The clinical features of 106 horses presenting with chronic colic exam
ined over a 5 year period were reviewed, Chronic colic was defined as
colic signs observed daily for 3 days or longer, except when masked by
analgesics, The diagnosed causes of chronic colic included colonic im
paction (31%), peritonitis (16%), enteritis/colitis (7%), colonic disp
lacement/torsion (6%) and lymphosarcoma (4%). A variety of other disea
ses were diagnosed in a small number of cases, including intestinal ad
hesions, ileal obstructions, grass sickness, liver disease, caecal imp
actions, thromboembolic disease, intussusceptions etc, No diagnosis wa
s reached in 8% of cases, Diagnosis was relatively easily achieved in
most cases of colonic impaction and peritonitis by results of transrec
tal palpation and evaluation of peritoneal fluid, Specific clinical fe
atures, transrectal palpation, abdominal paracentesis and laboratory e
valuations of blood were helpful in the diagnosis of some of the other
diseases, but exploratory laparotomy remained necessary in a few case
s to achieve a diagnosis.