Chapter 37 - Large Colon

Question 1

What is the first part of the large (ascending) colon that receives contents from the cecum?

Answer 1

Right ventral colon.

Question 2

How is the large colon divided into four parts based on location within the abdomen?

Answer 2

Into the right and left ventral colon, and the left and right dorsal colon.

Question 3

What are the three flexures of the large colon mentioned

Answer 3

The sternal, diaphragmatic, and pelvic flexures.

Question 4

At what level does the ventral colon form the sternal flexure, and where does it bend sharply?

Answer 4

At the level of the xiphoid cartilage; it bends sharply toward the left ventral abdomen.

Question 5

What is the third part of the colon formed after the pelvic flexure?

Answer 5

The left dorsal colon

Question 6

Where is the diaphragmatic flexure located in the large colon?

Answer 6

At the level of the diaphragm and left lobe of the liver.

Question 7

What is the fourth and last part of the large colon?

Answer 7

The right dorsal colon.

Question 8

Which part of the colon becomes the transverse colon at the level of the diaphragm and left lobe of the liver?

Answer 8

At the level of the medial surface of the cecal base, the right dorsal colon crosses the abdomen dorsally to become the short and narrow transverse colon which then becomes the small colon at a level just ventral to the left kidney and cranial to the mesenteric root

Question 9

What is the approximate length of the large colon, and what is its average diameter? What capacity?

Answer 9

3 to 3.7 m long with an average diameter of 20 to 25 cm.
50 to 60 L

Question 10

Where does the colon become narrow (8 to 9 cm) beyond the pelvic flexure?

Answer 10

At the ampulla coli it is the maximum 50 cm just before its diameter decreases at the funnel-shaped terminal narrowing, the transverse colon.

Question 11

What is the role of the mesocolon in connecting the dorsal and ventral components of the large colon?

Answer 11

It connects them with two layers of peritoneum, containing fat and connective tissue, housing lymphatics, nerves, arteries, and veins.
The outer mesothelium secretes a serous peritoneal fluid

Question 12

What are the constrictions in the ventral colon called, and what are the bands within it called?

Answer 12

Constrictions are plicae semilunares coli, and bands are teniae coli.

Question 13

Which component of the large colon has alternating constrictions and sacculations?

Answer 13

The ventral colon.

Question 14

How are the ventral colon bands primarily characterized, elastic or muscular? dorsal colon bands?

Answer 14

Primarily elastic for the ventral.
Primarily muscular for the dorsal

Question 15

The transverse colon is attached to what?

Answer 15

The transverse colon is attached by mesocolon to the ventral surface of the pancreas dorsally, the cecal base laterally and indirectly to the diaphragm and liver

Question 16

The lateral mesenteric band is covered by the ___________ and the medial mesenteric band by the _____________ and _____________

Answer 16

The lateral mesenteric band is covered by the mesocolon and the medial mesenteric band by the vessels and lymph nodes

Question 17

Name the four tenial bands of the ventral colon

Answer 17

four tenial bands (teniae coli): namely lateral and medial free bands, and lateral and medial mesenteric bands.

Question 18

does the dorsal colon has teniae and sacculations?

Answer 18

yes it has teniae, but it doesn’t have sacculations

Question 19

What connects the right ventral colon to the cecum?

Answer 19

The cecocolic ligament (lateral band of cecum).

Question 20

Which arteries supply blood to the ventral and dorsal colon, respectively?

Answer 20

The **colic branch **of the ileocolic artery supplies the ventral colon,
right colic artery supplies the dorsal colon.

Question 21

Where do the veins draining the right colic and left colic veins ultimately drain into?

Answer 21

The** right colic vein** drains into the caudal mesenteric vein,

and the** left colic vein** drains into the cranial mesenteric vein, both of which drain into the portal veins.

Question 22

What is the histological composition of the colon, including its layers and cell types?

Answer 22

It consists of a:
1 - luminal mucosa consists columnar epithelium with crypts and glands - no villi
2 - submucosa (nerves, blood vessels, lymphatic)
3 - tunica muscularis (inner circular and outer longitudinal smooth muscle layers),
4 - and a serosal surface,

Question 23

Describe the numbers and vessels

Answer 23

Figure 37-3. Blood supply to the equine large colon. 1, Stump of cranial mesenteric artery; 2, stump ofjejunal arteries; 3, lateral cecal artery; 4, medial cecal artery; 5, ilial artery; 6, colic branch of ileocolicartery; 7, right colic artery; 8, middle colic artery.

Question 24

name the venous return in the colon

Answer 24

The right colic vein drains into the** caudal mesenteric vein **
the** left colic vein **drains into the cranial mesenteric vein and both drain into the portal veins

Question 25

The lymph nodes in the mesocolon drain into…

Answer 25

mesenteric lymph nodes

Question 26

Small parasympathetic ganglia forms submucosal plexus called

Answer 26

Meissner plexus

Question 27

Preganglionic parasympathetic neurons synapse with postganglionic nerve fibers that supply the muscularis mucosae provide supply to…

Answer 27

muscularis mucosae

Question 28

The inner circular muscle layer is consistent throughout the large colon; however,the outer longitudinal smooth muscle layer is thin except where it forms tenial bands. This are innervated by…

Answer 28

myenteric plexus (Auerbach plexus), lies between the circular and longitudinal muscle layers and is responsible for motor innervation to both muscle layers

Question 29

The myenteric plexus (Auerbach plexus) provides parasympathetic or sympathetic input?

Answer 29

Both sympathetic and parasympathetic

Question 30

What is the primary function of the equine large colon?

Answer 30

Hydrolysis of structural carbohydrates (dietary plant fiber) to soluble sugars leading to anaerobic fermentation that originates short chain fatty acids by colonic microbes

Question 31

How are volatile short-chain fatty acids utilized for the horse’s energy needs?

Answer 31

They are absorbed through the colonic mucosa and used to meet the majority of the horse’s energy needs.

Question 32

What is the major respiratory fuel for colonic epithelial cells?

