Horse Colic: Surgical and Medical Management
- Mar 1, 2010
Next to old age, the most common cause of death in horses is colic. But, realistically, this is like comparing apples to oranges. Old age is caused by one thing: being old. Colic, on the other hand, simply refers to the presence of abdominal pain, has a myriad of causes, and the prognosis (chance of a positive outcome) can vary remarkably, depending on the underlying cause.
Virtually every horse owner is already terrified of colic and likely has at least one horror story to share with horsey friends. The goal of this article is to help you understand colic basics and the recent advances made in equine practice that make colic not as scary as it used to be.
"Recovery from colic episodes is quite high, and in recent years, the equine clinician's ability to diagnose and treat horses with colic has improved dramatically," wrote Frank M. Andrews, DVM, MS, of Louisiana State University's School of Veterinary Medicine, in the August 2009 edition of the journal Veterinary Clinics of North America: Equine Practice. In his preface, titled "New Perspectives in Equine Colic," he continued, "Recent advancements in diagnosis and treatment has led to this dra-matic improvement in outcome and improved the health of horses with colic."
The following article was written with the advice and support of Fairfield T. Bain, DVM, Dipl. ACVIM, ACVP, ACVECC, an internist/pathologist at Equine Sports Medicine & Surgery in Weatherford, Texas.
Medical or Surgical?
So, your horse is colicky and you are panicking. That's normal. In addition to worrying about whether or not your horse will live to see another day, you are also wondering if he will require surgery or not. When is colic an emergency and how do you know if it is a "surgical" colic or a "medical" colic?
Unfortunately, this remains a gray area in emergency medicine.
"There are no strict parameters or a checklist for veterinarians to follow when deciding whether a case should be managed surgically or medically," relays Bain. "Every case is unique, and the decision often needs to be made quickly, in the barn, often based on the horse's history and the physical examination findings alone."
Hallmark signs that the veterinarian should consider surgery include:
- Uncontrollable pain, often necessitating repeated administration of anti-inflammatory medications, such as flunixin meglumine, or sedatives, such as detomidine;
- A large volume of gastric reflux obtained via nasogastric intubation;
- Finding distended loops of small intestine, displacement (abnormally located large colon), or a foreign body; or
- Lack of gut sounds on auscultation.
Nathaniel A. White, DVM, MS, Dipl. ACVS, Jean Ellen Shehan professor and director of Virginia Tech's Marion DuPont Scott Equine Medical Center in Leesburg, wrote the following in his abstract describing research he presented at the 11th Congress of the World Equine Veterinary Association, held Sept. 24-27, 2009, in Guaruja, Sao Paulo, Brazil: "Horses that have constant pain, particularly after an analgesic has been administered, are significantly more likely to need surgery. Horses that have return of pain or those requiring a second administration or multiple administrations of an analgesic are also significantly more likely to need surgery. The key is monitoring of signs and adjusting one's tolerance for any recurrence of pain, as horses may show pain after administration of an analgesic, but the sign of colic can be markedly decreased."
"Ultrasound examination of the colic patient has dramatically changed the pre-surgical diagnostic evaluation and adds sig-nificant information in most cases," adds Bain. "Ultrasonography helps when deciding whether to go to surgery or to continue with medical management alone. Often, we can identify specific lesions via an ultrasound exam that require surgical manage-ment or those that suggest an inflammatory process or displacement that might be managed medically."
Under the Knife: Surgical Management of Colic
Once the vet and horse owner have made the decision to take a horse to surgery, either with or without a firm diagnosis of the underlying cause of the colic, then the main goals of surgery are to:
- Relieve pain;
- Correct physiologic imbalances (i.e., fluid and electrolytes);
- Identify/repair the colic's cause; and
- Stimulate/maintain intestinal transit.
Attempting to tackle the topic of colic surgery itself in this article would be an exercise in futility, as the subject could fill a textbook all on its own. One unifying feature of the various surgical approaches is the possibility that postoperative complications will develop.
Battling Surgical Complications
As if preparing a horse for abdominal surgery, fishing through scores of feet of intestines, locating the problem, and fixing it aren't hard enough, the plethora of potential postoperative fallouts adds a whole other dimension to the complexity of treating a colicky horse.
Common postoperative complications include problem recoveries from general anesthesia, incisional issues, postoperative ileus, adhesions in the abdominal cavity (where the gut "sticks" to the abdominal wall or other internal structures as it heals), laminitis (founder), jugular thrombophlebitis (inflammation of the vein) at the site of the intravenous catheter where drugs are administered, and continued pain and/or inflammation.
Ileus Postoperative intestinal ileus is failure of normal propulsive motion through the intestines, and it can result in colic from eventual fluid distension of the intestines and stomach.
According to Bain, "One of the most common postoperative challenges, and the one that probably increases the total costs of hospitalization, is postoperative ileus."
Ileus is a major cause of morbidity (illness) and mortality (death) during the post-surgical period in horses. The causes of ileus remain unknown, but experienced clinicians speculate that there is an imbalance in the incoming signals from the central nervous system, resulting in decreased propulsive movements of the intestinal tract. The currently recommended diagnostic tactic is ultrasonography. Horses with more than three distended loops of small intestine, with a concomitant (accompanying) decrease in intestinal contractility and mobility coincident with gastric distension and reflux from the nasogastric tube, are considered to have ileus.
