Colic and Digestive Health

AAEP State of the Art Lecture: Colic

Each year the American Association of Equine Practitioners (AAEP) elects an outstanding practitioner and awards him or her the Frank J. Milne trophy to recognize a lifetime of service in a particular area of expertise. The 2006 designate was Nat White II, DVM, MS, Dipl. ACVS, the Jean Ellen Shehan Professor and director of the Marion duPont Scott Equine Medical Center at the Virginia-Maryland Regional College of Veterinary Medicine, and chairman of the AAEP Foundation Advisory Committee. White has spent a lifetime in service to the horse, specifically in researching and treating equine colic.

This year's presentation was sponsored by the AAEP Foundation ( and Platinum Performance (

White has authored more than 150 articles and 35 book chapters, in addition to writing several books, including Equine Acute Abdomen and Handbook of Equine Colic, as well as the surgical texts Current Techniques in Equine Surgery and Lameness and Current Practice of Equine Surgery. White, a former director at large of the AAEP, is a past president of the American College of Veterinary Surgeons (ACVS) and has served as director of the ACVS Veterinary Symposium since 1997.

He gave his presentation, "Equine Colic: A Real Pain in the Gut," on Dec. 4, 2006, in San Antonio, Texas, and it was attended by nearly 3,000 industry representatives and equine practitioners. White recounted a timeline of understanding equine colic using case examples from his clinical experience and research. He used computer-generated videos done in collaboration with at team at the University of Georgia to show intestinal diseases and rectal examinations.

Reality Check

"When you teach you are constantly reminded about reality," began White. "In a lecture hall I once asked the students, 'If you only had an hour to live, what would you do?' Students answered differently: 'I would want to listen to you because every minute is like an eternity."

White said the goal of his lecture was that the next horse anyone in the room saw with colic would be looked at a little differently. "There should be a progression in your examination," he stated.

The Glass Horse project group founded by Jim Moore, DVM, PhD, of the University of Georgia with support of American Live Stock Insurance, worked with White to create some new animations to help veterinarians and others better understand colic. For more on the Glass Horse visit

White has spent a career caring for horses with all types of problems, but the mystery of colic has never lost its appeal.

"I remember when I was at UC Davis doing my residency and had 15 surgical colics in one month, and 14 died," recalled White. "The surviving horse came back and died with liver disease. I figured there had to be a better way."

Then he met Moore and Doug Byars, DVM, Dipl. ACVIM, who started the Bolshoi Colic Research Program at the University of Georgia that's named after a horse that died of colic and whose owners wanted to help fund research on the problem. That meeting focused White's interest in colic.

White's complete presentation can be found in the AAEP's convention Proceedings, which can be purchased through

Colic Research and Risks

Colic, defined as any abdominal pain, has resulted in the deaths of horses throughout recorded history, stated White. In fact, today it is second only to old age as the number one cause of equine deaths in the United States. White said it is one of the most difficult diseases to study since there are so many things that can cause colic.

White and others have studied the incidence of colic. He said out of 100 horses in a population, four to 10 cases of colic can be expected per year. That number can vary widely between farms, ranging from zero to 35 cases per 100 horses per year.

About 10-15% of colic cases happen in horses that have had clinical signs of colic before, with some horses having two to four episodes per year. Fortunately, a majority of colic cases (80-85%) are termed "simple" because they either resolve by themselves or can be treated medically.

A small portion of colic cases (2-4%) require surgery. Large colon torsion is the most common portion of the bowel to be struck with strangulation obstructions, with strangulations of the small intestine causing the highest fatality rate.

In one study based on a sample of 28,000 horses in 1998:

  • Average loss of use due to colic was two to three days;
  • Value of horses lost due to colic in the United States was about $70 million;
  • Total cost of colic to the U.S. industry was about $144 million.

White said another study estimated the number of colic surgeries in the United States annually is 12,000-24,000 cases, or possibly as many as 2.7 colic surgeries per hour.

While parasites were a major cause of colic earlier in the history of the horse, they became less important with the creation of modern anthelmintics. But White said as parasites become resistant to those drugs, there could be more colic caused by parasites in our horses' futures.

In 1966, the first work was done looking at the strangulated colon at Colorado State University. By 1970 there was more surgery being done to try and correct severe colic causes (twists, displacements, intussusceptions--when the gut telescopes back into itself).

"In 1978 Banamine came along and made us look at what was happening in the gut," said White. That was followed by research into ischemia reperfusion, endotoxic shock, and epidemiology. Discovering there were specific risk factors for colic helped veterinarians and horse owners begin to prevent colic, although not all of the answers have been discovered.

