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Basics ⬇

Outline

BASICS

Definition!!navigator!!

RDDLC

Anatomic relocation of the LC owing to migration of the pelvic flexure between the cecum and the right abdominal wall.

LDDLC

Anatomic relocation of the LC in a dorsal direction between the left body wall and the spleen towards the nephrosplenic space, where it can entrap.

Pathophysiology!!navigator!!

Speculative. Hypothetical factors:

  • Lack of mesenteric attachment of the LC to the body wall makes it very mobile
  • Excess soluble carbohydrate diet may cause increased fermentation and gas production in the LC
  • Alteration of normal colonic motility patterns
  • Rolling episodes

RDDLC

  • Can occur in 2 directions—clockwise and counterclockwise (as viewed from the surgeon's perspective at surgery with horse in dorsal recumbency)
  • Counterclockwise (most common)—the pelvic flexure moves craniad and then caudad between the cecum and the right body wall. The pelvic flexure often crosses the abdomen caudal to the cecum and continues in a cranial direction towards the diaphragm
  • Clockwise (less common)—the pelvic flexure crosses the abdomen caudal to the cecum and displaces in a caudal-to-cranial direction between the cecum and the right abdominal wall

LDDLC

  • The left colon ascends dorsally between the spleen and the body wall until entrapped in the nephrosplenic space
  • The entrapped colon commonly rotates ventromedially 180°
  • In type II LDDLC, the sternal and diaphragmatic flexures migrate cranially and dorsally to the stomach, which hampers nasogastric intubation
  • Displaced colon may obstruct duodenum and therefore cause reflux

Vascular Compromise

Both displacements are non-strangulating; however vascular compromise can occur in:

  • Volvulus of the LC at the root of the mesentery (RDDLC) or at the site of entrapment over the nephrosplenic ligament (LDDLC)
  • Longstanding (>24 h) nephrosplenic entrapments causing colonic congestion, edema, and/or mural damage in the absence of volvulus

Systems Affected!!navigator!!

GI

  • The LC is displaced, and this may lead to other abdominal GI tract displacements (cecum, small colon, and small intestine)
  • Mechanical traction on the mesentery can result in considerable pain
  • Although uncommon, vascular obstruction results in compromise, and potentially necrosis of the LC

Cardiovascular

With long duration or vascular compromise, dehydration and fluid shifts may cause circulatory compromise.

Genetics!!navigator!!

N/A

Incidence/Prevalence!!navigator!!

  • In 1 study, 14% of exploratory celiotomies were nonstrangulating LC displacements
  • In another study, 23% of all colic cases presented to a referral practice were LC displacements

Signalment!!navigator!!

No particular signalment; foals can also be affected. Mares, particularly following parturition, may be predisposed to displacement of the LC.

Signs!!navigator!!

  • Referable to the amount of colonic distention and any vascular compromise
  • Mild to moderate abdominal discomfort after 12–24 h
  • Colic usually responds to analgesia or fasting initially but returns when the analgesic efficacy decreases and horse is re-fed
  • Acute progression of signs is associated with increased bowel distention or compromise
  • Gastric reflux is inconsistent but was present in up to 43% of horses with LDDLC. Nasogastric intubation may be difficult in horses with type II LDDLC
  • Heart rate often is less than might be expected from the degree of pain displayed (LDDLC)

Causes!!navigator!!

  • Potentially, alteration to the intestinal motility and changes in the weight of the colon because of excess gas formation or mild impactions
  • Changes in intra-abdominal volume and GI activity after parturition may predispose postpartum mares to LC displacement
  • LDDLC—in addition to the above, gastric distention resulting in displacement of the spleen from the body wall, splenic contraction, and displacement of the spleen because of adhesions between the spleen and previous ventral midline celiotomy incisions

Risk Factors!!navigator!!

  • Adhesions of the spleen to midline (previous celiotomies), previous LC displacements, and other forms of colic may cause a horse to roll
  • Sudden dietary changes

Diagnosis ⬆ ⬇

Outline

DIAGNOSIS

Differential Diagnosis!!navigator!!

  • Colonic/cecal tympany
  • Retroflexion of the pelvic flexure
  • Colonic impaction
  • Colonic volvulus
  • Enterolithiasis

CBC/Biochemistry/Urinalysis!!navigator!!

  • CBC and biochemistry most commonly normal, with mild alkalosis to mild acidosis in cases of nonstrangulating displacements
  • Decreased hematocrit may result from sequestration of red blood cells in the spleen
  • If strangulation of the colon occurs, significant dehydration, with a relatively decreased protein and metabolic acidosis, is common
  • Horses with RDDLC showed higher serum γ-glutamyltransferase than horses with LDDLC

Other Laboratory Tests!!navigator!!

  • Peritoneal fluid usually normal, unless the bowel is compromised
  • In LDDLC, splenocentesis may occur as the spleen is forced medially and ventrally

Imaging!!navigator!!

Ultrasonography

RDDLC

  • Large intestine distended with gas and fluid
  • Abnormally located colonic vessels along the right lateral abdomen are a good indicator of RDDLC and/or 180° LC volvulus

LDDLC

  • Failure to visualize the left kidney because of gas in the LC and/or the dorsal border of the spleen partially obscured by colon or displaced ventrally
  • A false-positive diagnosis can result from a gas-distended viscus near the left kidney, obstructing visualization of the kidney
  • A false-negative diagnosis can result from lack of gas in the entrapped colon or angling the ultrasonography probe dorsoventrally
  • 1 study reported a correct diagnosis in 88% of cases of nephrosplenic entrapment, with no false-positive results

Other Diagnostic Procedures!!navigator!!

