Efeitos gastrointestinais e sistêmicos em eqüinos submetidos à sobrecarga dietética com amido

Abstract

This work aimed to evaluate gastrointestinal and systemic disturbances, and mucosa and gut contents of gastrointestinal tract of horses subjected to overload carbohydrate. Eight crossbreed mature horses were used with body weight (BW) average of 364kg, geldings, adapted to diet composed by grass hay and concentrate, in a 60:40 proportion. A complete randomized design was used with horses allocated in three treatments. Treatment I: (Control) (n=2) horses were slaughtered without overload carbohydrate; Treatment II (n=3) and III (n=3), horses subjected to overload carbohydrate, with gastric infusion of 17.6 g starch/kg BW, and slaughtered after 24 and 36 hours, respectively. Horses were subjected to clinical, hematological and fecal evaluations before the overload and 2, 4, 8, 12, 16, 20, 24, 28, 32 and 36 hours after overload. Four hours after overload horses became depressed and keeping until the end of evaluation, and one horse presented lameness 36 hours after overload. Any difference (P>0.05) were observed in heart rate, respiratory rate, body temperature and hoof temperature. Increase in packed cell volume and plasma protein concentration were observed 24 hours after overload, varying from 26.7 to 32.0% and 7.1 to 8.1 g/dL, respectively (P<0.05). Differences were observed (P<0.05) in plasmatic lactate concentration in zero, 20 and 28 hours after overload, with values of 0.7, 1.04 and 1.22 mmol/L, respectively. Plasma endotoxin concentration didn't cross 0.1000 EU/mL and may be not present. There were any difference (P>0.05) in fecal and digesta water content, however, fecal pH reduced along 36 hours post-overload (P <0.01), varying from 6.09 to 4.46. Content of large intestine in horses subjected to overload presented whitish-green color, milk aspect, with gas bubbles and acid odor. There weren t difference (P>0.05) in water content of feces and digesta, however, fecal pH reduced along 36 hours post-overload (P <0.01), varying from 6.09 to 4.46. Buffering capacity of ceco-colon digesta and feces were reduced in horses subjected to overload. Right dorsal colon, transverse colon and descendent colon were segments, except stomach, that presented lower pH values, varying from 4.49 to 4.56. Eosinophils infiltration were presented in mucosa and submucosa of all horses, however, only horses submitted to overload presented neutrophils and eosinophils leucocitoestase with neutrophils predominance restricted to large intestine. Tract gastrointestinal circulatory alterations observed were congestion, edema and lymphatic vessels dilatation, more evident in submucosa, with larger inflammatory cells infiltration in horses subjected to overload. Intestinal mucosa 36 hours after overload presented larger degree of imunorreactivity anti-myeloperoxidase, followed by horses evaluated at 24 hours after overload and control horses, varying from 2.7 to 4.0, 1.0 to 3.7 and 1.0 to 2.5, respectively. Overload carbohydrate in horses promoted intensive fermentation in ceco-colon, predisposing clinical disturbances, digesta alterations and mucosa and submucosa lesions at gastrointestinal tract of horses with light to moderate degree,36 hours after overload.