Conditional Antioxidant Protection of Stallion Spermatozoa by Butylated Hydroxytoluene Under Induced Oxidative Stress. Despite advances in the method, equine semen cryopreservation still leads to a marked decline in sperm quality, partly attributed to oxidative stress, which motivates the search for lipophilic antioxidants capable of stabilizing the plasma membrane during cooling and freezing. This study performed three experiments to evaluate butylated hydroxytoluene (BHT) as an additive to commercial skim milk-based (Botu-Sêmen) and egg yolk-based (Botu-Crio) extenders. In Experiment 1, a dose-response curve (0.5, 1.0, and 1.5 mM) was performed using stallion semen to assess toxicity and establish a safe ...
Intra-articular hydrogel therapeutics exhibit anti-inflammatory effects on cytokine-stimulated equine cartilage and synovial membrane explants. To investigate whether IA hydrogel therapeutics alter the inflammatory and/or degradative responses of articular cartilage (AC) and synovial membrane (SM) to cytokine stimulation. Unassigned: AC and SM tissue explants were stimulated with interleukin-1β (IL-1β) or tumor necrosis factor-α (TNF-α) and simultaneously treated with triamcinolone acetonide, hyaluronic acid, collagen-elastin hydrogel microparticles (CEHM), or 2.5% polyacrylamide hydrogel (2.5% iPAAG) at 3 doses. Synovial membrane (n = 9 explants, 3 horses) was stimulated/treated for 18 hours, whereas AC (12 explants, 6 horses) wa...
Main causes of death in aged horses in a retirement facility in California can be attributed to the digestive and musculoskeletal systems. To determine the main causes of death in aged horses residing at a retirement facility in California. Unassigned: A retrospective cross-sectional study design was utilized to evaluate signalment, medical history, and necropsy reports of horses aged 20 years or older at death and housed at a single retirement facility. All cases underwent a standard post mortem evaluation from 2010 through 2020 by the University of California-Davis William R. Pritchard Veterinary Medical Teaching Hospital. Euthanasia decisions were made by the retirement facility staff in consultation with a veterinarian. The m...
Global distribution of Neorickettsia risticii, the causative agent of potomac horse fever: a systematic review. Potomac Horse Fever (PHF), also known as equine neorickettsiosis (EN) or equine monocytic ehrlichiosis is an acute, potentially fatal infectious disease in horses caused by the monocytotropic rickettsia bacterium Neorickettsia risticii. This obligate intracellular bacterium is maintained throughout the life cycle of digenetic trematodes which utilize multiple intermediate and definitive hosts. Research on N. risticii is scattered across multiple continents, with most studies originating from North and South America. Therefore, a systematic review is needed to consolidate global evidence, clari...
Multicentric Malignant Melanoma in a Grey Mare: A Case Report. Grey coat color in horses, resulting from a 4.6 kb copy number variation (CNV) within the syntaxin 17 (STX17) gene (Grey locus), is linked to progressive hair depigmentation and a markedly increased risk of melanoma, likely to its function as a melanocyte-specific enhancer. Objective: This report details the clinical, pathological, and genomic findings of a 26-year-old flea-bitten grey mare with multiple melanocytic tumors, progressive dyspnea, and congestive heart failure. Due to the poor prognosis the horse was euthanized and submitted for necropsy to the Long Island University - Lewyt Colle...
Synthesis and Characterization of Deuterated Detomidine for Use in Equine Medication Regulation. Detomidine, 5-[(2,3-dimethylphenyl)methyl]-1H-imidazole, is a tranquilizer/sedative/analgesic widely used in equine medicine and regulated by several different analyte concentrations of detomidine and its hydroxydetomidine and carboxydetomidine metabolites in plasma and urine. Accurate regulatory quantitation of detomidine at low picogram/mL concentrations requires the availability of a stable isotope internal standard of detomidine; however, to the best of our knowledge, no certified deuterated internal standard of detomidine is commercially available and its synthesis has not been reported. ...
Effect of heat acclimation training frequency on the physiological adaptations of Thoroughbred horses. Heat acclimation enhances thermoregulation and cardiovascular function. While daily training protocols are typically recommended for humans, optimal training protocols for Thoroughbred horses remain unclear. Here, we compared the effects of two heat acclimation protocols, consecutive and intermittent, in Thoroughbred horses. In a randomized crossover study, eight trained Thoroughbred horses completed either a consecutive (CONS: 9 consecutive days) or an intermittent (INT: 3 days/week for 3 weeks) heat acclimation protocol, comprising 30 min of exercise in hot conditions (WBGT 30°C). Increment...