Answer 32

Butyrate that improves mucosal barrier function, maintains homeostasis

Question 33

name the collection of lymph

Answer 33

the lymphatics drain to the colic lymph nodes in the mesocolon ten into cranial mesenteric lymph nodes and then** cisterna chyli**

Question 34

What is the role of propionate in the large colon?

Answer 34

It is mainly used by the liver as a precursor for gluconeogenesis.

Question 35

How long does cellular digestion and terminal fermentation in the large colon require?

Answer 35

48 to 72 hours.

Question 36

Which part of the colon has the highest capacity for fiber digestion?

Answer 36

The right ventral colon.

Question 37

What is the impact of metabolic disturbances on the colon?

Answer 37

Metabolic disturbances can lead to high lactic acid production and dysbiosis.

Question 38

Which bacterial phylum is predominant in the colon?

Answer 38

Firmicutes.

Question 39

What are the two types of Interstitial cells of Cajal (ICC) observed in the gastrointestinal tract?

Answer 39

Intramuscular (in the longitudinal and circular muscle layers) and myenteric.

Question 40

What is the role of VIP-reactive neurons in the pelvic flexure region of the colon?

Answer 40

VIP-reactive neurons can cause smooth muscle relaxation, contributing to the possible pacemaker function of the pelvic flexure.

Question 41

How does sympathetic hyperactivity affect intestinal motility?

Answer 41

Sympathetic hyperactivity results in splanchnic vasoconstriction and decreased propulsive motility.

Question 42

Which volatile short-chain fatty acids are produced by colonic microbes during fermentation?

Answer 42

Acetic, propionic, iso-butyric, N-butyric, iso-valeric, and N-valeric.

Question 43

What effect does parasympathetic hypoactivity have on intestinal motility?

Answer 43

Parasympathetic hypoactivity causes a reduction in motility and a decrease in intestinal secretion.

Question 44

What is the large colon responsible for in terms of water absorption?

Answer 44

Absorbing large volumes of water (approximately 20%–30% of the body weight daily).

Question 45

What are the nonstrangulating obstructions in colon?

Answer 45

1. Large colon tympany ++ cause of abdo pain
2. Large colon impaction
3. Sand impaction
4. Enterolithiasis
5. Right dorsal displacement
6. Left dorsal displacement
7. Fecalith
8. Congenital: atresia coli, duplications, malformations
9. Neoplasia
10. Inflammatory lesions

Question 46

What percentage of horses with colic in primary care practice is attributed to tympany?

Answer 46

Over 75% to 80%.

Question 47

During which months does tympany in horses appear to peak?

Answer 47

Spring and autumn.

Question 48

What are some management factors associated with simple colonic obstruction and distention?

Answer 48

Crib-biting/windsucking, stabling for 24 hours per day, recent changes in exercise or diet, and absence of anthelmintic administration.

Question 49

Which drug may be used as an anticholinergic spasmolytic in horses with colonic tympany?

Answer 49

N-butylscopolammonium bromide (Buscopan) 25 mg/kg IV

Question 50

What is the most common location for large colon impaction in horses?

Answer 50

Left ventral colon at the pelvic flexure or
right dorsal colon at the transverse colon

Question 51

80% of horses respond to medical treatment what is it?

Answer 51

*Fluid therapy:10-12 ml/kg every 0.5-2hrs, either per NGT or IVFT

Analgesics (NSAIDS, α2-agonists, butorphanol)
MgSO4 at 0.5-1mg/kg

Question 52

What season shows a peak incidence of large colon impaction?

Answer 52

Autumn and winter months.

Question 53

What neurotransmitters are used by the enteric nervous system?

Answer 53

Neuropeptides including vasoactive intestinal peptide (VIP), methionine-Enkephalin, calcitonin gene-related peptide, substance P, and other neurokinins, as well as nitric oxide.

Question 54

Which factors have been associated with sand colic in horses?

Answer 54

Grazing on sandy soils, eating off the ground, and living in sandy geographical areas.

Question 55

What clinical signs may be observed in horses with sand accumulations in the gastrointestinal tract?

Answer 55

Nonspecific chronic poor performance, weight loss, diarrhea, and recurrent colic.

Question 56

How is sand identified in the feces of horses?

Answer 56

By placing fresh feces in a rectal sleeve with water, observing sand sediment after 20 minutes.

Question 57

Grade sand

Answer 57

Question 58

Answer 58

Figure 37-7. Radiographic images of colonic sand accumulation. (A) Sand accumulation in the cranioventral abdomen (arrows) in a horse with chronic diarrhea. Based on the cranioventral location, number of accumulations, density, thickness, and length, a score of approximately 10/12 (Table 37-2) or a score of 375,76 would be given indicating that the accumulation may be clinically relevant. (B) Larger sand accumulation with a score of at least 10/12 (Table 37-2)

Question 59

Answer 59

Figure 37-8. Sand identified in the right (A) and left (B) ventral colon with transabdominal ultrasonographic evaluation. Note the flattening of the sacculations, and large amount of hyperechoic, homogenous shadowing material within its lumen (black arrow). (

Question 60

Answer 60

Spherical =solitary (top) and polytetrahedral (bottom) = multiple enterolith.

Question 61

What are sand sounds, and where are they auscultated in horses?What is the complementary exam better than US?

Answer 61

Sounds produced by sand particle friction during intestinal motility; auscultated in the ventral abdomen just caudal to the xiphoid process.

Radiography

Question 62

What is the medical tx of sand impaction? % of success? surgical tx?

Answer 62

*Psyllium at 1g/kg daily, +/- MgSO4,
mineral oil 1-3L SID NSG, IV fluids, analgesia
*Medical treatment successful in 76%
Surgery = Pelvic flexure enterotomy

Question 63

What grading system is used for assessing sand accumulations based on radiography?

Answer 63

The grading system considers:
- the number,
- opacity,
- homogeneity,
- rib width to length ratio,
- and rib width to height ratio.

Question 64

What is the prognosis for horses that are managed medically or recover from surgery due to colonic impaction?

