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Topic:Oxidative Stress
Oxidative stress in horses refers to an imbalance between the production of reactive oxygen species (ROS) and the ability of the horse's body to detoxify these reactive intermediates or repair the resulting damage. It can occur as a result of various physiological and environmental factors, such as exercise, illness, or exposure to toxins. Oxidative stress can lead to cellular damage, affecting lipids, proteins, and DNA. In horses, it is studied in the context of its potential impact on performance, health, and disease progression. This page compiles peer-reviewed research studies and scholarly articles that explore the mechanisms, effects, and management of oxidative stress in equine health.
Pituitary Pars Intermedia Dysfunction. Pituitary pars intermedia dysfunction (PPID) is one of the most common equine endocrine disorders. It is caused by oxidative damage to dopaminergic neurons in the hypothalamus and results in loss of inhibition of the pituitary pars intermedia. This leads to increased circulating concentrations of adrenocorticotropic hormone (ACTH) and related peptides. Diagnosis is based on increased resting and/or thyrotropin releasing hormone-stimulated ACTH concentrations. Assessment of insulin regulation is also important, as insulin dysregulation occurs in at least one-third of PPID cases and is associate...
The Effect of Different Extenders and Testicular Anaesthesia During Orchiectomy on Post-Thawed Spermatological Parameters of Stallion Epididymal Spermatozoa. Cryopreservation of epididymal stallion spermatozoa is a valuable tool for fertility preservation, particularly after orchiectomy. However, the potential interactions between local anaesthesia and extender composition on post-thaw spermatozoal quality remain poorly understood. This study investigated the effects of intratesticular lidocaine injection and the efficacy of various extender (egg yolk [EY] vs. lecithin [LC]) and cryoprotectant (glycerol [GLY] vs. dimethyl sulfoxide [DMSO]) combinations on stallion epididymal spermatological parameters. Using a paired factorial design, epididymal s...
Effects of Exercise on Ocular Parameters and Oxidative Stress Biomarkers in Saliva and Tear Fluid of Horses. Physical exercise is a physiological stressor in horses and may induce oxidative stress through increased production of reactive oxygen species. Saliva and tear fluid are accessible non-invasive matrices that may reflect oxidative balance, while ocular parameters including intraocular pressure (IOP), tear secretion (TS) and central corneal thickness (CCT) are key components of ocular homeostasis. Objective: To evaluate the effects of a standardised submaximal exercise session on IOP, TS and CCT, and on oxidative stress biomarkers (CAT, SOD, GSH, MDA, IMA) measured in saliva and tear fluid. Met...
Oxidative Stress and Inflammatory Responses in Horses Naturally Infected with Theileria equi. Equine piroplasmosis, caused by the intraerythrocytic protozoan , is a globally distributed tick-borne disease characterized by persistent infection and variable clinical manifestations. Although oxidative stress has been implicated in the pathogenesis of several hemoprotozoan diseases, information regarding redox imbalance and its relationship with inflammatory responses in horses naturally infected with remains limited. This study aimed to evaluate oxidative stress, antioxidant status, inflammatory cytokines, and clinicopathological alterations in horses naturally infected with . Thirty-fiv...
Oxidative Stress and Immunomarkers in Equine Dermal Melanomatosis: Single-Case Comparison with Healthy Individual. Dermal melanomatosis is a common tumor in grey horses, characterized by cutaneous/subcutaneous lesions with metastatic potential. While clinically well-described, oxidative stress involvement remains poorly understood. This case report compared oxidative stress markers and antioxidant enzymes' activities in total protein extracts from melanomatosis lesions (grey horse) versus healthy control skin (black horse), alongside histopathology and immunohistochemistry, to correlate oxidative imbalance and tumor behavior. Melanomatosis tissue exhibited decreased antioxidant defenses confirmed by catala...
Combined effects of pre-freeze cholesterol-loaded cyclodextrin and post-thaw pentoxifylline on the functional longevity of cryopreserved stallion sperm. Cryopreservation causes structural and metabolic damage to stallion spermatozoa, impairing post-thaw functional competence. Objective: This study evaluated whether cholesterol-loaded cyclodextrin (CLC) supplementation before freezing, combined with pentoxifylline (PTX) after thawing, improves the functional quality, oxidative status, mitochondrial activity, and preliminary fertility outcomes of cryopreserved stallion semen. Methods: Semen from twelve stallions was assigned to four CLC concentrations (0, 1, 1.5, and 2 mg), frozen, thawed, and divided into subgroups with or without PTX supplemen...
