Toxoplasma gondii infection is widely recognized as an important cause of reproductive losses in goats and sheep. However, the impact of this parasitic infection in mares remains poorly investigated, reflecting the neglect of this pathogen in equine production. The present study aimed to conduct a serological survey in 100 mares from farms enrolled in embryo transfer (ET) programs in Northeastern Brazil, report the first molecular detection of T. gondii in the placenta and aborted fetus of a mare in the country, and evaluate potential risk factors associated with infection. Anti-T. gondii IgG antibodies were detected using the indirect fluorescent antibody assay (IFA) with a cutoff of 1:64, followed by serial titration. Placentas and fetal organs from three mares from a farm with an abortion outbreak were also analyzed by PCR targeting the 18S rRNA gene of the family Sarcocystidae and the 529-bp repetitive element of T. gondii. A total of 31% of mares were seropositive (95% CI: 22.3-40.9), and both the fetus and placenta from one mare tested positive for the 18S rRNA gene and the 529-bp RE. The presence of cats on the farms and a history of abortion were identified as factors associated with seropositivity. These findings provide novel evidence contributing to the understanding of T. gondii infection in equine production systems.
Previous research has shown that forage nutritive analyses are not used to any large extent in equine nutrition. As forages differ widely in nutritional quality, knowledge of the nutritive value is essential to avoid under- or overfeeding of horses. The aim of this study was to investigate how forage nutritive analyses were used among horse owners in Sweden, and to identify challenges horse owners encounter with such analyses. Data was collected through an online survey with questions about the respondent, access to forage analytical reports, if and how the respondent used such reports and how the use of it could be facilitated. The survey yielded 425 complete responses, and 84% of the respondents (356 of 425) had access to a forage nutritive analytical report. Of these, 185 (52%) used it for calculation of feed rations followed by 160 (45%) using it for estimates of forage allowance amounts. Of the 16% (69 of 425) who did not have access to a report, 39% (27 of 69) stated that difficulties in obtaining a representative sample was the main reason for not conducting analyses while 26% (18 of 69) stated it was unnecessary. A lower price for the analysis (40%, 168 of 425) and specific feeding recommendations (32%, 135) were suggested to facilitate use of forage analyses in equine feeding. A high proportion of survey respondents had access to a forage analytical report, but improved information on how to use the report could facilitate further use of it.
Vitrification rather than slow-freezing has become the method of choice for the cryopreservation of in-vivo produced embryos. It is a simple technique that does not require a programmable freezing machine and relies chiefly on placing the embryo on a surface, rather than within a straw, in a small volume of vitrification solution to achieve extremely rapid cooling rates. However, in the field of equine embryo vitrification size truly does matter. Methodologies for both vitrification and warming prior to transfer are largely dictated by the size of the embryo. Since embryo size is directly related to age, the developmental changes that occur as an embryo develops have a direct impact on the protocols used for vitrifying and warming equine embryos. Embryos ≤450 μm offer the most practical option for vitrification and are associated with the highest success rates for practitioners wishing to vitrify and warm embryos. Larger embryos, however, require aspiration of the blastocele prior to vitrification, a procedure that necessitates technical expertise and the use of specialised equipment such as a micromanipulator. This review paper focuses on the vitrification of in vivo produced equine embryos and the advances made in vitrification and warming techniques aimed at improving practicality and pregnancy outcomes.
This study evaluated an enzyme-linked immunosorbent assay (ELISA) for the detection of Coll2-1, a peptide fragment of type II collagen released during cartilage degradation in horses using a kit originally developed for dogs. The objectives of this study were to: 1) assess the analytical applicability of the canine Coll2-1 ELISA in equine serum and 2) explore the correlations between Coll2-1 concentrations and radiographic scores of osteoarthritis (OA) in horses. Twelve Lusitano stallions, of similar age and workload but presenting different radiographic scores were included. Radiographic studies of the stifle, tarsi, fetlocks and distal limbs were done and the classification of the radiographs was performed using a 0-4 scale. Blood samples were obtained at rest and the Coll2-1 concentration in equine serum measured using Coll2-1 ELISA. Analytical performance was evaluated by measuring intra-assay and inter-assay precision and regression analysis. Data distribution was assessed using the Shapiro-Wilk test. Non-parametric methods were applied when normality was rejected, and correlations between Coll2-1 concentrations and radiographic scores were evaluated using Kendall's Tau-b. Intra-assay and inter-assay CVs ranged from 5.6 to 19.3% and 3.6 to 22%, respectively. The regression analysis yielded a determination coefficient of 0.94, with all analytical parameters within manufacturer's recommendations. No significant correlations were observed between serum Coll2-1 concentrations and radiographic OA scores. Using serum, Coll2-1 did not appear to be a sensitive biomarker for identifying OA in this population. However, the canine ELISA demonstrated acceptable analytical performance in equine serum, supporting its use in another disease.