Answer 64

Excellent

Question 65

What is the main intraoperative complication when managing a horse with an unresponsive impaction?

Answer 65

Colonic rupture.

Question 66

What is the most common location for sand impaction in the gastrointestinal tract?

Answer 66

1. Right dorsal colon
2. Transverse colon
3. or PFlexure
concurrent large colon displacements or volvulus were found in 25% to 54% of horses with sand impactions.

Question 67

How is sand identified in the feces of horses during treatment?

Answer 67

when the feces are removed from the rectum prior to abdominal palpation per rectum or can be identified by placing fresh feces (200 g) from the rectum in a rectal sleeve, mixing in water (1 L l) and observing sand sediment in the fingertips of the sleeve after 20 minutes (Table 37-1) The appearance of sand in the feces is indicative of sand clearance.
more than **95% of the fecal sand and over 5 mm **of sand sediment was considered to be clinically relevant

Question 68

What is the reported sensitivity and specificity of ultrasonography for detecting sand accumulations?

Answer 68

Radiography is reported to be better than ultrasonography for evaluating sand accumulations. The specificity of ultrasonography for detecting sand accumulations was 87.5% and the sensitivity 87.5%, with small and dorsally located sand accumulations being more difficult to identify.

Question 69

Diagnosis

Answer 69

Figure 37-10. Radiographic image of a 20-cm-diameter enterolith (black arrows) in the right dorsal colon.

Question 70

What are enteroliths?

Answer 70

Enteroliths are intestinal calculi or “stones” that form in the **ampulla coli **of the right dorsal colon.

Question 71

How would you describe the surface of enteroliths?

Answer 71

Enteroliths have a smooth-surfaced spherical or polytetrahedral appearance.

Question 72

What is the predominant component of enteroliths?

Answer 72

Struvite (NH4MgPO4⋅6H2O) is the predominant component of enteroliths and osme have magnesium vivianite

Question 73

What are their ions composition?

Answer 73

Enteroliths contain variable quantities of Na, S, K, and Ca with variation being attributable to concentrations in the soil, water supply, or feed

Question 74

What is the central nidus in enteroliths commonly composed of?

Answer 74

The central nidus is commonly composed of rock fragments, disaggregated mineral grains, and may include feed material, plastic rope, horse hair, cloth, and metallic objects.

Question 75

What is the association between struvite precipitation and the environment in the colon?

Answer 75

Struvite precipitation is associated with Mg2+ supersaturation in the presence of NH4+ and PO4^3− in an alkaline environment.

Question 76

What factors contribute to the formation of enteroliths in horses?

Answer 76

Risk factors include** feeding alfalfa hay** or more than 50% of the diet as alfalfa hay, feeding less than 50% of the diet as oat hay or grass hay, and spending less time (≤50%) at pasture.

Question 77

Which horse breeds appear to be predisposed to enterolithiasis?

Answer 77

Arabians, Arabian-crosses, Morgans, American Saddlebreds, miniature horses, and donkeys appear to be predisposed.

Question 78

Where is the prevalence of enterolithiasis particularly high?

Answer 78

The prevalence of enterolithiasis is particularly high in some geographic areas, including California.

Question 79

What is the high magnesium content in alfalfa hay associated with?

Answer 79

The **high magnesium **content in alfalfa hay can contribute to struvite precipitation, especially due to its alkalinizing effects on colonic contents.

Question 80

How can a tentative diagnosis of enterolithiasis be made?

Answer 80

A tentative diagnosis can be made based on history, physical examination findings, and geographic region.
Radiograph excllent specificity of >90% for dianosis - gas can decrease specificity

Question 81

What is the recommended treatment for horses with enterolithiasis? What are the sites of obstruction?

Answer 81

Surgical intervention with multiple enterotomy sometimes WHY? to prevent complications such as gastrointestinal necrosis and rupture.

*Obstruction in RDC 32%,
transverse colon 23%,
small colon 45%

Question 82

What postoperative complications are commonly observed in horses after surgery for enterolithiasis?

Answer 82

Common postoperative complications include diarrhea (12%–23%),
anorexia (21%),
incisional infection (8%–17%),
fever (9%),
incisional hernia (5%),
phlebitis (4%),
salmonellosis (4%),
laminitis (1%–3%),
septic peritonitis (1%–3%),
and adhesions (2%

Question 83

How does right dorsal displacement occur anatomically?

Answer 83

Answer: Right dorsal displacement occurs when a section of the colon moves around the cecal base, lying between the cecum and the right body wall.

Question 84

What are the proposed directions for counterclockwise and clockwise right dorsal displacements?

Answer 84

Counterclockwise displacement involves retroflexion and movement towards the cranial abdomen, while clockwise displacement occurs when the left colon migrates medially towards the right side of the abdomen

Question 85

What breeds are often affected by large colon displacement, including right dorsal displacement?

Answer 85

Large colon displacements, including right dorsal displacement, often affect mature horses, especially large breeds such as Quarter Horses, Thoroughbreds, and Warmbloods.

Question 86

Is there a seasonal pattern observed in the occurrence of large colon displacement?

Answer 86

Yes, there appears to be a seasonal pattern, with peaks in spring and autumn.

Question 87

What are potential factors contributing to right dorsal displacement?

Answer 87

Limited attachment of the large colon to the body wall or other abdominal structures, along with alterations in diet, exercise, and management similar to those predisposing horses to impaction and gas colic, are likely contributors.

Question 88

Diagnosis of RCDisplacement?

Answer 88

Dx made based on signalment, history, physical examination findings, and palpation per rectum.
On palpation per rectum, a horizontally oriented gas distended colon is identified coursing across the abdomen cranial to the pelvic inlet.
It is usually not possible to palpate the cecum because of the colonic displacement

Question 89

What is the proposed pathophysiology linking a high-grain diet to right dorsal displacement?

Answer 89

Rapidly fermentable carbohydrates in a high-grain diet can lead to gas formation, increased viscosity, and stabilization of froth, potentially causing malposition of the colon and displacement or volvulus.

