As one might expect in a gathering of equine veterinarians discussing colic, much of the Sunrise Session dedicated to the topic covered evaluation of the colicky horse to determine severity and decide on medical vs. surgical management. Moderators Dana Zimmel, DVM, Dipl. ACVIM, Dipl. ABVP, assistant professor of equine extension at the University of Florida's Department of large animal clinical sciences; and Liz Santschi, DVM, Dipl. ACVS, clinical associate professor and chief of large animal surgery at the University of Wisconsin-Madison, discussed their take on several hypothetical colic situations.

When evaluating a colicky horse, Zimmel said she starts with the horse's vital signs and interprets them. "Go back to the basic mechanisms of pain in the horse, and interpret them in context of the horse's age," she said. "I teach that if the horse's heart rate (which rises with pain) is more than 60 beats per minute, my actions will be different than if it is lower than that. I'll reflux the horse (pass a nasogastric tube to attempt to relieve pressure in the stomach) quick because I'm worried about a distended stomach. If the horse's heart rate is over 100 beats per minute, the horse has a decreased chance of survival.

"After getting significant reflux from the horse (say, 10-15 liters), I take his heart rate again," she said. "If it doesn't decrease, that implies that the horse may have a more serious problem such as ischemic bowel. A rectal exam and an abdominal tap are indicated to obtain the diagnosis. One attendee asked if they would refer the horse to a hospital if there was a lot of reflux, because of a likely obstruction. "There's no one thing to do," said Santschi. "Different practitioners have different skills and situations like distance to the referral hospital. It also depends on the character of the reflux. If it's grass, OK, but if it's yellow, bloody stuff, I'll investigate. If I get more than four liters of reflux and a distended small intestine, I'll prepare for surgery."

Another attendee asked if heart rate was a less accurate indicator of pain in heavy horses, citing a case where a draft's heart rate was only about 24, but he wanted to roll for two days. Then when they opened him up, his colon was black (dead). "You can't get hung up on just one thing," Santschi said. "If the heart rate is low but the horse is flipping around like a flounder out of water, he goes to surgery. Also, I've seen many horses with a volvulus of the large colon (twisted obstruction) with a low heart rate, especially if the pain is recurrent.

"It also depends a bit on the client--whether they are willing to have a wasted trailer trip if the horse passes manure on the way," she added. "It also depends on how far you are from the hospital. If you have a four-hour ride ahead of you, let's get going!"

They also discussed when to run various lab tests and what the results might mean. Outside of the normal complete blood counts, they noted that there are several tests that are more specific for particular problems--these can help if a horse has extreme values for the tests, but don't help as much for more average levels, Santschi noted.


"Large colon torsion is very uncommon prepartum (before delivery), but very common afterward," Santschi said. Also, enteroliths can cause small colon problems in these horses, as can mesenteric rents (tears in the membrane that anchors the intestines to the abdominal wall). This causes colic when either the flow of ingesta (eaten food) or vascular (blood) supply is impeded.

"You often see these (mesenteric rents) as old ones; they've probably had small intestine passing in and out of them for awhile," she commented.

As for when to refer a late-term broodmare for surgery, Zimmel noted that the decision is probably mare and surgeon-specific. "Many would take the foal via C-section if the mare is very sick and her chance of survival is slim.  Most veterinarians would prefer to leave the foal to be born on his own time," she said.

One attendee asked if anesthetizing the mare for surgery posed any problems for the foal; Santschi answered that hypoxia is usually the only issue. "It can be tough in these situations when the client won't decide the first priority--mare or foal," she added.

Another practitioner asked if Zimmel or Santschi would change their normal drug protocols for a broodmare; neither does anything different, they said.

Uterine rupture has a good prognosis if the mare gets to surgery quickly, said Santschi--but it's a disaster if you wait a few days. "Medical treatment is a complete waste of time for these mares," she added.

Zimmel noted that the incidence of ileus seemed to be much lower than it was 15 years ago, likely because many mares are referred earlier. Another attendee commented that decreased time in surgery with better methods has definitely helped the success rate as well.


"I love ruptured bladders (in foals)--my mother can fix those!" said Santschi with a laugh. "The only tricky part is the electrolytes. The rupture isn't an emergency, but the electrolyte imbalance can be. If it's been going on awhile, I'll lavage the inside of the abdomen with saline solution to help norm out the electrolytes.

"These foals tend to be quite acidotic, and bicarbonate can help quite a bit," she added. "Adhesions are very rare, and the foals can often go home the next day. I don't catheterize them; if you sew it up and it's watertight, you don't need to catheterize. Some rents can heal just by keeping the bladder decompressed with a catheter, although surgical repair is the preferred method of treatment."

Zimmel noted that surgery for meconium impaction is almost never done any more, because these foals (those undergoing surgery for this reason) often present later for adhesions. Santschi added that she didn't think foals get adhesions any more than adults, but that they do often get nastier diseases resulting in more problems.

A recently published paper on minimizing adhesions in foals was mentioned; this study reportedly found that anti-inflammatories such as Banamine and intravenous DMSO decreased adhesions after an exploratory abdominal surgery (Sullins KE, White NA, Lundin CS, Dabareiner R, Gaulin G. Prevention of ischaemia-induced small intestinal adhesions in foals. Equine Veterinary Journal. 36(5):370-5, 2004 Jul.). Santschi noted that she prefers to use DMSO postoperatively as an abdominal lavage for the same reason. Zimmel noted that abdominal ultrasound using a 5 MHz rectal probe was good for diagnosing problems in foals, but unable to penetrate the large abdomen  for most adults.


Banamine, an anti-inflammatory medication, is widely used by both practitioners and owners to combat pain and inflammation associated with several conditions. "It's a wonderful drug," said Santschi. "It can make them look a little better than they are, and the problem is abuse. If you've given a horse 10 ccs every four hours, then you need to do something different!"

Zimmel added that less savvy owners need specific instructions about what to do and what to look for, i.e., signs that would tell them to call the veterinarian back out for another look.

One attendee asked about the relatively new anti-spasmodic medication Buscopan. Another warned that a horse can go into ileus (bowel obstruction) with the decrease in gut motility with certain types of colic. Another noted that it was useful with spasmodic colic and some types of diarrhea that are associated with colonic hypermotility (excessive bowel muscle activity). Santschi added that it is widely used in the United Kingdom, and may require some additional time for U.S. veterinarians to become familiar with its appropriate usage.

About the Author

Christy M. West

Christy West has a BS in Equine Science from the University of Kentucky, and an MS in Agricultural Journalism from the University of Wisconsin-Madison.

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