Serum cortisol concentration is one of the common physiological reference standards for evaluating stress in animals. However, it only evaluates acute stress at the moment of blood collection. Hair cortisol concentrations (HCC) could provide a method for assessing cortisol concentrations over extended periods of time, giving an estimate of chronic stress levels. In this case, high HCC results could help equine managers alter management practices to improve welfare. To evaluate the effect of the month of collection and the storage method on equine HCC. Tail hair was collected from 32 mature horses in February and August of the same year, both times from the same location. Samples were split and packaged in resealable plastic bags, with half stored in a cardboard box in a climate-controlled environment at 21.1°C (ROOM) and the other half stored in a freezer at -20°C (FROZEN). February collections were stored for eight months before analysis, while August collections were stored for two months. FROZEN samples had higher HCC (P = 0.0278), as did August samples (P = 0.0067), but there was no significant interaction between storage method and month of collection. It is likely that higher HCC in August were the result of horse exposure to longer daylight hours. Results from this study suggest that storing hair samples in a frozen state will better preserve cortisol concentrations.
Artificial intelligence (AI) platforms are becoming increasingly popular as resources for equine information. However, these platforms generate responses from a wide range of sources and do not always distinguish between fact and opinion. The objective of this study was to assess the accuracy and quality of AI-generated answers to equine-related questions. Researchers hypothesized that AI platforms could answer basic equine questions effectively but would perform poorly on complex topics or questions. Forty questions were written covering general horse care, facilities management, nutrition, genetics, and reproduction. Each question was categorized by difficulty level: beginner, intermediate, advanced, or trending. Three AI platforms were tested: ChatGPT (CGPT), Microsoft Copilot (MicCP), and ExtensionBot (ExtBot). Responses were scored for accuracy, relevance, thoroughness, and source quality (5 points each; total 20). Data were analyzed using PROC GLM in SAS (v. 9.4). Total score was affected by level (P = 0.002). Intermediate questions had the highest total score (15.95 ± 1.99). Accuracy was affected by platform (P < 0.001), level (P < 0.001), and topic (P = 0.015). CGPT (4.18 ± 0.93) and MicCP (4.08 ± 0.83) outperformed ExtBot (3.26 ± 1.21). Relevance was affected by platform (P = 0.042) and level (P < 0.001). Thoroughness was affected by platform (P < 0.001). Source quality differed by platform (P = 0.037). AI platforms could be resources; currently they fall short of the knowledge that Equine Extension Specialists can offer. AI platforms had difficulty addressing complex topics and demonstrated inconsistent performance across criteria.
Treating primary back pain in horses can be challenging and often necessitates a multimodal approach. Whole-body vibration therapy (WBV) has been used in both horses and humans to alleviate pain and strengthen muscles. A recent study showed worsening back pain following a 30-minute session of WBV; however, the immediate effects of WBV were not evaluated. The purpose of this study was to assess the immediate effects of whole-body vibration therapy on horses with back pain after a single session of WBV. The objective of the current study was to determine the immediate effects on mechanical nociceptive thresholds (MNTs) after a single treatment of WBV in horses with thoracolumbar pain. Eight horses with thoracolumbar pain and pathology were enrolled. Horses underwent WBV for a single 30-minute session (frequency of 40 Hz, amplitude of 0.8 mm, acceleration of 4.9m/s2, vertical vibration). MNTs were measured approximately 2 cms to the left and right of midline at the thoracic spine (T13, T18), lumbar spine (L3, L6), and sacrum (S2) before WBV, immediately following WBV, and 24 hours later. Mean MNTs were on average 0.2 times higher immediately following WBV with no significant difference from baseline (P = 0.98). Mean MNTs were on average two times lower than baseline 24 hours after WBV (P < 0.0001). Mean MNTs decreased regardless of back pathology, initial pain or location of MNTs. The immediate effects of WBV therapy in horses with thoracolumbar pain may result in minimal improvement in pain and may exacerbate pain when used short-term. Short-term use of WBV should be used with caution in horses with thoracolumbar pain.
