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what are most common sites for large colon impaction? are they palapable on rectal?
- pelvic flexure, left colon (can palpate via rectal )
- right dorsal colon - transverse colon junction (in front of cecum, can't palpate)
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what is classic sign noted with large colon impaction?
constipation
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what are clinical signs associated with large colon impaction?
- mild colic; mild dehydration
- minimal systemic deterioration unless prolonged w/o tx
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what is peritoneal fluid like with large colon impaction?
typically normal, if left untreated can see elevated TP
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what is seen on US? rectal palpation? gastric reflux?
- US: wnl
- unmistakable lesion w/rectal palpation; pelvic flexure at pelvic inlet
- generally no reflux
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what is treatment for large colon impaction?
- isotonic *enteral fluid therapy* to hydrate + stim. gastrocolic reflex
- laxatives; Mg therapy to pull fluid into lumen
- *NPO*
- analgesia
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what is complication associated w/returning horse to feed after relieving large colon impaction?
- re-obstruction
- -return slowly, monitory water intake
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what gets entrapped in nephrosplenic space?
- left dorsal colon
- - pelvic flexure or entire left colon
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what are perfusion parameters like with nephrosplenic entrapment? colic signs?
- normal
- mild-severe colic signs
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what is determined via rectal palpation?
- feel taenia/bands of L ventral colon coursing dorsocranially
- enlarged spleen - displaced ventromedially
- gas/feed in colon
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what would US show with nephrosplenic entrapment? Peritoneal fluid?
- US shows colon btwn kidney and spleen
- fluid is normal (caution not to puncture spleen)
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what are the 4 options for treating nephrosplenic entrapment?
- 1: restrict feed + fluids, hope for spontaneous recovery
- 2: phenylephrine (alpha agonist) - splenic contracture - jog to free
- 3: IV GA and roll (R lateral - Dorsal recumbency - L lateral)
- 4: surgery - GA, ventral midline
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what are options to prevent reoccurrence of nephrosplenic entrapment?
- laparoscopy to ablate the space
- colopexy and colonic resection (more side effects)
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what minerals comprise an enterolith?
magnesium ammonium phosphate crystals around a nidus
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what is geographic distribution for enterolithiasis? what breed? what age? what feed?
- SW, California, Florida, Indiana
- arabians
- adults/mature horse
- alfalfa (high Mg concentration)
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what are clinical findings associated w/enterolithiasis?
- recurring acute bouts of pain
- if obstructs transverse colon - severe pain and distended prox. colon
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can you palpate enteroliths via rectal? what will peritoneal fluid be like?
- not usually, if in transverse can't feel them
- normal fluid
- can see on rads
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what is treatment for enterolithiasis?
- surgery - pelvic flexure enterotomy
- (perfectly round - single stone; polyhedral/flat - look for more)
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what is signalment associated with fecaliths?
- miniature horses; ponies (dental problems; dietary indiscretion)
- young; <1yr and older too
- no sex predilection
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where is fecalith usually found? what signs are associated?
- small colon
- no feces being passed
- mild to mod. colic
- severe abdominal distention
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what is recommended treatment for fecalith?
- surgical removal - pelvic flexure enterotomy
- (trocharize cecum prior to surgery if necessary to improve venous return/ventilation)
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what leads to small colon impaction? what season is associated?
- dehydrated feces (winter, decr. water intake)
- inspissated fibrous fecal material
- foreign body
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what is felt on rectal palpation with small colon impaction?
- feel impaction in small colon
- could be difficult to feel due to distention proximal to impaction
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How are perfusion paremeters with small colon impaction?
endotoxemia common (blood from SC bypasses liver -strait back to heart/circulation)
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what is a common complicating feature of small colon impaction?
salmonellosis
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T/F: Small colon impaction should be considered in any horse presenting for colic or w/history of diarrhea, and a rectal should be performed.
true
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how is small colon impaction treated?
- can try medical (fluids + laxatives)
- surgery usually necessary (colon massage or enterotomy)
- - also do pelvic flexure enterotomy to remove ingesta proximal so small colon can "rest"
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what is the cause of thromboembolic colic?
strongylus vulgaris migrating through cranial mesenteric artery - arteritis from molting L4-5
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what are clinical findings associated with thromboembolic colic?
- large intestine gas distention
- fremitus (when rectal - cr. mesenteric a.)
- mild-mod-severe colic signs
- CV failure
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how old are horses affected by thromboembolic colic?
>1 year due to long prepatent period of the strongyle
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how is thromboembolic colic treated?
- surgical resection of the infarct
- Ivermectin as prevention (highly effective)
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what is signalment commonly associated with large colon volvulus?
- brood mares
- lush pastures/high CHO
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what are clinical signs associated w/large colon volvulus?
- severe unrelenting pain; sudden onset
- non-responsive to analgesia = hallmark
- abdominal compartment syndrome (severe gas distention - depressed ventilation/venous return)
- +/- gastric reflux
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what is treatment for large colon volvulus?
- SURGICAL EMERGENCY
- resection of devitalized sections (may not be devitalized if only rotated 270 degrees)
- colopexy to prevent recurrence
- laminitis prophylaxis post-op
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