid administration as well as the effect of corticosteroid-induced metabolic derangements warrant further investigation as risk factors for corticosteroid-associated laminitis.

INTRODUCTION: Understanding the pharmacokinetics and pharmacodynamics of fentanyl in horses is crucial for optimizing pain management strategies in veterinary medicine. METHODS: Six adult horses were enrolled in a randomized crossover design. Treatments included: placebo, two 100 mcg/h patches (LDF), four 100 mcg/h patches (MDF), and six 100 mcg/h patches (HDF). Patches were in place for 72 h. Blood was obtained for fentanyl plasma concentration determination, thermal threshold, mechanical threshold, heart rate, respiratory rate, and rectal temperature were obtained prior patch placement and at multiple time points following patch placement for the following 96 h. Fentanyl plasma concentration was determined using LC-MS/MS. Data were analyzed using a generalized mixed effects model. RESULTS: Mean (range) maximum plasma concentration (Cmax), time to Cmax, and area under the curve extrapolated to infinity were 1.39 (0.82-1.82), 2.64 (1.21-4.42), 4.11 (2.78-7.12) ng/ml, 12.7 (8.0-16.0), 12.7 (8.0-16.0), 12 (8.0-16.0) h, 42.37 (27.59-55.56), 77.24 (45.62-115.06), 120.34 (100.66-150.55) h ng/ml for LDF, MDF, and HDF, respectively. There was no significant effect of treatment or time on thermal threshold, mechanical threshold, respiratory rate, or temperature (p > 0.063). There was no significant effect of treatment on heart rate (p = 0.364). There was a significant effect of time (p = 0.003) on heart rate with overall heart rates being less than baseline at 64 h. CONCLUSIONS: Fentanyl administered via transdermal patch is well absorbed and well tolerated but does not result in an anti-nociceptive effect as measured by thermal and mechanical threshold at the doses studied.

BACKGROUND: Dexamethasone is routinely administered to horses but its effect on the antibody response to a commercial EIV/EHV vaccine is unclear. HYPOTHESIS: Horses receiving dexamethasone will have lower postvaccination antibody levels against EIV and EHV-1 than vaccinated controls. ANIMALS: Fifty-five healthy adult research horses. METHODS: Randomized cohort study. Control (no vaccine, group 1), vaccination only (EIV/EHV-1/EHV-4, Prestige 2, Merck Animal Health, group 2), vaccination and concurrent single intravenous dose of dexamethasone (approximately .05 mg/kg, group 3), vaccination and 3 intravenous doses of dexamethasone at 24 hours intervals (group 4). Serum SAA levels were measured on day 1 and day 3. Antibody levels against EIV (hemagglutination inhibition assay, Kentucky 2014 antigen) and EHV-1 (multiplex ELISA targeting total IgG and IgG 4/7) were measured on day 1 and day 30. RESULTS: Significantly increased mean antibody titers after vaccination were only noted against EIV and only after the vaccination alone (n = 14, prevaccine mean [prvm] 166.9, SD 259.6, 95% CI 16.95-316.8; postvaccine mean [povm] 249.1, SD 257.2, 95% confidence interval [CI] 100.6-397.6, P = .02) and the single dose dexamethasone (n = 14, prvm 93.14, SD 72.2, CI 51.45-134.8; povm 185.1, SD 118, CI 116.7-253.6, P = .01), but not after multiple doses of dexamethasone (n = 14, prvm 194.3, SD 258.3, CI 45.16-343.4; povm 240.0, SD 235.7, CI 103.9-376.1, P > .05). CONCLUSION: The effect of dexamethasone on the postvaccine antibody response varies depending on the dosing frequency and the antigen-specific antibody type.

Summary Background Objective Study design Methods Results Conclusion Uterine torsion (UT) is an infrequent serious obstetric disorder in pregnant mares.To record the outcome of standing flank laparotomy (SFL) for correction of UT in Straight Egyptian Arabian mares.Retrospective analysis of medical records.Hospital records of all pregnant mares that underwent SFL for correction of UT between 2018 and 2022 were analysed. The signalment, history, clinical signs, results of diagnostic techniques, direction and degree of UT, treatment and outcome, rebreeding and recurrence were retrieved and analysed.Out of 97 mares treated with SFL for correction of UT, 87 (89.7%) animals were Straight Egyptian Arabian mares. The median age of the Straight Egyptian Arabian mares presented with UT was 12 ± 2.3 years (Range: 5–18 and IQR: 7–15 years). The median gestational age at the time of occurrence of UT was 270 ± 2.4 days (Range: 210–315 and IQR: 255–260 days). The majority of UT (75.9%) was recorded ≤270 days. The direction of torsion was clockwise in 36 (41.4%) mares and anticlockwise in 51 (58.6%) mares. The degree of UT ranged between <180° and ≥360°. After surgery, 82/87 (94.3%) mares successfully delivered a live foal. However, four mares (4.6%) aborted after 2–15 days of surgery and one mare (1.1%) died after surgery due to rectal tears and intestinal prolapse. Following SFL, 86/87 (98.9%) mares survived. Of the surviving 86 mares, 82 (95.3%) gave birth to viable mature foals. In contrast to the direction of torsion and gender of the foal, the stage of gestation at which UT occurred significantly affected foal survival (p = 0.018).Pregnant Straight Egyptian Arabian mares are at risk of developing UT during the third trimester of pregnancy. Standing flank laparotomy is an effective operation for treating UT in mares, with good foal and mare survival rates. [ABSTRACT FROM AUTHOR]

ABSTRACT Salbutamol is a short‐acting and selective beta‐2 adrenergic agonist. Inhaled (IH) administration of salbutamol is widely used to control lower respiratory tract disease in horses. Here, we estimated the pharmacokinetic parameters of salbutamol after a single intravenous (IV) or IH administration in six horses, and we statistically analysed the detection times with various dosing regimens. Plasma and urine concentrations of salbutamol were measured by liquid chromatography–tandem mass spectrometry, and data were modelled by using a nonlinear mixed effect model followed by Monte Carlo simulation (MCS). With IH salbutamol, the maximum plasma concentration was 0.12 ± 0.06 ng/mL at 0.29 ± 0.17 h after administration. Typical values were, for clearance, 1.53 L/kg/h; distribution volume at steady state, 5.43 L/kg; terminal half‐life, 6.06 h; IH bioavailability, 19.0%; and urine to plasma ratio, 2057. Statistically estimated 95th percentile detection times in the urine at levels below the international screening limit (0.5 ng/mL) proposed by the International Federation of Horseracing Authorities, as simulated in 5000 horses by MCS, were 44 h after 1.6 μg/kg q 24 and 54 h after 1.6 μg/kg q 4 h over a 3‐day IH administration period. [ABSTRACT FROM AUTHOR]

Study objective was to evaluate whether the application of a lip twitch could be proposed as conditioning stimulus in the context of a novel Conditioned Pain Modulation (CPM) assessment paradigm for use in horses. The study was a prospective, experimental, randomized trial. Twelve healthy horses were evaluated in two experimental sessions. The lip twitch was used as the conditioning stimulus in both sessions; electrical stimulation was used as the test stimulus in one session, while mechanical and thermal stimulations were used in the other. Differences between thresholds recorded before and during twitching (Δ) as well as their percent (%) change were computed for each stimulation modality as a measure of CPM. Heart rate and respiratory rate were recorded throughout the experiments to monitor physiological reactions, while the general level of stress and aversiveness toward twitching were scored using ad hoc behavioural scales. Based on these scores, interruption criteria were defined. Ten and seven horses completed the electrical and mechanical/thermal experimental sessions respectively. For electrical stimulation, median (IQR) Δ was −2.8 (−3.9, −1.1) mA and% change 87.9 (65.7–118.2)%; for mechanical stimulation, Δ was −18.2 (−6.4, −21.4) N and% change 343.5 (140, 365.3)%; for thermal stimulation, Δ was −3.1 (−9.2, −2.1)°C, while% change was not calculated. Heart rate and respiratory rates varied significantly over time, with higher values recorded during twitching. Median stress and aversion scores did not differ between the two sessions. As lip twitching consistently affected thresholds to all stimulation modalities, it can be proposed as effective conditioning method for CPM assessment in horses. The exclusion of subjects due to severe aversion shows that this paradigm cannot be indistinctively applied to all horses and that stringent interruption criteria are necessary to guarantee adequate welfare during testing. [ABSTRACT FROM AUTHOR]