Although racehorses represent a dominant segment in equine industry, there are growing concerns regarding injury prevention, with hoof conformation increasingly recognized as a contributing factor. To morphologically and radiographically evaluate the forelimb digits of racehorses at the São Paulo Jockey Club in order to determine the prevalence of dorsopalmar hoof distortions and to compare morphological and radiographic methods for assessing the hoof-pastern axis. The forelimb digits of 59 thoroughbred horses aged 3 to 4 years were evaluated using standardized photographic and radiographic imaging techniques. A broken-backward hoof-pastern axis was identified in 100% of cases by all three radiographic methods, compared to only 55.2% by photographic analysis. Radiographic evaluation also detected high prevalences of hoof distortions, including low heel angles (85%), underrun heels (97%), low palmar angles (87%), and negative palmar angles (56%). The high prevalences of dorsopalmar imbalance-associated hoof distortions in this population are alarming and highlight the need for improved hoof trimming and shoeing practices to prevent injuries, ensure animal welfare, and promote long-term sustainability of this equine activity.
Gastrointestinal (GI) parasitic infection remains one of the most prevalent and economically significant health challenges in equine populations. The infective stages of GI parasites can activate systemic inflammatory responses and disrupt lipid metabolism leading to exacerbation of parasitic infection. Moreover, age-related low-grade chronic inflammation may further contribute to the persistent infection which impacts the health status of individual horses. This study examined serum levels of the inflammatory marker C-reactive protein (CRP) and lipid profile parameters to identify age-related patterns in horses in the high prevalence area of GI parasitic infection in Southern Thailand. Seventy-seven horses were categorized into four age groups: foal (<1 year); young (1-3.99 years); early adult (4-10 years); and late adult (>10 years) and were examined for fecal helminth eggs and fecal egg count (EPG) using a modified McMaster technique. The serum CRP, and lipid profile parameters including total cholesterol (TC), total triglyceride (TG), high-density lipoprotein (HDL-C), and low-density lipoprotein (LDL-C), LDL: HDL, and TC:HDL ratios were determined. Strongyle nematodes, including cyathostomins and Strongylus vulgaris were detected with the prevalence >60% of horses across all age groups. CRP, TC, and LDL-C levels increased significantly with age (p < 0.01), while HDL-C levels significantly declined in the late adult group when compared with other age groups (p = 0.0037). Among all age groups of horses, Spearman correlation (ρ) and binary logistic regression (odd ratio: OR [95%CI]) revealed that serum CRP, and LDL-C levels were positively associated with the EPG of strongyle nematode helminths. While HDL-C levels showed negative correlation. HDL, and TC:HDL ratios were identified as the risk factors for strongyle nematode GI infection. Using the ROC analysis, the cut-off values of CRP (>0.49 mg/L; %sensitivity [SS] = 72.97, %specificity [SP] =75.00), LDL: HDL (>2.476; %SS=64.29, %SP=71.43), and TC: HDL (>5.198; %SS=51.22, %SP=83.33%) could help predict the strongyle nematode GI parasitic infection in horses. These findings highlight the diagnostic potential of CRP and cholesterol index as the prognostic biomarkers and disease monitoring in equine strongyle nematode infection to provide the proper management and intervention to current parasite management strategies.
