There is a long, exhaustive list of the causes of Colic and includes anything from heart problems to infection. It is, therefore, simpler to break the causes into two main groups; digestive tract related and non-digestive tract related.
Non-intestinal tract related illness can include, but not limited to; foaling, placenta retention, abortion, uterine torsion, pleuritis, botulism, renal and bladder stones, ruptured bladder, hepatitis, myositis and laminitis.
However Colic is much more commonly due to Digestive Tract conditions and diseases. The horse's intestinal tract is highly complex and has evolved over 1,000’s years to adapt to a diet of continuous grazing and the breaking down of the complex cellulose molecule found in grass. However, this finely tuned system is susceptible to disruption and consequently can result in these common conditions;
1) Distension: the digestive tract cannot perform the worm like movement to move food along.
2) Simple obstruction or blockage: Food cannot move along the tract due to a blockage.
3) Obstruction or blockage and partial or complete blood supply cut off: This can cause severe pain and can quickly develop into septicaemia.
4) Inflammation: Swelling can cause distension and stasis of the digestive tract.
5) Colon Displacement: more commonly found in Warmbloods. If the displacement of the colon is to the left, it will become lodged between the Spleen and left Kidney. If it is to the right, it will invade the area of the Cecum (a large digestion vat).
Delving a little deeper we can take a look at the more common root causes of these conditions;
1) Gas accumulation: this is the most common and can be due to a decrease in the horse's movement (i.e. if they are standing still for long periods of time) and accumulation of feed.
2) Impactions: feed impactions can be the result of poor dental health or dehydration, this can then lead to gas accumulation. Sand impactions, as suggested is the result of ingesting sand from feeding off the ground. Sand ingestion will be more problematic depending on the geographical location, for example, it is a common problem in California.
3) Enteroliths are mineral accumulations and can form a rock like substance in the large colon, remain there and accumulate over time and consequently can eventually become obstructive. Genetics plays a part, but this is more likely to be related to diet;
Arabian’s are predisposed to the condition.
4) Lipomas Are fatty tumours and are usually a disease of old age. In the later stages of the disease, they can block the tract and cut off the blood supply.
5) Infection: Examples include Salmonella, Clostridium and Potomac Horse Fever and will result in inflammation. Parasite infection can also result in impactions.
So there we have it. An extremely simplified, guide to how and why Colic may occur. With so many root causes it’s easy to understand why Colic is such a common occurrence in our four legged friends. Knowing the pathology also allows us to calculate how Colic can be avoided. Thus, following on from this, our next instalment of our Colic series will be top 10 Techniques to Prevent Colic.