T. M. Hess

Comparison of oxidative stress and antioxidant status in endurance horses in three 80-km races

This study tested our hypothesis that during an 80-km Research Ride in 2002 (R2) horses that did not finish (NF) the ride would have elevated muscle enzyme activities in the blood and changes in biomarkers of oxidative stress as compared to horses that finished (F) the ride. These results were then compared to previous rides – Old Dominion (OD) and the Research Ride 2001 (R1). For R2, 40 mostly Arabian horses competed and had blood samples collected before, at 27, 48 and 80 km, and 170 to 190 min after the 80-km race. Blood was collected similarly in R1 and OD. Blood was analysed for plasma lipid hydroperoxides (LPO), α-tocopherol (TOC), creatine kinase (CK), aspartate aminotransferase (AST), red and white blood cell total glutathione (GSH-T) and glutathione peroxidase (GPx). Data were analysed using a repeated measure ANOVA in SAS. Associations between muscle enzymes and antioxidant status were determined using Pearsons or Spearmans correlations. Activities of CK and AST were higher ( P r = −0.21; P = 0.005), GPx and AST ( r = −0.15; P = 0.05), and a positive correlation was found with GSH-T and CK ( r = 0.18; P = 0.02). Values of CK, LPO, GPx and GSH-T were higher ( P

Lipoic Acid as an Antioxidant in Mature Thoroughbred Geldings: A Preliminary Study

alpha-Lipoic acid (LA) has demonstrated antioxidant effects in humans and laboratory animals. The objective of this study was to determine whether the effects of LA are similar in horses. Five Thoroughbred geldings were supplemented with 10 mg/kg/d DL-alpha-lipoic acid in a molasses and sweet feed carrier and five received only the carrier as a placebo (CON). Blood samples were obtained at baseline (0 d), after 7 and 14 d of supplementation, and 48 h postsupplementation (16 d). Blood fractions of red and white blood cells (RBC and WBC, respectively) and plasma were analyzed for glutathione (GSH), glutathione peroxidase (GPx) and total plasma lipid hydroperoxides (LPO). An experienced veterinarian observed no adverse clinical effects. Plasma LPO baselines differed between groups (P = 0.002). When covariates were used, there was a decrease over time in the LA group (P = 0.015) and concentrations were lower in the LA group than in the CON group at 7 and 14 d (P = 0.022 and P = 0.0002, respectively). At baseline, GSH concentration was 69 +/- 7 in WBC and 115 +/- 13 mmol/mg protein in the RBC, with no differences resulting from either time or treatment. The GPx activity was 47 +/- 4 and 26 +/- 5 U/g protein at baseline WBC and RBC, respectively, with a lower concentration in the LA groups WBC at 7 (P = 0.019) and 14 d (P = 0.013). The results show that 10 mg/kg LA had no evident adverse effects, and moderately reduced the oxidative stress of horses allowed light activity. These findings encourage studying of LA in horses subjected to strenuous exercise.

Effects of two different dietary sources of long chain omega-3, highly unsaturated fatty acids on incorporation into the plasma, red blood cell, and skeletal muscle in horses.