Summary The most common disorder affecting the salivary glands in horses is trauma to the parotid gland or duct. Several management techniques have been described, each with their own set of complications. The objective of this case report was to describe the direct injection of botulinum toxin type A into the parotid gland and its outcome in two clinical cases involving damage to either the parotid salivary gland or its duct. Both cases involved iatrogenic damage to either the parotid salivary gland or its duct. Treatment for both cases involved the injection of 200 units of botulinum toxin type A into the parotid gland in order to reduce salivary production and to prevent the potential development of a chronic fistula. Follow‐up assessment after the treatment was conducted via telephone consultation and photographs from the owners. In both clinical cases, a marked reduction in saliva production from the parotid gland was noted within 2 days after toxin injection and the wounds healed without complication. In the first case, the treatment was repeated after 3 weeks. No short‐ or long‐term side effects after injection were reported by the owners. Limitations were the small number of cases and the lack of literature regarding the dose and treatment regime for botulinum toxin type A in horses. It was concluded that the administration of botulinum toxin type A appears to be a safe and effective therapeutic alternative or complementary procedure for the treatment and prevention of parotid gland or duct fistulas in horses. [ABSTRACT FROM AUTHOR]

Gastrointestinal disease is a leading cause of death in mature horses. A lack of in vitro modeling has impeded the development of novel therapeutics. The objectives of this study were to develop and further characterize a small intestinal monolayer cell culture derived from equine jejunum including establishing normal measurements of intestinal permeability and restitution. Three-dimensional enteroids, derived from postmortem sampling of equine jejunum, were utilized to develop confluent epithelial monolayers. The presence of differentiated intestinal epithelial cell types and tight junctions were confirmed using histology, reverse transcription PCR (RT-PCR), RNAscope, protein immunofluorescence and transmission electron microscopy. Transepithelial resistance (TER) and macromolecule flux were assessed as measurements of paracellular and transcellular permeability. Scratch assays were utilized to model and assess intestinal restitution. Monolayer cell cultures reached 100% confluency by ~5–7 days. Equine jejunum monolayers were confirmed as epithelial in origin, with identification of differentiated intestinal epithelial cell types and evidence of tight junction proteins. Function of the intestinal barrier was supported by acquisition of physiologically normal TER values (179.9 ± 33.7 ohms*cm2) and limited macromolecule flux (22 ± 8.8% at 60 min). Additionally, following a scratch wound, epithelial cell monolayers migrated to close gap defects within 24 h. In conclusion, this study describes the development of a novel intestinal epithelial monolayer cell culture for equine jejunum, and provides evidence of intestinal epithelial cell differentiation, formation of physiologically relevant barrier function and use as a model of intestinal restitution to test potential therapeutics for equine colic. [ABSTRACT FROM AUTHOR]

Introduction: Animal welfare is of great concern in equestrian sports and has been evaluated in athletic horses competing at different levels. However, the impact of consecutive days of jumping competition and the extent of resultant stress responses remains unclear. To address this point, the present study compared the changes in stress response via heart rate variability (HRV) in horses participating in two national jumping events on consecutive days. Methods: The study involved six experienced horses equipped with heart rate monitoring devices. HRV variables were measured before, during, and after jumping at 10-min intervals for 60 min on each competition day. Results: Multiple HRV variables decreased to varying degrees on both days from warm-up until 30 min post-jumping. Meanwhile, the mean heart rate increased during jumping and returned to normal levels at 50 min post-jumping on the first day (for all intervals, p < 0.05–0.001), while it remained elevated beyond 60 min post-jumping on the second day (for all intervals, p < 0.01–0.001). Additionally, maximum heart rate and respiratory rate were higher on the second day than in the first round during the warm-up phase (p < 0.05 for both variables). The proportion of the HRV low-frequency band was higher during riding on the second day (p < 0.05), while the proportion of the high-frequency band was reduced during warm-up on the first day (p < 0.05) and during course riding on the second (p < 0.01). Meanwhile, the sympathetic nervous system index took longer to return to baseline on the second day than on the first. Discussion: These results suggest that autonomic regulation differed in horses between jumping rounds on two consecutive days, with horses experiencing higher sympathetic activity and potentially increased stress in the second round. This information is important for riders, highlighting the need to be mindful of potential stress that could, at least in part, impact the welfare of horses participating in the same jumping competition on consecutive days. [ABSTRACT FROM AUTHOR]

This pilot study sought to explore the contribution of the large intestine microbiota to energy metabolism and exercise performance through its ability to degrade fibers into short‐chain fatty acids (SCFAs). To investigate this, a correlational study was carried out on athlete horses under the same management conditions. Fecal microbiota diversity and composition, fibrolytic efficiency and SCFAs were analyzed. An incremental running test was carried out to estimate the maximal running speed (MRS) of the horses, and blood samples were taken to measure energy metabolism parameters. MRS was positively correlated with the efficiency of the fecal microbiota in degrading cellulose in vitro (r = 0.51; p = 0.02). The abundance of fibrolytic bacterial taxa was not associated with MRS, but functional inference analysis revealed a positive association between MRS and pathways potentially related to fibrolytic activity (r = 0.54; p = 0.07 and r = 0.56; p = 0.05 for butyrate metabolism and thiamine metabolism, respectively). In contrast, the metabolic pathway of starch degradation appeared negatively associated with MRS (r = −0.55; p = 0.06). The present findings suggest a potential contribution of the large intestine microbiota and dietary fibers digestion to exercise capacity in equine athletes. [ABSTRACT FROM AUTHOR]

Background: Morphometric traits discrepancies are associated with production, reproduction, adaptation and behaviours in horses. It also determines the design of harnessing implements, physical injury level and working performance of the native horses. Thus, the study was conducted to evaluate morphometric traits and body conformation indices of horse ecotypes reared across four districts of Bale Zone, Ethiopia. Methods: Data of croup height, croup length, hip height, mid‐back height, wither height, hip width, thoracic depth, chest width, body length, sternum height, thorax perimeter and cannon perimeter were measured in 500 horses (294 male and 206 female). Using those traits, 17 body conformation indices were calculated to define the horses for multi‐faceted performances. Results: The study revealed that croup height, hip height, wither height, hip width, croup length, body length, thorax perimeter and sternum height were significantly (p < 0.0001) different among the studied districts. The district effect was also significant at p < 0.05 for mid‐back height, thoracic depth, chest width and cannon perimeter. The sexual dimorphism effect was statistically significant for all measured traits; however, females were inferior to males except for cannon perimeter. Body conformation indices of pelvic index, body index, transversal pelvic index and weight were highly significant (p < 0.0001) among the studied districts. The sex dimorphism effect was significant (p < 0.001) for dactyl‐costal index, pelvic index, longitudinal pelvic index, transversal pelvic index, weight, tare index 1 (trot or gallop), tare index 2 (walk) and riding comfort degree, while non‐significant (p > 0.05) for the remaining indices. The studied horses were classified as mediline, elipometric, light, small and suitable riding ecotypes with a medium‐conforming body structure and good capacity for carrying loads on carts and backs for functional effectiveness. The correlations of body conformation indices ranged from very high to low, with positive and negative associations for functional capabilities. Conclusion: Therefore, selection for improvement needs to rank morphometric traits and body conformation indices in correlation to developing racing and modern sport horses in the highlands of the Bale eco‐regions. Further, molecular studies will be essential to determine whether the predominated phenotypic multiplicity is genetic or environmentally progressed. [ABSTRACT FROM AUTHOR]