Histone deacetylase inhibition alters mRNA expression of cell cycle- and senescence-associated genes in primary equine chondrocytes. Cellular senescence is a biological state of a cell that triggers inflammation and gradually contributes to pathological conditions. Unlike programmed cell death, prolonged inhibition of cell division induces a metabolic state in senescent cells, in which they release pro-inflammatory factors that drive inflammation affecting the tissue microenvironment. Along with prolonged excessive mechanical stress, low-grade inflammation raised by senescent chondrocytes may contribute to articular cartilage defects, which are prevalent in ageing populations. Moreover, the use of chemotherapeutics used to ...
Synovial fluid oxidative stress index as a biomarker for arthritis severity in thoroughbred racehorses. Arthritis is a major cause of lameness in racehorses. Even when lameness improves, it may recur after training resumes, making it difficult to determine the disease state and when to end treatment. This retrospective observational study examined whether oxidative stress in synovial fluid could assess arthritis status in racehorses. Synovial fluid samples obtained during routine clinical practice from horses with arthritis and control samples obtained from horses without clinical or radiographic evidence of carpal joint disease were retrospectively analyzed. A total of 72 Thoroughbreds in Japan...
Redefining stallion sperm bioenergetics: lessons from a decade of change in mammalian sperm metabolism. In brief: Sperm bioenergetics is now understood as an integrated system in which ATP production, redox homeostasis, substrate availability, and cellular heterogeneity jointly determine sperm function. This review uses the stallion as an oxidative-biased model to synthesize advances from 2016 to 2026 and proposes a metabolically plastic framework with direct implications for semen preservation and fertility assessment. Abstract: Over the last decade, mammalian sperm metabolism has moved from a binary view centered on glycolysis versus oxidative phosphorylation to an integrated model in which AT...
Exploration of the relationship between laboratory stress parameters and leukocyte coping capacity in ponies exposed to repetitive handling during a research project. Stress is an umbrella term indicating increased allostatic load with the potential to reach a pathological state of the organism. In this context, cortisol concentration and neutrophil granulocytes-to-lymphocyte ratio (NEU: LYM) are expected to increase. On the functional pathway, stress reduces the oxidative burst capacity of neutrophils and therefore, the leucocyte coping capacity (LCC) quantifying this oxygen radical generation of neutrophils. Therefore, we hypothesized that in ponies subjected to repetitive handling, LCC will decrease and will be negatively correlated with cortisol concent...
Evaluation of oxidative stress in ill neonatal foals: a preliminary study. Oxidative stress both contributes to and results from sepsis pathophysiology, but its role in ill foals remains poorly characterized. Objective: Ill foals will exhibit decreased antioxidant defense activity and increased oxidative products compared with healthy foals, and these changes will be associated with higher sepsis scores, lower survival scores, and non-survival. Methods: Twenty-six foals < 14 days old: 16 hospitalized foals (11 sick non-septic, 5 septic; median age, 1.5 days; range 1-13) and 10 healthy Standardbred foals (2 days old). Nine of 16 ill foals survived to discharge...
Effect of Spirulina platensis extract (C-phycocyanin) supplementation to the semen extender on kinematic and oxidative parameters of Marwari stallions during freezing. The current research aimed at examining the impact of different quantities of Spirulina platensis extract (C-phycocyanin) supplemented to the semen extender on the post-thaw quality of Marwari stallion spermatozoa. Semen samples were obtained via an artificial vagina from six fertile stallions and diluted with an extender containing Spirulina platensis extract (C-phycocyanin) at concentrations of 10, 20, and 50 µg/mL, or without Spirulina as a control. Aliquots of diluted semen were subjected to cooling (4 °C, 120 min) and then frozen (-196 °C, 1 day), after which the kinematic paramet...
Pharmaceutical and Nutraceutical Therapies for Liver Disease. Liver dysfunction may reduce the metabolism of drugs that undergo extensive hepatic processing. This will lead to reduced clearance and elimination, and can cause accumulation of the drug, increasing the risk of toxicity. Pentoxifylline and ursodeoxycholic acid are 2 pharmaceuticals that can provide benefits for a variety of equine hepatic diseases. Nutraceuticals are frequently used in horses with hepatopathy, targeting oxidative stress, inflammation, and hepatocellular injury. Neutraceuticals such as S-adenosylmethionine, silymarin and vitamin E are most commonly used although extensive rese...