Acute colitis is an inflammatory condition of the equine colon associated with high morbidity and mortality. In these horses, epithelial barrier function is critical but the mechanisms underlying large intestinal epithelial damage and recovery are incompletely understood. Our objectives were to (1) identify intestinal colitis-associated transcriptional pathways, and (2) determine the effect of in vitro choline supplementation on the epithelial barrier. We performed RNA-sequencing on rectal biopsies from healthy and colitis horses (n = 3/group). Downregulated SLC5A7, a gene encoding CHT1 (High-Affinity Choline Transporter 1), was confirmed using qRT-PCR and immunofluorescence on large intestinal (cecum, right ventral colon (RVC), right dorsal colon (RDC), and rectum) biopsies from additional healthy and colitis horses (n = 8-20/group). Primary monolayer epithelial cultures derived from healthy RDC (n = 4 horses) were treated with 0-250 µM choline and monitored for cellular proliferation and barrier permeability. We identified a colitis-associated transcriptome in rectal biopsies, including upregulated inflammatory response, cell cycle, and epithelial reorganization gene sets. There was decreased SLC5A7 expression throughout large intestinal biopsies of colitis horses (healthy cecum mean log2 fold change 1.8, 95% CI [1.12, 2.67] vs colitis cecum mean log2 fold change -0.5, 95% CI [-1.42, 0.42]). Apical epithelial CHT1 immunofluorescence was diminished in cecum, RVC, and RDC biopsies from colitis horses. Choline supplementation increased cellular proliferation and decreased time to confluency of epithelial monolayers, however no difference in barrier permeability post-confluency was observed. Acute equine colitis has a distinct transcriptomic signature. Our findings suggest that choline supplementation may encourage epithelial barrier recovery.
This case reports the successful use of vincristine in a Quarter Horse with presumed immune-mediated thrombocytopenia. A 15-year-old Quarter Horse gelding presented for a pinch skin graft procedure on the left forelimb over the cannon bone. On day 10 of hospitalization, the horse developed a fever (102.6°F, RI: 99-101°F), and severe petechiae of the mucous membranes. A complete blood count (CBC) (Advia 2120i) revealed a severe thrombocytopenia (16,000 platelets/μL, RI:100,000-400,000/μL). Diagnostic testing was negative for Anaplasma phagocytophilum by PCR, Theileria equi and Babesia caballi by cELISA, and equine infectious anemia (EIA) virus by agar gel immunodiffusion. A sternal bone marrow aspirate was suggestive of megakaryocyte hypoplasia. However, the sample was not of good quality and was suspected not to be a good representation of the marrow. Over a 20-day treatment period, the horse received multiple immunosuppressive medications (dexamethasone, prednisolone, azathioprine) and vincristine in attempt to improve the thrombocytopenia. Following vincristine administration, the platelet count increased substantially and eventually normalized. Vincristine is thought to stimulate thrombopoiesis and increase megakaryocyte fragmentation within the bone marrow. Based on response to vincristine, exclusion of infectious agents, and lack of a consumptive process (e.g., disseminated intravascular coagulation [DIC], chronic hemorrhagic lesion), a presumptive diagnosis of immune-mediated thrombocytopenia (IMTP) was made. To the authors' knowledge, this is one of only two reported cases in equine medicine describing successful treatment of IMTP with vincristine. This case report offers novel treatment information, previously well documented in domestic small animals.
Pregnancy loss remains a significant challenge for the equine breeding industry, with substantial economic and management consequences. Chromosomal abnormalities have emerged as a central driver of pregnancy loss, particularly during early gestation, highlighting the need to better understand the etiology of this inherent genetic instability. Concurrently, the rapid expansion of assisted reproductive technologies (ART) offers promise for improving equine reproductive efficiency alongside the traditional practice of natural cover. However, the increasing use of in vitro embryo production (IVP) raises important questions regarding the genetic stability and long-term health of resulting offspring. Here we extensively review the mechanistic basis, putative origins, and subtypes of genetic abnormalities, underscoring specific biases in points of lethality during pregnancy loss. Although evidence remains limited, we also examine emerging data suggesting distinct patterns of developmental tolerance and genetic instability between IVP and in vivo derived (IVD) embryos. Notably, available studies report complex and widespread genomic disruptions associated with IVP embryos, underscoring the need for systematic characterization of genetic profiles and offspring outcomes across breeding modalities. Decoding the genetic consequences of ART represents an important frontier in equine reproduction research, with broad implications for optimizing ART protocols and maintaining healthy and sustainable equine lineages.
