What to consider when contemplating sending your horse to colic surgery

You’ve been with your colicky mare for hours, hand-walking her and waiting to see if she’ll respond to medical therapy. When your veterinarian finally calls it and says you need to take her to the local referral center for a surgical consultation, your stomach drops. The barn closes in, and you suddenly feel like you’re in a nightmare version of the game “Would you rather.” Would you rather take your horse to surgery and risk major complications during or after? Or humanely euthanize so she is no longer in pain and won’t undergo a major operation?

“Surgical treatment comes with the risk of complications, which we define as any deviation from the ideal postoperative course,” says Marco Gandini, DVM, PhD, associate professor in the University of Turin’s Department of Veterinary Sciences, in Italy. “Complications are unexpected negative outcomes. These differ from procedural failures where the purpose of the procedure itself was not fulfilled and from surgical sequelae, which are adverse effects inherent to a given procedure.”

Such unexpected complications can develop despite exemplary pre-, intra-, and postoperative care. And in the case of colic surgery, even the most minor complications can spiral, with some severe ones leading to euthanasia. Complications might also cause in-hospital costs to skyrocket despite a technically successful surgery.

“That said, depending on the type of colic and surgical procedure, complication rates can be low and survival rates can be quite high,” says David E. Freeman, MVB, MRCVS, PhD, Dipl. ACVS, Appleton endowed professor in the University of Florida’s Department of Large Animal Clinical Sciences, in Gainesville.

How high can those survival rates reach?

Some published studies relay exact figures. Spadari et al. (2023), for instance, stated the short-term survival rate was 68.5% for all horses undergoing surgery and 80% for all horses surviving anesthesia.

Freeman hesitates to give his clients a flat percentage when discussing survival after colic surgery. “If we give an 80% survival rate, it’s okay if you’re in that 80%. But someone has to be in the 20%,” he says. “You have to present survival rates carefully, and I would never present just a rate alone but as part of a discussion.

“Something simple such as a displacement, intraluminal obstruction, or nonstrangulating disease generally has a pretty good prognosis, close to 95-98%,” he adds. “But for the strangulating diseases, it’s not as high. I emphasize that when we do the surgery, we will learn more about the prognosis. But my typical approach is to give the horse a chance within reason.”

So how do you decide if you’re going to take your horse to surgery?

Playing the Odds

Although colic is a major reason for emergency consultations with equine veterinarians, most cases can be managed medically. Only an estimated 8-20% of cases require hospitalization for intensive care. Many of those can still be successfully managed medically (Stratico et al., 2022; Dybkjaer et al., 2022).  Further, only 19-43% of horses hospitalized due to colic need surgical treatment (Dybkjaer et al., 2022).

These data are in line with those Freeman presents: “Approximately 1.4-17.5% of horses with colic require or undergo surgery.”

Motivators and Barriers for Surgical Consent

In a recently published study, Kate Averay, BSc, DVM, and her colleagues at the University of Sydney School of Veterinary Science, in Australia, reported results from a questionnaire horse owners in Australia and New Zealand completed about motivators and barriers for consenting to exploratory surgery in colicking horses. Of the 1,502 owners that completed surveys, 18.7% stated they would absolutely consent to surgery, and 26.1% relayed they would not.

“Thus, half of all survey respondents said they would consider exploratory abdominal surgery if their horse was colicking,” says Averay.

High chance of survival and the horse’s emotional value were top factors supporting an owner’s decision to choose surgery. Owners who originally said they would consider or consent to surgery said financial costs, uncertain probability of survival, and concern for the welfare of their horse would make them reconsider their answer, electing not to pursue surgery, says Averay.

“Additionally, owners who originally said they would not consent to surgery did state that they might reconsider if there was a high probability of survival and if the only alternative was humane euthanasia,” she explains. 

She also found that owners of insured horses were more likely to consider or consent to exploratory surgery. When owners anticipated survival rates below 50%, reduced athleticism, or a convalescent time of more than 12 months, they were less likely to consider surgery. Further, owners of older horses were less likely to elect surgery.

“The results of this survey highlight the importance of educating clients regarding colic surgery to help them to make informed decisions,” says Averay. “I recommend owners consider in advance whether they would take their horse to colic surgery if needed. If they have a horse in which colic surgery would be an option, it is important to have decided your equine referral hospital of choice, have transport to the hospital arranged, and have the necessary funds or deposit available. It may also be prudent to have investigated options for veterinary insurance coverage.”

What to Expect With the ­Unexpected

Gandini and colleague Gessica Giusto, DVM, PhD, reviewed colic surgery literature. They identified a wide range of reported postsurgical complications in colic patients. They then proposed a classification system for defining postoperative complications. It grades complications as Class 1 through 6 based on whether the condition resolved medically with the treatment of symptoms or if the complications were severe enough to require a second surgery or euthanasia. They applied the classification system (see the table below) to data from 190 horses that underwent colic surgery at their ­institution.

Gandini and Giusto reported that 47 of the 190 horses (24.7%) had no complications following colic surgery. 