Question 90

What clinical finding can be associated with right dorsal displacement based on gamma glutamyl transferase (GGT) levels?

Answer 90

Horses with right dorsal displacement may have a higher GGT, with about half of them having elevated GGT levels. High GGT can differentiate right dorsal displacement from left dorsal displacement.

Question 91

What imaging modality can be used to support the diagnosis of right dorsal displacement?

Answer 91

Transabdominal ultrasonographic examination can be used to support the diagnosis. Colonic mesenteric vessels adjacent to the right body wall are strongly associated with right dorsal displacement.

Question 92

What are the sensitivity and specificity of US for RCD? where do you do US?

Answer 92

sensitivity of 68%, specificity of 98%, positive predictive value of 96%
Identification of colonic mesenteric vessels coursing horizontally along the right body wall between the 12th and 17th intercostal spaces at the level of the costochondral junction with the probe oriented transversely to the spine was strongly associated with either a right dorsal displacement or 180-degree large colon volvulu

Question 93

Answer 93

Figure 37-12. Ultrasonographic identification of dilated colonic mesenteric vessels (white arrow) on the right side of the abdomen dorsal to the costochondral junction at the 13th intercostal space.

Question 94

Answer 94

Figure 37-11. Right dorsal displacement of the ascending colon. The normal anatomic relationship of the ascending colon (shown in A; ventral view). The most common direction for a right dorsal displacement is migration of the pelvic flexure in a counterclockwise direction when viewed from the caudal and ventral aspect of the horse at the time of surgery (shown in B; ventral view). Although less common, the ascending colon may develop a right dorsal displacement characterized by a clockwise migration of the pelvic
flexure when viewed from the caudal and ventral aspect of the horse at the time of surgery (shown in C; ventral view).

Question 95

What is the primary method of treatment for horses with a presumed right dorsal displacement?

Answer 95

Medical management involves with holding feed, administering IV fluids, analgesia, and light exercise. Medical management was successful in 64% of cases.

Question 96

What is the prognosis for surgical correction of right dorsal displacement?

Answer 96

the prognosis for surgical correction is excellent (>90%), with recurrence reported in 15% of cases undergoing exploratory laparotomy.

Question 97

In what cases should colon resection or colopexy be considered?

Answer 97

Colon resection:
1. prevention of recurrent displacement;
2. removal of compromised bowel;
3. masses, strictures, adhesions

Colopexy should be considered in horses where recurrence is a problem.–> contra-indicated if severe colon oedema and evacuation of the colon previously advised

Question 98

What should be considered in horses with recurrent colic to determine underlying pathology?

Answer 98

Colon biopsy should be considered in horses with recurrent colic to determine if there is underlying pathology leading to dysmotility and pain.

Question 99

What liver enzyme may be increased in horses with right dorsal displacement, and what is its significance?

Answer 99

Gamma glutamyl transferase (GGT) may be increased in horses with right dorsal displacement, and its increase is attributed to transient extrahepatic bile duct obstruction, resolving with surgical correction. High GGT can support the diagnosis in conjunction with other clinical findings.

Question 100

What is left dorsal displacement in the context of the large colon?

Answer 100

Left dorsal displacement occurs when the left colon becomes displaced between the spleen and the left body wall.

Question 101

In which direction is the colon usually displaced in left dorsal displacement?

Answer 101

The colon is most often displaced in a cranial to caudal direction, with the pelvic flexure directed toward the caudal abdomen.

Question 102

What breeds are reported to be predisposed to left dorsal displacement?

Answer 102

Geldings and Warmbloods are reported to be predisposed to left dorsal displacement.

Question 103

What percentage of horses referred for colic were diagnosed with nephrosplenic entrapment?

Answer 103

Nephrosplenic entrapment was diagnosed in 9% of horses referred for colic

Question 104

What is the recommended treatment for left dorsal displacement without entrapment?

Answer 104

Left dorsal displacement without entrapment is managed medically by withholding feed and providing enteral or intravenous fluids (20mL/kg =10L hypertonic followed by 2-4 mL/kg/hr isotonic) and analgesic drugs.

Question 105

What is the reported success rate of medical management for nephrosplenic entrapment?

Answer 105

Success with medical management of nephrosplenic entrapment varies and is reported to be approximately 75%.

Question 106

How is phenylephrine used in the management of nephrosplenic entrapment?

Answer 106

Phenylephrine, an α1-adrenergic agonist, can be used to induce splenic contraction.
The dose rate is 3 μg/kg/min for 15 minutes
or 20 mg for an adult horse given over 15 minutes.

Question 107

What molecule is phenylephrine?

Answer 107

α1-adrenergic agonist

Question 108

what are the adversal effects of phenylephrine?

Answer 108

profound bradycardia and HR should be monitored
also associated to fatal hemorrhage in horses older than 15 years old

Question 109

What does consist the exercise following phenylaphrine?

Answer 109

20 m circle for 20 min (10 min counterclockwise and clockwise) and rolling

Question 110

What is the dosage of phenylaphrine?

Answer 110

IV fluidotherapy 20mg diluted in 1 L of Nacl 0,9% over 10 minutes immediately prior to exercise

Question 111

What technique involves rocking the abdomen of a horse to replace the colon in cases of nephrosplenic entrapment? what is the success rate?

Answer 111

Rolling is a technique involving positioning the horse in** left lateral recumbency, hoisting into dorsal recumbency, rocking the abdomen, and positioning in right lateral recumbency.**

84% success rate when used with hoist and people feet

Question 112

How is surgical correction performed in cases of nephrosplenic entrapment, and what is the prognosis?

Answer 112

Surgical correction involves reaching across the abdomen, pushing the spleen ventrally and medially to free the colon, and exploring the abdomen.
The prognosis is** excellent (>90%)**

Question 113

What is the reported recurrence rate of nephrosplenic entrapment?

Answer 113

Nephrosplenic entrapment is reported to recur in up to 8% to 23% of horses.