Which horses are at risk for postoperative ileus? According to one study, 88% of horses that developed small intestinal ileus had a strangulating obstruction as the initial cause of colic. Examples of strangulating obstructions include intussusceptions (in which part of an intestine prolapses into another), volvulus (in which the bowel twists on itself), and dis-placement of intestines through a hole (hernias). Another study found that 41% of postoperative ileus cases had a large intestinal lesion at the time of surgery.
Adhesions These are bands of scar tissue that form between two structures that are not normally connected, such as adjacent loops of intestine. Adhesions also can form between a loop of intestine and other organs or structures located within the abdominal cavity. Adhesions can also "incarcerate," or constrict, the intestine. Regardless of how/where they form, adhesions can cause the horse to re-colic at a later point in time, necessitating an additional surgery, which can create more adhesions that could necessitate additional surgery ... and so the cycle continues.
This leads one to the question, "How much can one horse (and owner) take?"
The various means of decreasing rate of adhesion formation include: using an atraumatic surgical technique; preoperative intravenous administration of the potent free radical scavenger dimethyl sulfoxide (DMSO), the antibiotic potassium penicillin, and the non-steroidal analgesic agent flunixin meglumine; and the intraoperative administration of sodium carboxymethylcellulose (CBMC) or intraperitoneal unfractionated heparin.
"Heparin reportedly decreases adhesion formation by helping to impair fibrin formation that could result in eventual fibrous adhesion formation" explains Bain.
In contrast, CBMC is a very thick solution that lubricates the bowel to reduce trauma during surgical manipulation of the intestines and serves as a physical barrier between adjacent loops of intestine (or other structures within the abdominal cavity) to minimize adhesion formation. Researchers on a study published in 2008 reported horses receiving CBMC intraoperatively were twice as likely to survive compared to untreated horses (see TheHorse.com/13637). This finding has prompted routine use of CBMC in colic surgeries.
"Historically, adhesions could become so severe that humane euthanasia during subsequent surgeries in affected horses was not uncommon," says Bain. "In my experience, adhesions have become less of a problem than in the past, likely due to more selective management, such as better handling of the intestines during surgery.
"I rarely see this complication in my practice," he adds.
Finally, studies have also demonstrated that performing an omentectomy-- surgically removing the fatty fold of tissue that suspends the abdominal organs from the wall of the abdomen--significantly decreases rate of adhesion formation. Various experts agree that an omentectomy is easily and quickly performed during abdominal surgery and that it decreases post-operative complications and improves the long-term prognosis in colic survivors.
Incisional Issues A large number of complications can occur along the surgical incision line on the abdomen. Fluid swelling (edema), infection, hernia, and even dehiscence--separation of the layers of the surgical wound that results in spillage of the internal organs--can happen post-surgically. As such, commercially available abdominal or "belly" bandages are recommended as part of routine postoperative care.
Based on the available data, abdominal bandages appear effective in preventing edema and minimizing other types of inci-sional complications. What's more, their use is simple and relatively economical (although some can cost several hundred dollars).
Medical Management of Colic
Managing horses medically might seem on the surface to be an easier task than managing them surgically, but it is just as complicated. Here is a recommended seven-pronged approach to managing horses with abdominal pain:
- Withhold food and water;
- Administer analgesics;
- Administer antispasmodics;
- Administer fluid therapy--either intravenous or orally (via nasogastric intubation);
- Administer laxatives via nasogastric tube;
- Alter intestinal mobility pharmacologically; and
- Use controlled exercise.
There are multiple drugs that the veterinarian can employ to decrease pain and intestinal cramping, modify intestinal motility (if appropriate), and maintain hydration and appropriate electrolyte levels. Minimizing the occurrence of drug interactions and ensuring toxic levels of drugs are not reached, particularly non-steroidal anti-inflammatory drugs, becomes increasingly difficult as the number of drugs a colicky horse is receiving increases. Moreover, if complications such as laminitis (founder) or gastric ulcers develop during treatment, then case management becomes even more challenging.
A Note on Insurance
Add "phone insurance company" to the checklist you need to follow when your horse is colicking.
"If a horse is insured, there is now a second party that needs consideration when faced with whether or not to proceed with surgery," says Bain. "Owners should know the specifics of their insurance policies and have the appropriate contact information on hand when heading to the hospital with a colic patient. In some circumstances, choosing euthanasia over surgery when there is a correctable condition could void the policy. It is, therefore, important to know the policy details and be able to quickly contact the insurance adjuster when these situations arise."
Other indications of colic severity that can help a veterinarian make a decision about how to manage a colic case can include an increased pulse rate (transient or sustained) and certain findings on rectal exams. Opinions and circumstances vary, so ask your veterinarian if you have questions regarding how he or she differentiates a medical from a surgical colic.
Colic is a stressful event for everyone involved. With proper preventive strategies owners and veterinarians can, in the vast majority of cases, successfully manage colicky horses. Advances in diagnostics and aggressive medical and surgical treatment of severe colic have, and continue, to increase the horse's chance of survival.
About the Author
Stacey Oke, MSc, DVM, is a practicing veterinarian and freelance medical writer and editor. She is interested in both large and small animals, as well as complementary and alternative medicine. Since 2005, she's worked as a research consultant for nutritional supplement companies, assisted physicians and veterinarians in publishing research articles and textbooks, and written for a number of educational magazines and websites.
POLL: University Equine Hospitals