OBJECTIVE: To evaluate sedation and IV xylazine requirements to achieve 45% of baseline head height above ground measurements following oral (PO) administration of 2 trazodone dosages. METHODS: 8 healthy, adult mares of various weights and breeds belonging to a university teaching herd were utilized in a blinded, crossover study design. Horses were randomly assigned to 1 of 3 PO treatments: control (no trazodone), trazodone at 3 mg/kg (low dose [LD]), or trazodone at 6 mg/kg (high dose [HD]). Before treatment, cardiac auscultation, EquiSed sedation score, and head height above ground (HHAG; cm) measurements were performed (baseline) followed by feeding of the treatment mixture. After 120 minutes, sedation score and HHAG were recorded. Xylazine was administered IV (0.25 mg/kg bolus followed by 0.1 mg/kg/min) until HHAG reached 45% of baseline or a total dose of 1 mg/kg was reached. Individual data for xylazine dosage, sedation scores, and HHAG were analyzed using mixed linear models with repeated measures. RESULTS: Sedation scores were significantly improved (LD, P = .045; HD, P = .01) and HHAG was lowered (LD, P = .045; HD, P = .09) by trazodone administration. Xylazine dose requirements were increased by LD trazodone administration (increase of 0.26 ± 0.26 mg/kg; P = .03) and unchanged by HD (increase of 0.13 ± 0.25 mg/kg; P = .38). CONCLUSIONS: Oral trazodone administration increases quantifiable sedation in horses. Xylazine requirements are significantly increased by LD trazodone administration. CLINICAL RELEVANCE: Oral administration of LD trazodone may increase xylazine requirements. Further clinical studies are required to fully assess the CLINICAL RELEVANCE: of this finding on other parameters such as cardiovascular physiology. [ABSTRACT FROM AUTHOR]

OBJECTIVE: Slow hoof growth poses a clinical challenge when hoof wear exceeds natural growth. Many treatment options have been reported without controlled prospective trials. The objective of this study was to evaluate the effect of transdermal CO2 on the rate of growth in treated hooves. METHODS: A prospective, randomized, blinded, crossover study of 14 Warmblood mares. Horses were randomly assigned a number and allocated for treatment of the front feet with room air or CO2 for 30 minutes 3 times per week, and groups were switched after 5 weeks. Hoof growth was measured on the dorsal midline and the quarters of each front foot. The distance from coronary band to lines made on the hoof wall was measured at the beginning, middle, and end of the study. The percentage of change in length at each location relative to baseline was evaluated at 5 weeks and 10 weeks using nonparametric analyses. RESULTS: All treatments were successfully administered. The left front medial (P = .028) and right front lateral (P = .03) sites of the CO2-treated hooves increased growth compared to the room air group at the 5-week point. CONCLUSIONS: The Results of this study suggest that repeated, noninvasive transdermal application of CO2 may accelerate hoof growth in normal horses over a 5-week treatment period. CLINICAL RELEVANCE: This study suggests that transdermal CO2 may increase the rate of hoof growth in normal horses. The mechanism of action of this treatment is unclear, and further studies are required to fully elucidate the potential effects. [ABSTRACT FROM AUTHOR]

Complications from general anesthesia, including pneumonia and decreased wound healing, are influenced by changes in immune cell function secondary to sedatives and anesthetics. It was hypothesized that immune cell function would be depressed in the early postanesthetic period. The objective was to investigate airway immune cell function before and after a general anesthetic episode in an equine in vivo model using ex vivo cell stimulations with lipopolysaccharide (LPS) for assessment of immune function. Prospective experimental study. Six healthy, adult, institution-owned horses. Each horse underwent a bronchoalveolar lavage (BAL) 3 days before and immediately after a 2 hour general anesthetic. The BAL fluid was examined for cytology, total nucleated cell count and isolation of immune cells. Airway immune cells were treated with LPS or media (control) for 6 hours and supernatant was analyzed via a commercially available immunoassay for cytokines [tumor necrosis factor alpha (TNFα), interleukin (IL)-1β, IL-6, interferon gamma (IFNγ) and CXC motif chemokine ligand 8 (CXCL8)]. Data were compared using t -tests and Mann–Whitney tests. Before anesthesia (baseline), LPS stimulation induced a significant increase in all cytokines of interest, except CXCL8, versus control samples. Unstimulated cells, after an anesthetic episode, had a significant 1.8-fold increase in IL-1β (p = 0.029), and a significant decrease in IL-6 and TNFα (p = 0.028 and 0.033, respectively) versus baseline. Following anesthesia, stimulated cells had a significant decrease in IL-6 and TNFα (p = 0.037 and 0.042, respectively) versus baseline. This study supports the use of an equine in vivo model to assess airway immune cell function in relation to general anesthetic use. [ABSTRACT FROM AUTHOR]

Summary: Abdominal ultrasonography is an important diagnostic tool in the evaluation of colic, yet primary care equine veterinary practitioners are often limited by availability and access to low‐frequency (2–5 MHz curvilinear array or sector) abdominal transducers. Use of high‐frequency (5–10 MHz linear array) transrectal transducers has not previously been compared with use of abdominal transducers for transcutaneous abdominal ultrasonography. One recent pilot study established that there was no significant difference in organ detection by the two transducers on the right side of the equine abdomen, but the stomach, liver and kidney on the left side were less likely to be detected using the transrectal transducer in healthy horses. A clinical study found that the transrectal transducer can be used successfully using the FLASH protocol in horses presenting with colic, with high‐quality images that detected abnormalities of the peritoneal fluid, small intestine and large intestine. The transrectal transducer had decreased visualisation of the stomach and left kidney and was less likely to detect pathology surrounding these organs. This is the first series of studies to evaluate use of transrectal transducers in abdominal ultrasonography of the horse, a tool that is readily accessible to the field practitioner. [ABSTRACT FROM AUTHOR]

Summary: A 3‐year‐old Quarter Horse gelding originating from Texas presented for fever and inappetence. An encapsulated, mixed echogenic cranial mediastinal mass visible ultrasonographically in the left and right fourth intercostal space that displaced the heart caudally was identified. Histological evaluation of needle biopsies obtained under general anaesthesia revealed a severe pyogranulomatous inflammatory process associated with intralesional round, 15–25 μm in diameter, thick double‐contoured cell wall fungal structures. Sequencing of products obtained from DNA extracted from the paraffin‐embedded biopsy sample and a panfungal PCR assay targeting the large ribosomal unit region had a 99.1% identity to either Coccidioides immitis or C. posadessii. Bronchoscopy revealed purulent exudate in the right primary bronchus. Cytological evaluation of bronchial alveolar lavage fluid (BALF) contained 96% moderately degenerative neutrophils and 4% macrophages. Fungal structures were not appreciated in the BALF. However, the mediastinitis could have resulted from inhalation and dissemination of arthroconidia through lymphatics or directly from the lung parenchyma. Quantitative immunodiffusion of serum for the presence of coccidioidal IgG antibodies yielded a titre of 1:256 suggestive of disseminated coccidioidomycosis. After oral fluconazole for 24 months, the horse's general health and athletic performance had returned to normal and the mediastinal mass was not appreciated sonographically. [ABSTRACT FROM AUTHOR]

