Reference range of blood biomarkers for oxidative stress in Thoroughbred racehorses (2-5 years old)

Evaluation of oxidative stress in foals with Rhodococcus equi infection-induced pneumonia for the judgment of therapeutic effect

Forty-five foals with Rhodococcus equi infection and pneumonia symptoms were classified into a surviving group and a dead group. Using serum samples, the oxidative stress index (OSI) was determined at the first visit and the follow-up visit. The OSI of the surviving group was significantly lower at the follow-up than that at the first visit. No significant difference was observed between the OSI of the dead group at the first and follow-up visits. In the surviving group, treatment at the first visit mitigated inflammation and reduced OSI. However, in the dead group, poor response to the treatment provided at the first visit led to continued inflammation, and no change was observed the OSI.

Monitoring the redox status in dairy cows by using plasma dROMs, PAT, and OSI biomarkers

The aim of this work was to determine the changes of redox indicators such as reactive oxygen metabolites (dROMs), plasma antioxidant test (PAT) and the oxidative stress index (OSI) in dairy cows at different stages of lactation using a diagnostic equipment which is suitable for in vivo oxidative stress (OS) monitoring procedures. In total, 628 dairy cows were examined in the pre-parturient period (days in milk [DIM]: -21 to -1 day; n = 117), in the calving and maternity period (DIM: 0 to 7; n = 137), in the early lactation period (DIM: 8 to 30; n = 139), and the in the peak lactation (DIM: 31 to 150; n = 235). The dROMs and OSI values were significantly different (P < 0.05) when comparing the 1st and 2nd+ lactation cows in each group. The highest mean value of dROMs was detected at the calving and maternity stage in 1st lactation cows (141 ± 25 U. Carr) and the lowest (103 ± 29 U. Carr) was found in peak lactation. The OSI developed similarly, with the highest value of 5.58 ± 0.94 in the calving and maternity period in the 1st lactation cows and the lowest value of 4.05 ± 1.21 in peak lactation and significant differences were found in many cases. Based on the results, the measurement of dROMs and OSI may be suitable for detecting oxidative stress in different lactation stages.

Polymorphisms at Myostatin Gene (MSTN) and the Associations with Sport Performances in Anglo-Arabian Racehorses

One hundred and eighty Anglo-Arabian horses running 1239 races were sampled for the present study. DNA was extracted from the blood and myostatin gene, MSTN, was genotyped. Moreover, prizes won and places were achieved for the 1239 races to perform association analyses between the different genotypes and sport traits. Two SNPs already reported in previous studies regarding the Thoroughbred breed, rs69472472 and rs397152648, were revealed as polymorphic. The linkage disequilibrium analysis investigating the haplotype structure of MSTN did not evidence any association block. Polymorphism at SNP rs397152648, previously known as g.66493737 T>C, significantly influenced sport traits, with heterozygous horses TC showing better results than homozygotes TT. The portion of variance due to the random effect of the individual animal, and the other phenotypic effects of sex, percentage of Arabian blood and race distance, computed together with the genotype at MSTN in the statistical models, exerted a significant influence. Hence, this information is useful to improve knowledge of the genetic profile of Anglo-Arabian horses and a possible selection for better sport performance.

Evaluation of Oxidative Stress Parameters in Healthy Saddle Horses in Relation to Housing Conditions, Presence of Stereotypies, Age, Sex and Breed

Oxidative stress plays an important role in the development of many horse diseases and it has been shown that housing has important implications for the psychophysical well-being of horses. The aim of this study is to determine if there are any differences between the redox status in horses in relation to housing conditions. The four housing conditions analyzed were: single box, without external access and without contact (Cat A), single box with external access and possibility of partial contact (Cat B), group housing with box and large paddock (Cat C), pasture with more than 7 horses and the possibility of green forage for the whole year (Cat D). A group of 117 healthy horses were selected in several private stables in Northern Italy. All subjects treated with any type of drug were excluded. At the end of the enrollment, the 117 selected horses were divided into the four housing categories. Stereotypies were highest in the group of horses in single box, without external access and without contact (Cat A). Oxidative stress was evaluated by testing plasma or serum samples for the following parameters: superoxide anion (WST), nitric oxide (NO), reactive oxygen species (d-ROMs), ferric reducing ability of plasma (FRAP), and the activity of superoxide dismutase (SOD). Simultaneously with the blood sampling, the owners completed a questionnaire with all the management aspects of the horse (signaling, feeding, equestrian activity, vaccinations, foot management etc.). The statistical evaluation was carried out based on the categories previously described, on the presence and absence of stereotypies and on some signaling data obtained from the questionnaire. There were no significant differences in the parameters analyzed between the categories. No significant redox status differences were detected based on the presence or absence of stereotypies. Interestingly, when the age was introduced as selection (<14 and >14 years old) parameter inside the categories, statistical significance was observed for some of the stress markers considered. Finally, independently of the housing conditions, the horses of the most two represented breeds exhibited different values of FRAP. All these aspects are commented in the discussion.

