Cyathostomins are ubiquitous equine nematodes. Infection can result in larval cyathostominosis due to mass larval emergence. Although faecal egg count (FEC) tests provide estimates of egg shedding, these correlate poorly with burden and provide no information on mucosal/luminal larvae. Previous studies describe a serum IgG(T)-based ELISA (CT3) that exhibits utility for detection of mucosal/luminal cyathostomins. Here, this ELISA is optimised/validated for commercial application using sera from horses for which burden data were available. Optimisation included addition of total IgG-based calibrators to provide standard curves for quantification of antigen-specific IgG(T) used to generate a CT3-specific 'serum score' for each horse. Validation dataset results were then used to assess the optimised test's performance and select serum score cut-off values for diagnosis of burdens above 1000, 5000 and 10,000 cyathostomins. The test demonstrated excellent performance (Receiver Operating Characteristic Area Under the Curve values >0.9) in diagnosing infection, with >90% sensitivity and >70% specificity at the selected serum score cut-off values. CT3-specific serum IgG(T) profiles in equines in different settings were assessed to provide information for commercial test use. These studies demonstrated maternal transfer of CT3-specific IgG(T) in colostrum to newborns, levels of which declined before increasing as foals consumed contaminated pasture. Studies in geographically distinct populations demonstrated that the proportion of horses that reported as test positive at a 14.37 CT3 serum score (1000-cyathostomin threshold) was associated with parasite transmission risk. Based on the results, inclusion criteria for commercial use were developed. Logistic regression models were developed to predict probabilities that burdens of individuals are above defined thresholds based on the reported serum score. The models performed at a similar level to the serum score cut-off approach. In conclusion, the CT3 test provides an option for veterinarians to obtain evidence of low cyathostomin burdens that do not require anthelmintic treatment and to support diagnosis of infection.

Background Equine neuroaxonal dystrophy/equine degenerative myeloencephalopathy (eNAD/EDM) is an inherited neurodegenerative disorder associated with a vitamin E deficiency within the first year of life. Vitamin E consists of 8 isoforms metabolized by the CYP4F2 enzyme. No antemortem diagnostic test currently exists for eNAD/EDM. Hypothesis/Objectives Based on the association of α-tocopherol deficiency with the development of eNAD/EDM, we hypothesized that the rate of α-tocopherol, but not γ-tocopherol or tocotrienol metabolism, would be increased in eNAD/EDM-affected horses. Animals Vitamin E metabolism: Proof of concept (POC) study; eNAD/EDM-affected (n = 5) and control (n = 6) horses. Validation study: eNAD/EDM-affected Quarter Horses (QHs; n = 6), cervical vertebral compressive myelopathy affected (n = 6) horses and control (n = 29) horses. CYP4F2 expression and copy number: eNAD/EDM-affected (n = 12) and age- and sex-matched control (n = 11-12) horses. Methods The rates of α-tocopherol/tocotrienol and γ-tocopherol/tocotrienol metabolism were assessed in equine serum (POC and validation) and urine (POC only) using liquid chromatography tandem mass spectrometry (LC-MS/MS). Quantitative reverse-transcriptase PCR (qRT-PCR) and droplet digital (dd)-PCR were used to assay expression and genomic copy number of a CYP4F2 equine ortholog. Results Metabolic rate of α-tocopherol was increased in eNAD/EDM horses (POC,P < .0001; validation, P = .03), with no difference in the metabolic rate of γ-tocopherol. Horses with eNAD/EDM had increased expression of the CYP4F2 equine orthologue (P = .02) but no differences in copy number. Conclusions and Clinical Importance Increased α-tocopherol metabolism in eNAD/EDM-affected QHs provides novel insight into alterations in vitamin E processing in eNAD/EDM and highlights the need for high-dose supplementation to prevent the clinical phenotype in genetically susceptible horses.

Metabolic syndrome (MetS)—encompassing obesity, insulin resistance, dyslipidemia, and hypertension—is prevalent in both humans and horses, offering a unique opportunity to explore shared pathophysiological mechanisms across species in a controlled model organism. In this first report from the Pioneer 100 Horse Health Project (P100HHP), we conducted a longitudinal, multi-omic analysis of 108 deeply phenotyped horses to interrogate individual health trajectories for precision insights into MetS. We identified two primary metabotypes: one characterized by elevated unsaturated triglycerides (TGs) and the other by increased levels of primary bile acids (BAs), notably taurocholic acid and taurochenodeoxycholic acid. Horses with higher circulating levels of taurocholic acid had significantly higher plasma insulin concentrations, especially after an oral sugar challenge (P = 0.01), indicating that specific BAs are associated with hyperinsulinemia—a key phenotype of MetS. Metabolomic signatures predicted body condition score (relative adiposity) with high performance, underscoring their potential for precision diagnostics. Seasonal variations influenced BA levels and were associated with shifts in the fecal microbiota, particularly in Clostridium and Proteobacteria populations. Additionally, we observed an inverse relationship between genetic diversity—measured by runs of homozygosity—and insulin levels, suggesting a genetic component to MetS susceptibility. Our findings demonstrate the power of deep phenotyping and multi-omic approaches to effectively delineate MetS subtypes in horses, highlighting the pivotal roles of bile acids and the microbiome in MetS pathogenesis. These insights not only advance the understanding of equine MetS but also establish the horse as a valuable translational model for human MetS, with potential implications for targeted diagnostics and therapeutics in both veterinary and human medicine

Background: Equine neuroaxonal dystrophy/equine degenerative myeloencephalopathy (eNAD/EDM) is an inherited neurodegenerative disorder associated with vitamin E deficiency. In humans, polymorphisms in genes involved in vitamin E uptake and distribution determines individual vitamin E requirements. Hypothesis/Objectives: Genetic polymorphisms in genes involved in vitamin E metabolism would be associated with an increased risk of eNAD/EDM in Quarter Horses (QHs). Animals: Whole-genome sequencing: eNAD/EDM affected (n = 9, postmortem [PM]-confirmed) and control (n = 32) QHs. Validation: eNAD/EDM affected (n = 39, 23-PM confirmed) and control (n = 68, 7-PM confirmed) QHs. Allele frequency (AF): Publicly available data from 504 horses across 47 breeds. Methods: Retrospective, case control study. Whole-genome sequencing was performed and genetic variants identified within 28 vitamin E candidate genes. These variants were subsequently genotyped in the validation cohort. Results: Thirty-nine confirmed variants in 15 vitamin E candidate genes were significantly associated with eNAD/EDM (P < .01). In the validation cohort, 2 intronic CD36 variants (chr4:726485 and chr4:731082) were significantly associated with eNAD/EDM in clinical (P = 2.78 × 10−4 and P = 4 × 10−4, respectively) and PM-confirmed cases (P = 6.32 × 10−6 and 1.04 × 10−5, respectively). Despite the significant association, variant AFs were low in the postmortem-confirmed eNAD/EDM cases (0.22-0.26). In publicly available equine genomes, AFs ranged from 0.06 to 0.1. Conclusions and Clinical Importance: Many PM-confirmed cases of eNAD/EDM were wild-type for the 2 intronic CD36 SNPs, suggesting either a false positive association or genetic heterogeneity of eNAD/EDM within the QH breed.