Ask The Vet: What to Expect During a Colic - April 09

The epiploic foramen is an anatomical window in the horse’s abdomen that is created by part of the liver, the large vein that carries blood to the liver for detoxification (the portal vein), and a ligament of the stomach and pancreas. An Epiploic Foramen Entrapment happens when small intestine works its way into that window and becomes lodged, cutting off the blood supply. The entrapped intestine, devoid of its blood supply, starts to die and causes significant abdominal pain manifested as a severe, rapidly occurring, colic episode. Every horse has an epiploic foramen, but an entrapment does not occur commonly. We generally know that less than 10 percent of all colic cases require surgery. We also know that of those that need surgery, less than five percent are due to epiploic foramen entrapment. There are suspected predisposing factors for development of epiploic foramen entrapment, such as cribbing behavior, increased amount of time in a stall and horses that have a history of colic. We don’t know what the mechanism is that causes intestine to enter the foramen and much of our understanding of epiploic foramen entrapments comes from retrospective data. These entrapments can be very tricky because the fatal risk of rupturing the portal vein while trying to reduce the entrapment at surgery is high. Most often, the intestine that was entrapped will require a resection and anastamosis. This means the unhealthy intestine is surgically removed and the healthy intestine is sutured back together. This process comes at a cost after surgery. Horses that have had small intestinal surgery may develop a condition called ileus postoperatively during which time the normal motility pattern of the intestine is not intact and fluid backs up into the stomach, which then requires decompression through a nasogastric tube. (Horses cannot vomit.) Additionally, the risk of adhesion formation is higher and the likelihood of future colic episodes is also higher. From the retrospective data, long-term survival (more than 12 months) for epiploic foramen entrapments postoperatively ranges from 35 to 70 percent, but horses that had epiploic foramen entrapments were more than four times more likely to require another surgery following the first.

This certainly sounds like an age related event to me. Oftentimes, older horses will have arthritic joints. While they may get around just fine, they spend more time than they did as a youngster laying down. From the information offered in this question, it certainly doesn’t sound like colic and obviously the horse is well taken care of by loving owners. Another reason that I see horses laying down more often than normal is laminitis. In this case, it doesn’t sound like this horse would be at risk for laminitis, but for our owners reading this column, keep laminitis in mind when you have a horse that becomes acutely stiff, doesn’t want to move, rocks back on their hind legs in an effort to relieve pain on their front feet or lays down a lot when they normally don’t. This is always a reason for a veterinarian to examine your horse as soon as possible.

This is a great question and one that may not have an exact answer. The different symptoms usually revolve around the duration (how long the signs have been present) and the severity (how bad it is) of the pain. Typically, colic secondary to impactions and gastric ulcers will cause mild to moderate pain such as the horse being off feed, looking at their flank, laying down (but not rolling), kicking at their belly and/or grinding their teeth and usually have a gradual onset over many hours or even days. Gas (or sometimes called “spastic”) colic can occur with weather changes, feed changes or can even occur without an explanation. While gas colic can be mild, it also can easily mimic a surgical condition. Think of how you feel the day after partaking in an all-you-can-eat authentic Mexican buffet. It doesn’t feel very good. Neither does a colic caused by excessive gas accumulation. A horse can be violently painful to the point of rolling, sweating, being very anxious and even throwing themselves on the ground or against the wall in an effort to get away from the pain. This can resemble cases where intestine has become strangulated and requires surgery. (See our previous posting regarding strangulation colics). These are cases that are typically very painful right away. The answer to this question is also a good place to educate the owners of stallions or geldings on what is commonly thought of as a urinary problem. When a male horse is seen camped out and “trying to pee” without producing a stream of urine, this is often a sign of colic. Urinary tract infections are not common in horses and by stretching out, some horses find a bit of reprieve from abdominal pain.

When considering the generalities of colic, colic can be classified into two different categories; obstructive and strangulating.

Obstructive colic would include impactions, gas accumulation, enteroliths, etc. Obstructive colics are more often treated medically (with the exception of enteroliths). Strangulation, on the other hand, occurs when the blood supply to a segment of intestine has been compromised. This is always surgical. It can happen to the small or large intestine for a number of different reasons, none of which are preventable. It occurs in all sizes, all breeds, all ages and all disciplines. Strangulation typically happens acutely (meaning quickly). There is no rhyme or reason why it occurs to some horses and not to others. It really is just bad luck and my sympathies go out to this owner.

Equine Protozoal Myelitis(EPM) is a disease of the neurologic system and does not cause colic. But, I do agree that the colic should be resolved prior to starting treatment for EPM.