The Oxidative Stress Markers of Horses-the Comparison with Other Animals and the Influence of Exercise and Disease

Diacron-reactive oxygen metabolite (d-ROM) and biological antioxidant potential (BAP) levels in the serum of horses were measured (ponies, n = 15; thoroughbred, n = 31; other full-sized horses, n = 7). The mean d-ROM levels in horses were significantly higher (p < 0.001) than those in dairy cattle (n = 25) and dogs (n = 31). However, d-ROM levels in horses were lower than the standard levels reported in humans. When d-ROM and BAP levels were plotted graphically, the points for horses with a disease (ringbone in 1 Japanese sports horse, cellulitis in 1 thoroughbred, melanoma in 1 Lipizzaner) fell outside the group of points for other (non-diseased) horses. A similar separation was seen (using data from other authors) for a horse with Rhodococcus equi, a horse following castration surgery, and a mare following delivery. These results, comparing horses, other animals, and humans, are interesting from the standpoint of comparative medicine, and they contribute to the sparse literature available on d-ROM and BAP levels in animals. Because the level of d-ROM and BAP levels were changed depending on the situation of health, those indexes are promising as indices of health in horses.

Clinical Effects of the Extract of the Seeds of the Indian Celery-Apium Graveolens-In Horses Affected by Chronic Osteoarthritis

The extract of the seeds from Indian celery, Apium greaveolens (CSE), tested in experimental animals (rodents), and in humans affected by chronic osteoarthritic diseases, exhibits anti-inflammatory effects that can be compared, to some degree, to those of non-steroid anti-inflammatory drugs (NSAID). In view of a potential use of CSE in the equine species, it was tested on horses affected by chronic articular pathologies. The trial was performed on 20 horses divided into three different groups, orally treated with 0 (controls), 7.0 or 30 g of CSE BID. Basic orthopedic examinations were conducted, vital signs were observed, and blood samples collected. Improvement was observed at the highest dosage tested (30 g of CSE BID), as reflected in the score values of three clinical parameters, (i) amplitude and (ii) sensitivity to passive flexion and (iii) flexion test. Since the improvement of these parameters can be correlated with a lower perception of the pain, the present data suggest that the CSE treatment can have an analgesic effect in horses affected by chronic osteoarthritic diseases.

Markers for oxidative stress in the synovial fluid of Thoroughbred horses with carpal bone fracture

Arthritis is thought to cause oxidative stress in synovial fluid in humans, but there have been few reports in horses. To evaluate oxidative stress in synovial fluid in horses, this study used 19 horses with unilateral fracture of the carpal joint bone. Synovial fluid was collected from the carpal joint on the fracture (arthritis group) and contralateral (control group) sides. Diacron-reactive oxygen metabolites (d-ROMs) and biological antioxidant potential (BAP) were then measured, and the oxidative stress index (OSI) was calculated. d-ROMs and OSI of the arthritis group were significantly higher than the control group. BAP of the arthritis group was significantly lower than the control group. Thus, this study revealed that oxidative stress develops in the synovial fluid of horses during arthritis.

Comparison of oxidative stress under different propofol administration protocols in Thoroughbred racehorses by bOS and bAP assessment

It is desirable to reduce surgery-induced oxidative stress (OS) because it can cause immune suppression and delayed wound healing. Propofol is known to have antioxidant potential and to reduce OS in humans, but there have been no studies of this issue in horses. This study was conducted to evaluate OS under three different propofol administration protocols in Thoroughbred racehorses undergoing arthroscopic surgery with sevoflurane anesthesia. Blood oxidative stress (bOS) and blood antioxidant power (bAP) were used as OS biomarkers. Both bOS and bAP significantly decreased after surgery in all groups, but no differences in these reductions were found among them. Different propofol administration protocols with sevoflurane anesthesia did not cause a difference in OS in Thoroughbred racehorses that underwent arthroscopic surgery.

