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The aim of the study was to evaluate markers of the acute phase response ( APR) in eventing horses by measuring acute phase proteins ( APP) (haptoglobin, Hp, and serum amyloid A, SAA), lysozyme, protein adducts such as pentosidine-like adducts ( PENT), malondialdehyde adducts ( MDA), hydroxynonenal adducts ( HNE) and total advanced glycation/glycoxidation end products ( AGEs), complete blood count and lymphocyte subpopulations ( CD4+, CD8+ and CD21+) both at rest and at the end of an eventing competition. Blood samples were collected from eight Warmblood horses (medium age 10 ± 3) during an official national 2-day event competition at rest ( R) and 10 min after the arrival of the cross-country test on the second day. Exercise caused a significant increase in red blood cell number, haemoglobin, packed cell volume, neutrophils, white blood cell and lymphocyte number; however, these values remained within the normal range. The CD4+ and CD8+ cells significantly increased, whereas the CD21+ lymphocytes decreased; a significant increase in serum SAA, lysozyme and protein carbonyl derivates was also observed. Two-day event causes significant changes in APR markers such as lysozyme, protein carbonyl derivates ( HNE, AGEs, PENT) and lymphocyte subpopulations. The data support the hypothesis that 2-day event may alter significantly APR markers. Limitations of the study were the relatively small sample size and sampling time conditioned by the official regulations of the event. Therefore, further studies are needed to investigate the time required for recovery to basal values in order to define the possible effects on the immune function of the athlete horse. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate workload using suitable parameters related to the physical effort exerted by horses involved in eventing competitions in order to describe the workload intensity and energy demands placed upon such horses. Heart rate (HR), running speed (S), distance covered (Dist), performance duration (D) and blood lactate (Lact) concentrations were measured in horses competing at either the intermediate level (IL) or advanced level (AL) in order to identify workload differences between experience classes. Ten warmblood horses were monitored during an official two-day eventing competition; mean HR (HRmean, bpm), maximum HR (HRmax, bpm), mean S (Smean, m/min), max S (Smax, m/min), D (min) and Dist (m) were assessed during the warm-up and competition phases of each eventing test (dressage, show jumping, cross country). To calculate heart rate recovery (HRR), HR data were collected within the first 3 minutes following the completion of each of the 3 competition phases. Energy expenditure (EE) was estimated using the HR/VO2 relationship. Differences between the groups (AL vs. IL) in HRmean, HRmax, %HRmean, %HRpeak (HR expressed as a percentage of the maximum HR peak obtained during a fast gallop training session), S, D, and Dist were assessed using one-tailed unpaired t-tests for both warmup and competition phases; also differences for EE were evaluated. The relationship between HR and S was also determined for warm-up and competition phases using one-tailed Person's correlations. The relationship between HR decrease during the first 3 min following competition phase completion and recovery time was investigated by multiple nonlinear curve estimation procedures. The results reveal the cross country test to be the most demanding of the eventing competition, requiring significantly greater levels of muscular and energetic effort, in terms of Lact production and EE, with higher values recorded in the AL horses compared to IL horses. The data also show that riders need to optimise warm-up duration and quality in accordance with their competition category. The calculation of HRR is also shown to be an appropriate approach for gauging workload after high-intensity exercise, but not after low-intensity exercise since HRR may be influenced by external factors, like how excited a horse is. [ABSTRACT FROM AUTHOR]

Non-steroidal anti-inflammatory drugs (NSAIDs) inhibit cyclooxygenases (COX), and the inhibition of COX-2 rather than COX-1 can limit the onset of NSAID-related adverse effects. The pharmacodynamic properties of eltenac, naproxen, tepoxalin, SC-560 and NS 398 in healthy horses were investigated using an in vitro whole blood assay. To predict COX selectivity in clinical use, eltenac and naproxen were also studied ex vivo after intravenous administration. SC-560 acted as a selective COX-1 inhibitor, tepoxalin as a dual inhibitor with potent activity against COX-1, and NS 398 as a preferential COX-2 inhibitor. Eltenac was a preferential COX-2 inhibitor in vitro but un-selective in the ex vivo study. Naproxen maintained its non-selectivity both in vitro and ex vivo. These findings have demonstrated that in vitro studies may not accurately predict in vivo NSAID selectivity for COX and should be confirmed using an ex vivo whole blood assay [ABSTRACT FROM AUTHOR]

Abstract: The effect of dynamic exercise on complete blood cell count, lymphocyte β-adrenergic receptor and plasma catecholamine (adrenaline and noradrenaline) levels in horses performing different disciplines were investigated during rest and after exercise. Blood samples were collected from jumping horses (n =6), Arabian Endurance horses (n =6) and Standardbred trotters (n =6) before and immediately after competition. Dynamic exercise caused a significant increase in red blood cell count (Standardbred trotters: P =0.0012), haemoglobin concentration (jumping horses: P =0.001; Standardbred trotters: P =0.01), haematocrit percentage (Standardbred trotters: P =0.005), neutrophil percentage (jumping horses: P =0.0003), lymphocyte percentage (jumping horses: P =0.0003), monocyte percentage (Standardbred trotters: P =0.0008), lymphocyte β-AR numbers (jumping horses: P =0.01; Arabian Endurance horses: P =0.016; Standardbred trotters: P =0.05), plasma adrenaline concentration (Standardbred trotters: P =0.0001) and plasma noradrenaline levels (Standardbred trotters: P =0.003). It is concluded that acute increases in plasma catecholamine concentrations depended on the exercise performed and may induce up-regulation of β-AR in equine lymphocytes. However, the exact mechanism of β-AR up-regulation still remains unclear. [Copyright &y& Elsevier]

Abstract: Phenylbutazone and flunixin meglumine are non-steroidal anti-inflammatory drugs with antiinflammatory and analgesic activities widely used for the treatment of bone and joint inflammations, laminitis and soft tissue inflammation in the horse. The aim of the present study was to develop a new, selective, sensitive and fast analytical approach for phenylbutazone and flunixin quantitative detection in equine plasma. Differential pulse voltammetry experiments were performed with a portable electrochemical transducer by using miniaturized disposable graphite based screen-printed electrodes. The electrochemical detection by differential pulse voltammetry was coupled to prior selective extraction using dedicated molecularly imprinted solid phase extraction (MISPE) columns to reduce/avoid possible interferences present in plasma. Recovery after MISPE for both phenylbutazone and flunixin was >96%, with intra-day values below 5.0% and inter-day values below 6.5%. Method limit of quantification was 0.01μg/ml for both phenylbutazone and flunixin. The results obtained with DPV method showed a good correlation with those provided by an HPLC reference method. The method can be proposed as a suitable alternative to the existing chromatographic methods for the determination of phenylbutazone and flunixin in equine plasma samples. [Copyright &y& Elsevier]