For this horse, a general colic exam is warranted.

Horses are funny creatures. I don’t know why this mare had colic episodes so regularly for just a short period of time. I have seen mares colic because of painful ovulations during their estrus cycles, but since this mare did not have a history of colic prior to the consistent episodes, this is just a guess. The timing of the episodes would make me think weather, feed or environmental changes would have had little to do with them, but they certainly may have. Other reasons that horses can have recurrent colic episodes include formation of adhesions between the intestines and other abdominal organs or the abdominal wall, but in an otherwise healthy horse with no previous history of colic, this would be very unlikely. I am happy to hear that she is doing well now.

What is being described here is not colic, but a syndrome commonly known as “tying up”. Horses that are used to a daily heavy exercise routine, allowed a period of rest and then are exercised again, can experience muscle cramping. (This was historically called “Monday morning sickness” when horses were used for plowing fields. They were given Sunday off and when put back into work in the fields Monday morning, they would get muscle cramps.) There are a number of different causes of muscle cramping in horses and this is an area of active research. Horses may be more prone to a specific form of cramping depending on their breed. Depending on what “type” of myopathy (muscle disease) this horse has will determine whether or not the cramping can be expected to return. The good news is that many of these syndromes can be managed nutritionally. To know which syndrome this horse has will require a muscle biopsy (a minor procedure done with sedation and local anesthetic) and can be performed by the regular veterinarian. The biopsy sample will then be sent to a laboratory specializing in the analysis of these samples. (Dr. Stephanie Valburg at the University of Minnesota is an excellent resource). The sample will come back with a diagnosis and recommendation for nutritional management of the specific syndrome. The reason Lasix (a diuretic) was used in this case is because when a horse ties up and muscle cells break down, they release myoglobin and lactic acid into the blood stream. Myoglobin can be damaging to the kidneys and we want to make sure the kidneys are perfused adequately to prevent permanent damage. The dark brown urine resulted from the myoglobin, which is a reddish color, being filtered through the kidneys into the urine. I would recommend a muscle biopsy for this horse so it can be determined what kind of diet will be best for treatment of his specific syndrome.

This is an interesting case. It sounds like the management of this horse is top notch. He has good care, good feed and turnout and is leading the life all horse’s dream of. There are certainly a number of horses that have recurrent colic that we cannot explain. It may be that they have a more sensitive gastrointestinal tract than their herdmates, or that their motility patterns aren’t exactly normal and cause them to get gassy, or weather changes cause them to colic, etc. The one clue given in this question is that the horse routinely colics after eating. While the topic of the month was not meant to revolve around gastric ulcers and there certainly are so many more reasons that horses colic besides gastric ulcers, this is one case that I would for sure have the horse scoped for ulcers because of this clue specifically. The other thing that I didn’t gather from this history is whether or not a veterinarian has treated this horse for his colic episodes. If not, it would be in the horse’s best interest to have an examination by a veterinarian to rule out other causes for his colic.

It sounds like the horse presented in this question is one that would fall under the heading of a “hard keeper”. A horse in this category has a metabolism such that they can eat all day, have minimal exercise, good grain and deworming program and still have a hard time keeping weight on. Gastric ulcers can certainly cause a horse to go off feed. However, the ONLY way to diagnose gastric ulcers is to use a gastroscope (for more on this procedure see the first question this month on the topic of ranitidine) to view the lining of your horse’s stomach. Despite what some people believe, a “grunt test” where pressure is applied to the bottom of a horse’s abdomen with a fist to see if he’ll grunt or not is not diagnostic for gastric ulcers. Nor is a fecal test looking for blood in the feces.

After having a definitive diagnosis of ulcers, the question comes to what to use as treatment. There are a myriad of medications that have been compounded (not FDA approved!) for the treatment of gastric ulcers and most are being done illegally. Gastrogard, Ulcergard and some of the others discussed in the previous posting mentioned above, have been shown to work and they are worth the price you pay for them.

Compounded medications don’t heal ulcers and end up costing more in the long run. Ulcers can occur in any horse and are associated with stresses (among other things). The best way to prevent them is to keep your horse in a routine and minimize the stress on him. If you know he will be stressed (going to a show, a rodeo, long trail ride, trailering for an extended period of time, etc.) Ulcergard can be used as a prophylactic to keep ulcers from forming. Your veterinarian should be able to help you with diagnosing and treating gastric ulcers (or refer you to a facility with a gastroscope), and other issues related to weight loss (making sure teeth are properly floated, proper deworming protocol, etc.).

