Colic is the most common medical condition of the horse, comprising up to 50 percent of the medical cases seen by the equine practitioner. Thus, it behooves equine clinicians to have thorough knowledge of the various causes of colic as well as various methods used in diagnosis and treatment.
Does the Horse Have an Abdominal Problem?
Colic is not a disease; rather, it is a clinical sign of a disease. While the term “colic” generally refers to pain originating from the abdominal tract, other diseases—laminitis, foaling or exertional myopathies, to name a few—can have clinical signs that mimic abdominal pain and prompt calls from worried horse owners.
In some cases, the first goal of a veterinarian attending a horse for “colic” should be to ensure that the clinical signs are caused by an abdominal problem and not from somewhere else.
In most cases, a thorough physical examination will help the practitioner determine whether the horse truly has an issue specifically related to an intestinal disorder. For example, an elevated body temperature is typically associated with the need for medical care, but not colic surgery.
Is the Case Surgical or Medical?
For practitioners working on horses in the field, the primary goal of case management is to determine whether the problem will more likely than not require surgical management. While the vast majority of colic cases will resolve with appropriate medical management, cases requiring surgical management must be recognized quickly and referred to a surgical facility—assuming, of course, that the owner opts for referral.
Indications that a horse may require surgery include failure to respond to alpha-agonist analgesia, unrelenting or severe pain, elevated heart rate and sometimes, identification of pathognomonic signs on rectal examination (e.g., palpation of an enterolith).
Other commonly used, although somewhat less useful, diagnostic techniques include abdominocentesis and assessment of mucous membranes.
Medical management of colic typically involves trying to address several parameters that typically accompany such cases.
Pain: Distension, obstruction, torsion, displacement, volvulus and other conditions of the viscous are often associated with varying degrees of pain. Pain is reflected in the typical signs of colic—rolling, pawing, lying down—and they can be a source of considerable distress for the horse and for the owner.
Owners typically will walk a horse suffering from colic, thinking this is an effective treatment. While there is likely some element of distraction involved with walking a horse (for horse and owner), walking does not appear to be directly therapeutic. That said, some colic cases can resolve while a horse is being walked. This is a good example of the post hoc ergo propter hoc fallacy (“After this, therefore because of this”).
Nonsteroidal anti-inflammatory and pain-relieving drugs are readily available to most horse owners, and many will administer such medications on their own, especially flunixin meglumine. Flunixin, however, is not a potent pain reliever; it should not be expected to control the more severe signs of colic pain that accompany colic caused by gas distension or by various conditions that require surgical management for resolution.
The alpha-agonists detomodine and xylazine provide the most profound relief of visceral pain. Detomodine has a longer duration of action, and xylazine may allow for rapid reassessment of the colic patient should surgical referral be an option.
While not directly pain- relieving, buscopan is an antispasmodic (spasmolytic) and anticholinergic drug that suppresses spasms of the digestive system. As such, it may help relieve pain secondarily and may be used to help facilitate rectal examinations.
Hydration: The colic patient’s hydration status is always an important consideration. Fluid administration, either oral or intravenous, is often an important part of care.
Cases of fecal impaction can be assisted by simply giving water via nasogastric tube. As often as every hour has been reported to be helpful in more serious cases.
Balanced oral electrolyte solutions may be preferred by some practitioners but appear to offer no clear advantage.
Intravenous fluid support is often given to horses with colic, especially in hospital settings. Administering large volumes of intravenous fluids can be time- and labor-intensive but can be successfully done in the field.
Target the Intestinal Contents
Mineral Oil: Light mineral oil has been a standard colic treatment for decades. However, how well or even if it works is still subject to some debate. Explanations that mineral oil lubricates the passage of ingesta are perhaps simplistic, and while there is some evidence of mineral oil’s role in the treatment of human childhood constipation, there is little in horses. Some clinicians may assert that mineral oil serves as a marker for the passage of ingesta.
DSS: Dioctyl sodium sulfosuccinate (DSS) is an anionic surfactant that found some popularity in the treatment of colic in the late 20th century. DSS has been used as a fecal softener, wetting agent and cathartic. However, overdosing horses with DSS can cause paralytic ileus, severe dehydration and diarrhea, and possibly death, so it should be used with appropriate caution.
Magnesium Sulfate: Magnesium sulfate (MgSO4 ), or epsom salt, has been administered to horses with impaction-type colic as an osmotic laxative. It is sometimes given orally concurrently with intravenous fluids in hope that the hyperosomotic environment in the intestinal lumen will prompt fluid movement into the bowel, rehydrating the ingesta.
Recently, daily nasogastric tubing for three to seven days with psyllium or magnesium sulfate at a rate of 1 gram for each kilogram of body weight has been advocated for sand impaction colic.
A minority of colic cases require surgical treatment. Surgery should be considered if:
- Pain cannot be controlled, especially with alpha-agonist drugs.
- The horse does not improve despite medical treatment.
- Specific findings at the time of examination are indicative of the need for surgery.
Dr. David W. Ramey is a Southern California equine practitioner who specializes in the care and treatment of pleasure horses. His website is www.doctorramey.com.
Originally published in the January 2017 issue of Veterinary Practice News. Did you enjoy this article? Then subscribe today!