Summary: The inflammatory response to a truly closed castration procedure in 51 horses using an inguinal approach was quantified by serum amyloid A (SAA) measurements to be on average 94 mg/L on day three after surgery. The average SAA value after field castrations, using a scrotal approach, was reported by four different investigations to be between 480 and 708 mg/L on day three post‐operatively. The discrepancy in SAA levels between these different approaches proved to be significant (p < 0.001), quantifying a substantially lower inflammatory response of the closed inguinal technique over regular field castrations using a scrotal approach. [ABSTRACT FROM AUTHOR]

Summary: Equine piroplasmosis is a haemoprotozoal disease caused by Theileria equi and Babesia caballi. Clinical presentations vary in severity according to infectious load, host immunity and endemicity. In endemic regions, equine piroplasmosis is rarely acute or peracute in presentation. Here we report a case of a 10‐year‐old pony gelding presented for fever and acute inspiratory dyspnoea. Clinical signs of hypovolemic shock were observed. Blood smear examination revealed a mild anaemia and thrombocytopenia with the presence of intraerythrocytic inclusions resembling Babesia caballi merozoites. Acute lung injury, ischaemic myocarditis, acute renal failure, pancreatitis and myopathy were detected. We made a presumptive diagnosis of acute babesiosis, with secondary systemic inflammatory reaction and multiple organ dysfunction syndromes. Supportive therapy was initiated, but imidocarb was not administered due to potentially fatal adverse reactions in a horse in shock. Anaemia worsened, with the development of acute pulmonary oedema, respiratory distress and disseminated intravascular coagulation. The gelding was euthanised and post‐mortem examination confirmed the formation of microthrombi within small vessels, leading to venous stasis and vasculitis. [ABSTRACT FROM AUTHOR]

Summary: A 15‐year‐old multiparous Quarter Horse mare with a pre‐existing (>1 year) prepubic tendon rupture was presented pregnant (approximately 310 days gestation) with mild signs of generalised discomfort and an advanced degree of cervical relaxation. The foal was declared to be the priority in an emergency situation; therefore, intravenous dexamethasone (0.1 mg/kg bwt i.v. q24h) was administered in an attempt to mature the fetus in case urgent induction of parturition was required. Within 36 h of admission, the mare developed a complete rupture of the caudoventral body wall and skin, from the anus to the cranial aspect of the mammary gland. Because eventration had occurred, the mare underwent immediate euthanasia and terminal caesarean section via a modified approach. The colt foal was euthanised on humane grounds, due to an inability to breathe without a ventilator, following 72 h of intensive care. Rebreeding mares with prepubic tendon rupture is not recommended, this case report presents important evidence that rebreeding mares with this condition can have fatal consequences. [ABSTRACT FROM AUTHOR]

Summary: A 7‐month‐old Warmblood cross colt was presented for the assessment of a laceration of the right hind pastern of 4‐days duration. At presentation, the colt was in poor body condition and had a rough, dull coat. Cardiac auscultation revealed a grade 5/6 pansystolic murmur on the left side and grade 4/6 continuous murmur on the left and right sides and a regular cardiac rhythm. Electrocardiographic examination confirmed sinus tachycardia. Echocardiographic examination showed malformation of the aortic and mitral valves, with associated regurgitation and evidence of left atrial and ventricular volume overload. Dysplasia of the mitral, tricuspid and aortic valves was confirmed by post‐mortem examination. Valvular dysplasia is a rare cause of cardiac failure in horses. [ABSTRACT FROM AUTHOR]

Summary: Although respiratory distress is encountered infrequently in equine practice, it can be serious and potentially fatal, requiring immediate and decisive intervention. History and physical examination can often give sufficient clues to identify the cause of respiratory distress and initiate emergency treatment. Ultrasonography can also be invaluable when assessing distress caused by lower respiratory tract issues. Upper respiratory tract obstruction, tension pneumothorax and occasionally pulmonary oedema can be rapidly fatal and require immediate intervention by emergency tracheotomy, thoracocentesis and evacuation of pleural air or administration of furosemide and oxygen, if available. Acute severe asthma and substantial pleural effusion are often not an immediate threat to life but nonetheless require fast intervention including administration of bronchodilators and corticosteroids or pleurocentesis, respectively. [ABSTRACT FROM AUTHOR]

Summary: Point‐of‐care ultrasonography is a powerful tool for the practitioner in determining diagnosis and prognosis in unwell horses. Proper case selection and patient preparation are keys to successful ultrasonographic examinations of the equine thorax and abdomen. Practitioners can expand the use of their equipment to augment evaluations for multiple clinical complaints. The most common application for body cavity ultrasonography in the adult horse is acute abdominal pain. [ABSTRACT FROM AUTHOR]

Summary: Background: Equine anoplocephalid cestodes are tapeworms that occur worldwide in horses and are known to cause pathological manifestations and clinical disease within the digestive system of horses. Objective: While these clinical manifestations and the efficacy of currently available anthelmintics against equine tapeworms have been well documented, a recent study has demonstrated treatment failure of praziquantel and pyrantel pamoate, suggesting resistance; however, this has not been heavily investigated. Study design: This case study examined 24 Thoroughbred yearlings on one Kentucky Thoroughbred horse farm to investigate the elimination of tapeworm eggs after administration of routine anticestodal anthelmintics after confirmation of positive faecal egg counts. Methods: The Mini‐FLOTAC faecal egg counting method was used to count anoplocephalid eggs in yearlings treated with pyrantel pamoate paste (13.2 mg base/kg), moxidectin‐praziquantel (0.4 and 2.5 mg/kg) and ivermectin‐praziquantel (0.2 and 1 mg/kg) over a 6‐month period in 2022. Results: Data demonstrated that tapeworm egg shedding persisted post‐deworming with all three anthelmintic products. Out of the 24 Thoroughbred enrolled, 11/24 (45.8%) had persistent infections in the month of March and 3/24 (12.5%) had persistent infections in April after deworming with ivermectin‐praziquantel. With moxidectin‐praziquantel, 2/24 (8.3%) remained egg count positive. For pyrantel pamoate, 3/24 (12.5%) were detected with tapeworm eggs post‐treatment. During July and August, selected yearlings had faecal sampling done before and 2 weeks post‐deworming with moxidectin‐praziquantel. For July 1/6 (16.7%) horses had tapeworm eggs both before and after deworming, and one additional horse was positive in the post‐treatment sample only. For the August treatment, 4/14 (28.6%) were egg count positive both before and after deworming, with one additional horse being positive in the post‐treatment sample only. Conclusions: This study demonstrated evidence of anthelmintic treatment failure against equine tapeworms by means of regular faecal egg count monitoring. Veterinarians should be aware of this development and implement strategies to monitor anticestodal treatment success. [ABSTRACT FROM AUTHOR]