Question 114

Describe the laparoscopic portals for nephrosplenic space closure

Answer 114

Feed is withheld for 12 hours prior to surgery
three portals are created: (1) 17th intercostal space or caudal to 18th rib, level with the tuber coxae (laparoscope/instrument portal), (2) paralumbar fossa midway between the 18th rib and mid tuber coxae (laparoscope/instrument portal), and (3) paralumbar fossa 3 to 5 cm ventral to portal (2) (instrument portal).
The abdomen is insufflated with CO2 (4–15 mm Hg).
simple continuous pattern beginning at the cranial aspect and extending caudally. Suturing is completed in a dorsal to ventral direction through the nephrosplenic ligament opposite the dorsal border of the spleen and in a ventral to dorsal direction through the dorsomedial splenic capsule. The first suture is placed between the perirenal fascia and dorsomedial splenic capsule with the needle being retrieved and passed through a small loop in the suture end to secure the suture line cranially. At the caudal extent of the nephrosplenic ligament, the suture pattern is reversed and extended three throws cranially prior to tying the extracorporeal knot or a modified Roeder knot or a
barbed knotless suture
or polypropylene mesh atrached to the dorsal aspect of nephrosplenic ligament with laparoscopic tacking device

Question 115

which size is the laparoscope for closure of nephrosplenic space?

Answer 115

a 10-mm-diameter, 50- to 57-cm-long laparoscope with a 30-degree viewing angle

Question 116

What is the common location for fecalith-induced large colon obstruction?

Answer 116

Typically at the
pelvic flexure,
in the** left dorsal colon** adjacent to the pelvic flexure,
or in the right dorsal colon.

Question 117

How can a fecalith causing obstruction be managed?

Answer 117

It may be hydrated with liquid colonic contents proximal to the obstruction and then broken down with massage through the colon wall or removed through a pelvic flexure enterotomy

Question 118

Name three congenital abnormalities of the colon mentioned in the text.

Answer 118

**Atresia coli,
duplications,
**and malformations.

Question 119

What are the clinical signs of atresia coli in neonates?

Answer 119

Signs of colic occurring within a few hours of birth, abdominal distention, and a lack of meconium staining.

Question 120

How are horses with colonic duplications classified, and what age can they present?

Answer 120

Classified as simple cysts, diverticula, or tubular colonic duplications.
They can present at any age.

Question 121

What is the management approach for a congenital colonic diverticulum?

Answer 121

It may involve successful resection, but outcomes can vary based on associated congenital abnormalities.

Question 122

Name two malformations associated with mesocolon abnormalities, as mentioned in the text.

Answer 122

Stellate and T-shaped malformations.

Question 123

What is a reported association with colonic neoplasia in horses?

Answer 123

Uncommon in horses, but they may present acutely with or without a history of recurrent colic; weight loss; lethargy; exercise intolerance; or diarrhea.

Question 124

What types of colonic neoplastic conditions are mentioned in the text?

Answer 124

Adenocarcinoma,
lymphoma,
gastrointestinal stromal tumors (GIST),
and leimyoma.

Question 125

What may be associated with adenocarcinoma in horses?

Answer 125

Enteric clostridiosis and osseous metaplasia of the tumor.

Question 126

How are most colonic neoplasias diagnosed in horses?

Answer 126

Most are diagnosed during exploratory celiotomy or at necropsy.

Question 127

What inflammatory lesions in horses may necessitate surgery?

Answer 127

Colitis, right dorsal colitis, and occasionally inflammatory or infiltrative bowel disease.

Question 128

What is right dorsal colitis associated with, and how can it be managed medically?

Answer 128

Associated with NSAID toxicity. It can be managed medically by discontinuing NSAID administration and treatment with specific measures, including diet adjustments.

Question 129

Describe a diagnostic method for confirming right dorsal colitis.

Answer 129

Transabdominal ultrasonographic evaluation of the right dorsal colon, with increased thickness being a diagnostic indicator.

Question 130

If you do exploratory celiotomy in colitis what can you give as treatment intra op?

Answer 130

Performing a pelvic flexure enterotomy with evacuation of the colonic contents and intraluminal administration of **di-tri-octahedral (DTO) smectite **may be beneficial

Question 131

What are the clinical signs of colitis and lab values?

Answer 131

fever,
dull demeanor,
and diarrhea, occasionally horses can present with
acute severe colic signs and abdominal distention.

Laboratory data including leukopenia/neutropenia, (relative) hypoalbuminemia, and hyponatremia may be suggestive of colitis

Question 132

what is the aspect of the colon following colitis when you do exploratory celiotomy?

Answer 132

The colon is often edematous with petechiation of the serosal surface, a hemorrhagic mesocolon, and fluid contents

Question 133

what is the normal wall thickness of the right colon on US?

Answer 133

Normal = 0.22–0.59 cm thick
Right dorsal colon thick is 0.72 to 1.59 cm

Question 134

What are the surgical procedures described for managing right dorsal colitis?

Answer 134

1. Bypass of the right dorsal colon,
2. resection of the affected right dorsal colon,
3. combination of resection and bypass.

Question 135

What types of inflammatory or infiltrative bowel diseases are mentioned in the text?

Answer 135

1. Eosinophilic,
2. lymphocytic/plasmacytic,
3. granulomatous colitis.

Question 136

What is the size of biopsy and where should you place it? are eosinophils normally present?

Answer 136

8 mm biopsy punch or full thickness biopsy during PF enterotomy.
Close site with 2-0 or 3-0 polyglactin 910 or polydioxanone in a cruciate.
Place it in 10% neutral buffered formalin volume 10 x the piece and highest nºs of eosinophils are normally present in the cecum and large colon.

Question 137

Inflammatory lesions are more common in SI or colon?

Answer 137

SI but segmental eosinophilic colitis adjacent ot the PF primarily in LDC with LVC impaction can happen

Question 138

What is large colon volvulus, and what are the risk factors associated with it?

Answer 138

Large colon volvulus is the rotation or twisting of the colon, with risk factors including increasing height, multiple colic episodes, quidding behavior, and mares, particularly those that have previously foaled

Question 139

What are the resection proposed accordingly to short segment, moderate segment or long segment affected?

