SummaryReasons for performing study: This study was designed to consider the complexity of the physical effort inherent to horses in polo competitions and the absence of reports in the literature on the effort, intensity and electrolyte changes resulting from a collective team training session aimed at preparing for a polo championship. Objectives: To determine the effort and ion changes caused by an outdoor polo training match for a 25 goal handicap (elite) based on physiological variables including acid-base status (venous pH, PCO2 and HCO3 -), packed cell volume (PCV), haemoglobin (Hb), lactate, glucose, sodium, chloride and potassium and strong ion difference (SID) as well as creatine kinase (CK) activity. Methods: Twenty-three clinically healthy 'high-goal' polo ponies were used, which included 10 geldings and 13 females. The horses performed a training match, as a preparation for a 25 goal tournament, consisting of 6 chukkas of 7 min duration each. Blood samples were collected during resting, and at 5 min, 6 and 12 h after each chukka. Data were analysed using ANOVA for repeated measures followed by Tukey's test. Results: Differences (P<0.001) were evident mainly in post exercise for all variables studied. There was a reduction in pH, PCO2 and HCO3 -and SID, together with an increase in PCV and Hb, lactate, glucose, Na + and Cl -. K + levels remained constant at all times of collection. The average resting value for CK was 255 Ϯ 9 iu/l, and 6 h after effort there was a 35% increase in enzyme activity. Conclusions: This study indicates that the horses participating in a training match underwent a high-intensity effort with alterations in electrolytes and acid-base equilibrium. Potential relevance: Training matches should be carefully conducted, with a suitable recovery period before the main match. evj_278 191..195

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This study shows the variation between protocols of the LMS test for determining the onset of blood lactate accumulation but also reveals that, at least for Arabian horses, the P1 protocol of the LMS has good agreement with the MLSS.

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Since the emergence of West Nile virus (WNV) in North America in 1999, there have been several reports of WNV activity in Central and South American countries. To detect WNV in Brazil, we performed a serological survey of horses from different regions of Brazil using recombinant peptides from domain III of WNV. Positive samples were validated with the neutralisation test. Our results showed that of 79 ELISA-positive horses, nine expressed WNV-specific neutralising antibodies. Eight of the infected horses were from the state of Mato Grosso do Sul and one was from the state of Paraíba. Our results provide additional evidence for the emergence of WNV in Brazil and for its circulation in multiple regions of the country.