Equine Med- Non-strangulating or Strangulating obstructive diseases of the Large Intestine

wilsbach's version from 2016-02-22 20:12

Non-strangulating lesions

Large Intestinal Colic: Cecal impaction and pelvic flexure impaction

Question Answer
"large intestines" includes what anatomy? Cecum, Large Colon & Small Colon
what does level of pain depend on? Level of pain depends on lesion-- Low to moderate (except torsions)
what is gastric reflux like with large int colic?Often no net gastric reflux
how painful are cecal impactions?Often not painful until very severe
what are CS of cecal impaction like?Often not painful until very severe... Partial anorexia & less manure production
cecum impaction is often associated with? (who tends to be at risk?)Associated with change in exercise + surgery-- often Very active horses suddenly on stall rest due to Orthopedic surgery
what is a problem with cecal impactions relating to how they treat them? Can be easily masked by Bute® / Banamine® (meaning they are hiding the bigger prob)
prog of cecal impaction?High fatality rate due to Rupture before showing severe signs
pic showing cecal impaction an what is going on in it
what is medical management/tx of cecal impaction like?try to attempt medical before sx management. Give Enteral fluids / laxatives, and IV fluids. BE CAREFUL OF USING PAIN MANAGEMENT (might mask if a bigger prob is coming)
what is sx management of cecal impaction like? Typhlotomy to empty the cecal contents (Good prognosis if caught early)
Large colon impaction--> WHERE in the large colon is the most likely place for impaction?PELVIC FLEXURE!!! another high risk area is there the Right Dorsal Colon-->Transverse (basically the places where the lumen narrows are the highest risk)
what are some risk factors which contribute to large colon (pelvic flexure) impaction? Ingestion of coarse feed, Meal feeding concentrates, Inadequate mastication, Poor dental health, Insufficient water supply, Reduced water intake (look at teeth! is water frozen? etc)
how severe is the colic from a pelvic flexure impaction?mild and intermittent
what are the clinical signs of a pelvic flexure impaction? Mild (intermittent) colic, Decreased appetite, Reduced fecal output (dry/mucus coated), Mild tachycardia, Still G-I sounds present, Mild dehydration (initially)
what might feces look like with a pelvic flexure impaction?dry/mucus coated (bc reduced output)
where would you feel a pelvic flexure impaction? firm mass in the pelvic flexure palpable…….in pelvic inlet (it IS a PELVIC flexure after all)
what will pelvic flex impaction look like on US?WNL
what will happen if you place a NG tube with a pelvic flexure impaction?no reflux
what is peritoneal fluid like with a pelvic flexure impaction?normal
Pelvic Flexure Impaction: Tx-->what is the best way to give fluids in this case? why? what kinda fluids do you want to give?want to give ENTERAL FLUID! because this Stimulate gastrocolic reflex (increase in motility of the colon in response to stretch in the stomach and byproducts of digestion in the small intestine.). Use ISOTONIC fluids as not to disrupt their electrolyte balance. **always check for reflux. (also provide analgesics)
when should you feed a horse with a pelvic flex impaction?not till it is resolved!!! and start out slow again
if the pelvic flex impaction is more severe/doesnt respond to enteral fluids, what should you do to tx?Cecal trocharization in more serious cases, with Serial rectal exams. (consider IV fluids? / Mineral oil?)
prog of Pelvic Flexure Impaction? Excellent Prognosis: go slow with refeeding!!

Large intestinal colic: Left Dorsal Displacement (LDD) of the Large Colon (nephrosplenic entrapment), ENTEROLITHIASIS, FECALITHIASIS

Question Answer
Left Dorsal Displacement (LDD) of the Large Colon--> where does it get stuck??NEPHROSPLENIC LIGAMENT
what is the theory behind why Left Dorsal Displacement (LDD) of the Large Colon occurs? colonic gas distention occurs, spleen contracts in response to pain, gas filled colon displaces dorsally, and when the spleen re- engorges it hooks the displaced colon
what is the severity of the colic from LDD?Mild-moderate-severe colic
what does LDD feel like with rectal exam?Nephro-splenic ligament is not free! Taenia LVC palpable coursing dorsocranially to the left kidney
what does LDD look like on US?colon visible near kidney
what will putting a NG tube in be like with a LDD?+/- reflux
what are the 4 tx choices for tx LDD?(1) Conservative (2) Phenylephrine (3) Rolling under general anaesthesia (4) sx intervention
Prognosis of Nephrosplenic Entrapment?good
explain the conservative tx of LDD/nephrosplenic entrapment?the thought is it may resolve on its own... have NPO, iv fluids. allow colon time to empty and Entrapment may resolve. Horses need space and are allowed to roll (might dislodge it)
what is Phenylephrine, how can it help treat nephrosplenic entrapment?it is a alpha-1 adrenergic agonist which causes Vasoconstriction / splenic contracture. 20mg/1000lb: diluted in Saline given over 10 min. Then Jog the horse. The Idea behind this is: spleen shrinks and entrapped colon bounces up and off the ligament, resolving the entrapment
explain how you could go about treating the nephrosplenic entrapment by rolling the horseprovide either short term IV anaesthesia or General Anaesthesia (xylazine, ketamine, valium). Horse is dropped into lateral recumbency, Then rolled in dorsal recumbency, Then rolled to the left side.
when would you consider sx intervention for nephrosplenic entrapment? what would you do in this case? do if If options 1-3 have been unsuccessful, or if there has been colon torsion after initial rolling (rare)! Also Persistent pain / severe distention. For chronic offenders you do a Ablation nephrosplenic space
what is an enterolith? what causes these to happen?Enterolith is a Stone formation within the GI tract. It is usually Minerals deposited around a nidus (Magnesium ammonium phosphate). Occurs in certain environments: Sandy soil, california, texas, southwest USA
what is the colic like with enterolithiasis? Intermittent colic- As stone moves in and out of smaller spaces
where is the trouble area in the colon with enteroliths?where RDC goes into transverse colon (narrow!)
what is the breed which is particularly prone to enteroliths?Arabs/ Arab crosses
what would you feel on rectal palp with enteroliths?not palpable (due to location)
what would you see with radiographs of enterolith? may be visible
how do you treat enteroliths?surgical removal via Pelvic flexure enterotomy
WHO is MOST prone to getting FECALITHS? WHY?Common cause of colic in Miniature Horses due to Dietary indiscretion and Breed associated dental problems
WHERE do FECALiths most often obstruct?Small colon obstruction most common
what IS a fecalith?Concretions of feed material
what are the CSs of a fecalith?Gas distention / bloat, no feces
how do you tx fecaliths?sx removal
which can you see on radiographs- enteroliths or fecaliths or both?ONLY ENTEROLITHS-- those are made of MINERALS (mg ammonium phosphate) but fecaliths are hard food material and are less likely to be seen (i mean i imagine maybe possibly, but...)