Answer 139

(1) a wedge resection, whereby only the segmental vessels were ligated leaving the colic artery and vein intact and an end-to-end anastomosis was performed (short segment of affected colon); (2) a segmental resection and end-to-end anastomosis with ligation of the adjacent segment of the colic artery and vein (moderate segment of affected colon); or (3) colon resection and side-to-side anastomosis

Question 140

What is the prognosis for horses with a large colon volvulus, and what factors are associated with lower short-term survival?

Answer 140

Generally considered guarded to favorable (50%–70%).
Factors associated with lower short-term survival include:
- higher admission heart rate
- surgery duration
- intraoperative variables like serosal color, tachycardia, and hypotension.

Question 141

Horse when makes torsion most of the times is to which side? How should you turn the colon to correct?

Answer 141

Degas if needed and enlarge the incision because the gas can lead to rupture during manipulation.
Stand on the left side of the horse because colon always twists the same way (dorsomedial) so you turn clockwise and you de-torse it.

Note: horses can twist the colon at its base (involving cecum and colon) which can trick you because the cecocolic ligament will still be straight. Must also confirm that dorsal colon runs into the transverse colon and ileum runs straight to the cecum to be sure that torsion is correct

Question 142

What are the indications for pelvic flexure enterotomy?

Answer 142

Pelvic flexure enterotomy include:
- impaction of the pelvic flexure or right dorsal colon,
- sand impaction,
- enterolithiasis,
- or foreign body removal.

Question 143

What technique is described for colonic evacuation during pelvic flexure enterotomy?

Answer 143

Colonic evacuation during pelvic flexure enterotomy involves making a ~10-cm enterotomy and using warm tap water through two hoses—one for lavaging the bowel and the other fed through the enterotomy into the colon lumen.

Question 144

What suture material and pattern are typically used for closing the enterotomy site during pelvic flexure enterotomy?

Answer 144

closed using 2-0 synthetic, absorbable suture material in a full-thickness simple continuous pattern, followed by oversewing with a Cushing pattern during pelvic flexure enterotomy.

Question 145

Describe an alternative technique for enterotomy closure mentioned in the text.

Answer 145

An alternative technique for enterotomy closure involves using a Thoracoabdominal (TA-90) Premium stapling device. The enterotomy site is occluded, and the stapler is applied across the enterotomy, firing it twice if the incision is longer than ~8 cm.

Question 146

What is the prognosis for horses undergoing pelvic flexure enterotomy?

Answer 146

excellent, with a success rate of over 90%, and it is dependent on the primary lesion.

Question 147

What vessels are ligated during large colon resection, and what methods can be used for vessel occlusion?

Answer 147

The** right colic** and colic branch of the ileocolic arteries and veins are ligated during large colon resection.
Vessel occlusion can be achieved using either absorbable suture with a distal transfixing and proximal encircling ligature or a TA-90 stapling device.

Question 148

What complications are associated with pelvic flexure enterotomy?

Answer 148

Rare. They may include diarrhea, surgical site infection, life-threatening hemorrhage, omental adhesions to the enterotomy site, and the possibility of reimpaction.

Question 149

What are the common indications for large colon resection?

Answer 149

1. Large colon resection is commonly performed to prevent recurrent colonic displacements or volvulus,
2. remove compromised large colon following correction of a large colon volvulus,
3. and address conditions such as adhesions, masses, colonic stricture, fecaliths, enterolithiasis, and Richter hernia.

Question 150

What are the two main techniques for large colon resection, and how is the choice between them determined?

Answer 150

Large colon resection can be performed using a:
1. stapled or hand-sewn side-to-side
2. hand-sewn end-to-end technique.

The choice between them is often based on surgeon preference.

Question 151

Answer 151

Figure 37-20. A hand-sutured, side-to-side anastomosis of the ascendingcolon. (A) Placement of stay sutures at either end of the proposedanastomosis. The seromuscular layers of the ventral and dorsal colonsare apposed using a simple continuous pattern with an absorbable suturematerial. (B) After incision of the intestine, the two sides of the stomaare closed in a full-thickness simple continuous pattern (C).
(D) Thecompleted stoma is oversewn to complete the anastomosis.
Describe the technique step by step

Question 152

Colon resection can be performed using (name the tx

Answer 152

• stapled or hand-sewn
  side-to-side
• or hand-sewn end-to-end technique.

Question 153

Short term survival for large colon resection

Answer 153

Colon resection, however, did not significantly improve outcome in horses with a large colon volvulus in one retrospective study.
Short-term survival for horses with a hemorrhage score of less than 3 was 82% (18/22) without resection and 100% (12/12) with resection, and with a hemorrhage score of 3 or above only one horse (33%) without resection survived whereas 5/10 (50%) of horses with resection survived (see Table 37-3).

Question 154

Indications for large colon resection

Answer 154

indications for large colon resection are
adhesions of viscera to the large colon,
masses,
colonic stricture,
fecaliths,
enterolithiasis,
and Richter hernia

Question 155

where is the resection of colon is performed at what level?

Answer 155

cecocolic ligament

Question 156

What is the preparation steps for colon resection?

Answer 156

1 - Moistened laparotomy sponges are positioned to protect the body wall and peritoneal cavity from contamination
2 - Enterotomy of PF and do not leave excessive fluid on right colons (risk of contamination)
3 - ligate right colic and colic branch of ileocolic arteries with absorbable suture or TA-90

Question 157

Answer 157

Figure 37-19. The ascending colon is placed on a colon tray with the vessels facing uppermost. The colonic vessels are isolated from within the mesentery and double or triple ligated before transection (insert).

Question 158

What is the purpose of creating a pelvic flexure enterotomy before large colon resection?

Answer 158

Before large colon resection, a pelvic flexure enterotomy is performed to evacuate the colonic digesta and prevent excessive fluid in the right colons, which can cause contamination during resection and anastomosis.

