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Displacement colics refer to a group of intestinal conditions in horses, including right dorsal displacement, left dorsal displacement, and large colon volvulus.

Intestinal displacement is a serious concern for horses, and describes abnormal positioning of the intestines within the abdominal cavity.

These conditions can lead to blockages that disrupt the normal flow of food, gas, fluids, and blood through the digestive tract. Such blockages result in significant pain, known as colic, along with other distressing symptoms. Left untreated, displacement colics are life-threatening.

Understanding the anatomy of the horse’s hindgut, the types of displacement colics, and their causes, symptoms, and treatment options is important for effective management and timely intervention.

Displacement Colics in Horses

Displacement colics are a group of conditions that occur in the hindgut of the horse. These conditions are individually known as: [1]

  • Left dorsal displacement
  • Right dorsal displacement
  • Large colon volvulus

Displacements occur when a portion of the horse’s intestines moves from its normal position within the abdomen and becomes trapped by other structures. Entrapment of the colon can lead to blockage of the digestive tract, which restricts the normal passage of food and gases. [1]

In severe cases, entrapment may also cut off blood supply to the affected section of the tract, which results in oxygen deprivation and potential tissue death. [1]

These conditions result in severe abdominal pain (colic) and other life-threatening symptoms.

Anatomy of the Colon

To better understand displacement colics, it’s useful familiarize yourself with the colon of the horse. The colon is a long, muscular tube that forms part of the hindgut, consisting of the large colon and small colon.

This section of the gastrointestinal tract can hold up to 80 liters (21 gallons) of food and water. [2] It is responsible for absorbing water and nutrients, and houses microbes that ferment fiber.

Microbes in the colon help break down fibrous plant material, producing volatile fatty acids (VFAs), which serve as the horse’s primary source of energy. [3]

Visually, you can think of the colon as being made of two horseshoe shapes, stacked one on top of the other. The “heels” of these horseshoes point towards the horse’s back end on the left and right sides of the body. The curves at the “toes” point to the horse’s head. [2]

Horse's Cecum and Colon - Digestive Anatomy

The bottom horseshoe is called the ventral colon. The top one is called the dorsal colon. [3][4]

Ventral Colon

The ventral colon starts at the rear of the horse. The right ventral colon begins at the cecocolic orifice, where it receives food material (ingesta) as it leaves the cecum. [2]

The right ventral colon runs along the right side of the horse’s abdomen toward the head, reaching the “toe” of the lower horseshoe. At this point, it makes a gradual turn, called the sternal flexure, and continues as the left ventral colon, moving back toward the horse’s rear. [2]

At the “heel” of the lower horseshoe, the colon makes a sharp hairpin turn, called the pelvic flexure. [2]

Dorsal Colon

After passing the pelvic flexure, the colon travels back towards the head stacked on top of the ventral colon. The first part of this segment travels towards the head along the left side of the horse’s abdominal cavity. This is known as the left dorsal colon. [2]

At the “toe” of the horseshoe, it makes a gradual turn at the diaphragmatic flexure and makes its way back towards the hindquarters along the right side. This segment is called the right dorsal colon. [2]

The colon concludes at the next part of the digestive tract, known as the transverse colon.

Digestive Anatomy & Displacement Risk

The horse’s colon is both free-floating and mobile, which makes it susceptible to entanglement with adjacent structures and itself.

Unlike the structures of the foregut, the anatomical features in the hindgut are not attached to the abdominal wall by the mesentery. They float freely in the abdomen. [5]

Furthermore, like the rest of the digestive tract, the hindgut structures consist of two layers of muscle. These muscles contract and relax in a coordinated rhythm, producing peristaltic waves that push ingested material (ingesta) through the system. These contractions mean the structures are constantly moving in close proximity to each other, making them vulnerable to tangling. [5]

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Types of Displacement Colic

There are three types of displacement that can occur in the equine colon: [5]

  • Left dorsal displacement: Also known as nephrosplenic entrapment or renosplenic entrapment, this occurs when the left dorsal and ventral portions of the colon move into the space between the spleen and the kidney and get stuck. [5][6][7][8][9]
  • Right dorsal displacement: Occurs when the pelvic flexure moves between the cecum and the body wall and gets stuck. The colon can also rotate on its axis, twisting the tract, similar to filling a sausage casing. [5]
  • Large colon volvulus: The most serious form of intestinal displacement. [5][7] This occurs when the whole colon rotates laterally. In this scenario, the orifices leading from the cecum to the transverse colon are pinched off, which is a medical emergency. [7]

Each type of displacement colic presents unique challenges, with varying severity depending on how much of the colon is involved. Timely diagnosis and treatment are crucial for the horse’s survival, especially in cases of large colon volvulus, where immediate surgical intervention may be necessary.