According to research findings, change in diet or feeding of large amounts of grain (greater than 5 kg/day in adult horses) increases the risk of colic by 6.3 times, and feeding concentrates at a rate of 2.5-5 kg/day increases colic risk by 4.8 times, noted White.

Here are some other findings of colic associations:

  • It has been reported that some breeds are more susceptible to colic (Thoroughbreds, Arabians, Standardbreds, gaited horses, and Warmblood stallions);
  • Middle-aged horses are at higher risk for simple colic;
  • Older horses with colic are more likely to need surgery;
  • Weanlings and yearlings are more likely to have ileocecal (at the junction of the small and large intenstines) intussusceptions;
  • Older horses (greater than 12 years) are at a higher risk of developing strangulating lipomas (fatty benign tumors that can develop around the intestines);
  • Male horses and older horses have a slightly higher risk of entrapment of the small intestine in the epiploic foramen (the passage connecting the two sacs of the abdominal cavity;
  • Horses with sudden decreases in activity (such as strict stall confinement) are at greater risk of cecal and large colon impactions.
  • Location and management can be associated with colic (i.e., enterolith (intestinal concretion) formation related to diet and geographic region, such as California);
  • Cribbing is associated with increased risk of simple large colon obstruction and entrapment of the small intestine in the epiploic foramen;
  • Tapeworms are associated with ileocecal intussusception or cecocecal (pertaining to the cecum) intussusception;
  • Pregnant mares have an increased risk for colon displacement or volvulus intestinal obstruction due to a twisting or knotting of the bowel);
  • Ulcers can predispose a horse to colic;
  • Transportation has been linked with an increased colic risk;
  • Weather has been found to change management techniques, which resulted in feeding/turnout changes that are associated with colic.

More, and More

The information distilled above was only a small portion of White's presentation. He also covered Intestinal Response to Injury; Diagnosis: Determining the Need for Emergency Abdominal Surgery; Treatments for Colic, Prognosis and Prevention; and Future Research. More on these subsets of his talk will be presented in the online version of the AAEP Wrap-Up.

Colic: An Overview for Horse Owners

What's the one word that strikes fear into the hearts of all horse owners? Colic. It can strike any horse at any age for a myriad of reasons--there's impaction colic, gas/spasmodic colic, strangulating colic, and many other versions. At the recent Healthy Horses Workshop, an owner education session held Dec. 2, 2006, in San Antonio, Texas, in conjunction with the 52nd annual American Association of Equine Practitioners Convention, colic was the first topic of discussion.

According to a 1998 USDA National Animal Health Monitoring Study, colic was second only to old age as leading cause of death in horses over 30 days of age, said David Freeman, MVB, PhD, Dipl. ACVS, professor/associate chief of staff and chief of the large animal surgery department at the University of Florida. Colic ranked second and third in causing days of lost use and morbidity (illness), respectively.

But colic treatment success continues to improve; Freeman noted that while from 1968-1986, 49% of horses undergoing small intestinal surgery died, in 2005 that number was down to 12-18%.

"We are constantly learning about this disease," he said. "We know a lot of things, but not all we'd like to know.

Types of Colic

Freeman noted that the overall incidence of colic is about 10-36%, according to the 1999 Handbook of Colic by White and Edwards. This breaks down into various types of colic as follows:

  • Mild idiopathic (of unknown cause) colic: 83%. "I suspect that most idiopathic colics are impactions," Freeman commented.
  • Impaction: 7%. "Those related to diet are mostly from fine-textured coastal Bermuda grass, particularly in the Southeast," he reported.
  • Gas/spasmodic colic: 4%. "Gas is associated with all colics," he noted.
  • Intestinal strangulation (twisting): 3%. "Strangulations require surgery," he stated.
  • Gastric (stomach) rupture: 2%
  • Enteritis (intestinal inflammation): 1%. "Enteritis mostly manifests as diarrhea, but there are other manifestations as well," Freeman said.

Colic can result from odd non-food things horses eat as well. "Horses are supposed to be picky eaters," he commented. "But all of us who do colic surgery have these little trophies to disprove that theory (part of a lead rope, sand, gravel chunks, etc.). One horse I treated ate nipped-off clinches (pieces of horseshoe nails left after farriers clinch and clip the nails when setting shoes) from the ground and enteroliths (solid rocklike masses in the gut) formed around it. These can be as big as a football, but usually they're softball size."

Prognosis varies with the type and location of the colic. For example, Freeman reported that lesions of the large colon have a better prognosis than those of the small intestine, and the prognosis for a strangulated (twisted) intestine is not as good as that for a non-strangulating lesion.

You Can Fight Colic

Freeman described these steps to helping your horse survive colic:

Establish a solid working relationship with your veterinarian, preferably before the horse gets sick. Include the veterinarian at the referral hospital if you can, he recommended.

