Equine Colic Risk Factors
Horses that are kept on pasture or that spend more time grazing seem to exhibit fewer colic episodes.
Photo: Anne M. Eberhardt/The Horse
A number of risk factors are associated with increased incidence of colic, and horses that have a history of colic occurrences and/or previous colic surgery might be more likely to exhibit future bouts.
Management factors might also affect the likelihood of colic episodes. Dietary management practices such as using certain types of feed, increased amounts of feed, and increased concentrations of feed may be associated with higher incidences of colic, laminitis (a painful foot condition), and endotoxemia, a condition in which toxins are released from dying bacteria (cell walls) within the body and circulated in the blood.
Changes in the diet, such as in the type and/or quality of feed and hay or other dietary forage, might lead to higher colic incidence.
In reality, a limited number of risk factors for colic can be directly controlled by owner intervention. Using good feeding practices and dietary management, parasite control, and good health practices are probably the extent of our ability to minimize the risk factors for colic in the horse.
Although specific and predictable relationships of feeding practices to the incidence of colic are often unclear, dietary management is universally considered to be important when evaluating risk factors associated with developing colic.
Furthermore, constant access to fresh, palatable water is also universally regarded as a controllable facet of management that may significantly impact the incidence of colic.
The incidence of colic may be associated with the manner in which horses are housed. Horses in densely populated environments, horses that are being moved from pasture to a stall, and horses with unrestricted access to lush pasture may all be at increased risk of colic.
Horses that are kept on pasture or that spend more time grazing, provided the grass is not too lush, seem to exhibit fewer colic episodes.
Changes in Activity Level
Changes in activity levels have been associated with colic. However, the specific relationship of activity to colic incidence is poorly defined and speculative. There may be an association of increased incidence of colic with exercise at either extreme (lack of exercise and highly intense exercise).
Regular dental care is thought to be an important component in preventing colic. However, there is no concrete documentation of this association. Poor mastication can lead to maldigestion, esophageal, and intestinal impactions. For these reasons (and others) it is advisable your horse(s) receive regular dental care.
A judicious parasite control program is also considered to be important in the prevention of colic (see updated American Association of Equine Practitioners’ 2013 Parasite Control Guidelines and consult your veterinarian for recommendations).
Generally speaking, colic episodes are likely to be fewer on farms that practice good parasite control. However, the manner in which a successful parasite control program is instituted varies greatly and depends on farm management practices, horse density, geographic location, and economics.
Often, parasite control programs are designed to minimize the cyathostome (small strongyle) infections in horses. The larval forms of cyathostome parasites can encyst in the equine intestine and are often associated with increased colic episodes and/or overall poor health. Tapeworm infestations may occur less frequently but have also been associated with various types of colic such as intussusception, ileal impaction, and spasmodic colic.
While parasites can trigger colic, deworming medications also have been implicated in inducing colic, but whether a specific medication is more likely to cause colic is unclear. Although there is no real evidence of this relationship, a recent deworming could be associated with colic episodes.
Ambient Temperature and Weather
The debate continues and conclusions vary about the effect of ambient temperatures and weather on the incidence of colic. Warmer conditions have been associated with increased dehydration and, subsequently, increased incidence of colic. Colder temperatures have been associated with a reduced amount of water consumption and increased incidence of colic.
Overall, clear association between such environmental factors as temperatures, temperature changes, rainfall, or barometric pressure and the incidence of colic has not been shown on a repeatable basis. Nonetheless, clinical experience and some epidemiologic evidence suggest an association between temperature variables and colic incidence.
Some specific horse behaviors have been suggested to cause colic. Cribbing is commonly believed to lead to colic through the “swallowing” of air that might accumulate in the stomach and intestines. Wood chewing and pica (indiscriminate consumption of non-food items) may lead to colic from digestive upset and foreign body obstruction. Pica (eating manure) is probably more common in younger horses, and horses that chew wood may be lacking dietary roughage.
The cause(s) of any colic episode often goes undiagnosed. Many times colic episodes may be initiated by a combination of factors. Although some factors are believed to play an associative role in increasing colic incidence, the reality is most colic episodes occur due to undefined causes and all or none of the above risk factors for colic may be at work for any one episode.
About the Author
Brad Bentz, VMD, Dipl. ACVIM, ABVP, ACVECC, owns Bluegrass Equine Performance and Internal Medicine in Lexington, Ky., where he specializes in advanced internal medicine and critical care focused on helping equine patients recuperate at home. He’s authored numerous books, articles, and papers about horse health and currently serves as commission veterinarian for the Kentucky State Racing Commission.