Risk Factors

All horses are at some risk of displacement colic, though the risk factors for each specific type of entrapment can vary.

For left dorsal displacement, the physical structure and shape (morphology) of the horse determines the risk. Some horses are born with a deeper than average space between the kidney and spleen, making them more susceptible to this type of displacement. [5]

Left dorsal displacement affects horses at all ages. [5] Research suggests it may affect warmbloods more than other breeds. [5][10]

Large colon volvulus is most commonly observed in: [1][5]

  • Broodmares and horses that have recently given birth
  • Horses with recent dietary changes
  • Horses with recent access to lush pasture

Diet and Nutrition

An optimal diet for horses should follow a balanced, forage-based approach with fiber from hay or pasture as the primary energy source. The horse’s hindgut is adapted to ferment structural carbohydrates in fibrous plant material into volatile fatty acids, which the horse can then use for energy. [5]

However, consuming too much starch or hydrolyzable carbohydrates (HC) from grains or lush pasture can overwhelm the digestive system and disrupt the gut microbiome. Rapid dietary changes can also trigger gut dysbiosis, causing excess fermentation, gas buildup, and increasing the risk of displacement colics. [5]

Causes

The precise etiology of displacement colics remains uncertain, with contributing factors varying according to the specific type of displacement. [5]

Left dorsal displacement appears to be related to the production of excessive gas and changes in the movement of the colon. As gas accumulates in the intestines, it can cause the colon to shift, potentially pushing the spleen aside and creating space for the colon to become trapped between the spleen and the kidney. [5]

Right dorsal displacement appears to result from movement in the pelvic flexure, a bend in the colon where it transitions from the ventral to the dorsal side. The colon shifts between the cecum and the body wall, where it can become trapped. [5]

The cause of large colon volvulus is unknown, but may be associated with excess gas build up. Factors contributing to excess gas build up include: [11]

Symptoms

The signs of displacement colics in horses vary depending on the specific type of entrapment.

Horses with left dorsal displacement show varying degrees of pain ranging from mild to severe. [7] They also tend to have extremely distended abdomens and a large amount of gastric reflux during veterinary examination. [7]

Horses with right dorsal displacement often show signs of pain, with pain decreasing when they are withheld from food. [5] They usually produce only small amounts of manure. [5]

Horses with large colon volvulus sometimes exhibit signs of colic for a day or more, followed by pain that suddenly becomes severe. Others show sudden uncontrollable pain without any colic. [1][5] Pain is often so severe that it is not improved by pain medications. Some horses lie on their backs to attempt to alleviate the pain. [1]

Colic is a medical emergency requiring prompt veterinary intervention

 

Eventually, the colon becomes severely distended, which causes the abdomen to swell. [1]. The colon displaces surrounding organs, including the lungs and diaphragm, leading to cardiovascular symptoms. [1][5]

Cardiovascular symptoms observed in affected horses include: [1]

  • Rapid breathing
  • Coughing
  • Arrhythmia (irregular heart beat)
  • Tachycardia (rapid heart rate)
  • Changes in gum color
  • Weak pulse
  • Collapse

Severity

The severity of each specific type of displacement colic varies depending on the degree of displacement, duration of the condition, and the extent of vascular or intestinal compromise. Other factors also impact the severity of this condition.

Left Dorsal Displacement

The severity of left dorsal displacement depends on: [5]

  • Volume of gas trapped
  • Duration of displacement prior to intervention
  • Where the structures are trapped
  • Presence of other gastric complications

In some cases, the colon moves into the space between the spleen and the body wall, but does not slide all the way back to the kidney. This is a less severe situation and causes the horse less pain. [5] In more severe cases, the colon gets squeezed into the space between the spleen and kidney, which results in severe pain. [5]

Typically, left dorsal displacement does not disrupt blood supply to the colon. In cases where the displacement lasts longer than 24 hours, damage to the tissues can occur. [5]

In very rare cases, both the colon and small intestine become trapped between the spleen and the kidney at the same time. [5]

Right Dorsal Displacement

Horses with right dorsal displacement typically exhibit mild symptoms at first. [5] If the flow of ingesta through the intestines is not fully cut off, symptoms can become chronic. [7]

Cases are considered more serious if the colon continues to twist and the flow of ingesta is interrupted. [5] If the colon rotates, the blood supply to the area can be disrupted, leading to tissue death. [5]

Large Colon Volvulus

The severity of large colon volvulus in horses depends on the degree of rotation in the twist.