The objective of this study was to examine the effects of different sources of dietary omega-3 (n-3) fatty acid supplementation on plasma, red blood cell, and skeletal muscle fatty acid compositions in horses. Twenty-one mares were blocked by age, BW, and BCS and assigned to 1 of 3 dietary treatments with 7 mares per treatment. Dietary treatments were: 1) control or no fatty acid supplement (CON), 2) 38 g of n-3 long chain, highly unsaturated fatty acid (LCHUFA) supplement/d provided by algae and fish oil (MARINE) containing alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and docosapentaenoic acid (DPA), and 3) 38 g of n-3 LCHUFA supplement/d provided by a flaxseed meal (FLAX) containing ALA. Each supplement was added to a basal diet consisting of hay and barley and was fed for 90 d. Blood samples and muscle middle gluteal biopsies were taken at d 0, 30, 60 and 90 of supplementation. Plasma, red blood cell and skeletal muscle fatty acid profiles were determined via gas chromatography. Plasma linoleic acid (LA) and ALA were at least 10 and 60% less (P < 0.01), respectively, in the MARINE compared with the FLAX and CON groups. Plasma EPA and DHA were only detected in the MARINE group, and EPA increased 40% (P < 0.001) from d 30 to 60, and DHA 19% (P < 0.01) from d 30 to 90. Red blood cell LA and ALA were not different among treatments. Red blood cell EPA and DHA were only detected in the MARINE group, where EPA increased 38% (P < 0.01) from d 30 to 60, and DHA increased 56% (P < 0.001) between d 30 and 90. Skeletal muscle LA was at least 17% less (P < 0.001) in the MARINE group compared with the other treatments. Skeletal muscle ALA was 15% less (P = 0.03) in the MARINE group compared with FLAX and CON groups. Skeletal muscle EPA was at least 25% greater (P < 0.001) in MARINE group compared with other treatments and increased (P < 0.001) by 71% from d 30 to 60. Skeletal muscle DHA was at least 57% greater (P < 0.001) in the MARINE group compared with other groups and increased (P < 0.001) by 40% between d 30 and 90. As far as the authors are aware, this is the first study to demonstrate that dietary fatty acid supplementation will affect muscle fatty acid composition in horses. Incorporation of n-3 LCHUFA into blood and muscle depends directly on dietary supply of specific fatty acids.

Vitamin E intake and systemic antioxidant status in competitive endurance horses

The objective was to compare vitamin E content in the total diet of Arabian horses competing in the 80 km Research Ride 2002 to the oxidative stress and antioxidant measures throughout the race. Prior to the race, riders completed a detailed nutritional survey, which was used to calculate vitamin E intake. Blood samples, temperature and heart rate were taken the day before the race, at 27 and 48 km during the race, at race completion or elimination and 3 h after race completion. Plasma lipid hydroperoxides, α-tocopherol (TOC), creatine kinase (CK), aspartate aminotransferase (AST), albumin, red and white blood cell total glutathione and glutathione peroxidase were measured. Data were analyzed by Pearsons correlation in SAS. From the survey, it was estimated that horses consumed 2265±114 IU day −1 of vitamin E. A negative correlation was found between the vitamin E intake and CK ( r = −0.23; P = 0.002), and AST ( r = −0.22; P = 0.003). A positive correlation was found between the vitamin E intake and plasma TOC ( r = 0.15; P = 0.005) at all sample times. This suggests that intensely exercising horses supplemented with vitamin E may not have an improved welfare and performance if they are supplemented vitamin E versus what is naturally found in forages and commercial feeds.

Mammary adenocarcinoma in a mare

A non-lactating 17-year-old grey barren Mangalarga Marchador mare was referred to the Large Animal Veterinary Hospital of the Federal Rural University of Rio de Janeiro (UFRRJ), presenting enlargement of the mammary gland. The owner reported that the animal had a lesion in the mammary gland for at least two years, diagnosed and treated as chronic mastitis. Initially only the right gland was involved, presenting ulceration and exudation on the cutaneous surface. After 20 months, the left gland also became affected. The diagnosis of tubulo-papillary adenocarcinoma was based on the typical microscopic lesions. This work shows the importance of the histopathological examination in the differential diagnosis between the neoplasms and the chronic inflammation in the mammary gland of mares, as well as, to show that the cytological examination cannot detect the tumor, in case the puncture is made in areas of secondary infection.