Question 159

Describe side to side technique

Answer 159

Evacute the colon first
- Anastomosis prior to resection - WHY? it prevents the right dorsal and ventral to be dragged back
*Stay sutures are placed in the R ventral and R dorsal 30 to 35 cm apart proximal to vessel ligation site
*25-30 cm simple continuous between right dorsal and ventral colon
*15-25 cm stoma blade or GIA90 above and bellow the continuous suture previously performed
After incision of the intestine the two sides of the stoma are closed in a full-thickness simple continuous pattern monofilament
Before resection** occlude lumen with Doyen or Scullins-Scudder **intestinal clamps before cutting
*Then resection the lumen of right dorsal and close in 2 layers (use cushing or lembert) or Parker-kerr

Question 160

name the tx

Answer 160

Figure 37-21. A hand-sutured, side-to-side anastomosis of the ascending colon. The transected extremity of the ventral colon is being sutured with the intestinal clamp in place, while the transected dorsal colon closure is being completed in two layers.

Question 161

describe end to end technique in colon resection

Answer 161

Used for focal resection of PFlexure or resection and anastomosis of small segment of dorsal or ventral colon
* Prepare before empty PF, ligature vessels, prepare surgical site
Resect right ventral transverse to long axis**
**Resect right dorsal 30° obliquely to long axis → match up different lumen sizes and so antimesenteric border is shorter
*End to end technique with N0 synthetic absorbable suture in a Connell or simple continuous pattern oversewn using cushing or lembert
START with mesenteric borders
Suture wider in RVC to obtain adequate alignment with the RDC.
Final stoma size is 12 to 14 cm

Question 162

What complications are associated with large colon resection?

Answer 162

diarrhea,
colic,
tachycardia,
severe hypoproteinemia,
pyrexia,
jugular vein thrombophlebitis,
incisional infection,
laminitis,
ileus,
endotoxemia,
abortion,
adhesions,
hemorrhage from the mesenteric stump, septic peritonitis, and long bone fractures during recovery from anesthesia (tibia/femur in old broodmares)

Question 163

What is the purpose of performing a colopexy in horses?

Answer 163

Colopexy is performed to prevent large colon displacement and volvulus, especially in cases of recurrent colon displacement. It can be done during repeat laparotomy or as an initial procedure in young broodmares at high risk for recurrence.

Question 164

What are the different techniques for performing colopexy?

Answer 164

Colopexy techniques (lateral free tenial band of the left ventral colon to the body wall, ) include:
1. recumbent parallel to the laparotomy incision
2. recumbent and dissect skin and subcut tissue from EXTERNAL sheath of rectus abdominis muscle

3. recumbent incorporating the left ventral colon into the ventral midline body wall closure
4. performing laparoscopic colopexy.

Question 165

Describe the colipexy technique

Answer 165

One colopexy technique involves suturing a 20- to 35-cm section of the lateral free tenial band of the left ventral colon to the body wall approximately 6 to 10 cm to the left of the midline and parallel to the laparotomy incision.
The left body wall is elevated with towel clamps and an incision is made through the parietal peritoneum and retroperitoneal fat to expose the internal sheath of the rectus abdominis muscle.
An incision is made through the skin and subcutaneous tissue directly ventral to the incision to expose the external sheath of the rectus abdominis muscle to facilitate suture placement through the body wall including the external rectus sheath.
The colopexy is performed midway between the sternal and pelvic flexure using** No. 2 polypropylene or nylon in a simple continuous or preferably an interrupted cruciate pattern.** Eachs suture bite should span the entire width of the tenial band and be 10 to 15 mm apart, without penetrating the lumen. The ventral midline incision and the subcutaneous tissue and skin at the colopexy site are closed routinely.

Question 166

Name the size, which band, which colon
which muscle incised
which suture, pattern and size of bite apart in colopexy

Answer 166

involves suturing a 20- to 35-cm section of the lateral free tenial band of the left ventral colon to the
body wall approximately 6 to 10 cm to the left of the midline and parallel to the laparotomy incision.
Incision inside the abdomen and outside the abdomen to exxpose the internal sheath and external sheath of the rectus abdominis muscle
** Midway PF and sternal flexure
** N2 polypropylene or nylon
** Cruciate pattern**
each suture bite should be** 10 to 15 mm apart**

Question 167

How is laparoscopic colopexy performed, and what are its advantages?

Answer 167

Laparoscopic colopexy is performed with the horse under general anesthesia using insufflation (15 mmHg) and instrument portals. It involves suturing the lateral free tenial band of the left ventral colon to the body wall.

Surgeon on right side and video on L side
-1st laparo portal ** is placed just cranial to the umbilicus**
-2 instrument portals LEFT CAUDAL 5cm and 15 cm to the of the midline) 10-12 mm obturator
-skin incision of 25 cm starting 5 caudal to the 1st portal parallel to the ventral midline and extend 20 cm cranial
**3rd portal instrument: 8 cm caudal **to the xiophoid and **2 cm to the left of the midline
25 cm long incision of the skin and subcut 15 cm to the left of the midline this will expose the rectus abdominis muscle the cranial extent of the incision is 20 cm cranial to the umbilicus
Use babcock forceps throught the cranial instrument portal
Start extraabdominally suturing using No2 nylon through body wall into peritoneal cavity - place in the lateral free tenial band of LVC using inline laparoscopic needle holders and than through the entire body wall once again
Sutures placed 2 cm apart**
Knots are tied in the subcutaneous tissue
Continuous pattern
**No2 nylon with a swaged **on large reverse cutting needle

Question 168

What was the foaling rate reported after colopexy in mares that were pregnant at the time of surgery?