Laminitis is a serious health condition that can cause severe pain and lameness in horses. Due to lack of understanding of laminitis, treatments often fail to achieve the desired results. In recent years, we have begun to recognize that laminitis may involve a complex interaction between local and systemic inflammation. Dysbiosis of the gut microbiota has been linked in the development of systemic inflammation, and our previous findings suggest that the development of laminitis is closely linked to the production of harmful metabolites of the gut microbiota. In addition, it was found that localized lesions in the hoof, especially lamellar injuries, are the most direct cause of laminitis. Matrix metalloproteinases have been found to be strongly associated with the development of laminitis. Recent discovery has found that methylated tirilazad has a role in repairing laminar tissue in vitro. However, its efficacy in horses never has been studied. Therefore, we aimed to investigate the efficacy of methylated tirilazad (product name: PTP-102) in the prevention/treatment of oligofructose-induced laminitis. The results showed that oligofructose successfully induced laminitis in horses, resulting in detreated clinical signs. Blood indices (including inflammation-related indices and other related indices) were significantly increased. Observations of dissection and staining showed significant bleeding, swelling, and damage to hoof tissue. Analysis of the gut microbiota showed a significant decrease in abundance and diversity, and a significant increase in the relative abundance of specific bacteria. Following methylated tirilazad intervention, there were a significant improvement in clinical signs, blood markers and lamellar tissue damage. Additionally, methylated tirilazad positively influenced the gut microbiota structure by reducing the relative abundance of genera closely associated with the development of equine laminitis. This suggests that some of the therapeutic mechanism of methylated tirilazad may be linked to its effects on the gut microbiota. Notably, methylated tirilazad had better effect in the treatment group than the prophylactic group, indicating the post-diagnosis utility of methylated tirilazad for laminitis management. [ABSTRACT FROM AUTHOR]

Background: Fractures of the paracondylar process of the occipital bone may cause headshaking, neck pain and neurologic deficits. The condition is being recognised more frequently with increasing availability of computed tomography. However, to date only limited information is available as to presentation, treatment, surgical approach and outcome. Objectives: To describe the clinical signs, imaging findings, treatment, surgical approach and outcome in three horses diagnosed with paracondylar process fracture. Study design: Retrospective case series. Methods: Clinical records and diagnostic images of affected cases were reviewed. Results: Two cases had ventral nonunion fractures—one of these presented with neck pain, headshaking and behavioural changes, while in the other the fracture was a suspected incidental finding in a case of poor performance. A third case with a more dorsal fracture presented with acute facial nerve paralysis. Diagnosis was by computed tomography in all cases, although imaging of ventral fractures by radiography was found to be feasible. Where clinical signs could be associated confidently with the fracture, conservative management resulted in improvement but not complete resolution. Repeated recurrence of clinical signs after prolonged periods of remission necessitated surgical removal in one case, which was readily accomplished with the aid of ultrasound guidance, and led to rapid resolution of clinical signs without significant post‐operative complications. The surgical approach is described. Main limitations: Limited follow‐up was available. Conclusions: Paracondylar process fracture should be considered as a differential diagnosis for headshaking, neck pain, poor performance and facial paresis, and is a justification for performing computed tomography in such cases. A multi‐disciplinary approach is beneficial due to the potential for orthopaedic, neurologic, ophthalmologic and behavioural clinical signs, with additional need for expertise in diagnostic imaging and pain management. Surgical fragment removal should be considered for ventral fractures. [ABSTRACT FROM AUTHOR]

Background: Castration is the most common surgical procedure in domesticated equids; surgical techniques used and perioperative management vary considerably. Objectives: To identify and chart the current evidence on perioperative complications associated with different methods of surgical castration in domesticated equids. Study design: Joanna Briggs Institute systematic scoping review. Method: CAB Abstracts, Medline and Embase databases were searched using terms related to equine castration complications. Two authors independently and blindly screened publications against eligibility criteria. Data on study methods, perioperative management, surgical techniques, and perioperative complications were extracted. Surgical techniques were grouped into categories depending on technique; open, closed or half‐closed, and whether the parietal tunic was open or closed at the end of surgery. Results: The search identified 1871 publications; 71 studies met the final inclusion criteria. The data reported 76 734 castrations, most of which were open or closed, with the vaginal tunic remaining open at the end of surgery. Twenty‐five studies reported information regarding surgical techniques and perioperative management, allowing detailed charting and comparisons, of which analgesia and antimicrobial usage varied notably. Eighteen different complications were reported, with swelling or oedema being the most common. Evisceration was most commonly reported in draught breeds and Standardbreds, and the risk appeared low if the parietal tunic was closed at the end of surgery. Main limitations: Grey literature and studies not available in English were not included. Existing studies varied greatly in perioperative management, surgical techniques and reporting of outcomes, making evidence consolidation problematic. Conclusion: A lack of consensus regarding complication definitions creates uncertainty and discrepancies between complication rates associated with different surgical techniques and perioperative management. The implementation of standardised systems for describing surgical techniques and complications is recommended for future studies. A number of studies did not follow current recommendations for perioperative analgesia and use of antimicrobials. [ABSTRACT FROM AUTHOR]

Background: Reported complication rates after dental repulsion for equine exodontia are high (up to 80%), but repulsion methods have changed notably in the last 20 years. Objectives: Describe the outcome for 20 cases after dental repulsion using small diameter repulsion pins. Study design: Retrospective case series. Methods: Records of horses that underwent cheek tooth repulsion were reviewed (2014–2023). Inclusion criteria included: mandibular or maxillary cheek tooth extraction where oral extraction failed and repulsion was used to complete extraction, and where clinical follow up information was available. Repulsions were carried out under sedation with a regional nerve block or under a short general anaesthetic, using a small diameter repulsion pin (3–5 mm). Intra‐operative radiographs facilitated instrument placement. The alveolus was packed with polymethyl methacrylate post‐extraction. Horses were re‐examined at 4–6 weeks post‐operatively. Results: Twenty cases were included. Patients had a mean age of 10.3 years old (range 5–16 years). The majority (75%) of teeth had pre‐existing dental fractures. Maxillary (n = 15) and mandibular cheek teeth (n = 5) were all successfully repulsed, with 16 cases performed with the horse standing and 4 with the horse under general anaesthesia. Intra‐operative complications included damage to the mandibular bone (n = 1). Short‐term complications (n = 2) included superficial surgical site infection, and dehiscence of one sinus flap. Long‐term complications included the recurrence of sinusitis (n = 1) and small intra‐alveolar fragments causing persistent bitting problems in another patient. Main limitations: Retrospective study design, small number of cases. Conclusions: When oral extraction fails, cheek tooth repulsion using small diameter repulsion pins is an effective extraction technique. The total intra‐ and post‐operative complication rate was 25%, which is comparable to previously published complication rates for repulsion using Steinmann pins and also those encountered after trans‐buccal screw extraction. [ABSTRACT FROM AUTHOR]

Background: There is no objective information reporting the effect of unilateral laser ventriculocordectomy (VeC) on arytenoid abduction or stability. Objectives: To evaluate arytenoid stability and abduction in horses with severe recurrent laryngeal neuropathy (RLN) before and after unilateral laser VeC. Study design: Prospective cohort. Methods: Eight horses with grade C or D exercising laryngeal function that underwent unilateral laser VeC were included. Exercising endoscopy was performed before and ≥6 weeks after left‐sided laser VeC. Arytenoid stability at maximal exercise was calculated by measuring the left‐to‐right quotient angle ratio (LRQ) of the corniculate processes at the points of maximal arytenoid abduction (expiration) and maximal arytenoid collapse (inspiration). For each horse, means of measurements obtained for four breaths pre‐ and post‐operatively were used for statistical analysis. Results: The difference in LRQ between inspiration and expiration was lower post‐operatively (median 0.039; interquartile range [IQR] 0.032–0.047) compared with pre‐operatively (median 0.158; IQR 0.083–0.249; p = 0.01) confirming the left arytenoid was more stable following unilateral laser VeC. The degree of improvement was significantly greater for grade D horses compared with grade C horses (p = 0.04). The LRQ measured on maximal abduction was also lower post‐operatively (median 0.467; IQR 0.444–0.506) compared with pre‐operatively (median 0.578; IQR 0.554–0.655; p = 0.02) indicating the left arytenoid was less abducted following surgery. Main limitations: The sample size was small, no racehorses were included and post‐operative assessment was conducted at a variable time after surgery. Conclusion: Unilateral laser VeC in grade C and D RLN‐affected horses results in slightly reduced left arytenoid abduction but increased arytenoid stability. [ABSTRACT FROM AUTHOR]