“Our data also showed that the less severe complications occurred more frequently than severe complications,” Gandini says. “In fact, of those horses that had some complications (143), 116 (81.1%) were successfully managed medically. Seven (4.9%) required a second surgery, and 14 (9.8%) unfortunately required euthanasia.”

Thus, approximately 89% of horses either had no complications or complications successfully managed medically, he explains.

Horses might have more than one complication concurrently. Of the 190 horses in the study, 25.8% had one complication, 20% had two complications, 13.2% had three, 11.6% had four, and 4.7% had five.  

Specific Complications

Incisional Issues

Based on Gandini and his colleagues’ data, the most frequently reported complications are incisional issues. A minor surgical complication such as a mild incision infection could lead to more severe complications, such as a hernia or even complete dehiscence (reopening) and evisceration (protrusion of the intestines through the surgical site). In their study incisional drainage was a Class 2 complication, affecting 23.7% of the horses.

Postoperative Colic

“Two of the most common Class 3 complications we identified were postoperative colic (POC) and postoperative reflux (POR, where GI fluid accumulates and fills the stomach and must be removed by nasogastric intubation),” says Gandini. “These complications may have many causes, ranging from adaptation of the intestine to anastomosis (where a section of intestine was removed and the healthy parts reattached) to failure of the intestine to regain normal motility (movement of digesta through the GI tract).”

“We usually see these complications following small intestinal surgery, and they need aggressive and prompt management, potentially even a second surgery,” says Freeman.

One cause of postoperative colic is a segment of bowel that is twisted or strangulated or dies after the first surgery, he says.

“Lots of things can go wrong,” he adds. “When we’re faced with POC, we can administer intravenous fluids, remove fluid from the stomach, and provide analgesics for pain relief. But I don’t like to wait too long before taking these horses back to surgery.”

For owners concerned about a second surgery, Freeman says, “A second surgery might not fix everything. But what we do know is that for uncontrollable POC there is no choice. The only options are humane euthanasia or surgery.”

Postoperative Reflux

“For every surgeon performing small intestinal surgery, POR is a big concern,” says Freeman. “My typical approach to POR is managing these horses medically for 48 hours or so, and if they don’t respond to treatment in that time, we have a serious discussion for the need for a second surgery.”

Findings during a second surgery can include an impacted anastomosis site in the small intestine. “Sometimes we don’t find anything except the anastomosis is simply not working. If we redo the anastomosis, some horses do fine,” he says.

Freeman reports a “good survival rate” and elimination of reflux after a second surgery in most cases.

Laminitis

“Laminitis is a terrible complication, and the long-term prognosis is not good,” says Freeman. “It’s unfortunate because the gastrointestinal tract is often functioning very well in these patients.” Laminitis is a painful disease in which the tissues that suspend the coffin bone within the hoof capsule become damaged and inflamed. In severe cases they separate, releasing the coffin bone to rotate downward or sink.

Sepsis (bodywide inflammation) can play a role in the development of laminitis. However, horses with equine metabolic syndrome might have a higher risk of ­postoperative laminitis than nonmetabolic horses.

“And we can never predict the outcome,” he says. “We can say it’s a mild case. But then a week later they’re sinking and the coffin bone is coming through the sole.”

Dispelling Myths

“Owners are still embracing myths regarding colic that they need to shed immediately,” Freeman says.

One is that older horses can’t tolerate anesthesia and surgery or that the horse “isn’t the same” after surgery. “This is simply not true,” he says. “Colic surgery is not a death sentence, just an interruption in progress. Those horses can meet their full athletic potential.”

Freeman says owners can be overly pessimistic about proceeding with colic surgery on older horses. However, many studies have clearly demonstrated that senior horses (20-plus years old) can handle transportation, anesthesia, and surgery as well as younger horses, with similar survival and complication rates.

“Colic in older horses is most likely caused by a strangulating lipoma, which should be approached as a true emergency that prompts immediate referral to a surgical facility,” Freeman says.

Secret to Success: Early Referral

Freeman acknowledges that primary care veterinarians are very good at treating and managing colic on the farm with diagnostics, analgesics, and fluid therapy. Perhaps too good, he says.

“Treating the horse on the farm appeals to the owner a lot,” he explains. “But it’s expensive and delays surgery. This costs money that the owner won’t have for surgery if that is needed. It also adds an unnecessary and life-threatening delay.”

He says if the referring veterinarian suspects the case needs another opinion because of a lack of progress, owners must make that decision sooner.

“If the surgeon gets the horse early enough, then they might not need a resection and anastomosis,” Freeman says. “They might just need a simple correction. We showed that horses that came quickly enough, even with a strangulating disease, did much better than those that required resection and anastomosis (Rudnick MJ et al., 2022).

“I’ve said many times, if I had only got this horse 12 hours earlier, a favorable survival rate would have been much more likely,” he adds. “It may have been 95% then. But if there is a delay in referral, then by the time I see it the chances of success are down to 65-75%.”

Take-Home Message

There are no promises when it comes to colic surgery in horses. The good news is mild complications occur far more frequently than serious ones, if at all. What is the easiest way to reduce postoperative complications? “Get them to a surgical facility, and get the surgery done ASAP,” says Freeman.