COLIC
Dr. Angie Struck

Colic is a clinical symptom, but the term is commonly used in conjunction with a general process. It is the number one killer of horses, despite the fact that of all colics, most are mild and resolved with medical care. Many of the problems that we see today are a result of the changes that we have made in the way that horses are managed. The horse was designed to roam 25 miles a day, grazing 18 hours per day eating very small amounts continuously. Horses are a flight, versus fight, animal with a very small, streamlined gastrointestinal tract. Humans have increased the demands put on horses, decreased the amount that they are able to move around, increased the parasite load, and changed them in to meal eaters. All of these things set horses up for GI insult.

Recognizing colic
Abdominal pain can be induced by causing traction or tension on abdominal viscera and by inflammation of the viscera. So, there are only a number of physiological reasons in which pain is induced in horses, but each individual horse can be very different in the manner in which they show abdominal pain. I have seen a horse with a colon torsion just stand quietly quivering and I have seen horses with mild gas colic rolling around the stall. It is very important to trust your veterinarian’s assessment of the clinical parameters in order to determine the route of treatment. Some of the ways horses show pain are looking at their sides, pawing, biting at belly, kicking at belly, stretching, sitting like a dog, sweating, getting up and down, rolling, decrease appetite, decrease GI sounds, increase respirations, increase heart rate, Flehmen response, sweating, and obtunded behavior.

What to do
CALL THE VET!!!! Remove the food! You can leave water, if the horse isn’t dunking his head in response to pain. If the horse is rolling, you can walk the horse. If the horse is resting quietly, it is okay to leave it alone. KEEP A CLOSE EYE ON THE HORSE. Don’t only check it every few hours if it is actively uncomfortable.

Veterinary exam
TPR, GI sounds, Mucous membranes, Digital pulses, Rectal, NG tube, Belly tap, PCV/TP.

Medical history---Has the horse had any surgeries? Have there been any recent changes in environment or diet?

Causes
Feed mismanagement, feed selection, parasites, dental issues, sand, decrease water intake, ingestion of toxic plants, mold, blister beetles, infectious processes, medications, and weather changes.

Classifying colic

• Intestinal motility insult
• Intestinal accident
• Inflammation (stress, medications, infection, parasites)

Treatment
Pain relief (Mixed class of opiods=Butorphanol, Alpha-2 agonists =Dormosedan and Xylazine, and Anti-inflammatories= Banamine or bute).

• Fluid—(NG tube or IV)
• Mineral Oil
• Surgery
• Foal---enema

Prevention
Colic is very commonly a disease of management. Horses do very well on a routine, so keep it as simple as possible. High quality feed, parasite control, keep up with dental work, ensure a good water source is available at all times, decrease stress, maintain records, take care in transporting horses, and keep a very close eye on pregnant mares.

I CAN NOT EMPHASIZE ENOUGH THE IMPORTANCE OF QUICK ACTION!!!!!!!!! IF YOU WAIT TO CALL THE VET, IT WILL COST IN THE LONG RUN.

SPECIFIC DISEASES INVOLVING GASTROINTESTINAL SYSTEM---- These are just a few of the many reasons that horses can colic.

