What is it?
Whilst colic is a very common condition, the vast majority of patients do not require surgical treatment, about 5-10% of all cases of colic end up on the operating table. Colic is a clinical sign, it is not a diagnosis; there are many different causes of colic, some are physiological i.e. they affect the gut activity, while some are anatomical i.e. they result in some sort of blockage or obstruction.
Most cases of colic respond to a single injection of pain killer or anti-spasmodic injection, usually these cases involve spasms or cramping of the gut, possibly with a build-up of gas within the intestine. Lungeing of some of these cases helps dislodge any trapped gas and the increased adrenalin levels helps to normalise the gut activity.
Some cases of colic may need to be hospitalised following the first examination if there is any suspicion that the cause may be more serious. Once hospitalised, a series of further tests may be undertaken to help determine the cause.
Internal examination – a rectal examination is often undertaken to attempt to identify physical blockages, enlarged or displaced intestine.
Ultrasound examination – external ultrasound exam through the body wall may help identify lengths of distended small intestine, often associated with a surgical condition
Belly tap – the collection of body fluid that surrounds the outside of the bowels within the belly. This fluid changes when certain conditions, particularly surgical conditions, are present.
Bloods – blood sampling is usually used to assess the status of the circulation in terms of hydration and cardiovascular abnormalities.
The decision for surgery
The decision to operate on a patient with colic is not often very straightforward. Sometimes it is possible to identify the cause during the course of the investigation such as feeling enlarged intestine full of gas or fluid during internal examination. However, often the patient is operated on because it has failed to respond to medical treatment, or, the colic pain cannot be controlled by painkiller injections, or the patient’s condition has deteriorated despite medical treatment. For the surgeon, the exact cause of the colic and its severity may not be known until the abdomen is opened on the operating table.
Common surgical conditions
Surgical colic can be divided into several common general categories
Twisted bowel – can be the small or large intestine, often involves a fatty lump growing on the bowel wall on a long cord and wrapping itself around a length of gut, cutting off the blood supply. Any of the gut can be affected, from a few centimetres to several metres. Lengths of intestine may or may not have to be removed, depending on how long the gut has been trapped.
Displaced bowel – usually the large intestine, the bowel moves into an abnormal position, sufficient to stop the passage of food, liquid and gas, but not enough to cut off the blood supply. The bowel normally needs to be replaced into its normal position and may have to be emptied of solid, liquid or gaseous contents.
Physical obstructions (impactions) – These are normally caused by blockages of food such as straw, foreign material such as sand and foreign bodies such as plastic wrapping, or large worm burdens. They can also be caused by the growth of tumours in the gut wall. The bowel would usually need to be opened and emptied or a section of gut removed if a tumour is involved.
Torsion – similar to twisted bowel, but instead of being trapped by a fatty lump, the bowel is twisted around on itself, cutting its own blood supply off. The effect is similar and lengths of dead intestine may have to be removed.
Common medical conditions
There are many, many causes of non-surgical colic, some of which can initially be surgical problems such as a displacement, which can be treated successfully without surgery in some cases.
Spasmodic colic – Probably the most common cause of mild colic, this involves waves of cramp passing along the intestines, causing the patient to have repeated bouts of discomfort, interspersed with periods of normality. The cause is varied and non-specific patients usually respond to a single episode of painkiller injection, along with physical exercise.
Gas colic - Certain parts of the intestine can fill up with the normal gases that are produced in the equine gut. If the gas cannot escape, the patient can become extremely painful and may show signs of quite severe colic. Gas colic can lead to displaced and twisted bowel as the distended gut floats out of position. Painkiller injections combined with periods of intensive physical exercise such as lungeing, are necessary to release the trapped gas.
Parasites – Despite the widespread use of wormers, all the different species of intestinal worms are still relatively common, apart from the large red worms. Small red worms and tapeworms are both common causes of colic, which can range in severity from mild, intermittent discomfort, through to severe colic requiring surgical treatment. Unfortunately, inappropriate and incorrect usage of wormers has increased the incidence of resistance to the chemicals. We recommend regular worm egg counts (see separate display) and strategic use of wormers rather than blanket use of the drugs.
Sand enteritis – As well as causing a blockage, requiring surgical treatment, smaller quantities of sand can accumulate on the bowel floor, moving back and forth as the gut moves, causing irritation to the gut lining, resulting in inflammation and recurrent bouts of colic. Treatment involves the use of a bulking agent called psylium, that is fed daily long term, while ensuring that the patient is not grazed on sandy paddocks, especially when the grass is short.
Gastric ulceration – Inflammation and ulceration of the stomach lining is frequently recognised in the horse population. However, the relationship with the occurrence of colic is not quite so clear, as many horses have ulceration with no history of colic episodes. Diagnosis requires the use of a long endoscope, usually about 3 metres in length, passed through the nostril into the stomach, to visualise the lining. The only effective treatment for gastric ulceration is a drug named Gastroguard, which reduces stomach acid secretion, allowing the lining to regenerate. Modifying the diet to include more roughage, along with trickle feeding a constant supply of feed, should reduce the risk of recurrence.