The term colic is loosely applied to all abdominal pains from whatever cause they may arise. It is thus allowed to embrace all diseases of the abdomen. In its more restricted sense in which it will here be considered it may be held to indicate abdominal pain without inflammation or any structural lesion.
It may however be well to note the most common causes of abdominal pain so that the distinction may be more definitely reached by a process of exclusion.
1st. Simple spasmodic colic. 2d. Enteralgia or neuralgia of the intestines. 3d. Colics from indigestion, a tympanitic, b from overloading with ingesta, c from impaction or constipation, d from calculi or concretions or from sand, or gravel taken with the food or from foreign bodies swallowed, e from worms in the intestines, f from worms in the mesenteric vessels (thrombo-embolic), g from irritants taken with the food or otherwise. 4th. Colics from structural lesions of the intestines; a from inflammation of intestine, b from bacteridian inflammation of the bowels, c from protozoan inflammation, d from chemical or other irritants, e from intestinal strangulations, f from adhesions, g from volvulus, h from invagination, i from mesenteric omental or phrenic hernia, j from strangulated inguinal, femoral ventral or umbilical hernia, k from wounds, ruptures or perforations of stomach or intestines, l from peritonitis or pleuritis, m from metritis or ovaritis, n from hepatitis or biliary calculus, o from pancreatitis or pancreatic calculus, p from nephritis, nephritic, uretral, cystic or urethral calculus, q from neoplasms affecting any of the abdominal organs. 5th. Colic due to lead poisoning.
Causes of enteralgia and spasmodic colic. Enteralgia may be defined as a neuralgic pain of the bowel which may therefore be free from spasm or any other appreciable structural or functional change. Its existence in the lower animal is necessarily somewhat problematical, as it can only be inferred from the analogy of the animal with man, and of the enteron with the superficial parts that are more frequently attacked with neuralgia, and also from the absence of visible spasmodic contractions in the bowel which has been the seat of intense pain, yet shows no inflammatory lesion. But whether this is accepted or not, the occurrence of spasm is undeniable and as both are functional nervous disorders the same causative factors will apply to both.
In some nervous animals, especially high bred horses and dogs, there is undoubtedly an idiosyncrasy which shows itself in a special susceptibility of the nervous system. In such animals an exposure to cold or wet, or the presence of a local irritant which would have been without effect under other circumstances, lights up the nervous disorder and produces an explosion, it may be as spasm or it may be as nervous pain. Animals that are kept under the best care, that are least accustomed to exposure and neglect, that are highly fed, and maintained in high spirits and are impatient of control are more susceptible than those that become inured to change and exposure, yet are kept in moderately good condition. On the other hand the subject which has become debilitated by overwork, underfeeding, exhausting disease, or the generation in the system of some depressing poison is likely to show a similar nervous susceptibility, so that at the two extremes of plethora and nervous susceptibility, on the one hand, and anæmia and neurasthenia on the other, we find a corresponding tendency to nervous disorder under comparatively slight causes. Thus it happens that a drink of ice cold water, an exposure to a cold blast or a drenching rain or a heavy night dew may seem to be the one appreciable cause of the trouble. If the animal has been perspiring and fatigued the attack is more likely to occur. In other cases a slight indigestion unattended by impaction or tympany, or the ingestion of an irritant which on another occasion, or in another animal would have been perfectly harmless, will induce a violent nervous colic. In some instances the attack is supposed to be of a rheumatic nature the causative action of the cold giving color to the theory.
Symptoms. The attack usually comes on suddenly especially if it has followed on a drink of cold water or a cold exposure.
Solipeds. The horse leaves off feeding or whatever he may have been engaged in, paws with his fore feet, moves uneasily with his hind ones or kicks with them, one at a time against the abdomen or out backward, he looks back at the abdomen with pinched, drawn, anxious countenance, bright anxious eye, and dilated nostrils, he moves uneasily from side to side of the stall or box, crouches for a few seconds with semi-bent knees and hocks and then throws himself down violently with a prolonged groan. When down he may roll from side to side over the back, and struggle in various ways, he may start to rise, sit for a moment on his haunches, then go down and roll as before. Or he may get up, shake himself and resume feeding as if entirely well. Soon the spasms reappear, suddenly as at first, and after a time subside as before. Thus the disease proceeds, each succeeding paroxysm diminishing in violence until they permanently subside, or increasing until the animal dies worn out with shock, suffering and exhaustion. If the paroxysms are severe the skin is usually bathed more or less in perspiration. Usually the peristalsis continues more or less, a rumbling is heard in the bowels and more or less fæces are passed in small solid balls or semi-liquid.
The course of the disease is usually rapid and followed by recovery. When prolonged it may become complicated by volvulus, invagination, indigestion or even enteritis.
Diagnosis. The characteristic symptoms are the suddenness of the onset, the extreme suffering during the paroxysm, the reckless manner in which the animal throws himself down, the intermissions with complete absence of pain, the natural condition of the pulse and temperature in the intermissions, the comfort with which the patient shakes himself, and the absence of all abdominal tenderness, manipulation and friction seeming to give relief rather than discomfort.
In the colic of acute indigestion there is the previous excessive or unwholesome meal, or the full drink after feeding; there is tympany, or a loaded state of the abdomen proving flat on percussion, there may be crepitation on auscultation, there is continuous pain with exacerbations (not complete intermissions), and there is rather a careful mode of lying down.