Stomach: Gastric ulceration is a common cause of recurrent mild bouts of colic. The horse has a stomach that is divided into glandular and non-glandular sections. There is a clear line of delineation between the two called the Margo Plicatus. Ulcers are seen at this site via endoscope. Severe colic involving the stomach usually consists of impaction. If feed can not get through the stomach, it can rupture. If fluid is backing up into the stomach from the small intestine, this too can end up in rupture.
Small Intestine: Inflammation of the small intestine, or enteritis is uncommon in our area. On the eastern half of the United States, this is more common and severe. Inflammation of the small intestine can occur from bacteria, virus, fungus, and parasites. The inflammation not only causes secretion of fluids into the lumen of the intestine, but also the mediators of inflammation (prostaglandins and histamine) cause the entire system to slow down, which leads to gas distension farther back in the GI system. Younger horses can be more susceptible to ascarid (roundworm) infection, and when dewormed, these ascarids can cause impaction that can lead to severe destruction of bowel wall, or can allow the intestine to get tangled. The small intestine is one of the common places for an intestinal accident. If it gets turned on itself, the blood supply can be cut off. This causes severe gas distension and necrosis of the bowel. Small intestine can also become entrapped in certain places, such as the scrotum of a stallion.
Cecum: The cecum can be the primary site of impaction. This can happen as a post-operative complication secondary to decreased motility or as a result of certain feeds. In Texas, they feed a lot of Bermuda grass hay. This is one example of a feed that is routinely involved in cecal impaction.
Large colon: If horses don’t take in enough water, are stressed, or have sudden changes in feed, the large colon is an easy place for feed to become impacted. Looking at the anatomical shape of the large colon makes it easy to see how this can happen. Sand can also accumulate in the large colon and cause inflammation or impaction, if severe enough. Alfalfa hays that contain a lot of magnesium, ammonium, and phosphate can cause the formation of enteroliths that usually reside in the large colon. These are basically large stones that can work their way into tight spots, where they cause a blockage of the flow of ingesta, and can cause severe damage to the bowel wall. These can be diagnosed on rectal palpation, radiology, or surgery. Inflammation of the colon, or colitis, can be caused by bacteria, fungus, medications, and parasites. The same process that we talked about in the small intestine can happen here, and usually results in severe diarrhea. The bacteria release endotoxin into the bloodstream of horses and can make them very ill systemically. Intestinal accidents can also occur in the colon. This usually is described as a displacement of the colon, when a portion of the colon fills with gas and is able to move to an incorrect position, or it is described as a torsion. When the colon twists, it is one of the most painful colic presentations a horse can have.
Small Colon: Impaction in this structure can be incredibly difficult to treat. Medical treatment is the method of choice, and can be very troublesome. The small colon can be severely affected before the horse tells us there is a problem.
Peritonitis: The fluid that normally inhabits the abdominal cavity can become infected with bacteria. The horse usually presents very painful and diagnosis is made with abdominocentesis. Treatment is aggressive antimicrobial and anti-inflammatory therapy.
Intra-abdominal abscess: The two most common bacteria that form abscesses in the horse’s abdomen are Streptococcus Equi and Corynebacterium pseudotuburculosis. These are otherwise known as Strangles and Pigeon Fever, respectively. These are diagnosed by rectal palpation, ultrasound, CBC, abdominocentesis, and serologic assays.

There are diseases in horses that aren’t directly related to the GI system that can cause horses to colic. Some examples of these are Renal disease, Respiratory disease, Musculoskeletal disease, Hepatic disease, and Reproductive diseases.

Foal Colic
The most common cause of colic in foals is meconium retention. The meconium is the material that is formed in the horse’s GI tract while the foal is in the womb. During gestation, the foal swallows small amounts of amnion. This is processed in the GI tract and forms thick, dark, sticky manure that the foal should defecate soon after birth. If the foal has difficulty getting rid of its meconium, it becomes very painful. Most of these impactions can be relieved with enema, fluids, and sometimes oil.

Foals can also suffer from bladder rupture. Stud colts are more prone. The buildup of urine in the abdomen causes a number of systemic changes as well as direct pain due to distension. Physical exam, bloodwork, ultrasound, and abdominocentesis are the usual methods of diagnosis. It is treated surgically.

Congenital anomalies also occur in foals. These are usually found at surgery when medical treatment of the foal does not relieve the colic symptoms.

Intestinal accidents can occur in foals, just as in adults. Intestine can be twisted on itself, foals tend to be more curious than adults and can ingest foreign bodies, intestine can be trapped in umbilical or inguinal hernias.

Enteritis can also affect foals as it can adults.

Foals that are under a lot of stress can develop gastric ulcers just as adults do.

Colic Surgery
I learned very quickly while working in California that to no fault of their own horse owners often times do not have a very clear understanding of what takes place during a colic surgery. If your veterinarian is telling you that your horse needs surgery to attempt to treat it’s problem, they are most often doing so in haste, because they know that if it does not receive surgery, it may be too late. So, I think it is important to give you an idea as to what colic surgery entails. Surgery is needed when 1) Your veterinarian found something during the initial workup that clearly indicated the need or 2) Medical therapy does not resolve the colic.

What indicates the need for surgery?

Rectal Palpation--- There are certain findings that, in combination with other perameters, indicate the need for surgery. Distended loops of small intestine are an example of one of these findings. Enteroliths are another.
Nasogastric intubation--- If large volumes of fluid are retrieved via NG tube, the likelihood of a lesion that requires surgery are high. The type of fluid retrieved is very important. Enteritis fluid is one example of a type of fluid that would not have you rushing to the operating table.
Abdominocentesis---Belly fluid in the horse should be straw-colored, very clear, should have a protein <2, and should have a low white blood cell count. This fluid continuously swims around and lubricates the intestine. If it comes into contact with intestine that is damaged or is leaking, it changes in color, texture, and consistency. The clinical parameters also change. If there is question as to the integrity of a piece of intestine, the horse will likely need surgery.
Response to treatment---If pain medications, IV fluids, and routine medical therapy do not make the horse comfortable, there is a point when you have to consider whether or not they are going to. If they do not relieve the horse, and surgery is an option, the decision is often times made on that basis.

Surgical procedure---
Anesthesia, positioning of the horse, entering the abdomen, exploring the abdomen, treating the problem, closing the abdomen, and waking the horse up, are all areas we will discuss thoroughly in class.