Equine genital leptospirosis (EGL) is associated with reproductive disorders in mares. However, its occurrence in embryo transfer (ET) programs remains poorly characterized. Given the scarcity of data on the circulation of Leptospira spp. in mares enrolled in ET programs, this study aimed to investigate the serological and molecular occurrence of Leptospira spp. in mares with a history of reproductive disorders from 13 stud farms dedicated to embryo transfer in Brazil. Serum and endometrial cytobrush samples (ECS) were collected from 70 unvaccinated mares. Serological analysis was performed using the microscopic agglutination test (MAT), and molecular detection was conducted by PCR targeting the lipL32 gene. Positive samples were subjected to sequencing. In the MAT, 68.6% (48/70; 95% CI: 56.9-78.2) of mares were reactive at titers ≥ 1:100. PCR detected pathogenic Leptospira DNA in 45.7% (32/70; 95% CI: 34.5-57.4) of ECS, with at least one positive mare identified in 92.3% (12/13) of farms. Sequencing of one sample showed ≥ 99% nucleotide identity with Leptospira interrogans. Functional classification was significantly associated with PCR positivity, with recipient mares presenting higher odds of detection compared to donors (OR = 3.15; 95% CI: 1.05-9.43; p = 0.040). These findings demonstrate high serological exposure and molecular evidence of infection in the reproductive tract of mares with reproductive disorders, reinforcing the importance of molecular investigation in breeding herds enrolled in ET programs.
Brucellosis is a chronic infectious disease in equids, characterized by suppurative lesions in joints and bursae, with potential impacts on animal performance and public health. To investigate the prevalence and spatial distribution of Brucella spp. seropositive equids in the state of Mato Grosso, Brazil. A total of 3,858 serum samples from 3,230 horses, 602 mules, and 26 donkeys were analyzed using the Buffered Acidified Antigen Test (AAT) and Complement Fixation Test (CFT), following Brazilian Ministry of Agriculture guidelines. Samples were obtained from all municipalities and included the Amazon, Cerrado, and Pantanal biomes. AAT screening identified 4.48% (173/3,858) reactive animals, of which 0.78% (30/3,858) were confirmed by CFT. The estimated prevalence was 0.82% (95% CI: 0.79-0.85%), with values of 0.91%, 0.88%, and 0.12% for the Amazon, Cerrado, and Pantanal biomes, respectively. No significant associations were found between seropositivity and age, sex, species, or management variables. Spatial analysis showed no evidence of clustering, indicating a homogeneous distribution of risk across the state. Additionally, no association was observed between equine seropositivity and bovine brucellosis foci. Equine brucellosis showed low prevalence and a diffuse spatial pattern in Mato Grosso, supporting the role of equids as incidental hosts and reinforcing the need for continued epidemiological surveillance of interspecies transmission.
Equine embryo transfer is a well-established procedure in horse breeding programs and it's used to increase the number of offspring from valuable mares, obtain embryos from mares in competition and produce foals from mares unable to carry a pregnancy to term. The success of embryo recovery depends mainly on the day of flushing, management of insemination, and the fertility of donor mare and stallion. Other relevant factors include donor age and reproductive status, number of ovulations, operator experience, and flushing technique. Pregnancy rates after transfer are influenced by donor-recipient synchrony, the recipient's day post ovulation, embryo quality and developmental stage. The transfer technique and the characteristics of the recipient mare are also essential for pregnancy establishment and maintenance. This review evaluates the current status of equine embryo transfer and examines the principal factors affecting its outcome in order to maximise the efficiency of conventional embryo transfer programs.
Microbial resilience is important to maintain a healthy gut environment in horses, especially after antibiotic administration, but the efficacies of post-antibiotic recovery strategies remain poorly characterized. We used microbial amplicon sequencing to compare spontaneous recovery, autologous fecal microbiota transplantation (FMT), and probiotic administration in 18 horses following antibiotic-induced dysbiosis. Clinically healthy horses received a combination of cephalothin and minocycline for 5 consecutive days before intervention. Fecal microbial recovery was longitudinally evaluated by using community-level dissimilarity metrics. Antibiotic treatment induced marked dysbiosis in all horses. Autologous FMT resulted in significantly faster recovery toward individual pre-treatment baselines compared with spontaneous recovery (significantly lower dissimilarity at day 3 post-treatment, P < 0.05), whereas the effects of probiotics were only evident in cumulative recovery metrics and not at specific time points. These findings indicate that autologous FMT has the potential to accelerate the recovery of the equine gut microbiota following antibiotic-induced dysbiosis.