Answer 168

80%

Question 169

you can do colopexy by incorporating the ventral midline

Answer 169

Using a cranial ventral midline laparotomy approach when there is a tentative diagnosis of large colon volvulus.
The cranial ventral midline laparotomy incision is created** 5 cm caudal to the xiphoid cartilage** and extending in a caudal direction for 15 to 25 cm. **
At the time of body wall closure, the colopexy is performed by incorporating the lateral free tenial band of the left ventral colon** into the laparotomy closure beginning 40 cm from the cecocolic ligament just beyond the sternal flexure.
The colopexy is 10 to 15 cm long and performed using No. 2 polyglycolic acid or polyglactin 910 in a simple continuous or interrupted cruciate pattern.
The lateral free tenial band was positioned level with the laparotomy incision using Allis tissue forceps.
Tissue bites in the tenia are 1 to 1.5 cm.

Question 170

Could you use chromic gut for the colopexy?

Answer 170

No it is not advised because it causes dissapearnce of the colopexy by 12 months after surgery

Question 171

What potential fetal-related complication is associated with colopexy, and why?

Answer 171

Performing a colopexy lateral to the ventral midline incision may be associated with the development of fetal musculoskeletal deformities due to intrauterine malposition of the fetus.

Question 172

advantages of laparoscopic colopexy

Answer 172

The advantages include a shorter convalescence period compared to laparotomy.

Question 173

Sinovich et al. VS 2019 did a sturdy EX vivo comparision of barbed sutures for pelvic flexure enterotomy. What were the conclusions?

Answer 173

*Bursting strengths of both unidirectional and bidirectional barbed sutures were LOWER than single and double layer closures – possibly less secure …
*Double layer closure HIGHEST BURSTING STRENGTH
*Unidirectional barbed REDUCTION IN LUMEN DIAMETER compared to bidirectional and single layerclosures
*Unidirectional barbed – single continuous cushing pattern
Construction time did not differ between groups

Question 174

prognosis for horses undergoing colopexy

Answer 174

good

Question 175

Complications of colopexy

Answer 175

**Mild intermittent colic **can occur during the first **4 weeks after surgery **and may be associated with tension on the colon
Colic signs appeared to occur more often if the colopexy site was too close to the cecocolic ligament
Weight loss may occur
Catastrophic rupture 4-12weeks after colopexy 1-6%
**Subcutaneous fistulous tracts **or enterocutaneous fistula in less than 2% - if you remve the sutures 2 to 3 weekes after surgery may resolve the drainage

Question 176

Decreasedapparent digestion of phosphorus and a negative phosphorusbalance are persistent features of large colon resection in horses, is it true?

Answer 176

Ponies undergoing resection of 75% of the large colon histologically did not have adaptive mucosal hypertrophy or hypoplasia at 6 months;however, some of the ponies were persistently hypophosphatemic.
Horses, however, generally do well following colonresection and maintain their body weight with the diet being adapted to the individual horse.

Question 177

Schoster et al 2020 JAVMA presents the outcome and complications following transrectal and trasnabdominal large intestinal trocaterization in equids with colic: 228 cases (2004-2018) what was the main complication? what was the percentage of survival to discharge?

Answer 177

Peritonitis - >10000cells abdo tap

73% survived to hospital discharge
None euthanasied due to peritonitis caused by trocarisation

Question 178

Pezzanite et al 2018 VS studied the tx associated outcomes in horses following large colon resection

Answer 178

Short and long term survival outcomes are not different between sutured end-to-end or stapled function end-to-end anastomoses in horses undergoing colectomy

Question 179

De Souza and Mair 2021refer which % of horse go back to work after nonstrangulating large intestinal displacement surgery?

Answer 179

61-90%

Question 180

What are the reasons for colonic dysfunction that could explain lack of performance?

Answer 180

Reduction in intestinal cells of Cajal density within pelvic flexure

Question 181

What are the factors that negatively affect return to athletic function after surgical correction?

Answer 181

Stall rest for ortho reasons prior surgery, incisional complications, hernia formation

Question 182

What is the prevalence of nephrosplenic space entrapment?

Answer 182

2,5-9%

Question 183

Gandini et al 2021 describes the presence of a fibrous band originating from nephrosplenic ligament. What was the suspected cause?

Answer 183

Gandini et al 2021 describes the presence of a fibrous band originating from nephrosplenic ligament. What was the suspected cause?

Question 184

Giusti et al 2022 EVE mentions that several cases of adhesions can happen without previous laparotomy, what are the risk factors?

Answer 184

Broodmares or geldings that were submitted to castrations

Question 185

Gillen et al Javma 2019 what is the % of horses that were tx successfuly with medical tx for nephrosplenic?

Answer 185

53% of horse were treated with phenylephrine hydrochloride that is a alfa1 adrenergic receptor agonist that with rolling or exercise facilitates medical resolution.

Question 186

Colonic viability assessment what does the surgeon evaluate?

Answer 186

serosal color,
bleeding from enterotomy site
mesocolonic and colonic edema
arterial pulses
peristalsis
mucosal color
clinical variables arterial pressurm PCV, lactate concentration, plasma proten

Question 187

Colonic blood flow can be evaluated how?

Answer 187

Colonic blood flow has been evaluated using fluorescein dye,1 Doppler flow, intraluminal pressures, and surface oxygen tension

Question 188

Intraluminal pressure greater than ____ cm H2O is associated with nonsurvival

Answer 188

38 cm H2O

Question 189

Pelvic flexure biopsy where I:C is greater than 1 the odds ratio for death are _____ times greater. Hemorrhage score greater than or equal to ___

Answer 189

ratio for death 13 times greater
Horses with mucosal hemorrhage score greater than or equal to 3 had an odds ratio for death 8.8 times greater (1.9–39.6)

Question 190

What are the variables associated with lower short-term survival?

Answer 190

higher admission PCV
higher admission HR
surgery duratioon
intraop serosal coloar
Tachycardia 24-48 post + colic+diarrhea or hemorrhagic diarrhea less favorable outcom
Posop lactte below 1mmol/L = survivors and nonsurvivors 3.24 mmol/L

Question 191

it is normal to have eosinophils in the equine intestine?

Answer 191

It is important to keep in mind that eosinophils are normally present within the equine intestine with highest numbers in the cecum and large colon (~400–500 eosinophils/mm2)

Question 192

name the instrument

Answer 192

Scullins scudder