Horse colic

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Colic in horses is defined as abdominal pain, but it is a clinical sign or a symptom rather than a diagnosis. The term colic can encompass all forms of gastrointestinal conditions which cause pain as well as other causes of abdominal pain not involving the gastrointestinal tract. The most common forms of colic are gastrointestinal in nature and are most often related to colonic disturbance. There are a variety of different causes of colic, some of which require surgical intervention and can prove fatal. Colic surgery is usually an expensive procedure as it is major abdominal surgery. Among domesticated horses, colic is a major cause of premature death. The incidence of colic in the general horse population has been estimated between 10 and 11 percent on an annual basis. It is important that any person who owns or works with horses be able to recognize the symptoms of colic and determine whether or not a veterinarian should be called.

Contents

[edit] Types

This list of types of colic is not exhaustive but details some of the types which may be encountered.

[edit] Pelvic flexure impaction

This is caused by an impaction of food material (Water, Grass, Hay, Grain) at a part of the large bowel known as the pelvic flexure of the left colon where the intestine takes a 180 degree turn and narrows. Impaction generally responds well to medical treatment, but more severe cases may not recover without surgery. If left untreated, severe impaction colic can be fatal. The most common cause is when the horse is on box rest and/or consumes large volumes of straw, or the horse has dental disease and is unable to masticate properly. This condition could be diagnosed on rectal examination by a veterinarian.

[edit] Spasmodic colic

Spasmodic colic is the result of increased peristaltic contractions in the horse's gastrointestinal tract. It can be the result of a mild gas buildup within the horse's digestive tract. The signs of colic are generally mild and respond well to spasmolytic and analgesic medication. Anecdotally, spasmodic colic may be caused by too much fresh grass.

[edit] Ileal impaction

The ileum is the last part of the small intestine that ends in the cecum. Ileal impaction can be caused by obstruction of ingesta. Other causes can be obstruction by ascarids (Parascaris equorum) or tapeworm (Anaplocephala Perfoliata) as mentioned below.

[edit] Sand impaction

This is most likely to occur in horses that graze sandy or heavily grazed pastures leaving only dirt to ingest. The term sand also encompasses dirt. The ingested sand or dirt accumulates in the pelvic flexure, right dorsal colon and the cecum of the large intestines. As the sand or dirt irritates the lining of the bowel it can cause diarrhea. The weight and abrasion of the sand or dirt causes the bowel wall to become inflamed and can cause a reduction in colonic motility and in severe cases even peritonitis. Historically medical treatment of the problem is with laxatives such as liquid paraffin or oil and psyllium husk. More recently doctors are treating cases with specific synbiotic (pro and prebiotic) and psyllium combinations. Some cases may need surgery. Horses with sand or dirt impaction are predisposed to Salmonella infection. Horses should not be fed from the ground in areas where sand, dirt and silt are prevalent although small amounts of sand or dirt will still be ingested by grazing. Management to reduce sand intake and prophylactic treatments with sand removal products are recommended by most veterinarians.

[edit] Enterolith

Enteroliths in horses are round balls of mineral deposits often formed around a piece of ingested foreign material, such as sand or gravel. When they move from their original site they can obstruct the intestine. Enteroliths are not a common cause of colic, but are known to have a higher prevalence in states with a sandy soil and where an abundance of alfalfa hay is fed, such as California. Once a horse is diagnosed with colic due to enterolith it usually requires surgery to correct the condition.

[edit] Large roundworms

Occasionally there can be an obstruction by large numbers of roundworms. This is most commonly seen in young horses as a result of a very heavy infestation of Parascarus equorum that can subsequently cause a blockage and rupture of the small intestine. Deworming heavily infected horses may cause dead worms to puncture the intestinal wall and cause a fatal peritonitis. A blockage of the small intestines by worms may well require colic surgery. A more conservative approach can be to give a horse a laxative (eg liquid paraffin) prior to deworming if a heavy worm infestation is suspected. It is often the result of a poor deworming program. Horses develop immunity to parascaris between 6 months age and one year and so this condition is rare in adult horses.

[edit] Tapeworms

Tapeworms at the junction of the cecum have been implicated in causing colic. The most common and harmful species of tapeworm in the equine is anaplocephala perfoliata.

