Foram examinados 20 eqüinos adultos portadores de abdômen agudo e submetidos à laparotomia. Dez recuperaram-se sem intercorrência pós-operatória (G1) e 10 foram a óbito sete a 10 dias após a cirurgia, com sinais de choque séptico (G2). Avaliaram-se temperatura retal, freqüências cardíaca e respiratória, tempo de preenchimento capilar e teores plasmáticos das proteínas de fase aguda - fibrinogênio, ceruloplasmina, proteína C-reativa, antitripsina, haptoglobina e glicoproteína ácida -, antes e até sete dias após a laparotomia. As leucometrias às 72h e no sétimo dia pós-operatório dos eqüinos que foram a óbito foram, respectivamente, 34,6% e 57,1%, mais altas que a dos animais curados. Os maiores valores de proteína de fase aguda ocorreram no sétimo dia após a cirurgia; os percentuais de elevação de fibrinogênio, antitripsina, glicoproteina ácida, proteína C-reativa, ceruloplasmina e haptoglobina de eqüinos do G2 em relação ao G1 foram 46,8%, 67,9%, 91,9%, 112,2%, 126,9% e 186,2%, respectivamente. ; Twenty adult horses with acute abdomen were examined and submitted to treatment by laparotomy; ten had no postoperative complication (group 1), and ten showed septic shock symptom and died from seven to ten days after surgery (group 2). Body temperature, heart and respiratory rates, filling capillary time, and plasma acute phase protein concentrations - fibrinogen, ceruloplasmin, C-reactive protein, antitrypsin, haptoglobin, and acid glycoprotein - were evaluated before laparotomy and until seven days after surgery. White blood cell counts at 72h and seven days after surgery in group 2 animals were, respectively, 34.6% and 57.1%, and were higher than those measured in group 1 horses. The highest values of acute phase proteins occurred on the seventh day after surgery. The increase percentages of fibrinogen, antitrypsin, acid glycoprotein, C-reactive protein, ceruloplasmin, and haptoglobin plasma concentrations in group 2 animals in comparison to group 1 animals were 46.8%, 67.9%, 91.9%, 112.2%, 126.9%, and 186.2%, respectively.