Record observations and a chronology of events. Observe your horse when he's normal so you can recognize the abnormal. It's not a bad idea to keep a log of observations if you notice a change in behavior.

Contact your veterinarian at first signs of colic.

Don't treat the horse yourself--especially don't give Banamine (flunixin meglumine) in the muscle! Myositis (voluntary muscle inflammation) is one complication. "I have seen three horses that by the time they got to clinic, their colic was over, but they died from the myositis," recalled Freeman. "It's not a risk you want to take."

Do not repeat Banamine doses frequently. The full dose should only be given once or twice a day. Kidney damage can result because the horse is often already dehydrated from not drinking. "The odds are low, but when it happens, that's it. You can't bring the kidneys back," said Freeman. Repeated doses can mask signs of pain from colic.

Freeman also discussed the value of several on-farm treatment and management practices for colic:

Painkillers "We have all these great painkillers now, but signs of pain are what you use to see how the horse is recovering or not," Freeman cautioned. "Don't say your horse is a baby about his clinical signs. They're a lot tougher than you think. Some horses show little pain even with severe problems. But if they paw, look at their flanks, roll, etc., after getting painkillers, that's bad."

Walking does prevent injury to horses, people, or property, he said. However, walking a horse excessively might mask signs of deterioration, he warned; stop frequently to assess the horse's demeanor. If he needs surgery, walking won't help.

Feed/Water Do not feed horses until colic is resolved, as this makes it worse, he warned. "I've seen a lot of really sick horses still eat," he said. "They're amazingly tough; far tougher than we are. It's not unusual for a colicking horse to have a good appetite." He also noted that water might not be recommended if the horse's stomach is already distended; adding water might rupture the stomach. Your veterinarian can examine the horse and tell you whether he should have water.

Oral medications Don't give these to a colicky horse, recommended Freeman.

Surgical vs. Medical Colic

Freeman said "referral" to a veterinary hospital for a colic case might include any of the following scenarios:

1) "Your vet has decided that colic is too severe to be managed on the farm. The horse needs to be monitored and observed closely. He might not need surgery--maybe 50% of horses referred don't need surgery. Perhaps it's the therapeutic trailer ride," he said with a smile.

2) The horse might need surgery, more intensive pain management, and/or more advanced diagnostic methods.

3) You can't watch the horse forever; you might have to go to work or somewhere else, and if he's at hospital, someone will be watching him continuously.

"We're probably 80% accurate on making that choice of whether a horse should be referred," he reported. Medical colics (those that can usually be managed without surgery) include impactions from feed material and colics due to inflammation (from enterocolitis, or inflammation of the small and large intestines; colitis, inflammation of the large intestine only; or proximal enteritis, inflammation of the upper gastrointestinal tract). Surgical colics include strangulations, displacements, and nonresponsive impactions.

Evaluating Colicky Horses

"When we work up a colicky horse, we get a history, what drugs he's been given and when (this is very important), do a physical exam, and check his cardiovascular system (this is critical; it tells us if he's in shock)," said Freeman. "We pass a stomach tube to see if there is reflux (backflow of stomach contents via stomach tube). Fluid in the gut will back up from the obstruction all the way to the stomach, so reflux is a diagnostic test, and it helps the horse feel better. The more reflux you have, the closer the obstruction is to the stomach. We usually see reflux with small intestinal disease, but not large intestinal disease."

He said he might also test peritoneal fluid (from the abdominal cavity); bloody color means the affected gut is probably dead. That is not a good sign. Rectal palpation might also be employed, or ultrasound, which is non-invasive and can be used to evaluate the whole abdomen to a depth of about six inches or so. Ascarids, intussusceptions (telescoping of one portion of intestine into another), and a variety of intestinal changes can be seen with ultrasound, he said.

Some bowel displacements can be corrected by anesthetizing the horse and rolling him and/or using other nonsurgical treatments. However, if a diagnosis can't be reached with the aforementioned procedures, surgery might be used for diagnosis as well as treatment, he noted. During surgery, bowel can be replaced if it is out of position, its contents can be removed (enterotomy), and it can be cut out if it is strangulated and dead. If this occurs, the healthy bowel on either side is stitched together (anastomosis).

Some horses might need a second surgery for complications, he reported.


Endotoxemia can occur with various infections or a strangulating lesion. Freeman said that when the gut is strangulated and black, it's dead--its surface cells die and its contents, which are full of endotoxin from bacteria, can get out into the bloodstream. Endotoxin makes the horse sick and causes the most serious complications of colic.

"Endotoxin itself is not damaging, but cells overrespond to it," he explained. "Flunixin (flunixin meglumine, or Banamine) is helpful because it blocks the body's response to endotoxin. There is some evidence that flunixin might interfere with healing of the small intestine, but it is doubtful that that effect is enough to not use it in these horses until we get a better drug for treatment of pain and endotoxemia."