Persistent breeding-induced endometritis (PBIE) is a major cause of infertility in mares. Recent research has shown that PBIE-affected mares treated with intrauterine N-acetyl cysteine (NAC) 12 hours before breeding showed no improvement in clinical signs at 12- and 60-hours post-breeding. The present study was designed to examine the effects of NAC treatment on the uterine inflammatory cytokine and chemokine profiles in PBIE-affected mares. Using a randomized, blinded, cross-over design, mares susceptible to PBIE (n=9) were allocated to Control and Treatment cycles with at least one washout estrous cycle between the cycles. Intrauterine infusion of 180 mL of 3.3% NAC (Treatment) or sterile saline (Control) was performed 12 hours before insemination. Uterine fluid samples were collected at 12- and 60-hours post-insemination to determine inflammatory cytokine and chemokine profiles. Endometrial biopsies were taken at the same time points to determine gene expression of selected inflammatory cytokines (Interleukin-6, Interleukin-10, Interleukin-1β and Tumor Necrosis Factor-α). There was no difference (p > 0.05) in the uterine fluid inflammatory cytokines and chemokines between Control and Treatment cycles. Similarly, gene expression of the selected inflammatory cytokines did not differ (p > 0.05) between the two cycles. The absence of any significant effects of NAC on the uterine inflammatory cytokines and chemokines provides a potential mechanism to explain the previously reported lack of improvement in clinical signs in PBIE-affected mares treated with NAC.
Equine in vitro embryo production has become very efficient and is used extensively worldwide for the clinical production of foals. What we know so far about offspring health and performance is promising; however, elements of the in vitro process remain unphysiological when compared to in vivo conditions. Studying the metabolism of oocytes and embryos can help inform the optimisation of culture systems and identify aberrations if they occur. Given the growing body of knowledge on the downstream effects of an inadequate peri‑conception environment, both in vivo and in vitro, it is imperative that fundamental research continues to optimise the culture systems we use. This review describes existing knowledge of the in vivo environment in the context of carbohydrate nutrient provision in addition to glucose and oxidative metabolism of the oocyte and early embryo. Areas are highlighted where further research is required.
Sodium and chloride are required nutrients and are typically met using sodium chloride (salt) via compressed blocks. The objective of this study was to compare salt intake using block or loose salt. Sixteen mature horses were blocked by housing style and assigned to block salt or loose salt (form) for four 7-day periods. Salt intake was measured by weight at the end of each period. Salt intake was not affected by form (P = 0.070) or period (P = 0.902). There was an effect of horse (P < 0.001). Horses consumed between 2 and 135 g of salt daily, however; over half of the horses in the study did not consume enough salt to meet requirements. Both salt and water intake are highly variable by horse. Horses that do not voluntarily consume enough salt to meet requirements should be supplemented with their daily feed ration.
The biochemical profile of horses is a cornerstone in equine clinical diagnostics, offering valuable insights into health status, disease progression, and physiological adaptation to internal and external stimuli. However, the interpretation of these biochemical parameters is far from straightforward, as they are subject to significant variation influenced by a range of physiological factors. Age, sex, breed, level of physical activity, nutritional condition, and reproductive status can all modulate baseline biochemical values, potentially leading to diagnostic inaccuracies if not properly contextualized. This article provides a comprehensive review of the physiological determinants that affect biochemical markers in horses under non-pathological conditions. By examining how these variables alter key analytes -such as enzymes' activity, metabolites, electrolytes, and hormonal concentrations- the study underscores the necessity of establishing context-specific reference intervals. Furthermore, it advocates an individualized approach to biochemical assessment in equine medicine, emphasizing the importance of integrating physiological context into clinical decision-making, to enhance diagnostic precision and therapeutic outcomes.