Small Colon Impactions, THROMBOEMBOLIC COLIC

Question Answer
what is possible multimodal etiology of small colon impaction?impaction of feces may be due to... Dehydration of feces, Inspissated (thickened) fibrous fecal material, Foreign body
is there a seasonality to SC impactions?yes
how do you dx SC impactions?rectal palp
what is the colic like with SC impaction?moderate to severe pain
what are clinical signs of SC impaction? Colic: moderate to severe pain. Tympany of colon & cecum 2º to obstruction, Signs of endotoxemia common
SC impaction might be associated with what other dz?Disease associated with Salmonellosis (Which causes diarrhea, so, weird.)
how do you treat a small colon impaction?MEDICALLY MANAGE-- NPO, IV fluids, enemas, laxatives, Anti-inflammatory & anti-endotoxemic therapy, Surgical resolution often needed
when the horse is recovering from a SC impaction, what should you be doing to help it?Laxatives & cautious refeeding: avoid re-impaction
CQ: best parameter to indicate sx is..UNRELENTING PAIN (not HR)
THROMBOEMBOLIC COLIC happens because of what happening to what anatomical region?Cranial Mesenteric Arteritis
what is the causative agent of thromboembolic colic?Happens because Strongylus vulgaris (equine large strongyle) causes Cranial Mesenteric Arteritis
what is the life cycle of strongylus vulgaris?
If you see this, what dz do you think this horse has? technically its just a strongyle egg, so it could be cyanthosomes (leading to chronic diarrhea) but since we are in the non-strangulating lesion section, this is probably the large strongyle Strongylus Vulgaris (which causes THROMBOEMBOLIC COLIC)
what is the pathophys of thromboembolic colic? Migration of maturing larvae causes cranial mesenteric arteritis--> Colonic infarct--> Thromboembolic colic (will see Large colon gas distention )
in what age do you tend to see Thromboembolic colic?>1yr old horses
tx of thromboembolic colic?sx resection
how can you prevent thromboembolic colic? Ivermectin

strangulating lesions


Question Answer
how many degrees must a colon rotate before it is considered a volvulus? Colon twisted at cecocolic mesentary from 270° to 720°
at what point (degrees of rotation) is blood supply compromised, meaning sx tx is required immediately? > 360° rotation: blood supply is compromised --> surgery immediately!
in which direction are most colon torsions twisted? 90% twisted counterclockwise
what is colic like with colon volvulus? Sudden onset of severe colic--> Pain is unrelenting / No response to analgesia!!!
explain the pathophys of what happens when the colon flips Abdominal compartment syndrome--> Severe gas distention of colon, Depression of ventilation, Depression of venous return
what happens when you pass a NG tube with colonic torsion?you will get gastric reflux.... unless abdominal distention is severe enough to prevent gastric emptying (so only maybe present)
what is the major indication for sx?UNRELENTING PAIN
what will colonic torsion be like with rectal palp? torsion often not palpable
what will you see on US with colonic torsion?may show thickened colon wall
would abdominocentesis be helpful dx a colonic torsion? usually not safe to perform
how do you tx colonic torsion?SX!!!!!
2 risk factors for colon torsion?(1) Brood Mares: after they have given birth, suddenly a big space available for colon to displace in. (2) Lush pasture (CHO) (proll gas distension/mobility changes)
how common is recurrence of colonic torsion, who tends to be recurrences, and how can you prevent this? Recurrence: 15% brood mares. Can Colopexy / colon resection
prog of colon torsion?VARIES: 80% in practices near large brood mare farms, 65% in other parts of the country
what are the major post-op complications to colon torsion? Damaged colonic mucosa, Peritonitis & Adhesions risk, Body wall hernia (provide IV fluids/plasma/laminitis prophy post op also)