Tracheal wash culture is not associated with bronchial infection, remodelling or inflammation in horses with asthma. Antimicrobials are commonly prescribed for the treatment of equine asthma, despite limited evidence supporting their use. Tracheal wash (TW) bacterial culture results are known to influence antimicrobial prescription decisions. Objective: To determine whether a positive TW bacterial culture in horses with asthma is associated with bronchial infection or colonisation, increased bronchial remodelling and airway inflammation by evaluating the presence of bacteria and airway remodelling in endobronchial biopsies, as well as bronchoalveolar lavage fluid (BALF) cytology and tracheal mucus scores. Me...
Novel application of a PMSG assay for measurement of circulating LH levels in horses. Luteinizing hormone (LH) plays a pivotal role in equine reproductive physiology, yet its measurement has traditionally relied on radioimmunoassays (RIA), which present safety, accessibility, and regulatory challenges. This study evaluates the use of a commercially available pregnant mare serum gonadotropin (PMSG) enzyme-linked immunosorbent assay (ELISA) as an alternative for quantifying circulating LH in horses. Given the 100% peptide identity between equine LH and PMSG, we hypothesized that the PMSG ELISA would detect LH with high specificity and sensitivity. Blood samples from healthy, cycl...
Prevalence of potential enteric pathogens in diarrheic and non-diarrheic foals in Brazil. Diarrhea is a significant cause of morbidity and mortality in foals. Our hypothesis is that foals with diarrhea have a greater prevalence of ≥2 organisms causing coinfections. We investigated the major microorganisms associated with diarrhea in 200 foals up to 1-y-old (100 diarrheic and 100 non-diarrheic). Fecal samples were analyzed by real-time PCR (rtPCR) for the detection of and toxin genes and , (genotyping for toxin-encoding genes), spp., , , , , , and spp. Rotavirus A and coronavirus were detected using reverse-transcription rtPCR. Fecal bacterial culture was also performed for ...
Horses Prefer Their Rider: A Strange Situation Test Adaptation Shows Behavioural Evidence for Partner-Specific Bonding. The relationship between horses and humans is often described as cooperative and affective, yet empirical studies on horse-rider bond remain scarce. Previous findings on horse-human relationships yielded conflicting results on whether and how horses show bonding like behaviour toward their owners. Objective: We tested whether horses show partner-specific approach and proximity toward their primary rider compared with an unfamiliar experimenter in an adapted Strange Situation Test, and whether the rider's presence was associated with behavioural patterns indicative of safe haven and secure base...
Evidence That GYPA (Glycophorin A) Encodes the K Blood Group System in Horses. Although serological and genetic studies of equine blood group systems have been conducted for many years, the molecular basis of erythrocyte antigens' variability has remained largely unexplored. In this study, we aimed to elucidate the genetic basis of serological variation within equine blood group K. Using mRNA extracted from peripheral blood samples (n = 100) collected from horses with known serological blood types (Ka or K-), we performed a transcriptome-wide association study (TWAS), which revealed a significantly associated region on equine chromosome 2 (ECA2). A detailed analysis ...
Postmortem characterization of cranial nuchal bursa and ligament in healthy horses reveals subclinical gross and histopathologic abnormalities. To investigate the presence of subclinical cranial nuchal bursitis and characterize its histopathologic features and association with Borrelia burgdorferi. Unassigned: This was a prospective descriptive cadaver study on a convenience population of horses in a B burgdorferi-endemic region (15 horses: 5 geldings and 10 mares of various breeds; 4 to 29 years old). Horses without history or clinical signs of cranial nuchal bursitis underwent euthanasia and tissue donation. Cranial nuchal bursa, synovial fluid, and nuchal ligament were collected postmortem. The bursa and ligament were evaluated via...
Effect of Acer species (red and Freeman maple) and horse characteristics, management, and location on the in vitro oxidation of equine erythrocytes. Red maple toxicosis arises when horses consume wilted maple leaves, resulting in methemoglobinemia and hemolytic anemia due to oxidative damage to erythrocytes. Objective: The objective of this study was to determine how maple species (red versus Freeman maple) and horse characteristics, management, and barn site contributed to in vitro methemoglobin production and hemolysis. Methods: Horse information was obtained through an owner questionnaire. Extracts from red and Freeman maple leaves were separately incubated with washed erythrocytes from each horse (n=120). The in vitro percentage methem...