Cytology profile and age influence in the equine bronchoalveolar lavage in healthy and asymptomatic inflammatory airway disease

Pulmonary inflammatory diseases have been observed in equine since their domestication. Non-infectious disease processes of the lower airways are amongst the most important diseases of the equine respiratory tract. This study aims to determine the cytology profile and effect of age on the evaluation of equine bronchoalveolar lavage (BAL) obtained from healthy animals and from horses with asymptomatic inflammatory airway disease (IAD). Thirty two horses, including 20 males and 12 females, without clinical signs of pulmonary disease and with age varying from 4 to 21 years, were assigned to two groups: 15 animals in the control group and 17 in the asymptomatic group. Groups were divided according to physical examination and mucous accumulation observed during tracheal endoscopy. The BAL results from healthy and asymptomatic horses were, respectively: 56.9% and 48.0% macrophages, 37.2% and 40.0% lymphocytes, 3.3% and 7.1% neutrophils, 1.7% and 1.4% mast cells, 0.3% and 0.7% eosinophils; 0,5% and 0.4% epithelial cells. When horses in the two groups were analyzed according to their age range, no differences were found. In conclusion, IAD in the asymptomatic group was significantly different from the control group. The asymptomatic horses presented a discrete infiltrate of neutrophils, which does not influence cytological evaluation of BAL.

Dietary Supplementation of Algae-derived Omega-3 Fatty Acids Influences Endometrial and Conceptus Transcript Profiles in Mares

ABSTRACT Maternal diet has been shown to impact fetal development across a variety of species. Given the reported effects of omega‐3 long‐chain polyunsaturated fatty acid (n‐3 LCPUFA) supplementation on health across species, it was hypothesized that supplementation of algal‐based n‐3 LCPUFA to mares around conception would alter the maternal uterine environment and modify gene expression in early conceptuses. Nonlactating, light horse mares were supplemented with concentrate (n = 6) or an isocaloric diet containing 0.06 g/kg body weight n‐3 LCPUFA (primarily docosahexaenoic acid [DHA], n = 7) at least 60 days before first sample collection. Four consecutive ovulatory cycles were monitored. Uterine endometrial samples were obtained 12.5 days postovulation from cycles 1 (uninseminated), 3, and 4 (bred to a common stallion); embryos were flushed from cycles 3 and 4. Biopsies from supplemented mares were greater in DHA and total omega‐3 fatty acid concentrations (P < .05), indicating successful tissue incorporation. Uninseminated n‐3 LCPUFA supplemented mares displayed increased PTGFS and reduced IL6 gene expression (P < .01) than controls. Supplemented pregnant mares had increased mRNA abundance of PTGES (P = .05), PTGFS (P = .03), and SLCO2A1 (P = .01), while supplemented barren mares exhibited lower PTGFS (P = .05) and IL6 (P < .01) expression than control mares. In the conceptus, relative transcript abundance of trophoblast and endoderm markers (GATA3, GATA4, GATA6, TFAP2A, ELF3) was greater (P < .05) in embryos from supplemented mares. These results indicate algae‐derived n‐3 LCPUFA supplementation prior to breeding alters the maternal uterine environment and modifies expression of genes in preimplantation equine conceptuses. HighlightsSupplementing algae‐derived docosahexaenoic acid altered equine endometrial fatty acid composition.Supplemented mares displayed altered endometrial gene expression.Conceptuses obtained from supplemented mares displayed altered gene expression.

Effects of Feeding Frequency Using a Commercial Automated Feeding Device on Gastric Ulceration in Exercised Quarter Horses

&NA; The objective of this study was to evaluate two feeding regimens: traditional grain feeding (twice a day, traditional fed [TF]) compared with horses fed with an automated feeder programmed to deliver grain in 20 equal aliquots (fractioned fed [FF]) and its effects on gastric ulceration, body weight, and body condition score (BCS). Thirty‐one Quarter Horses were maintained in individual stalls during the 60‐day experimental period and worked at moderate exercise intensity. Gastroscopies were performed before grain adaptation at 0, 30, and 60 days. Weight and BCS were evaluated biweekly. There were no changes in squamous (equine squamous gastric disease [ESGD]) ulcers in FF horses over the study period and higher ESGD ulcer scores in TF horses over both the 30 and 60‐day time points. The proportion of horses with equine glandular gastric disease (EGGD) were significantly lower with fractioned feed when compared with traditional feed on day 30, but no difference was seen at day 60. No significant differences were found when comparing the two groups for BCS or body weight throughout the study period. This study further supports that fasting period is a strong contributing factor for gastric ulcer formation. FF of the daily total grain led to a decrease in time fasting when compared with TF which reduced the severity and incidence of both ESGD and EGGD. The use of the commercial feeder for FF may aid in lessening prevalence of gastric ulcers in young training Quarter Horses.