Background: Large colon volvulus is a cause of colic in horses with high morbidity and mortality when not promptly treated. More treatment options are needed to improve the outcome of these cases by protecting against the damage caused by ischaemia and reperfusion injury. Objectives: To determine the effect of preconditioning with dexmedetomidine prior to induction of ischaemia–reperfusion (IR) injury in a large colon volvulus model in the horse. Study design: Randomised blinded in vivo experiments. Methods: Horses received either a dexmedetomidine (DEX) or saline (CON) constant rate infusion (CRI) immediately following induction of anaesthesia. Venous, arterial, and transmural occlusion of a section of the large colon was performed for 3 h, after which the ligatures and clamps were removed to allow for reperfusion for 3 h. Biopsies of the large colon were taken at baseline, 1 and 3 h of ischaemia, and at 1 and 3 h of reperfusion. Results: The severity of crypt epithelial loss (DEX = 2.1 [0.8–2.8], CON = 3.1 [2.5–4], p = 0.03) and mucosal haemorrhage was decreased (DEX = 2.1 [1.3–3], CON = 3.5 [2.5–4], p = 0.03) in group DEX compared to group CON when graded on a scale of 0–4. Crypt length remained longer (DEX = 369.5 ± 91.7 μm, CON = 238.5 ± 72.6 μm, p = 0.02) and interstitium to crypt (I:C) ratio remained lower (DEX = 1.4 (1–1.7), CON = 2.6 [1.8–5.9], p = 0.03) in group DEX compared to group CON during reperfusion. Main limitations: Clinical applicability of pharmacologic preconditioning is limited. Conclusion: Preconditioning with a dexmedetomidine CRI prior to IR injury demonstrated a protective effect histologically on the large colon in the horse. Further investigation into postconditioning with dexmedetomidine is warranted as a possible intervention in colic cases suspected of being large colon volvulus. [ABSTRACT FROM AUTHOR]

Background: Post‐operative reflux (POR) is rare following large colon volvulus (LCV) but does occur despite the absence of a small intestinal lesion. The prevalence, risk factors and association with survival of POR after LCV are currently unknown. Objectives: To determine the prevalence of POR in horses with an LCV and its association with survival. A further objective was to assess factors which may predict POR. The hypothesis was that horses with POR following LCV surgery have a worse outcome for survival compared to those without POR. Study design: A retrospective cross‐sectional study. Methods: Clinical data of client owned horses which underwent colic surgery at a single UK referral hospital between 2008 and 2021, where LCV was the primary finding, were retrieved from hospital records. Statistical analyses included chi‐squared, t‐tests and odds ratios (ORs). Horses with concurrent lesions, and those that did not survive past anaesthetic recovery, were excluded from analysis. POR was defined as ≥2 L of gastric reflux on at least one occasion. Results: A total of 128 horses were included in the study, 23 of which had POR (18%). Overall survival to hospital discharge was 86%, 95% in the non‐POR and 44% in the POR group. Horses with POR were less likely to survive to discharge than those without (OR = 26, 95% confidence interval [CI] [7.68–88.0], p < 0.001), and less likely to be alive 3 years after surgery (OR = 13.4, 95% CI [2.78–64.8], p < 0.001). Main limitations: Due to the retrospective study design, full data sets were not available for every case because clinical records were incomplete or, at that time, certain tests were not performed or clinical variables were not measured. Conclusions: POR in LCV cases is a negative prognostic indicator for survival. [ABSTRACT FROM AUTHOR]

Copyright of Equine Veterinary Journal is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Background: Small bowel obstruction (SBO) is a significant cause of surgery in adult horses presenting with colic pain. SBOs often require resection and anastomosis. While various techniques for intestinal anastomoses have been developed, it remains uncertain if any fully meet our clinical needs. Objective: To conduct a scoping review of publications on anastomosis techniques and outcomes for the treatment of SBO. Study design: Scoping review. Methods: A literature review was conducted using the CAB, Web of Science, Scopus, and PubMed databases. Peer‐reviewed scientific articles in English, published between 1992 and 2023, were included. A quality assessment was performed for potentially eligible articles. Experimental studies, case reports, and case series with less than five cases were excluded and relevant data on study methods and sample size were extracted and charted from remaining articles. Anastomosis type and outcome were reported for articles considered potentially eligible for meta‐analysis. Articles in which only overall outcome was reported or details on type of anastomosis were not reported were excluded for the final charting. Results: Of 3024 articles, 210 underwent a quality assessment. The most common study designs were case reports and case series (64.3%), followed by experimental studies (17.1%). After further exclusions, 104 articles met the inclusion criteria. In only 42 articles detailed data on type of anastomosis and relative outcome were reported. A total of 23 anastomosis types were reported for the treatment of SBO, with 6 different outcomes evaluated. Both short‐ and long‐term survival rates consistently exceed 70% for all types of anastomosis (jejuno‐jejunal, jejuno‐ileal, and jejunocaecal). Main limitation: Non‐English language studies and conference proceedings were excluded. Conclusion: The body of literature focused on surgical treatment for SBO exhibits low‐quality evidence. Several techniques of anastomosis were described for different pathologies. However, there is a lack of homogeneity in reporting outcome for each surgical technique. Furthermore, outcomes considered varied significantly among studies and were sometimes poorly reported, although success rates are generally high. Overall, there is a need for better‐structured studies on existing and commonly used techniques before comparing techniques and exploring other innovative approaches. [ABSTRACT FROM AUTHOR]

Background: The modified Meek technique is not commonly used in equine wound management, despite the consistent reliable and superior results compared with other grafting techniques. Major drawbacks are the need for specialised, expensive equipment and general anaesthesia. Objectives: To describe adjustments of the modified Meek technique enabling use in the standing horse without the need for the full equipment. This implied the use of full‐thickness skin grafts manually harvested from the pectoral area and manually cut into micrografts. Graft acceptance; healing progress; and final functional and cosmetic result were outcome parameters. Study design: Descriptive case series. Methods: Eight horses with traumatic wounds at the dorsal side of the carpus or tarsus, healing by second intention, were treated. Original wound areas and areas of graft acceptance and rejection were determined from post‐processing of digital photographs and percentage acceptance, wound contraction and epithelialisation were calculated. Results: The initial mean wound area was 55.4 cm2. Graft acceptance was 95.3 ± 2.5%. Wound closure was due to 46.0 ± 25.6% wound contraction and 54.0 ± 25.6% epithelialisation and resulted in 96.8 ± 1.9% reduction of the initial wound area 28.0 ± 8.5 days after grafting. The scar was flat, flexible and functional, usually with thin and regular hair growth. The adapted procedure was fast and efficient, with a learning curve for the increased manual work. Main limitations: Small study population. Conclusions: This adapted modified Meek technique can successfully be performed in the standing horse and obviates the need for the full expensive equipment and general anaesthesia. The acceptance of the full‐thickness grafts is excellent resulting in fast and satisfactory healing. [ABSTRACT FROM AUTHOR]