Effect of Antioxidant Supplementation on Systemic Oxidative Status in Breeding Stallions During Intensive Semen Collection. Breeding stallions are subjected to increased metabolic and physiological demands during the reproductive season, which may lead to enhanced production of reactive oxygen species and disruption of redox balance. The present study evaluated the effects of dietary antioxidant supplementation on oxidative status, metabolic profile, and hindgut fermentation in stallions undergoing intensive semen collection activity. Ten adult breeding stallions were assigned either to a control group or to a treatment group receiving a commercial antioxidant supplement (Oxyliver) for 60 days, followed by a 60-day...
Syndrome of High Gamma-Glutamyl Transferase in Racehorses. Horses in racing and race training can develop high gamma-glutamyl transferase (GGT) syndrome (HGS), or increased GGT without overt evidence of primary liver disease. Current evidence points toward overtraining and a response to oxidative stress, but the etiology is incompletely understood. Evidence for an association of HGS with poor performance is mixed. Without a clear understanding of the etiology, the only evidence-based treatment option is rest or reduced training intensity. More research is needed to determine whether HGS is a physiologic adaptation, perhaps indicative of overtraining b...
Recent Advances in Natural Products for Colitis: Mechanisms and Translational Perspectives. Colitis is a chronic relapsing inflammatory disorder characterized by persistent mucosal inflammation, epithelial barrier disruption, oxidative stress, immune dysregulation, and gut microbiota imbalance. Although current therapies have improved disease management, their long-term use is still limited by incomplete response, relapse, adverse effects, and high cost. Natural products have attracted increasing attention as promising candidates for colitis intervention because of their structural diversity, broad bioactivity, and multitarget regulatory potential. In veterinary medicine, colitis and...
Association Between Vaquejada Practice and Biomarkers of Oxidative Stress, Inflammation, and Muscle Damage in Quarter Horses. Vaquejada (VQ) is a traditional Brazilian sport demanding high performance from Quarter Horse (QH) athletes. This study aimed to identify modifications in hematological, biochemical, inflammatory, and oxidative stress biomarkers associated with VQ training, comparing conditioned and non-conditioned horses. Blood samples were collected at rest from 70 healthy QH horses: 60 athletes (VQ-conditioned athlete group-AG) and 10 sedentary controls (breeding horses-CG). Using Linear Mixed Models alongside comprehensive hematological and biochemical analyses, the study found that AG horses exhibited an ...
Mitochondrial dysfunction in equine ageing: Current evidence and clinical implications for geroscience. Ageing is a complex biological process affecting a growing geriatric human and equine population worldwide. Mitochondrial dysfunction is considered one of the hallmarks of ageing, representing a multifaceted process. This review synthesises current findings on mitochondrial dysfunction in aged equines, drawing parallels with human medicine and identifying current knowledge gaps. Integrating findings from human and equine research may bridge existing challenges and offer new opportunities, including the development of novel translational models for ageing research. Furthermore, it highlights th...
Nano-Encapsulated Vitamin E Enhances Cryo-Resistance of Stallion Spermatozoa: A Comprehensive Evaluation of Sperm Quality, Kinematic Parameters, Antioxidant Capacity, Microbiota and Ultrastructure. This experiment explores the comparative ability of vitamin E (VE) and its nano-emulsion (VEN) in enhancing cryo-resistance of stallion spermatozoa by examining semen quality, kinematic variables, acrosome integrity, apoptosis, antioxidant capacity, ultra-structural alterations and microbiota of cryopreserved stallion sperm. Semen from five stallions (8-10 years) was cryopreserved with 0.1 or 1 mM of VE or VEN; and a non-additive group served as the control. The VEN particles ranged in size from 72 to 172 nm, with a mean diameter of 287 nm. Supplementation with VE (1 mM) or VEN (0.1 ...
Membrane and mitochondrial antioxidants improve post-thaw functional quality of stallion spermatozoa. Cryopreservation of stallion semen induces oxidative stress that compromises sperm motility, membrane integrity, and mitochondrial function. Given the high mitochondrial reliance of equine spermatozoa and their susceptibility to oxidative damage, compartment-specific antioxidant strategies may improve post-thaw functional resilience. This study evaluated the effects of astaxanthin, a membrane-active carotenoid, and MitoTEMPO, a mitochondria-targeted superoxide scavenger, on the functional and oxidative status of frozen-thawed stallion spermatozoa. Ejaculates from nine stallions were cryopreser...