Having a beloved horse put to sleep is not an easy thing in any situation and I extend my sympathy to you. But in this situation, it appears to have been justified given the diagnosis of an esophageal rupture. The esophagus (the tube connecting the mouth with the stomach) has a very stretchy wall and is very compliant. This is what allows boluses of food to be passed easily and without discomfort. It is highly unlikely that the intubation in this case caused the rupture. The reason I say this is based on a number of different facts. First, the tubes that are used in colic treatment are soft and pliable. The more times the tube has been used, the stiffer it will become, but it takes quite a bit of force to rupture an esophagus and even an older tube is not stiff enough to rupture a healthy esophagus by itself. Second, it is very rare to have a primary disease (i.e. cancer or infection) of the esophagus in horses that would cause the wall to become less compliant and cause it to rupture with routine intubation. I would be interested to know if this horse had a post-mortem examination. It is most likely that the rupture occurred prior to the intubation and that is what caused the horse to show discomfort in the first place. I have seen cases of this where horses have swallowed foreign objects with sharp edges or when they have formed strictures in the esophagus secondary to chronic choking episodes and were unable to swallow past this narrowing.

As a final note, the blood in the tube may not have been from the esophagus. It is possible (and more likely) that the blood was from a structure in the nose called the ethmoids. These are not uncommonly bumped by the tube and can bleed. From the limited information given, this veterinarian appeared to have provided appropriate care and promptly referred the case to a hospital when his or her circumstances were not able to provide further care.

This is an excellent question. If your horse is rolling, it’s best to try to get him up and keep him walking. With that being said though, if your horse is violently colicking, rolling, throwing itself against the stall wall, and any other sort of self-destructive behavior in an effort to relieve its pain, you should stay away to avoid getting hurt. Those situations are not common, but they do happen and it is best to wait until a veterinarian is on site with strong sedation to avoid anyone being seriously hurt. Bute (phenylbutazone) or Banamine (Flunixin Meglumine) are two non-steroidal anti-inflammatory medications that work similarly and most barns or horse owners will have them in their emergency kit for situations such as this. It is wise to contact your veterinarian about your horse’s colic BEFORE you give ANY medication as it may affect the examination.

While it is true that horses may have an elevation in their blood glucose, this is a RESULT of the colic and not a CAUSE for the colic. Glucose (or “blood sugar”) is made and released by the liver and is necessary for the normal function of all cells in the body. When a horse colics, the stress of the colic causes the release of glucose by the liver to increase, making the level of glucose in the blood increase. It has no effect on severity of the colic. With that being said, serum chemistry profiles are routinely done on horses with vague or chronic colic signs at our hospital. Since colic is a general term for pain in the abdomen, it doesn’t necessarily need to occur because of a dysfunction of the gastrointestinal tract. Colic can be caused by kidney or liver problems, bladder stones, cancer within any abdominal organ, or a generalized infection of the abdominal cavity (peritonitis). And while blood glucose levels may not be very diagnostic in this situation, a blood test to evaluate function of the abdominal organs can certainly have diagnostic value.

Sudden changes to a horse’s diet can certainly cause some of them to have mild to moderate episodes of colic, mostly due to excessive gas buildup in the large intestine and cecum. A good rule of thumb when a diet change is expected (new load of hay, new barn, etc.) is to mix half the amount of the current hay or pelleted feed with half the amount of the new feed for a short period of time (i.e. a week or so) before totally switching over to the new feed. This will allow the horse’s digestive system to gradually compensate for the nutrient differences. While this isn’t always possible, it can make the transition to a new feeding program easier on the horse (and the owner!).

In reference to the specific feeding program in this question, both Tifton 44 and Vaughn hays are Bermuda Grass hybrids. The Vaughn variety is popular among horse owners because it is finer and has more leaves, making it easy to believe it is therefore more digestible. Since they are both considered “fine stemmed” among Bermuda grass hybrids, I don’t know that it matters which of the two varieties is fed. However, one DOES want to be cautious about the Coastal variety of Bermuda hay. If the Coastal Bermuda grass hay is of poor quality, this HAS been linked to ileal (the ileum is a segment of the small intestine) impactions specifically. The horse posed in this question sounds like one that may be very sensitive to diet changes, but once the gastrointestinal system becomes “used” to a diet you should have fewer diet related episodes of colic.