Rotation of the colon between 90 and 270 degrees is considered mild because it usually causes minimal disruption to the flow of ingesta and blood supply to the affected area. [7]

Rotation greater than 270 degrees, particularly if blood flow is compromised, is a very serious condition. [7] Horses with very severe large colon volvulus develop irreversible damage to the tissues of the colon after 3 to 4 hours. [1]

Diagnosis

Diagnosis of left dorsal displacement in horses is based on: [5][8]

  • Physical examination
  • Blood test
  • Abdominocentesis (testing a sample of fluid from the abdomen)
  • Nasogastric decompression
  • Ultrasound
  • Rectal palpation

Diagnosis of right dorsal displacement is usually based on rectal palpation as the pelvic flexure will no longer be palpable. Nasogastric decompression and ultrasound may also be used. [5]

Diagnosis of large colon volvulus is based on: [1][5][9]

  • Exploratory surgery
  • Ultrasound
  • Abdominocentesis
  • Rectal palpation

If you suspect your horse is affected by displacement colic, consult with your veterinarian promptly to obtain an accurate diagnosis and initiate treatment.

Treatment

Treatment of displacement colics in horses typically involves medical or surgical intervention depending on the severity.

Treatments for left dorsal displacement include: [5][6][10]

  • Intravenous fluids
  • Vasoconstriction drugs that narrow the blood vessels
  • Withholding feed
  • Pressor agents
  • Rolling the horse under general anesthesia
  • Controlled exercise
  • Manipulation of the colon manually via the rectum
  • Surgery
  • Needle decompression

In cases of right dorsal displacement and large colon volvulus, treatment is surgical to manually reposition the colon and restore normal function. [5][7]

Post-treatment care often includes careful monitoring, gradual reintroduction of feed, and management to prevent recurrence.

Prognosis & Prevention

The prognosis for horses with displacement colics is variable depending on the specific condition, the severity of the entrapment, and the level of disruption to the flow of ingested material and blood. [12] Large colon volvulus is the most severe form and carries the most guarded prognosis.

There are no proven preventative measures for displacement colics in horses. Feeding a forage-based diet and making gradual dietary changes can help control gas production in the hindgut and may lower the risk of displacement.

If you are unsure if your horse is getting everything they need from their diet, consult with a qualified equine nutritionist who can analyze your current regimen and make individualized recommendations based on your horse’s needs.

Summary

Displacement colics in horses occur when part of the colon shifts from its normal position and becomes trapped by other organs. This includes left dorsal displacement, right dorsal displacement, and large colon volvulus.

  • Left dorsal displacement occurs when the colon slides behind the spleen and sometimes gets stuck in the space between the spleen and the kidney.
  • Right dorsal displacement occurs when the pelvic flexure slides between the horse’s cecum and the body wall.
  • Large colon volvulus occurs when the whole structure of the colon flips over on itself.
  • The characteristic symptom of all three forms is colic (abdominal pain).
  • Diagnosis depends on the specific case but may include rectal palpation, imaging, and exploratory surgery.
  • Mild cases may be resolved with minimally invasive methods, but most displacements in horses require surgery to correct.

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References

  1. Reed, S. M., et al. Equine internal medicine. 3rd ed. Saunders Elsevier, St. Louis, Mo. 2010.
  2. Krunkosky, T. M., et al. Gross and microscopic anatomy of the equine gastrointestinal tract. The Equine Acute Abdomen. 1st ed. Wiley. 2017.
  3. Goff, J. P. Dukes’ Physiology of Domestic Animals. 13th ed. Wiley-Blackwell. 2015.
  4. Julliand, V., & Grimm, P. Equine digestive microbiota: Beneficial and detrimental effects to the horse? | IVIS. European Equine Health and Nutrition Congress. Utrecht. 2021.
  5. Blikslager, A. T., et al., Eds. The equine acute abdomen. Third edition. Wiley, Blackwell, Hoboken, NJ. 2017.
  6. Pye, J., & Nieto, J. The use of phenylephrine in the treatment of nephrosplenic entrapment of the large colon in horses. Equine Veterinary Education. 2020.
  7. Johnston, J. K., & Freeman, D. E. Diseases and surgery of the large colon. Veterinary Clinics of North America: Equine Practice. 1997.
  8. Hardy, J., et al. Nephrosplenic entrapment in the horse: A retrospective study of 174 cases. Equine Veterinary Journal. 2000. View Summary
  9. Albanese, V., & Caldwell, F. J. Left dorsal displacement of the large colon in the horse. Equine Veterinary Education. 2014.
  10. Lindegaard, C., et al. Nephrosplenic entrapment of the large colon in 142 horses (2000–2009): Analysis of factors associated with decision of treatment and short-term survival. Equine Veterinary Journal. 2011. View Summary
  11. Orsini. J. A. and Divers. T. J., Eds., Equine Emergencies: Treatment and Procedures. Fourth edition. Elsevier/Saunders, St. Louis, MO. 2014.
  12. Christophersen, M. T., et al. Sporting activity following colic surgery in horses: A retrospective study. Equine Veterinary Journal. 2011. View Summary