Equine Oocyte and Embryo Metabolism in the ART Setting: Current Knowledge and Clinical Significance. 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 th...
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 ...
Proteomic Insights into the Mechanism by Which Ferulic Acid Promotes Skeletal Muscle Fiber Type Conversion in Mongolian Horses. Ferulic acid is a bioactive phenolic compound with potential benefits for skeletal muscle health. In this study, Mongolian horses were used as experimental subjects and were orally administered ferulic acid at doses of 5, 10, or 15 g per horse per day for 40 consecutive days. Muscle biopsy samples were analyzed using proteomics to assess fiber type composition and regulatory protein expression. Ferulic acid supplementation increased the proportion of fast-twitch fibers and upregulated key differentiation factors such as MUSTN1, while modulating glycolysis, ECM remodeling, and calcium signaling...
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...
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.
Differences in Redox Biomarkers in Bronchoalveolar Lavage Fluid of Leisure Horses With and Without Severe Equine Asthma: Preliminary Results. Equine asthma is a common chronic respiratory disease characterized by airway inflammation and oxidative imbalance, particularly in its severe form. The aim of this study was to evaluate pro-oxidative substances, oxidative products, and antioxidant defense biomarkers in bronchoalveolar lavage fluid (BALF) from horses with and without a history of severe equine asthma (SEA). This prospective observational study included 21 leisure horses classified as SEA or non-SEA based on clinical history and BALF cytology. Bronchoalveolar lavage fluid was analyzed for derivatives of reactive oxygen metaboli...
The fertility of a sub-population of stallions is negatively affected by ambient climatic conditions, mediated through DNA damage. Exposure to systemic heat stress in male mammals adversely affects sperm production, fertility, and DNA integrity. To date, few studies have investigated this phenomenon in horses, particularly in industry-relevant environments. Therefore, this study examined the relationship between ambient climatic conditions and fertility within a population of commercially fertile stallions. Post-coital semen samples ( = 804) were collected weekly from 46 Thoroughbred stallions during two successive breeding seasons (NSW, Australia; 22 weeks total). Semen samples were processed via single-layer colloid...
Evaluation of oxidative stress and antioxidant defense biomarkers in healthy and colic horses: correlation with type of colic and outcome. Colic is a major cause of morbidity and mortality in horses, with oxidative stress implicated in its pathophysiology. Objective: Evaluate biomarkers (BIOs) of oxidative stress and antioxidant defense in healthy horses and those with non-strangulating colic (NSC) and strangulating colic (SC) and assess correlations with survival. Methods: Seventy-one adult horses: 10 healthy and 61 colic-affected (42 NSC, 19 SC) admitted to 3 veterinary teaching hospitals. Methods: Prospective, multicenter cohort study. Blood samples were collected at admission (T0) and up to 96 h post-admission. Biomarkers me...
Spirulina supplementation regulates inflammation and supports cartilage health in adult sedentary horses following moderate-intensity exercise. Horses experience rapid physiological, inflammatory, and oxidative responses during exercise. Spirulina, a nutrient-dense microalga with antioxidant and anti-inflammatory properties, may help modulate these responses and support recovery. Objective: This study evaluated the effects of 30-day dietary Spirulina supplementation on physiological, inflammatory, and oxidative stress responses to moderate-intensity exercise in sedentary horses. We hypothesized that 30-day Spirulina supplementation would modulate hematologic and inflammatory responses and support recovery from moderate-intensity exerc...
Endothelial glycocalyx of equine intestinal vessels: electron microscopic and immunohistochemical imaging. To visualize the endothelial glycocalyx in equine intestinal vessels using electron microscopy and immunohistochemistry and to evaluate the impact of induced endotoxemia on its integrity. Unassigned: 6 healthy horses free of gastrointestinal disease were anesthetized with dexmedetomidine, ketamine, and diazepam and mechanically ventilated under isoflurane anesthesia. Jejunal venous tissue samples were collected after perfusion fixation with lanthanum nitrate before and 120 minutes after endotoxemia induced by IV administration of 30 ng·kg-1 Escherichia coli lipopolysaccharide. For transmissio...