RDDLC

Rectal examination—absence of pelvic flexure, LC lateral to cecum, colon bands coursing transversely in the caudal abdomen, gas distention or impaction of the LC, cecum may not be found or is distended.

LDDLC

Rectal examination—colon on the left, colon bands coursing craniodorsally toward the nephrosplenic space; medial or caudal displacement of the spleen; different grades of colon distention and sometimes impaction. The colon entrapped in the nephrosplenic space may be clearly palpable in some horses. Rectal palpation confirmed diagnosis of left dorsal displacement in 61–72% of cases. In other conditions the colon may adopt a dorsal position within the abdomen but continues cranially rather than into the nephrosplenic space.

Pathologic Findings!!navigator!!

Left dorsal displacement—some cases present another primary lesion involving another segment of the GI tract.

Treatment ⬆ ⬇

Outline

TREATMENT

Appropriate Health Care!!navigator!!

  • RDDLC—medical treatment in patients with mild signs although close monitoring is required. Surgical correction is often required
  • LDDLC—conservative management, administration of phenylephrine (with or without controlled exercise), rolling the horse under general anesthesia, surgical correction: 7.5% of horses were reported to have another concurrent lesion (i.e. small intestinal obstruction, 360° colon torsion, etc.)
  • Choice of treatment depends on certainty of the diagnosis, degree of LC distention, and financial limitations
  • If the diagnosis is not certain or colonic distention is marked, rolling and controlled exercise may be contraindicated
  • Conservative treatment of both RDDLC and LDDLC is appropriate provided that diagnosis is accurate with no signs indicating surgical lesion or systemic compromise

Nursing Care!!navigator!!

  • Vital
  • Nasogastric intubation and gastric decompression are vital if mechanical obstruction of the small intestine
  • Exploratory celiotomy—fluid volume deficits and acid–base and electrolyte imbalances need to be addressed
  • Abdominal distention restricting respiratory tidal volume and requiring supplemental oxygen therapy is not common. Deflation of a markedly distended large intestine via percutaneous trocharization may be beneficial but may cause leakage of intestinal contents

Activity!!navigator!!

  • Controlled exercise may assist resolution of LDDLC
  • Uncontrolled rolling may convert a nonstrangulating to a strangulating displacement

Diet!!navigator!!

No food should be administered.

Client Education!!navigator!!

  • Counsel owners on the decision of whether to treat LDDLC conservatively or surgically
  • Stress that treatment without surgery has obvious benefits, but that risks are associated with conservative treatment—further compromise of a markedly distended entrapped viscus and less commonly rupture

Surgical Considerations!!navigator!!

When the colon is not strangulated, the condition usually is straightforward to correct.

Medications ⬆ ⬇

MEDICATIONS

Drug(s) of Choice

  • Standard analgesia for colic—see chapter Acute adult abdominal pain—acute colic. Drug use and dosage depend on nature of the colic and the therapy chosen
  • LDDLC—phenylephrine (10–20 mg diluted in 50 mL of saline injected IV slowly over 5–10 min) causes splenic contraction and may facilitate dislodging the LC from the nephrosplenic space

Follow-up ⬆ ⬇

Outline

FOLLOW-UP

Patient Monitoring!!navigator!!

  • Routine postoperative monitoring after surgery or conservative therapy
  • In 1 study horses with RDDLC were more likely to experience recurrent episodes of colic than other types of displacement
  • Recurrence of nephrosplenic entrapment is 7.5–8.5%; however, horses that have a recurrence episode even higher

Prevention/Avoidance!!navigator!!

  • The cause is poorly understood and avoidance is difficult
  • Minimize management that may alter colonic activity, production of excess gas, and formation of impactions. Institute nutritional changes gradually
  • Prevent horses from rolling when showing signs of mild colic
  • Ablation of nephrosplenic space reduces risk of nephrosplenic entrapment although displacement of the LC to the lateral aspect of the spleen or other displacements may still occur
  • Colopexy or colon resection is not routinely recommended

Possible Complications!!navigator!!

  • Displacement can progress such that the colon becomes strangulated secondary to volvulus of the displaced colon. Horses can then rapidly succumb to cardiovascular shock from endotoxemia and hypovolemia or to colonic rupture from devitalization of the colon
  • Administration of phenylephrine has been associated with fatal internal hemorrhage in older horses

Expected Course and Prognosis!!navigator!!

  • The prognosis is good, provided there has been no volvulus or significant vascular insult to the colon
  • Long-term survival of horses with nonstrangulating displacements is excellent (>90%)

Miscellaneous ⬆ ⬇

Outline

MISCELLANEOUS

Associated Conditions!!navigator!!

  • Cholestasis
  • Colonic volvulus
  • GI impaction
  • Gastric distention

Pregnancy/Fertility/Breeding!!navigator!!

  • The colon is held in place largely by its association with surrounding organs. The empty abdomen in postpartum mares may predispose to displacement
  • Volvulus rather than dorsal displacement is more commonly associated with postpartum mares

Synonyms!!navigator!!

LDDLC—nephrosplenic ligament entrapment.

Abbreviations!!navigator!!

  • GI = gastrointestinal
  • LC = large colon
  • LDDLC = left dorsal displacement of the large colon
  • RDDLC = right dorsal displacement of the large colon

Author(s) ⬆ ⬇

Author: Luis M. Rubio-Martinez

Consulting Editors: Henry Stämpfli and Olimpo Oliver-Espinosa

Acknowledgment: The author and editors acknowledge the prior contribution of Judith B. Koenig and Simon G. Pearce.

Additional Further Reading ⬆

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