As far as other management practices for this horse, our owner seems to be par for the course in encouraging water intake. If you are adding powdered electrolytes to the water bucket, I would encourage you to make another water source available that does not have electrolytes in it. Some horses do not like the taste the electrolytes give water. I do know of some owners who have tried the powdered Gatorade mixed into the water bucket instead of generic electrolytes to encourage horses to drink and, for some horses, that has done the trick. Horses are tricky animals and as the old saying goes, “You can lead a horse to water, but you can’t make him drink.” It does seem to me, though, that this horse is under excellent care and just needs a bit more time to adjust to diet changes.

Another avenue to pursue if your horses continue to colic from what you perceive to be diet related issues would be to contact an equine nutritionist (most well known feed companies have them on staff) or your county extension office to help you with a nutrition analysis of your program.

There is no link between steroid (Dexamethasone is only one of many in a veterinarian’s arsenal) administration and colic. However, it is possible that the lack of water intake leading to an impaction in your filly’s case may have been caused by her reluctance to move to the water bucket because her feet hurt. While the dose of Dexamethasone reported in the question above is considered well within the “safe” range for steroids, laminitis can be one of the uncommon, unfavorable side effects of administering any steroid. As far as the string of colic episodes experienced by your veterinarian, I’m sure any equine veterinarian will tell you that when the weather does weird things, horses colic. I’ve practiced in three distinctly different geographical areas of the United States and it doesn’t seem to matter where I’ve been, storms and weather changes result in more emergencies. It’s anyone’s best guess as to how a drastic change in barometric pressure causes horses to develop signs of colic. And since colic is not preventable, the best we can do is keep our management practices consistently up to snuff, make sure our horses have access to clean, fresh water and quality hay or pasture and have a veterinarian’s phone number handy for those times when, despite our best efforts, our horses colic.

While we’ve always recognized the fact that gastric ulcers can certainly cause a horse abdominal discomfort, what we’ve recently discovered is that ulcers are more prevalent than originally thought. What a horse does for a living (racing, showing, broodmare, etc.) can have an influence on the presence and severity of ulcers. Studies have shown that up to 94 percent of Thoroughbred horses in active race training and over 50 percent of show horses have some degree of ulceration. So why do horses get ulcers? There are many different factors that go into the equation, but they can include level of stress, alterations in the amount and acidity of acid produced by the stomach, alterations in natural protective barriers and some medications. Stomach ulcers in horses, termed Equine Gastric Ulcer Syndrome (EGUS), are scored according to their severity. A Grade 0 means that there is no ulceration present. The most severe grade is a Grade 4 and occurs when the ulcer is very deep. In rare instances, the ulcer will perforate (or rupture through) the stomach causing peritonitis (an infection of the abdomen) and can lead to death. Ulcers that have a higher grade and those located in certain areas of the stomach can cause colic. There is no way of knowing if colic is a result of a stomach ulcer without visualizing the stomach with an endoscope. This procedure is performed under sedation and a long flexible camera is passed up the horse’s nasal passage, down the esophagus and into the stomach. After determining that your horse has ulcers, there are many different treatments available. Most medications for ulcers have an effect on the amount and/or the pH of the acid produced by the stomach through different mechanisms.

This question asks about Ranitidine specifically. Ranitidine (Zantac in human medicine) is in a class of drugs that act to decrease the amount of acid produced by the stomach and increase the acidity of the acid that is present to allow the ulcer to heal. While Ranitidine is used most commonly in foals, it has been shown in certain studies to be effective in adult horses as well. In adults, the number of tablets that need to be used per dose and the variability in how it is absorbed, as well as the availability of other products that have a more consistent efficacy (Omeprazole or Gastrogard), make Ranitidine a less popular choice for treatment.

Considering it wasn't easy for you to tell your horse was having a bout of abdominal pain, this must have been a very mild colic, something like a gasious or spasmodic event. In general, it isn't safe to get on a horse that is experiencing colic, primarily because the horse is focused on its inner pain and will not notice you on his back if he decides to drop and roll. This puts you in jeopardy. However, one useful strategy to use when a horse is noticed with colic is to put him on the longe line or in the round pen and ask him to move out in a vigorous trot for 10 to 15 minutes, assuming he isn't on strict rest due to a musculoskeletal problem. The trotting action may relieve gas within or spasms of the intestinal smooth muscle, and when the horse stops, he feels no more pain and goes about his normal business. It is possible, in this case, that if you had asked your horse for a trot, you might inadvertently have done him some good. But, a general rule is that you should never ride a horse in colic distress. If you are away from the barn, get off and lead your horse to where it can receive prompt medical attention. If the horse doesn't respond quickly to the trotting attempt or within an hour of starting to colic, you should contact your veterinarian immediately.