Authors: Pablo Adrados/Alvaro Vázquez
EQUISAN Veterinaria Equina Integral

Colic syndrome is defined as a group of produced symptoms by a painful process whose origin comes from the abdominal cavity.
It constitutes the most frequent medical emergency in equine clinical health, judging the inverted time in the diagnosis and treatment of colic which plays a fundamental role in its resolution. It brings on changes in the animals behavior, pain and disruption of motility.
SYMPTOMS:
Normally infected animals show disquietude, with abnormal movements or postures (its frequent to see urination postures, rolling, pawing at the ground, flank watching), sweating, etc.... In the first examination we try to give an approximation overall of the etiology of the pain caused by colic, trying to differentiate when possible if it is to be treated or not a surgical colic.  
The following parameters must be observed and noted:
Rectal temperature
Pulse and respiratory rhythm
Degree of pain (on a scale of 1 to 3)
Mucous membranes and capillary refill time (TRC)
Abdominal auscultation (divide the flanks in two quadrants, upper and lower)
Abdominocentesis
Rectal exploration
Other helpful diagnostics are hematology for stabilizing the hematocrit (values between 50-70% that indicate the immediate need to establish fluidotherapy), the leukocyte count and the biochemical (complete alterations in protein, glucose and lactate are indicatives of circulatory failure).
CLASSIFICATION:
OBSTRUCTION:
- STOMACH: they are rare and are usually due to gastric dilation with stasis and fermentation. Their causes are unknown although they could be related with hypertrophy of the pylorus or stenosis and certain types of squamous cell carcinomas.
- SMALL INTESTINE: (or small bowel)
they are rare at the level of the duodenal and would be in the majority of secondary cases a displacement of the upper colon and erosive processes of the duodenal mucosa. Simple impactions usually affect the ileum and mainly the anterior portion of the ileocecal valve. They may also be the result of postoperative adhesions. Causes as ID obstruction have been described as well as lymphosarcomas and abdominal abscesses.
- CECUM: obstructions are usually simple impactions or cecal typanism. Within the first ones the impactions are distinguished with ample ingested material that hardens and those that are caused by cecal dysfunction, in which case the solid and liquid content of the cecum does not progress.

LARGE COLON:
Obstructions that are frequently found in equine clinical health and the typical form is by intake impaction. The location were it is more extended is at the level of the pelvic flexure, although it could be related to functional alterations in the right dorsal colon. Another type of impaction are those that are produced through sand intake. Tympanism of the large colon is normally related with displacement, although it is not exactly known if it is a cause or consequence.
LOWER COLON:
They are normally consequences of enteroliths or phytobezoars, which are very rare obstructions of the rectum (usually are secondary to painful processes such as fistulas and tears). The most common cause of rectum obstruction is MECONIUM retention (ingested and digested amniotic liquid) in a foal.
STRANGULATION-OBSTRUCTION:
It consists of external vasoconstriction with intestinal lumen closure. This includes anatomical changes, from a mesenteric loop to an intestinal volvulus via internal hernias with irrigation withdrawal. The cause of displacement is unknown but some seem to be due to congenital alterations including the mesodiverticular band. Acquired alterations include the widening of the epliploic orificium and with age develop into lipomas.