Background: Intravenous infusions of alpha‐2 adrenoceptor sedatives and opioids can potentially facilitate surgery in donkeys while standing. Literature on this subject matter is scant. Objectives: Evaluation of efficacy of sedation from α2‐adrenoceptors (dexmedetomidine or xylazine) and butorphanol during ovariectomy in standing donkeys. Study design: Randomised, masked in vivo experiment. Methods: Thirteen female donkeys were sedated with butorphanol (0.05 mg/kg bwt followed by 0.05 mg/kg bwt/h) IV. Concomitantly, 6 of the 13 jennies were sedated with dexmedetomidine 2.5 mcg/kg bwt followed by 2.5 mcg/kg bwt/h (Dex‐B group), while seven jennies were sedated with xylazine 0.5 mg/kg bwt followed by 0.5 mg/kg bwt/h (Xyl‐B group). A line block of the left flank and an infiltration block around uterine ligament were performed with lidocaine. While the jennies underwent ovariectomies standing, sedation scores and head height above ground were assessed at 2 and 10 min after sedative boluses and every 10 min thereafter. If sedation was too light or too deep, the dose of dexmedetomidine or xylazine was increased or decreased by 25% of the original infusion rate, while butorphanol infusion rate was constant. Physiological parameters were measured. Normally distributed data were compared using the two‐sample t test while repeatedly measured data were tested for differences between and within groups using repeated measures analysis of variance (ANOVA) by ranks followed by a Wilcoxon test with Tukey Honest Significant Difference for multiple testing. Statistical significance was set at p < 0.05. Results: Both Dex‐B and Xyl‐B caused moderate to marked sedation adequate for ovariectomy in donkeys. Evident sedation was absent by 60 min of termination of infusions. No adverse physiological effects were observed. Main limitations: Study on ovariectomy cases only, no pharmacokinetic profiling. Conclusions: Dexmedetomidine or xylazine and butorphanol sedation is feasible for ovariectomy in standing donkeys. [ABSTRACT FROM AUTHOR]

Copyright of Equine Veterinary Journal is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Dynamic nasopharyngeal collapse (NPC) is an obstructive upper airway disease that affects mainly the inspiratory phase of respiration in horses undergoing strenuous exercise. It occurs when the neuromuscular activity of the nasopharynx is overwhelmed by the intense negative pressures generated during exercise. This leads to collapse of at least one of the four components of the nasopharynx which is comprised of the two lateral walls, the dorsal roof and the ventral soft palate. As a result, the airway diameter and thus airflow become compromised. Even small changes in the airway diameter produces profound increases in negative inspiratory pressure, perpetuating the cycle of collapse. Compared to other dynamic upper respiratory tract disorders, the amount of literature on NPC as a disease entity is limited. The exact pathophysiology of NPC is unknown; however, it impacts up to one quarter of high‐performance equine athletes presenting for poor performance. There is currently no definitive treatment for this severely performance‐limiting condition. Thus, the prognosis for future athletic prognosis is guarded, with most horses being retired from racing or athletic use in general. Further research is warranted in this field to reduce the impact of disease and in turn, reduce the turnover rate and economic loss by enhancing the career longevity of elite equine athletes diagnosed with NPC. [ABSTRACT FROM AUTHOR]

Background: Mesodiverticular bands (MDBs) are an embryonic remnant of the vitelline artery. Information about the clinical significance of equine MDBs is currently limited. Objectives: To report the clinical features, surgical findings and outcomes of horses undergoing exploratory laparotomy where a MDB was identified. Study design: Retrospective case series. Methods: Case records of horses undergoing exploratory laparotomy for colic over a 14‐year period (2009–2022) were reviewed. MDBs identified at laparotomy were classified as the primary or contributory cause of abdominal pain, or as incidental. Results: MDBs were identified in 40/1943 horses (2.1%) and 15 were primary (32.5%), 10 contributory (25%) and 15 incidental (32.5%). Horses with primary MDBs (median 2 years, IQR 1–12) were significantly younger than horses with incidental MDBs (median 8 years, IQR 6–16; P = 0.01). MDBs were more likely to be incidental if located in the mid‐jejunum (5/5) (P < 0.001) or where a mesenteric pocket was absent (11/15) (P = 0.01). Primary MDBs caused extra‐mural obstruction due to mesenteric shortening (n = 4), small intestinal entrapment within the MDB pocket (n = 5) or in an adjacent mesenteric rent (n = 4), and volvulus around the MDB (n = 2), with intestinal resection required in 8/15 cases. For horses with primary MDBs, survival to hospital discharge was 60% overall (9/15) and 75% for horses that stood following anaesthesia (9/12) with 88.9% of cases discharged from hospital (8/9) surviving >1 year. Excision of MDB tissue was not associated with complications but 3/4 non‐incidental MDBs left in situ required relaparotomy to treat MDB‐associated colic. Main limitations: Retrospective single centre data. Conclusions: Most MDBs in horses undergoing surgical treatment of colic in this population were not incidental. MDB‐associated colic was most commonly classified as strangulating obstruction, but non‐strangulating extra‐mural compression was also identified. Excision of MDB tissue should be undertaken where possible, particularly in non‐incidental cases. [ABSTRACT FROM AUTHOR]

Summary Two horses kept on different farms at a geographical distance of 150 km were presented with acute neurological dysfunction. Ante‐mortem diagnostic tests including bloodwork, CT scan and cerebrospinal fluid analysis did not provide a diagnosis in either case. Due to rapid deterioration, both horses were euthanised shortly after admission. Postmortem histopathological examination revealed granulomatous meningoencephalitis with intralesional nematodes that were morphologically identified as Halicephalobus gingivalis. This is the first documentation of central nervous system infestation by H. gingivalis in horses residing in Belgium, emphasising the importance of considering aberrant parasitic migration in the differential diagnosis of acute neurological dysfunction. [ABSTRACT FROM AUTHOR]

Summary After starting feeding on a new batch of hay, 29 out of 33 horses showed clinical signs of oral ulcerative and bleeding papules and mucous membrane erythema of the gingiva of the mandible within 2–3 days. The results of the complete blood cell count and biochemistry analysis did not yield significant findings in relation to horses affected by ulcerative stomatitis. Swab analyses of the oral mucosa for vesicular stomatitis virus (VS, Type Indiana and Type New Jersey) were negative in all horses (n = 33). Common windgrass with long awns in the deeper stomal‐gingival ulcerations was confirmed through botanical analysis by botanical identification. The hay batch fed to the affected horses was assessed via botanical analysis, finding 15% common windgrass (Apera spica‐venti). After the removal of the contaminated hay batch, full recovery was seen in all horses within 2–6 weeks depending on the severity of the lesions. The grassland from which the hay was harvested belonged to a semi‐natural landscape restored to increase biodiversity and as a protection zone in case of overflow of the river Rhine. In conclusion, feeding forages harvested from these semi‐natural landscapes may be harmful to the health of horses. [ABSTRACT FROM AUTHOR]

