Percutaneous decompression of the cecum is a procedure that could be considered for horses with cecal gas distension. The aim of this study was to identify complications such as peritonitis and clinically relevant peritonitis (CRP) after transabdominal cecal trocarization in healthy horses using a cattle trocar and a cecal needle. Mixed breed horses were assigned to three groups (n = 6): horses that underwent trocarization with a cecal needle (G1) or a cattle trocar (G2), and a control group (CG) without cecal trocarization. The same horses were used in each group, respecting a three-month washout period between studies. A physical examination, serial blood, and peritoneal fluid sampling were performed, prior to cecal trocarization and 2, 6 and 12 hours after the first collection and 1, 2, 3, 7, and 14 days after the procedure. Acute-phase proteins in blood and peritoneal fluid were analyzed by polyacrylamide gel electrophoresis. Horses with a high cell count in the peritoneal fluid (i.e., 10,000 cells/μl) were considered to have peritonitis and CRP if they met at least two of the following clinical criteria: anorexia, lethargy, tachycardia, tachypnea, fever, ileus, abnormal oral mucous membrane color, abnormal white blood cells count, or high blood fibrinogen concentration (> 5 g/L). All horses recovered from cecal trocarization and abdominocentesis with no major complications. Cecal trocarization caused cytologic evidence of peritonitis in G1 and G2 during the 14 days of evaluation. CRP was not observed, although a decrease in cecal motility was observed in G1 and G2 during the experimental period and three horses, one from G1 and two from G2, showed a single moment of fever. None of the groups showed leukopenia or leukocytosis, although blood neutrophil count decreased at D7 and D14 in G1 and at D14 in G2 (p ≤ 0.05). After cecal trocarization, an increase in the total nucleated cells count, total proteins, globulins, alkaline phosphatase and acute phase proteins were observed in the peritoneal fluid of G1 and G2 during the 14 days of evaluation (p ≤ 0.05), without causing clinically relevant peritonitis. Transcutaneous cecal trocarization promotes peritonitis, which is more intense with a cattle trocar than with a cecal needle. The cecal needle should be considered for cecal trocarization of horses with cecal tympany., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2022 Dória et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)