Colic Species: horses

Equine colic is loosely defined as abdominal pain. The causes are numerous, and the signs of discomfort (rolling, kicking at the abdomen, pawing, sweating) are familiar to most experienced horse handlers.

Colic is one of the most common health emergencies, with an incidence of just over 9 cases per 100 horses in an average year. It is a leading reason for surgery and a frequent cause of death in horses.

Years of research have been devoted to sorting out management practices associated with causes of colic. Careful examination has led to some general caonclusions about factors that may put horses at increased risk. Below is a summary of trends identified by several independant studies.

Breed

Some studies identified Standardbreds, Thoroughbreds, Arabs and Warmbloods as having more frequent colics that other breeds, while other studies found the opposite was true. There are no proven trends.

Age

There is some eveidence that more colics occur in horses between the ages of two and ten. Consider: these are the years of heavy training and performamce. Horses may be under stress form frequent travel, competitions and changes in schedule.

Use

One study showed a higher risk of colic in eventers than in horses used for other sports. Another indicated that colic was more common in breeding stock than in pleasure horses. Consider: colonic twists are common in broodmares, and heavy lactation may induce dehydration or electrolyte imbalance.

Pasture/Stall

Horses pastured 24 hours a day have low rates of colic, and risk rises as stall time increases. Consider: stalled horses may get less exercise, eat less fresh forage and be under increased stress from boredom and lack of companionship.

Caregiver

Horses cared for by owners had fewer colics than horses cared for by trainers or managers. Consider: horses cared for by a trainer are somewhat more likely to be under stress because of exercise schedule, decreased turnout and a high-grain diet.

Concentrate portion of diet

Any inclusion of grain or concentrate increased colic risk over forage-only diets. Risk was greater as the amount of concentrate increased, even if the concentrate was split into several feedings per day. The highest risk was seen when horses ate pellets; a sequentially decreased risk was noted with consumption of whole grains (oats, barley), sweet feed and a combination of whole grains and processed feeds. Horses that were given more or less than their normal grain ration, a different type of grain, or any amount of mouldy grain had increased risk of colic.

Forage portion of diet

Horses getting 100% of their forage from grazing had the lowest incidence of colic. Horses that had hay added to their diet in the previos two weeks were at higher risk, as were horses starting into a new batch or a different type of hay. Orchard grass hay was linked with colic more frequently than alfalfa, coastal or Bermuda hay. Hay from round bales are associated with an increased colic risk. Feeding hay or grain on the ground was not identified as a colic risk factor.

Water

Water deprivation increased colic risk. Stall-kept horses with automatic waterers had more colic cases than horses watered from buckets. Consider: is it difficult to keep track of water consumption with automatic waterers, so an owner might not know if a horse had stopped drinking or had decreased its water intake. Horses should always have access to fresh, clean water.

History of previous colic

Horses that had been treated for colic were ore likely to have another episode than horses that had never suffered from colic. Consider: management strategies that led to the first colic could, if not modified, leave the horse at risk for further episodes. If colic surgery was done, adhesions or other complications could lead to another attack.

Other factors

Risk was somewhat higher for horses that had stable vices; were non-aggressive or at the bottom of the herd's pecking order; grazed rocky soil; were given more than two types of supplement; were fed bran either daily or weekly; had been given antibiotics, bute or other drugs in the previous 30 days; had been de-wormed in the previous two weeks; or had health problems other than colic.

What does this mean in terms of feeding and managing horses?

• Colic can occur even in the most carefully managed horses.
• Anything that changes a horse's routine may be linked to colic. Feeding changes (kind, amount, timing or sequence) seem to be the most significant, possibly because the horse's digestive tract is exquitively sensitive to disruptions in microflora, lactic acid concentration, proportion of volatile fatty acids, or pH. Horse owners should avoid change as much as possible and should make necessary feeding changes gradually over a period of several days or weeks.
• It is important to realize that, while some factors are associated with an increased risk of colic, these factors do not necessarily cause colic. For instance, although using an automatic waterer is assocaited with a higher risk of colic, this practice does not cause a horse to colic, and watering from a bucket will not prevent colic. Owners and managers need to evaluate management practices in light of the known risk factors, consdiering each factor as it relates to an individual horse's age, work, metabolism and feeding plan.
• There are limitations to any study that considers all types of colic as the same illness - conclusions that apply to one type of colic may have nothing to do with other kinds.