Effect of prolonged submaximal exercise on serum oxidative stress biomarkers (d-ROMs, MDA, BAP) and oxidative stress index in endurance horses

Background

Oxidative stress (OS) associated with an intense exercise may have a negative influence on equine health. The aim of this study was to determine the effects of endurance races on oxidative and antioxidative status of horses by evaluating changes in reactive oxygen metabolites (d-ROMs), malondialdehyde (MDA), biological antioxidant potential (BAP) and oxidative stress index (OSI) values. The study was carried out on 53 race starts (28 individual horses) competing at different endurance races according to distance (40 and 80 km) and difficulty (easy and demanding). Blood samples were taken before and after the race.

Results

Compared to levels of OS serum biomarkers before the race, an increase in values of d-ROMs (P <  0.01), MDA (P <  0.01), and BAP (P <  0.001), and a decrease in OSI (P <  0.001) have been noted after the race. Contrary to other measured biomarkers, BAP did not show significant individual effects of horses. Horses competing at shorter races have shown a significant change in d-ROMs (P = 0.002), BAP (P <  0.001) and OSI (P = 0.004), whereas those competing at longer races in MDA (P = 0.002), BAP (P <  0.001) and OSI (P <  0.001) post-race values. Endurance racing induced changes in values of d-ROMs, BAP and OSI during both easy and demanding races.

Conclusions

Changes in all measured OS biomarkers indicate that prolonged aerobic exercise during endurance race could contribute to the imbalance between oxidants and antioxidants in horses, mainly characterised by a pronounced antioxidant response. Biological antioxidant potential was found to be the most reliable biomarker of OS in endurance horses in the present study.

Lower plasma trans-4-hydroxyproline and methionine sulfoxide levels are associated with insulin dysregulation in horses

BACKGROUND

Insulin dysregulation in horses is a metabolic condition defined by high insulin concentrations in the blood and peripheral insulin resistance. This hyperinsulinemia is often associated with severe damage in the hooves, resulting in laminitis. However, we currently lack detailed information regarding the potential involvement of particular metabolic pathways in pathophysiological causes and consequences of equine insulin dysregulation. This study aimed to assess the dynamic metabolic responses given to an oral glucose test (OGT) in insulin-sensitive and insulin-dysregulated horses by a targeted metabolomics approach to identify novel metabolites associated with insulin dysregulation.

RESULTS

Oral glucose testing triggered alterations in serum insulin (26.28 ± 4.20 vs. 422.84 ± 88.86 μIU/mL, p < 0.001) and plasma glucose concentrations (5.00 ± 0.08 vs. 9.43 ± 0.44 mmol/L, p < 0.001) comparing basal and stimulated conditions after 180 min. Metabolome analyses indicated OGT-induced changes in short-chain acylcarnitines (6.00 ± 0.53 vs. 3.99 ± 0.23 μmol/L, p < 0.001), long-chain acylcarnitines (0.13 ± 0.004 vs. 0.11 ± 0.002 μmol/L, p < 0.001) and amino acids (2.18 ± 0.11 vs. 1.87 ± 0.08 μmol/L, p < 0.05). Kynurenine concentrations increased (2.88 ± 0.18 vs. 3.50 ± 0.19 μmol/L, p < 0.01), whereas spermidine concentrations decreased during OGT (0.09 ± 0.004 vs. 0.08 ± 0.002 μmol/L, p < 0.01), indicating proinflammatory conditions after oral glucose load. Insulin dysregulation was associated with lower concentrations of trans-4-hydroxyproline (4.41 ± 0.29 vs. 6.37 ± 0.71 μmol/L, p < 0.05) and methionine sulfoxide (0.40 ± 0.06 vs. 0.87 ± 0.13 μmol/L, p < 0.01; mean ± SEM in insulin-dysregulated vs. insulin-sensitive basal samples, respectively), two metabolites which are related to antioxidant defense mechanisms.

CONCLUSION

Oral glucose application during OGT resulted in profound metabolic and proinflammatory changes in horses. Furthermore, insulin dysregulation was predicted in basal samples (without OGT) by pathways associated with trans-4-hydroxyproline and methionine sulfoxide, suggesting that oxidative stress and oxidant-antioxidant disequilibrium are contributing factors to insulin dysregulation. The present findings provide new hypotheses for future research to better understand the underlying pathophysiology of insulin dysregulation in horses.