The Effects of Various Levels of Docosahexaenoic Acid (DHA) on Inflammatory Markers in conditioned horses during lactate threshold tests

&NA; Exercise stimulates the release of inflammatory cytokines and supplementation with n‐3 fatty acids reduces inflammation. The effects of different doses of docosahexaenoic acid (DHA) on inflammation in polo horses submitted to field lactate threshold tests (LT) were analyzed. We hypothesized that higher doses of DHA would reduce postexercise inflammation. Twenty polo horses were assigned to different treatments: control group fed (n = 5) grain and hay, 3 treatment groups (n = 5) fed 10, 20, or 50 g/day of DHA with grain and free choice hay during 60 days. Horses underwent LT tests before start, 30, and 60 days of supplementation. Blood samples were taken at rest for blood cytokine expression (CEx), plasma cytokine enzyme‐linked immunosorbent assay (CEL), fatty acid, vitamin E, and creatine kinase (CK) analysis, after LT for CEx analysis (interferon gamma, tumor necrosis factor alpha [TNF‐&agr;], interleukin‐1 [IL‐1], interleukin‐6 [IL‐6], interleukin‐10 [IL‐10]), CEL, and CK analysis. Effects of treatment, time, and exercise were analyzed by analysis of variance, significant results compared by least square means analysis, and significance set at P < .05. There was a dose‐dependent increase in plasma DHA, and highest arachidonic acid was found in 20 and 50 g. Vitamin E was lowest in 20 and 50 g. LT did not change IL‐6, downregulated IL‐1 and TNF‐&agr;, upregulated IL‐10, and interferon gamma. The 10 g led to postexercise downregulation of interferon gamma and IL‐10 CEx compared to other treatments. A lack of antioxidants in the supplements may have led to the absence of treatment effects in the 20 and 50 g. 10 g DHA helped moderate postexercise inflammation.

Possible Role of MicroRNA in Equine Insulin Resistance: A Pilot Study

&NA; MicroRNAs (miRNAs) are a class of small endogenous single‐stranded noncoding RNA molecules that have important roles in several biological processes. Research in human and laboratory animals has shown that miRNAs can regulate genes associated with type 2 diabetes mellitus and metabolic syndrome, and that the levels of specific miRNAs circulating in the bloodstream can serve as potential biomarkers for the diagnosis and prognosis of these diseases. We hypothesized that insulin‐resistant (IR) horses would have a different circulating miRNA profile than those that are healthy. Fifteen nonpregnant mares housed at the Virginia Tech Middelburg Agricultural Research and Extension Center were evaluated for insulin sensitivity, with the frequent sampling intravenous glucose tolerance test. Selected mares, representing the most insulin‐sensitive (IS, n = 3) and IR (n = 3) states, and paired for age, weight, and body condition, underwent miRNA profiling. Serum samples were collected, miRNA extracted, and microarray analysis performed to investigate the presence and relative amount of 340 equine miRNAs. Confirmation by quantitative real‐time polymerase chain reaction revealed that miRNA was present in the serum of all animals. Results demonstrated different miRNA profiles between groups: Six miRNAs were expressed only in IS mares, five miRNAs were found to have lower quantity in IR mares relative to the IS ones, and three miRNAs were higher quantity in IR mares relative to the IS ones. The novel results of this preliminary study suggest potential new tools that could be developed for the diagnosis and treatment of metabolic syndrome in horses. HighlightsThe use of microRNA as bio markers for insulin resistance in horses.Comparison of circulating microRNA profile in three insulin‐resistant and insulin‐sensitive horses characterized by a gold standard test.Evidence of different microRNA profiles in insulin‐resistant versus insulin‐sensitive horses.MicroRNAs found to have relation with insulin‐related pathways.