Lecture 8: Abnormal Conditions of Equine Large Intestine Flashcards

1
Q

What is included in large intestine

A

Cecum, large colon, small colon, rectum

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2
Q

Where is the cecum located

A

Between small intestine and large colon on right side

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3
Q

What are the three parts of the cecum

A
  1. Base- most dorsal
  2. Body- 4 longitudinal bands
  3. Apex- narrow blinded end directed cranially
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4
Q

What are the two primary functions of the cecum

A

Water absorption, microbial digestion

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5
Q

What is the most common pathological condition of the cecum

A

Cecal impaction

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6
Q

What is the fatality rate in cecal impactions and why

A

43%, due to rupture

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7
Q

What are some causes of cecal impactions

A

Poor dentition, feeding poor quality roughage, decreased water intake, patrurition, parasite induced thromboembolism, hospitalization with GA within 5 days, use of NSAIDS and lack of exercise

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8
Q

How do you diagnose cecal impactions

A

1.Mild signs of pain
2. lying down, looking at flank, decreased appetite, depression
3. HR normal to slightly elevated
4. Borborygmi decreased with decreased fecal production
5. Rectal palpation- tension in ventral cecal band, lack of sacculations, can’t pass hand dorsal over impaction

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9
Q

What does the rectal exam reveal for cecal impaction

A
  1. Tension in ventral cecal band
  2. Lack of sacculations due to increased filling
  3. Can’t pass hand dorsally
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10
Q

Is BW normal or abnormal in cecal impactions

A

Normal

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11
Q

What are some characteristics of type 1-mechanical cecal impactions

A

Causes: Firm, dry or doughy ingesta
Location: base or body
Impaction indented with fingers
Cecal wall does not feel thickened
Normal peritoneal fluid

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12
Q

What are some characteristics of type 2 cecal dysfunction

A
  1. Cecum is tightly distended with gas and ingesta
  2. More painful
  3. Higher heart rate
  4. May be endotoxin
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13
Q

How do you tx type 1 mechanical cecal impactions

A

Soften ingesta to allow cecal contractions to empty cecal contents into right ventral colon

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14
Q

How do you tx type 2 cecal dysfunction

A

Surgical- decompression, typhlotomy and evacuation, cecal bypass- cecocolic anastomosis

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15
Q

What are the medical treatments in cecal impactions

A
  1. Withhold feed
  2. IV fluids
  3. Oral laxatives via NG tube
  4. Psyllium
  5. Walking and limited controlled grazing to stimulate motility
  6. Analagesics
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16
Q

What analgesics do you need to have caution with in cecal impactions

A

Xylazine, detomidine, butorphanol

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17
Q

When should surgery be considered for cecal impactions

A
  1. No improvement on rectal palpation for 24-36hrs
  2. Systemic deterioration (increase HR)
  3. Increase pain
  4. Cecum feels tight enough to rupture
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18
Q

What is the large colon composed of

A

Dorsal and ventral colons connected by short mesentery

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19
Q

Describe the order through the large colon

A
  1. Right ventral colon
  2. Sternal flexure
  3. Left ventral colon
  4. Pelvic flexure
  5. Left dorsal colon
  6. Diaphragmatic flexure
  7. Right dorsal colon
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20
Q

What are some abnormal conditions of large colon

A

Tympany, impaction, sand, enteroliths, nephrosplenic displacement, right dorsal displacement, volvulus

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21
Q

What is the most commonly reported colic in horses

A

Large colon tympany

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22
Q

What is large colon tympany

A

Gas colic, spasmodic colic

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23
Q

What causes large colon tympany

A

Excessive gas fermentation, resulting in distention and pain

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24
Q

What are some risk factors for large colon tympany

A

Cribbing, increased time in stall, recent change to exercise, lack of deworming, hx of travel within 24hrs, recent lameness, infrequent dentals, tapeworms, diet with lots of carbs and less fiber

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25
Q

How do you diagnose large colon tympany

A
  1. Acute pain +/- visible abdominal distention
  2. Rectal palpation- moderate to severe gas distention of large colon
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26
Q

What are some differentials for large colon tympany

A

Large colon displacement, large colon torsion, ileus, impending colitis, small colon obstruction

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27
Q

What is treatment for large colon tympany

A

Withhold food, analgesics

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28
Q

If you suspect large colon tympany but horse does not respond to analgesics what is a more concerning differential

A

Large colon volvulus

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29
Q

What is the most frequent type of simple obstruction

A

Large colon impaction

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30
Q

What are some risk factors for large colon impaction

A

Cribbing, increase time in stall, lack of deworming, hx travel within 24hrs, recent changes to exercise, hx of colic, recent lameness, infrequent dentals, high grain diet, hospitalization, general anesthesia, medications (atropine and morphine)

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31
Q

What medications can cause large colon impactions

A

Atropine and morphine

32
Q

What is most common site of large colon impaction

A

Pelvic flexure

Then right dorsal colon > transverse colon

33
Q

What are some differentials for large colon impaction

A

Large colon displacement +/- right dorsal colon impaction

34
Q

What is the treatment for large colon impaction

A

Withhold feed, fluid therapy, NSAIDS, cathartics (magnesium sulfate, mineral oil)

35
Q

What are some indications for referral and surgery for large colon impactions

A

Uncontrollable pain, deteriorating cardiovascular status, abnormal changes in peritoneal fluid

36
Q

What is the surgical procedure for large colon impactions

A

Pelvic flexure enterotomy and evacuation

37
Q

What are some complications from surgery for large colon impaction

A
  1. Intraoperative rupture of large colon
  2. Post-op diarrhea
  3. Incisional drainage/infection
  4. Septic peritonitis
38
Q

