The objective of the present study was to investigate the coagulation disorders and acute phase protein (serum amyloid A) in horses with abdominal pain. A total of 80 native breed horses of both sexes were examined. Based on the history, physical and laboratory investigations, the examined horses were classified into two groups: group 1 (n = 30): Healthy served as a control, and group 2 (n = 50) exhibited clinical signs of abdominal pain. Animals in group 2 were retrospectively subdivided into 3 subgroups: Diarrhea (n = 10), Impaction (n = 18) and Spasm (n = 22).The obtained results revealed that all horses with abdominal pain showed restlessness, sweating, lip curling, flank watching, pawing, rolling, and an increase in the heart and respiratory rate as well as capillary refilling time (CRT). On abdominal auscultation, horses with spasm and diarrhea had intestinal hypermotility while there was reduction in intestinal sounds in horses with impaction. Hematological examination showed subtle changes in hemogram and leukogram in diseased group. Hemostatic profile showed significant decrease (p < 0.05) in platelet count (PLT×10⁴/ µl) in diarrheic and impacted groups (14.3 ± 1.35 and 14.9 ± 0.78, respectively) and significant increase (p < 0.05) in prothrombin time (PT/sec) in spasmodic group (14.00± 0.75) and marginally increase in diarrheic and impacted groups (12.40 ± 0.57 and 12.70 ± 1.37, respectively). Additionally, activated partial thromboplastin time (APTT/sec) was significant increased (p < 0.05) in spasmodic group (53.79 ± 2.44) and marginally increased in diarrheic and impacted group (48.3 ± 5.75 and 45.7 ± 4.13, respectively). Antithrombin III (AT III, mg/dl) was marginally decreased in horses suffering from diarrhea, impaction and spasm (29.0 ± 3.42, 29.7 ± 3.19 and 29.6 ± 2.73, respectively). Level of serum amyloid A (µg/ml) showed significant increase (p < 0.05) in diarrheic and spasmodic groups (2.03 ± 0.50 and 1.6 ± 0.16, respectively), while marginally increase in impacted group (1.32 ± 0.09).   In conclusion, abdominal pain in horses induces changes in the coagulation system and acute phase protein (serum amyloid A). Serum amyloid A is a sensitive biomarker for abdominal pain in horses and could be used as diagnostic biomarker for equine colic.