[edit] Cyathostomes

Acute diarrhoea can be caused by cyathostomes or "small Stronglus type" worms that are encysted as larvae in the bowel wall, particularly if large numbers emerge simultaneously. The disease most frequently occurs in winter time. Pathological changes of the bowel reveal a typical "pepper and salt" colour of the large intestines. Animals suffering from cyathostominosis usually have a poor deworming history.

[edit] Left dorsal displacement

Left dorsal displacement is a form of colic where the left dorsal colon becomes trapped above the spleen and against the nephrosplenic ligament. It may necessitate surgery although often it can be treated with exercise and/or phenylephrine, at times anesthesia and a rolling procedure must be performed to correct the condition medically. This condition can be diagnosed on rectal examination or through ultrasonography by a veterinarian.

[edit] Right dorsal displacement

Right dorsal displacement is another displacement of part of the large bowel. Although signs of colic may not be very severe, surgery is usually the only available treatment.

[edit] Torsion

Various parts of the horse's gastrointestinal tract may twist upon themselves. It is most likely to be either small intestine or part of the colon. Occlusion of the blood supply means that it is a painful condition causing rapid deterioration and requiring emergency surgery.

[edit] Intussusception

Intussusception is a form of colic in which a piece of intestine "telescopes" within a portion of itself. It most commonly happens in the small intestine of young horses and requires urgent surgery.

[edit] Epiploic foramen entrapment

On rare occasions, a piece of small intestine can become trapped through the epiploic foramen. The blood supply to this piece of intestine is immediately occluded. The intestine becomes trapped and surgery is the only available treatment.

[edit] Strangulating lipoma

Benign fatty tumors known as lipomas can form on the mesentery. As the tumor enlarges, it stretches the connective tissue into a stalk which can wrap around a segment of bowel, typically small intestine, cutting off its blood supply. The tumor forms a button that latches onto the stalk of the tumor, locking it on place, and requiring surgery for resolution.

[edit] Mesenteric rent entrapment

The mesentery is a thin sheet attached to the entire length of intestine, enclosing blood vessels, lymph nodes, and nerves. Occasionally, a small rent (hole) can form in the mesentery, through which a segment of bowel can occasionally enter. As in epiploic foramen entrapment, the bowel first enlarges, since arteries do not occlude as easily as veins, which causes edema (fluid buildup). As the bowel enlarges, it becomes less and less likely to be able to exit the site of entrapment. This problem also requires surgical correction.

[edit] Gastric ulceration

Horses form ulcers in the stomach fairly commonly. Risk factors include confinement, infrequent feedings, a high proportion of concentrate feeds, excessive non-steroidal anti-inflammatory drug use, and the stress of shipping and showing. Most ulcers are treatable with medications that inhibit the acid producing cells of the stomach. Antacids are less effective in horses than in humans, because horses produce stomach acid almost constantly, while humans produce acid mainly when eating. Dietary management is critical. Bleeding ulcers leading to stomach rupture are rare.

[edit] Other causes that may show clinical symptoms of colic

Strictly speaking colic refers only to signs originating from the gastrointestinal tract of the horse. Signs of colic may be caused by problems other than the GI-tract e.g. problems in the kidneys, ovaries, spleen, testicular torsion, pleuritis, or pleuropneumonia. Diseases which sometimes cause symptoms which appear similar to colic include laminitis and exertional rhabdomyolysis.

[edit] Symptoms

Symptoms of horse colic include refusal to eat, niping at their own sides, kicking at their abdomen, stretching or straining during defecation, violent rolling or shaking, excessive perspiration, lip curling, cool extremities, fewer bowel movements or a high pulse rate.

[edit] Prevention

Colic can be prevented by restricted access to carbohydrates, clean feed and drinking water, preventing the ingestion of dirt or sand by using an elevated feeding surface, a regular feeding schedule, regular deworming, a regular diet that does not change substantial in content or proportion and prevention of heatstroke.

[edit] Further reading

  • The Illustrated Veterinary Encyclopedia for Horsemen Equine Research Inc.
  • Veterinary Medications and Treatments for Horsemen Equine Research Inc.
  • Horse Owner's Veterinary Handbook James M. Giffin, M.D. and Tom Gore, D.V.M.
  • Preventing Colic in Horses Christine King, BVSc, MACVSc

[edit] External links