Summary Background Study design Objectives Methods Results Main limitations Conclusions Dentigerous cysts are well‐known congenital defects in horses, and the literature on this condition is extensive. Recently, a third type of dentigerous cyst, associated with an exostosis arising from the temporal bone, has been described. Today, computed tomography (CT) is often available and provides detailed information about the exact location and extent of dentigerous cysts, allowing for the description of new findings.This is a case series outlining the clinical, radiographic and computed tomographic features of dentigerous cysts in seven horses presented to the Equine Clinic at the Vetsuisse Faculty, University of Zurich, Switzerland.The aim of this case series was to describe the radiographic and computed tomographic findings, and the occurrence of exostoses arising from the temporal bone, in horses with dentigerous cysts.The medical records of the Equine Hospital at the University of Zurich were reviewed for horses admitted with dentigerous cysts between 2007 and 2023. Data collected and analysed included patient signalment, clinical history, clinical signs and their duration prior to referral, diagnostic imaging results, treatment and outcomes.The most common location for the cysts was the base of the ear, although in one case, the maxillary sinus was involved. Of the seven cases, four were Icelandic horses. CT proved superior to standard radiography for determining the extent and precise location of the cysts, as well as for identifying dental material and exostoses in the temporal region. CT also facilitated detailed surgical planning. All cysts were surgically removed with good long‐term outcomes.Overall, the incidence of dentigerous cysts in horses was low. The relatively high occurrence of dentigerous cysts in Icelandic horses in this study is an interesting finding, though the small sample size calls for further research.Two of the cases in this series were similar to a recently described variant of a ‘temporal dentigerous cyst associated with an exostosis in the temporal region’ and were closely connected to the bony structure and draining tract. [ABSTRACT FROM AUTHOR]

Summary Thrush is the term commonly used to describe nonproliferative pododermatitis of the frog epidermis caused by a bacterial infection. Thrush is commonly encountered in veterinary and farrier practices yet information on the pathogenesis, treatment and prevention of the disease in the equine veterinary literature is lacking. There is a plethora of proposed products and treatments on the market for thrush, yet most lack clinical evidence of efficacy. Clinical signs of thrush can range from black exudate in the sulci of the frog accompanied by a foul odour to bacterial invasion of the frog corium and digital cushion resulting in lameness. Thrush is primarily encountered in a conformationally compromised hoof capsule that is generally associated with an unhealthy frog. As thrush is rarely encountered in a healthy frog, it is important to focus on the farrier practices that may play a role in both the pathogenesis of thrush and its prevention. For successful treatment and prevention of thrush, good basic farrier principles must be incorporated into the treatment protocol. [ABSTRACT FROM AUTHOR]

Introduction: Quinidine (QND) sulfate is an effective treatment for atrial fibrillation (AF) in horses, and several dosage regimens have been proposed to address its wide variability in response and potential adverse effects. The purpose of this study was to analyze the variability in plasma quinidine concentrations using population pharmacokinetics to determine an effective and safe dosage regimen for Thoroughbred horses. Methods: Six healthy Thoroughbred horses were treated with 20mg/kg quinidine sulfate dihydrate (16.58mg/kg QND base) administered PO or 5mg/kg quinidine hydrochloride monohydrate (4.28mg/kg QND base) administered IV (single administration), and blood samples were taken regularly. Four healthy horses were treated with 20mg/kg quinidine sulfate dihydrate administered twice (every 6h) via PO route. For the other 19 Thoroughbred racehorses that developed AF, blood samples were taken during quinidine therapy. Quinidine concentrations were measured in all plasma samples using liquid chromatography with tandem mass spectrometry, and the data from 29 horses were modeled using a nonlinear mixed-effects model, followed by Monte Carlo simulations (MCS). Results: The median quinidine concentration for successful sinus rhythm conversion was 2.0 µg/mL (range: 0.5-2.7 µg/mL) in AF horses, while a median concentration of 3.8 µg/mL (range: 1.6-5.1 µg/mL) showed adverse effects. MCS predicted that plasma quinidine concentrations for quinidine sulfate dihydrate PO administration (loading dose: 30 mg/kg, maintenance dose: 6.5 mg/kg q 2 h) reached 1.4, 2.0 and 2.7 µg/mL in 90, 50 and 10% of the horse populations, respectively. Increasing the loading dose to 45 mg/kg and the maintenance dose to 9 mg/kg q 2 h, the plasma concentrations achieved were 1.9, 2.8, and 3.8 µg/mL in 90, 50, and 10% of horse populations, respectively. Discussion: Using simulations, different empirical dosing regimens were proposed to achieve plasma quinidine concentrations immediately or progressively, representing a tradeoff between optimizing therapeutic effects and minimizing adverse effects. A combination of these dosing regimens is recommended to gradually increase the therapeutic concentration levels of quinidine for safe and effective treatment of AF in racehorses. [ABSTRACT FROM AUTHOR]

Summary This case describes a mare with fungal placentitis of a novel aetiology with megaallantoic and megaamniotic vesicles in a late gestation pregnancy and subsequent fetal death. Management of the case revealed decreased fetal movement apparently due to the vesicles' large size. Pathological investigation of the fetal membranes and fetus showed severe fungal placentitis by Curvularia and Bipolaris spp., both saprophytic fungi never previously described in literature as aetiologic agents of placentitis in mares. Full consequence of the vesicles' relation to the placentitis and involvement in fetal death have yet to be determined or completely understood. [ABSTRACT FROM AUTHOR]

Summary Background Objectives Study design Methods Results Main limitations Conclusions Impinging dorsal spinous processes (IDSP) are a common cause of pain and loss of performance in sports horses, with a range of surgical and conservative treatments available.Identify relationships between treatment choice and the likelihood of returning to previous level of performance for horses diagnosed with IDSP.Cross‐sectional survey of owners with horses diagnosed with IDSP.A 14‐question online survey was circulated via social media. Data were collected for 260 horses and analysed for associations between treatment choice and return to pre‐diagnosis level of performance.Just under 50% of horses in the sample returned to their previous level of performance post‐treatment. Horses that were treated surgically had twice the odds of returning to their previous level than those that were not, and horses that underwent an exercise rehabilitation programme had 10 times the odds of returning to level.As this was an owner survey, self‐selection bias and recall bias could have influenced the findings.If the aim is for the horse to return to a competitive career post‐treatment, the most appropriate surgical intervention appears to be the best approach, and an exercise rehabilitation plan may have benefit. [ABSTRACT FROM AUTHOR]

Simple Summary: Numerous studies have examined the accessory ligament of the deep digital flexor tendon (AL-DDFT), focusing on both its normal and pathological anatomy. However, limited information is available regarding the precise relationship between the AL-DDFT and its surrounding structures. Clinically, this ligament is often implicated in desmitis and the formation of adhesions, yet the mechanisms driving these pathological changes are not fully understood. While previous investigations have suggested potential contributing factors, detailed descriptive studies are still necessary. In this study, macroscopic, microscopic, and morphometric analyses of the AL-DDFT were carried out. Through dissection and examination of E12 plastinated sections, we provide novel insights into the structural organization and interactions of the AL-DDFT with adjacent tissues. These findings enhance the current understanding of the anatomical and clinical aspects of the AL-DDFT, building upon and integrating previous research. The accessory ligament of the deep digital flexor tendon (AL-DDFT) plays a crucial role in the stay apparatus of the horse. This study aimed to investigate the anatomical relationship between the AL-DDFT, the superficial digital flexor tendon (SDFT), and other structures in the metacarpal region. Sixteen distal forelimbs from eight horses, aged 1 to 6 years, were evaluated through macroscopic, microscopic, and morphometric analyses, utilizing detailed dissection, E12 plastinated sections, and histological analysis. During lateral dissection, a connection was observed between the AL-DDFT and the SDFT. Histological evaluation revealed that this connection was a fibrous band (FB), extending the common synovial sheath (CSS) to the SDFT, along with associated collagen fibrils of the epiligament and peritenon. Additionally, two distinct forms of the AL-DDFT were identified, Type I and Type II, with Type II showing a greater cross-sectional area (CSA) than Type I. While numerous morphological and morphometric studies have explored the AL-DDFT and related structures, research incorporating plastination-based morphological and histological evaluations remains scarce. The findings provide valuable insights for both the morphological and clinical assessment of structures within the metacarpal region. [ABSTRACT FROM AUTHOR]