Category:Medical Colic in the Horse

Impaction, Colonic - Horse

Colic, Gastric Causes

Small Intestine

Spasmodic Colic

Spasmodic colic accounts for a large proportion of colic cases seen in first-opinion practice, however, little is known about its causes. It generally produces a mild colic, due to increased peristaltic activity in the gastro-intestinal tract. Cases are usually easily resolved by treating with a spasmolytic such as Buscopan, and a mild analgesic such as phenylbutazone.

Grass Sickness

Equine grass sickness, or equine dysautonomia causes a paralysis of the gastro-intestinal tract, by disruption of the autonomic nervous system. This leads to a pooling of ingesta throughout all parts of the gastro-intestinal tract. The condition may occur acutely, or progress chronically over several weeks, but all cases will eventually die. A definitive diagnosis is obtained by taking an ileal biopsy, and inspecting the intrinsic myenteric plexus. There is no effective treatment, although in the short to medium term, horses can be successfully managed by informed and attentive owners.

Caecum

Flatulent colic

Flatulent, or gas colic, occurs when caecal gases are produced faster than they can be removed by the caecum and colon, leading to a distension of the caecum. A diagnosis is strongly confirmed by a right sided abdominal distension, and auscultation/percussion of tympanitic sounds. Treatment involves withdrawal of fluid, and intra-venous fluid therapy. The distension can be relieved by trocharisation of the caecal head, via the right sub-lumbar fossa, which is ideally performed using ultrasound guidance.

Large Colon

Pelvic flexure impaction

A relatively common form of colic, that is often associated with a recent change in diet, management or exercise levels. Pain is moderate, and often persists despite adequate analgesia, a sign more commonly associated with colic of a surgical nature. However, rectal examination provides a definitive diagnosis, with a large, doughy structure occupying much of the pelvis. Treatment involves encouraging fluid output into the large colon, to help soften the impaction, firstly by ensuring adequate hydration with intra-venous fluids, and sometimes by administration of sodium chloride and sodium sulphate orally, to create an osmotic gradient. Large volumes of water, sometimes with Magnesium Sulfate with or without liquid paraffin (Mineral oil) are also given by naso-gastric tube, to help soften the impaction and encourage its movement.

Left dorsal displacement

Left dorsal displacement, or nephrosplenic entrapment, is a frequent cause of colic, where the left dorsal and ventral colon become displaced, and then trapped by the spleen laterally, the kidney medially, and the nephrosplenic ligament ventrally. It can be diagnosed by rectal examination. The first line of treatment is intra-venous phenylephrine injection, which acts to contract the spleen, so helping release the trapped colon. This is often combined with gentle exercise to encourage movement of the abdominal contents. Circling on the left rein is considered particularly helpful, as it increases the potential space between the spleen and the body wall, allowing more room for the colon to return to its normal location. If this fails, then general anaesthesia is needed. Replacement of the colon is then attempted by rolling of the horse. If this also fails then surgery is needed to correct the displacement.

Small Colon

Pelvic masses

A persistent mild colic may be found when intra-pelvic masses impinge upon the gastro-intestinal tract. Most commonly these are haematomas. Peri-anal lesions, such as melanomas may also produce these signs.

Neurological deficits

A complete or partial paralysis of the small colon and rectum may occur with polyneuritis equi, resulting in a lack of faecal expulsion, and consequent obstruction. A diagnosis is made via a neurological examination. Treatment is palliative only, although the condition can be managed for many years by manual emptying of the rectum.