Colic

The term colic describes the clinical signs that horses show when they have abdominal pain : they look at their flanks, sweat a lot, lie down, roll on their back or stretches out as if to urinate.

Colic, what are we talking about?

Some older horses and certain breeds might more stoic than others.
Most colic episodes in horses are linked to digestive problems. Far more rarely, pain can come from the urinary tract (bladder or urethral stones), or the reproductive tract (uterus torsion in pregnant mares). Build up of inflammatory (peritonitis) or blood (hemoperitoneum) in the abdominal cavity can also elicit pain.
Colic is a frequent reason for calling the vet and is the first cause of mortality in horses.

Colic of digestive origin

Horses are prone to have colic because of the particular anatomy of their digestive tract and their high sensitivity to stress and pain.
The digestive tract in horses is about 30 meters long and is made up of the stomach, small intestine, small colon, caecum, large colon and rectum. Several problems can affect these different segments.

Gastric ulcers

About 50% of sport horses and up to 100% of racehorses have gastric ulcers. Lifestyle (living in stall, alone, intense exercise) and feeding habits (2 to 3 large meals of concentrates per day, limited access to hay) are important contributing factors. Some NSAI treatments can also elicit ulcers. Horses with gastric ulcers can suffer from abdominal pain most frequently after their meal. However, all horses with gastric ulcers do not have colic.

Intestinal causes of colic

A specificity of horse anatomy is that the intestine is quite free in the abdomen with few fixed points. Thus the intestine “floats” in the abdominal cavity and can easily be displaced. Moreover, intestinal diameter is quite variable along the digestive tract and thus bottlenecks are prone to obstruction.
Principal intestinal causes of colic are:
° Spasmodic or “gas” colic secondary to the overproduction of gas by food fermentation. This type of colic often occurs as a result of abrupt changes in food habits when the intestinal microbiota does not have enough time to adapt to the new food. Treatment is medical and consists of giving NSAIs or sedatives to control pain, and antispasmodic drugs to alleviate unnecessary painful contractions of the intestine around gas pouches.

° Food impactions secondary to overconsumption of forage or bad quality forage, or to an insufficient water intake. Medical treatment is often sufficient, and consists of giving laxative products by naso-gastric intubation, NSAI and/or spasmolytic drugs for pain control, and possibly intravenous fluids to rehydrate the horse.

° Intestinal displacements are often a complication of an impaction. I the first place, they are treated like impaction. However, the medical treatment is sometimes not enough and surgery might be necessary to put the colon back into its normal position.

° Torsions, when the intestine rolls on itself. This is the most serious type of colic and the most painful because the intestine, when rolling, blocks the blood circulation. The tissues thus die quickly. Emergency surgery is needed in this case.

° Intussusceptions, less frequent: part of the intestine enters into another part like a telescope. In this case too, perfusion is compromised and emergency surgery is needed. This type of colic is more frequent in foals.

° Proximal enteritis and colitis: this is an inflammation of either the small intestine or the colon. T-Treatment is medical as there is no “mechanical” problem but it can take a long time and the prognosis is guarded.

Veterinary examination

To determine the cause of the colic, the vet performs a transrectal examination, which enables him to locate the intestinal segments and detect an impaction if present. He also uses a naso-gastric tube to evaluate the presence of gastric reflux: this is the intestinal content flowing back from the small intestine to the stomach when there is a small intestinal obstruction or a proximal enteritis. The vet also evaluates the cardio-vascular state of the horse to determine if it needs intravenous fluids, and its pain level to adapt the drugs he gives. The decision to send the horse to surgery depends on several factors including the cause of the colic, the pain status of the horse and his answer to treatment.

Risk factors

Several risk factors have been identified for colic: tic, previous episodes of colic, living in a stall, some intestinal parasites, straw bedding , feeding concentrates, low quality food, hot/cold/dirty water. Generally speaking, horses are animals of habit and every change in their lifestyle, environment, activity or food is a risk factor for colic.

Prevention

In order to limit the risks of colic, the horse’s natural lifestyle should be respected as much as possible as well as its need for regularity in its activity and feeding. When a change has to be made, whether it involves food, activity or environment, a transitional period should be respected.
Food is a key factor in the prevention of colic: to respect the horse’s digestive physiology, horse’s diet should be based on good quality forage (grass or hay) complemented with good quality and conserved concentrates if needed. In their natural life horses graze 18h a day. One should aim at reproducing this feeding rhythm by dividing their food into numerous small meals. Putting the horse to grass in the spring should be considered as a diet change and thus should be performed progressively. Diet should also be adapted to the level of activity of the horse.

All horses should have regular physical activity. This is particularly important for horses living in stalls.
Finally, in order to limit the risks linked to intestinal parasitism, a worm control program should be set up with your vet. Regular dental care ensures efficient mastication.

Autor : Julie Dauvillier.