Clinical nutrition in equine colic: a scoping review from an equine nutritionist’s perspective. Colic represents one of the leading causes of morbidity and mortality in equine medicine, with nutritional management recognized as a key modifiable factor influencing postoperative recovery. However, guiding principles for nutritional enteral support in horses after colic remain limited, and current practices are largely empirical. Objective: This scoping review aimed to (1) examine enteral nutritional support protocols reported in literature through a scoping review to map the available evidence on equine clinical nutrition in the context of colic, and (2) propose a physiology-based interpre...
Comparative Evaluation of Sperm Quality Assessment Methods in Purebred Spanish Horses. Evaluating semen quality in Purebred Spanish Horses is essential to determine reproductive potential and optimize assisted reproductive techniques. Objective: This study compared several sperm analysis methods in Purebred Spanish Horses to standardize protocols suitable for both laboratory and field conditions. Methods: Fifteen stallions were evaluated through three ejaculates, analyzing sperm parameters using different techniques. Sperm kinematics was assessed by Sperm Computer Analyzer (SCA-CASA) or iSperm mCASA. Viability was analyzed by eosin-nigrosin-Giemsa (ENG) staining or Hoechst 33258...
Changes in the Mare Oviduct Across Different Seasons Throughout the Year. At present, oviductal pathologies and their influence on mare fertility have not been clearly determined. Checking changes throughout the year in the oviductal structure may be relevant to understand the influence on the appearance of problems in oviductal functionality and, thus, the impact on fertility, which is the objective of this work. The oviducts of 56 mares were examined. Their anatomy, permeability, oviductal cellularity and the presence of pathologies were assessed to establish the correlations between the time of the year and each of these parameters. We cannot conclude whether the...
Is there a difference in pressures and forces under the roller with different pads when lunging horses with the Pessoa training aid? Elevated pressures beneath training rollers during the Pessoa training aid (PTA) use have been reported, particularly over the thoracic region, which may contribute to back discomfort. Objective: To investigate the effect of different pads on pressures and forces beneath a training roller during lunging with a PTA. Methods: Six clinically sound horses (13.8 ± 5.2 years) were lunged on a 16-m circle in trot and canter using a randomised crossover design under three conditions: no padding (Pad 1), a folded cotton saddle cloth (Pad 2), and a purpose-made roller foam pad (Pad 3). Kinetic data wer...
Orthoflavivirus-associated neurological disease in a UK horse. Keesjan Cornelisse and Andra-Maria Ionescu discuss the clinical presentation, investigation and diagnostic approach to a case of orthoflavivirus infection in a horse in south-west England.
Equine Protozoal Myeloencephalitis: An Ancient Parasite Meets Modern Compounding. EPM remains particularly rampant in racing populations due to transport stress, young age, and congregate housing conditions. For compounding pharmacists, understanding that we're managing chronic parasite suppression - not achieving cure - fundamentally changes our approach to formulation strategy, stability assessment, and client counseling. The two formulations presented separately represent years of refinement, demonstrating compounding's essential role when commercial products fall short.
Plasmidial virulence of Rhodococcus equi and its implications of livestock infections for human health: a possible foodborne pathogen? Rhodococcus equi, a versatile and adapted opportunistic in nature bacterium, infects animals and humans. This soil-borne microorganism widely occurs in farms. Its dissemination occurs by feces from domestic animals (particularly horses, cattle, and pigs). In the last decades, bacterial virulence has been strongly attributed to plasmid-encoded virulence-associated proteins (VAPs). To date, three virulence plasmid types have been recognized: pVAPA, pVAPB, and pVAPN, which are considered host- or livestock-adapted. The pVAPA type is related to equine isolates (horse-type), the pVAPB type is assoc...
Are antioxidants hindering stallion sperm capacitation? A perspective on hidden barriers to equine IVF success. Heavy use of antioxidants in equine in vitro fertilisation (IVF) media may suppress the reactive oxygen species (ROS) signals stallion sperm need for capacitation, which depends on high mitochondrial activity and a well-maintained endogenous redox homeostasis. A species-specific approach balancing oxidative protection with controlled ROS signalling could improve fertilisation efficiency and reduce prolonged incubation times.
