Constipation in horses

The intestines of the horse are very delicate and prone to colic. Constipation is just one form it takes. Knowing about it can help prevent it.

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  • #surgery
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  • #horse health

The topic of colic in horses is very extensive and complex. Colic is the acute manifestation of abdominal pain of intestinal origin. There are many forms of colic; one of these is the constipation of the caecum intestine.
​The caecum is the first section of the large intestine of the horse, It receives food from the small intestine through the ileum and allows the passage of food content to the following intestinal tract later, the ascending colon, through the cecocolic opening. This progression of the intestinal content does not take place before, inside the caecum, the digestive processes of fundamental importance have taken place. The caecum is located on the right side of the horse and is the main area of plant fibre fermentation; it takes the form of a sack, is approximately one metre long and is characterised by a large head anchored by a short ligament to the abdominal cavity. The small intestine discharges its contents inside the caecum just below the head and the material collected in the caecum flows into the ascending colon, the next, intestinal tract, through an opening that is located just below the outlet of the ileum. Undigested plant fibre from the small intestine is reversed in the caecum, where the force of gravity pushes it downwards. The contents of the caecum are then remixed and pushed upwards by the powerful muscles of the bowels, the act of which mixes this content with water, digestive liquids, enzymes and bacteria.
To allow this mixing process to take place in an appropriate manner and to enable the caecal content to be correctly pushed upwards in order to be able to flow into the ascending colon, it must contain a sufficient amount of fibre and liquid. Adequate intake of good quality forage and water is therefore essential for the proper functioning of the caecum. The food reaches the caecum two hours after ingestion and remains inside for approximately eight hours. During this time the intestinal flora ensures proper fermentation and digestion of the plant fibre introduced, resulting in the production of volatile fatty acids that are absorbed by the mucosa of the large intestine and provide significant quantities of energy, equal to over 30% of the energy requirements of the horse.

It may happen in certain situations that the delicate function of this section of intestine is affected by alterations, causing a stagnation and an accumulation of material inside it, resulting in distension of the caecum. This may be an acute phenomenon or become a chronic dysfunction. Constipation of the caecum is an intestinal disorder characterised by an obstruction of the intestinal transit and consists of an accumulation of liquid or solid food material that is dehydrated within this section of intestine. This condition is often accompanied by an alteration of the caecal ph and of the normal contractile capacity of the bowels and seems to affect athletic adult horses more frequently.

Constipation often begins with the accumulation of faecal material within the upper part or the head of the caecum. This, due to its weight, moves downwards and causes compression and obstruction of the opening between the caecum and the colon, preventing the complete or partial flow of intestinal contents. This causes the gradual accumulation of faeces, resulting in constipation of the body of the caecum, even if the accumulation of content may be limited to only the head of the bowels. The symptoms are often mild and barely noticeable, especially in the early stages of the disease. In some horses, constipation of the caecum becomes chronic and recurrent, characterised by the almost permanent emission of non-formed stools, foul-smelling and soft, weight loss and chronic recurrent colic symptoms accompanied by medium or mild pain intensity, constipation or bloating of the caecum. The causes of the development of the disease are still unclear and have been associated at the acute stage with the ingestion of coarse fibre, reduced water intake, prolonged treatment with non-steroidal anti-inflammatory drugs, tapeworm infestation, prolonged hospitalisation or exposure to stressful situations.

Neither are the causes of the chronic form of the disease clear, and are supposed to be linked to malfunctioning anomalies of the nervous complex that regulates the contraction and motility of the large intestine, with anomalies of innervation, alterations and dysfunctions of the normal contractility of the caecum, resulting in hypertrophy of the muscle layer. Horses prone to chronic or recurrent constipation of the caecum, in addition to having a deteriorating physical condition and suffering from recurrent colic, conditions that negatively and permanently affect their life and sports performance, risk experiencing spontaneous breaking of the caecum, resulting in fatal peritonitis. Acute constipation of the caecum is treated as ordinary constipation, although it is always important to address the problem aggressively to prevent the risk of rupture of the intestine caused by dilation, a complication that is always possible when the caecum is involved. In some cases that are slow to respond to medical therapy, in order to avert the risk of perforation, it may be necessary to subject the horse to surgery as a means of emptying the bowels. To manage chronic constipation of the caecum, several conservative and surgical treatment approaches are suggested in the bibliography. Conservative treatment consists, first and foremost, of treating the constipation at the acute phase, and then at the next stage, managing the diet of the horse, that is organised in such a way as to reduce the likelihood and frequency of relapses. For this purpose recommended remedies are the administration of probiotics, the periodic administration of low doses of laxatives as a preventive measure, ensuring the presence of highly digestible fodder of excellent quality in the diet, possibly given wet, always stimulating an adequate water intake and possibly reducing the intake of cereals or removing them completely from the diet. The efficacy of conservative treatment and food management in cases of chronic constipation of the caecum are extremely variable and the response depends on the severity of the disease and the individual sensitivity of the horses being treated. In the case of horses that are non-responsive to this approach, it is possible to perform surgery that involves the partial or complete and definitive exclusion of the caecum from the intestinal tract and thus from the digestive processes. This type of therapy generally has a success rate of between 50% and 60%. In the cases treated surgically, it has been demonstrated that the exclusion of the caecum from the digestive processes does not require the administration of particularly digestible food or variations and particular attention to diet.

It is always difficult if not impossible to predict which of the subjects experiencing an acute episode of constipation of the caecum will develop chronic disease. It is clearly just as difficult to explain and make the owner understand and accept that their horse, until then healthy, has suddenly fallen victim to a highly debilitating chronic disease that is scarcely compatible with life in the long-term. The chronic condition often begins with acute constipation, without the presence during the first clinical episode of the classic signs of chronic constipation of the caecum. The horses involved have usually never suffered from recurrent intestinal diseases before, are aged between eight and twelve years, and enjoy full athletic activities.

Chronic constipation of the caecum is a highly disabling disorder for the sports horse. Subjects that are affected experience recurrent colic with resulting and frequent administration of medications, weight loss and deterioration of physical condition and are therefore unable to maintain normal performance and sporting life. In most cases the chronic disease also leads to death in horses that suffer with rupture of the intestine in the medium to long term.
As mentioned previously, there are no scientific studies that reveal the causes of the development of the chronic disease, but exposure to stress and changes in nerve function of the intestine should be considered risk factors, they themselves without a specific triggering cause.