What are some risk factors for large colon sand impaction

A
  1. Insufficient roughage /fiber in diet
  2. Access to sand
39
Q

How can sand colic be determined

A
  1. Sand ausculted in ventral abdomen caudal to xyphoid
  2. Observation of sand in feces
  3. AUS
40
Q

What is medical treatment for large colon sand impaction

A

Remove horse from access to sand, rehydrate, laxatives, magnesium sulfate and/or psyllium

41
Q

How is surgery performed for large colon sand impaction

A

Pelvic flexure enterotomy and evacuated

42
Q

What site does sand like to sit, predisposed to rupture

A

Right dorsal colon

43
Q

What is the pelvic flexure pacemaker

A

Contractions of longitudinal muscle layers shorten length of left colons and move pelvic flexure toward diaphragm followed by caudal movement towards pelvis during relaxation

44
Q

What type of diet can cause large colon displacement

A

Increase carbs- excessive fermentation and gas distention

45
Q

What is nephrosplenic entrapment/ left dorsal displacement

A

Left dorsal and left ventral colons migrate later to the spleen in dorsal direction until entrapped in nephrosplenic space

46
Q

What age group is typically associated with nephrosplenic entrapment

A

Any age

47
Q

How do you diagnose nephrosplenic entrapment

A

Transabdominal US- presence of gas filled colon dorsal to spleen, precludes imaging of left kidney

Rectal palpation- mainstay diagnosing this

48
Q

What is medical treatment for nephrosplenic entrapment

A

Withhold feed, IV, phenylephrine- causes splenic contraction, rolling under GA, trocharization then lunge, therapeutic trailer ride

49
Q

What drug can you give to treat nephrosplenic entrapment and what does it do

A

Phenylephrine- causes splenic contraction, lunge after administration

50
Q

What is the surgical procedure for nephrosplenic entrapment

A

Standing flank laparotomy or ventral midline celiotomy

51
Q

What is right dorsal displacement

A

Retropulsive movement of pelvic flexure with subsequent migration cranial

52
Q

What is one of the most painful and devastating causes of colic

A

Large colon volvulus

53
Q

Without intervention in large colon volvulus death occurs within hours, what is death due to

A

Hypovolemia shock, progressive cardiovascular collapse, poor pulmonary expansion

54
Q

What horses have a higher prevalence for large colon volvulus

A

Broodmares

55
Q

What are the risk factors for broodmares getting large colon volvulus

A

Recent patrurition, recent dietary changes, recent access to lush pasture

56
Q

What is tx for large colon volvulus

A

Surgery

57
Q

What needs to be done pre-operatively for large colon volvulus

A

Stabilization measures taken- fluids!

58
Q

What is prognosis for large colon volvulus

A

Not great, mortality rates between 56%-65%

59
Q

What are the pre-operative parameters that indicate poor prognosis for large colon volvulus

A

PCV >50%, rectal temp>102%, heart rate >80%

60
Q

Where does the small colon sit

A

Caudo-dorsal quadrant of the abdomen

61
Q

What is function of small colon

A

Contractile activity and circular muscles produce fecal balls

62
Q

What are some simple obstructions of small colon

A
  1. Fecal impaction
  2. Enterolithiasis
  3. Fecaliths, phytobezoars, trichobezoars, meconium
63
Q

What are some vascular lesions of small colon

A

Intramural hematoma, mesocolic rupture, nonstrangulating infarction

64
Q

What are some strangulating lesions in small colon

A

Strangulating lipomas, intussception

65
Q

What are some risk factors for enteroliths

A
  1. Geographic- CA and FL
  2. Breeds: Arabians and minis
  3. Feeding alfalfa hay
  4. <50% time spent outdoors
66
Q

What is the most common site for enterolith obstruction

A

Small colon

67
Q

What is prognosis for enteroliths

A

Excellent if no local necrosis of bowel

68
Q

T or F: rectal tears are life threatening

A

True!

69
Q

Where do most rectal tears occur

A

Dorsal aspect of rectum, oriented parallel to longitudinal axis of rectum

70
Q

What are some signs indicating rectal tear

A
  1. Sudden release of pressure
  2. Direct palpation of abdominal organs
  3. Large amount of blood on sleeve/glove
  4. Hemorrhagic feces
71
Q

What do you do once you suspect rectal tear

A
  1. Assess severity
  2. Inform owner
  3. Apply tx
  4. Contact liability insurance
72
Q

What is the initial treatment for rectal tears

A
  1. Reduction of rectal activity- IV sedation, caudal epidural, lidocaine enema, buscopan
  2. Gentle fecal removal (after epidural)
  3. Treatment of septic shock and peritonitis with banamine and broad spectrum antibiotics
  4. Referral
73
Q

What are some causes of rectal prolapse

A

Tenesmus from diarrhea, dystocia, intestinal parasites, colic, rectal tumor

74
Q

What sex are rectal prolapses more common in

A

Females

75
Q

What is the treatment for rectal prolapse

A
  1. Caudal epidural to reduce straining and facilities reduction
  2. Reduce mucosal enema with topical glycerin/ sugar/ magnesium sulfate / lidocaine
  3. Purse string suture
  4. With hold feed 12-24hrs
  5. Mineral oil via NG tube
76
Q

Label 1-7

A
  1. Right ventral colon
  2. Sternal flexure
  3. Left ventral colon
    4.pelvic flexure
  4. Left dorsal colon
  5. Diaphragmatic flexure
  6. Right dorsal colon