How do you know if a horse has endotoxemia? If you see a red ring around the tops of his gums. "We call this a toxic ring," said Freeman. "Also, some horses so depressed the owners think he's quieter and getting better. But if he's got red gums and is in shock, with his skin cold and clammy, he's got severe endotoxic shock and he is not getting better."

Surgery Aftercare

After surgery, the horse will need frequent monitoring and physical exams, possibly antibiotics, fluid therapy, pain medication, and a gradual return to hay and water. He'll be hospitalized for four to seven days, said Freeman, then he'll need 60 days of rest at home before resuming normal activity. He recommends stall rest only for Days one to 14, then stall rest with hand walking on Days 15-30. If the horse is quiet, he can be placed in a small paddock or round pen if the incision is healthy for Days 31-60.

Feeding can resume when the surgeon thinks it's safe, usually 18-36 hours after surgery, and water should be provided free choice. "The bowel doesn't recover from surgery right away; initially it has lower motility called postoperative ileus," said Freeman. "Start with feeding little handfuls of hay and see how he handles it. Watch for feces; that means the plumbing is working."

Antibiotics will often be given for two to three days to inhibit infection at the surgical site. Banamine is usually given for at least two days to inhibit pain and inflammation. Check your horse's temperature (normal is 99.5-100.5°F) and report fevers to your veterinarian. Why not give antibiotics for a longer period? They don't kill everything, said Freeman, and if you get antibiotic-induced diarrhea, you might lose your horse.

"It kills off good bacteria and the bad ones take over," he said. "I like to keep any antibiotic treatment as short as possible. Plus it's a little like showing the enemy your weapon--they get resistant. Some major hospitals have been closed because of outbreaks of antibiotic-resistant salmonella."

Most horses will be quiet from the stress of the disease and surgery, and some might lose weight. Mild colic might also occur; report this to your veterinarian.

Possible incision problems include infection and hernia. "You'll always get swelling along the incision," said Freeman. "Get the veterinarian to look at it if you're worried or if it's draining fluid. This can lead to a weakened incision and hernia. Hernias aren't life-threatening; mares have had foals with them, and horses have competed with them. Some people have killed horses because of hernias; don't do that! Some hernias even self-resolve."

Ponies vs. Horses vs. Drafts

Freeman said that light-breed horses tend to come through colic surgery better than heavy horse breeds. Why?

"Everything is big, everything inside them is big, so the surgery takes longer and they're lying on that huge muscle mass for a long time--some can't get up after surgery because of muscle damage," he explained. "That's one of our challenges--improving their success rate."

But it's not a case of smaller is better--Miniatures and ponies have issues, too.

"When they're off feed, they will mobilize fat stores (full-sized horses don't do this as much)," he noted. "They will end up with hyperlipidemia (a lot of fat mobilized into the bloodstream) and end up with liver damage, so they don't do well either. They come through surgery fine, the surgery is very easy, but because they didn't eat before or after surgery, they need to be fed via tube, IV, whatever, or they'll die from hyperlipidemia."

Life After Colic Surgery

"The first six months after surgery is the critical period, and if you get to one year after surgery, you can relax a little," Freeman said.

"People think a horse after colic surgery is finished, but that's not true," he stated. "We now know that many of these horses go back to very top-level performance.

"For example," continued Freeman, "Left Bank was a Thoroughbred racehorse who colicked as a 2-year-old and had some small intestine removed. He raced from two to five years old, and had 24 starts and 14 wins (three of them Grade 1 stakes). He won $1.4 million lifetime and set records.

"A steeplechaser named Victorian Hill had large colon torsion and resection; he raced for five years and won $296,000 after surgery," he added. "He was a leading steeplechaser at the end of his career.

"There's no longer a perception that if a horse steps on the trailer for colic surgery, he's not coming back," Freeman said.

Owner Responsibilities

An owner's job involves preparation, says Freeman. He suggested:

  • If your horse is boarded, provide your contact information, assign responsibility for care decisions in your absence, provide insurance information, and establish limitations on treatment, if any.
  • Be prepared for emotional trauma; think about what you'd do in this situation ahead of time to avoid the "trapped-owner syndrome." It's hard to make decisions at 3 a.m. when you can't call anyone.
  • Maintain a positive relationship with your veterinarian and referral hospital.
  • Remain educated, but keep an open mind; there are many differences of opinion on colic treatment practices.

Prevent the Problem

What can you do to avoid this mess? Minimize abrupt management and diet changes, and keep plenty of fresh water available at all times, said Freeman. Maximize grazing time, feed good-quality roughage and few concentrates, and maintain a good deworming program.

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