_Symptoms._ A certain amount of impaction is not incompatible with ordinary health, but as this increases all grades of colic may be met with from the most simple and transient to the most persistent and severe. In the milder forms slight and transient colics come on after meals, for days in succession, before any serious attack is sustained. These are especially marked under dry bulky fodder (hay), less so on grain, and less on green food or roots. The animal paws, moves the hind limbs uneasily, looks at the flanks, he may even kick at the abdomen, lie down and roll, rise, pass a little manure or flatus, and seeming relieved may resume feeding, until the next attack. The intermissions may last a few minutes, a quarter of an hour or longer, and they gradually become more prolonged until they disappear for the time. Sooner or later, however, the obstruction becomes more complete and the colic more severe and persistent. To the ordinary symptoms of violent abdominal pain there are added symptoms which point to bowel impaction or obstruction. There is a special tension of the right side of the abdomen, with flatness on percussion. When down there is a tendency to sit on the haunches to relieve pressure on the diaphragm and lungs. When standing there is a disposition to stretch the fore limbs out forward and the hind ones backward. Fæces may be passed at first in a few small round balls at a time, but this soon ceases, and very little or none can be obtained even by the use of enemas. The straining is usually so violent as to expel the enemata as soon as introduced. The hand introduced into the rectum can easily detect the solid impacted pelvic flexure of the colon pressing backward into the pelvis or impinging on the right pubis. Another common symptom is the frequent passage of urine in dribblets, due to the irritation of the bladder by the pressure upon it of the impacted colon during straining. In cases of this kind the colon and cæcum become tympanitic as first shown by a resonant distension of the right flank obliterating the hollow in front of the ilium, and later by a similar condition of the left flank. The abdominal pain is usually less acute than in simple spasmodic colic or intestinal congestion. The face is less pinched and anxious, the eye less frightened, the kicking at the belly less violent, and the lying down more deliberate and careful. Very commonly the patient merely rests on his belly or side without attempting to roll. _Course._ The disease may last six to twelve hours, or even as many days before it ends in recovery or death. The colicy symptoms usually increase, with the complication of dyspnœa when tympany becomes well marked, hyperthermia in case of the supervention of enteritis, and signs of general peritonitis and collapse in case of rupture of the bowel. A sudden increase of the pain may otherwise indicate the occurrence of invagination.