Changes in blood-gas, biochemical and oxidative parameters in the horse associated with transport and fasting

The Australian and the European Animal Transportation Codes allow the transportation of horses without offering water for a maximum of 24 and 8 hours, respectively. This study aimed to document the effects of an 8 hour transportation event, devoid of water and feed, on physiological and metabolic parameters in horses. A total of 12 horses were transported in two identical transport events on different days (n=6 in each) for 8 hours around the Riverina district of NSW in a commercial truck without water and feed for the duration of travel. Arterial and venous blood samples were collected prior to transport (T0), at unloading (T1), and 24 hours after the trip (T2). At the same time points, body temperature, heart and respiratory rate were recorded. All data were analyzed by regression analysis using the mixed procedure of SAS, using time (T0, T1, T2) as a predictor variable and horse and day as random factors. Table 1 shows significant relationships generated by the regression analysis. There was no effect of the journey on pH, PaCO2, PaO2, SO2, AST, sodium, or reactive oxygen metabolites. Table 1. The means squared of the studied parameters at the different time points. Differing superscripts within rows indicate significant difference (A,B:P<0.01; a,b: P<0.05) (Tukey-Kramer test) Parameter Preloading (T0) Unloading (T1) One day after (T2) Standard error K+ (mmol/L) 3.94 Aa 3.48 B 4.23 Ab 0.08 Ca++ (mmol/L) 1.51 Aa 1.42 B 1.58 Ab 0.02 glucose (mmol/L) 5.24 A 6.71 B 6.10 C 0.30 lactate (mmol/L) 0.51 Aa 0.77 b 0.81 B 0.09 HCT (%) 35.34a 31.97 Bb 38.34 A 1.65 HCO3- (mmol/L) 31.68 a 29.51 b 31.25 a 0.51 HCO3std (mmol/L) 32.09 a 29.94 b 31.79 a 0.79 TCO2 (mmol/L) 33.53 a 31.30 b 33.18 0.83 BEecf (mmol/L) 8.00 A 5.76 B 7.91 A 0.74 BE(B) (mmol/L) 6.80 A 5.16 B 7.00 A 0.53 THb (g/L) 109.47 a 99.10 Bb 117.26A 5.67 T (°C) 37.52A 37.96B 37.54A 0.18 HR (beat/min) 34.80A 43.34B 36.44A 1.45 RR (breath/min) 13.19a 19.01Bb 12.10A 2.08 Total Protein (g/L) 65.09 A 69.63B 68.27B 1.37 Albumin (g/L) 28.18A 30.27B 29.72B 0.68 CK (UI/L) 248.82a 291.45b 292.55b 12.06 PAT (Ucorr) 2543.55a 2732.91Bb 2422.36Aa 80.28 Cortisol 5.26Aa 6.65Ab 2.97B 0.37 Transportation for 8 hours was associated with mild but significant effects on fluid and electrolyte balance, muscle enzymes, and mobilization of antioxidants, without causing metabolic acidosis or alkalosis. Further studies to evaluate frequency of rest and access to water and feed during transport are required to evaluate the need to update the current Australian equine transport code.