Elisa Diez de Castro

Equine Metabolic Syndrome (EMS) is a complex endocrine disorder characterized by obesity, insulin dysregulation (ID), and an increased risk of developing laminitis. Despite growing awareness of EMS, early and accurate diagnosis remains challenging. In this study, we investigated changes in the levels of circulating microRNAs (miRNAs) in plasma samples from horses diagnosed with EMS, compared to obese non-ID horses and healthy controls. Using a targeted real-time PCR OpenArray, we identified four miRNAs —miR-221, miR-186, miR-132, and miR-15a— that were differentially expressed across the groups. Functional enrichment analysis of their validated target genes revealed involvement in key insulin signalling mechanisms, including phosphatidylinositol 3-kinase (PI3K)/ protein kinase B (AKT), AMP-activated protein kinase (AMPK) and forkhead box O protein (FOXO) signalling pathways. Receiver Operating Characteristic (ROC) curve analysis demonstrated that combinations of these miRNAs provided discriminatory power between clinical groups (AUCs ranging from 0.79 to 0.93). These findings support the potential of circulating miRNA levels as non-invasive predictive biomarkers for EMS and related metabolic dysfunctions. Moreover, the signalling pathways identified provide mechanistic insight and establish a foundation for future studies aimed at therapeutic target discovery.

Environmental practices related to the inhalation of airborne dust have been identified as the main cause of equine asthma (EA) and reasonably, they are truly relevant in its treatment and control, especially for horses with its severe form. Vast research regarding environmental recommendations has been conducted in recent years. However, no recent exhaustive reviews exist that gather all this new evidence. The aim of this review is to report and compare the most pertinent information concerning the environmental management of EA. The main findings highlight the importance of the type of forage used for feeding but also its method of production and possible contamination during manufacture and/or storage. Procedures to reduce this, such as soaking and steaming hay, improve its hygienic quality, although they also decrease forage’s nutritional value, making dietetic supplementation necessary. Regarding stabling, despite some conflicting results, avoiding straw as bedding and improving barn ventilation continue to be the common recommendations if turning to pasture is not feasible. Finally, owners’ compliance has been identified as the most critical point in correct environmental control. Educating owners about the genuine benefits of these measures should be a cornerstone of EA management.

Background: Intravenous pharmacokinetics and oral bioavailability of cannabidiol (CBD) with different formulations have not been investigated in horses and may represent a starting point for clinical studies. Objectives: To describe pharmacokinetics after intravenous and oral administrations with oil and micellar formulations and simulate different treatments. Study design: Single intravenous experiment and two‐way randomised oral experiments, Latin‐square design. Methods: Eight healthy horses received intravenous CBD at 1.00 mg/kg dose, oral CBD in sesame oil and in micellar formulation, both at 10.00 mg/kg. Concentrations were measured using LC–MS/MS and fitted by nonlinear mixed effect modelling. Parameters obtained were used to simulate single and multiple treatments at steady state. Results: Intravenous and oral concentrations were simultaneously fitted using a three‐compartment model. Final estimates indicate that CBD has a volume of distribution of 36 L/kg associated with a systemic clearance of 1.46 L/h/kg and half‐lives ranged between 24 and 34 h. Oral bioavailability was close to 14% for both oral administrations. Simulated dose regimen of CBD every 12 and 24 h predicted similar percentages to reach effective plasma concentration with both oral formulation at 10.00 mg/kg. Main limitations: A small horse population was used (8 horses per trial). Conclusions and clinical importance: Oral bioavailability was low at the doses studied but fell within the range described for horse and other species. CBD had a high steady‐state volume of distribution, a high clearance and long half‐lives. No adverse reactions were detected at any dose or route. The micellar formulation showed a faster absorption and higher concentration peak, while the oil formulation presented lower levels, but more maintained over time. Simulations predicted that both could be useful in multiple oral dose treatments. These results indicated that CBD could be of interest, but further studies are needed to evaluate its clinical use in horses.

Obesity and its associated complications, such as metabolic syndrome, are an increasing problem in both humans and horses in the developed world. The expression patterns of resistin differ considerably between species. In rodents, resistin is expressed by adipocytes and is related to obesity and ID. In humans, resistin is predominantly produced by inflammatory cells, and resistin concentrations do not reflect the degree of obesity, although they may predict cardiovascular outcomes. The aim of this study was to investigate the usefulness of resistin and its relationship with ID and selected indicators of inflammation in horses. Seventy-two horses, included in one of the four following groups, were studied: healthy controls (C, n = 14), horses with inflammatory conditions (I, n = 21), horses with mild ID (ID1, n = 18), and horses with severe ID (ID2, n = 19). Plasma resistin concentrations were significantly different between groups and the higher values were recorded in the I and ID2 groups (C: 2.38 ± 1.69 ng/mL; I: 6.85 ± 8.38 ng/mL; ID1: 2.41 ± 2.70 ng/mL; ID2: 4.49 ± 3.08 ng/mL). Plasma resistin was not correlated with basal insulin concentrations. A significant (r = 0.336, p = 0.002) correlation was found between resistin and serum amyloid A. Our results show that, as is the case in humans, plasma resistin concentrations in horses are predominantly related to inflammatory conditions and not to ID. Horses with severe ID showed an elevation in resistin that may be secondary to the inflammatory status associated with metabolic syndrome.