Omics integration reveals how the gut microbiota of Warmblood horses responds to equestrian show jumping-a short-duration, high-intensity technical exercise stress. Intestinal microbial homeostasis and metabolic balance play a crucial role in maintaining normal physiological function in horses. Exogenous stress involving abrupt turns and jumps during show jumping significantly impacts intestinal microbial homeostasis and metabolic balance in these animals. Results: By comparing rectal (faecal) samples from 10 Warmblood horses collected before and immediately after a show jumping competition on the same day, we observed substantial alterations in intestinal microbial homeostasis and metabolic balance post-exercise. Microbial evenness significantly increase...
Detection of exercising ectopic atrial and ventricular beats using non-linear analysis of clinically normal racehorse electrocardiograms at rest or low-intensity exercise. Cardiac arrhythmias are common in healthy athletic horses and may lead to poor athletic performance or exercise-associated sudden death. Early detection of high-risk horses is an important goal of cardiovascular diagnostics. We hypothesised that non-linear analysis of electrocardiogram disorderliness can be used to identify horses exhibiting intermittent ectopic atrial and ventricular heart rhythm abnormalities at exercise using brief, artifact-free recordings of normal sinus rhythm electrocardiograms collected at submaximal heart rates. In a convenience prospective cross-sectional study, ambu...
Topical treatment of equine aural plaques with nitric acid and zinc solution. Equine aural plaque caused by equine papilloma viruses is common worldwide and affected horses can show severe clinical signs. Due to its viral aetiology, in some countries affected horses are not allowed to compete. Since lesions persist, showing no spontaneous regression, effective and safe treatment is required. Currently, the only treatment with consistent efficacy is imiquimod. Treatment time is prolonged and adverse effects are common. In humans, papilloma warts are successfully and safely treated with topical nitric-zinc complex solutions inducing a painless caustic effect. Objective: T...
Cardiac morphologic changes induced by a 10-week water treadmill training for show jumping horses: A preliminary evaluation. This study aimed to investigate cardiac adaptations and energy expenditure of jumping horses after water treadmill (WT) training. Six trained horses were evaluated before (PRETR) and after (TR) a WT training (20 min, twice/week, water at carpus height) for 10 weeks. Transthoracic echocardiography was performed at PRETR and TR with phased array transducer (1.9-4 MHz) to obtain interventricular septal thickness (IVS), LV internal diameter (LVID), and posterior wall thickness (LVPW) at end-diastole (d) and systole (s) and heart rate (HR). Left ventricule end diastolic volume (Vd) and end syst...
RAiSE (recognizing affective state in equine) and the assessment of equine affective state: Accuracy and application. Accurate interpretation of affective state (AS) of animals is critical to assessment of their wellbeing. Although horse owners may appreciate the importance of this skill, many lack the ability to interpret AS accurately. Objective: To test if the online course Recognizing Affective States in Equine (RAiSE) improves participants' assessment of AS in horses and increases use of AS in management. Methods: Participants completed pre (PRE), post (POST), and 90 day post (90POST) course surveys to assess accuracy in identifying AS in 20 videos, as well as use of AS in their horse interactions. Pre/p...
Spontaneous regression of equine sarcoids is an exceptional event. Sarcoids are benign, yet locally aggressive skin tumours that commonly affect horses and other equid species. The lesions are induced by bovine papillomavirus types 1, 2, and probably 13 in conjunction with other factors including trauma and a genetic predisposition. Although sarcoids have a substantial impact on the health and welfare of affected equids, information on the immune response to bovine papillomavirus infection and resulting sarcoids is limited. However, there is evidence that sarcoid disease is associated with an impaired immune response to bovine papillomavirus infection. This o...
Supramolecular Solvent Extraction for Doping Control Analysis of Prohibited Substances in Horse Urine. Despite the recent success in introducing supramolecular solvents (SUPRAS)-based extraction to drug analysis, its application and robustness in day-to-day regular urine testing have yet to be demonstrated. Moreover, the applicability of SUPRAS in equine doping control testing remains unexplored. In this work, we have successfully developed for the first time a simple, rapid, inexpensive, and environmentally friendly SUPRAS extraction method for analyzing 76 prohibited substances of different classes (selective androgen receptor modulators, hypoxia-inducible factor prolyl hydroxylase inhibitors...
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