Equine GI Sx II Flashcards
Cecal lesions
Impaction Intussusception (cecocecal, cecocolic) Volvulus or torsion Infarction Neoplasia Cecal rupture secondary to cecal impaction is not uncommon
Cecal impaction etiology and Dx
Most common cecal disease
- 40-55% of cecal diseases, 5% of all impactions
Multifactorial etiology
- Poor dentition
- Poor quality hay
- Decreased water intake
- Tapeworms
- Hospitalization or prior Sx, particularly orthopedic
. NSAIDs, anesthesia, immobilization
Dx: Rectal palpation (firm mass on midline)
Cecal impaction complications and Tx
High risk of rupture: dehydrated intestinal contents and progressive distension leads to stasis and fluid accumulation -> mural compromise and severe cecal distension
- Can also have primary motility dysfunction
Rupture can occur without any warning signs
Can be treated medically or Sx - controversial
Medical therapy: IV and oral fluids, oral laxatives, psyllium, walking, controlled grazing to stimulate motility, flunixin meglumine
- No xylazine and butorphanol if possible - decreases cecal motility
- Promotility agents controversial; neostigmine NOT recommended
Sx intervention probably best for horses with moderate to severe impactions
Large colon lesions
Large colon tympany (gas colic, spasmotic colic) Impaction Enterolith Nephrosplenic entrapment Right dorsal displacement Strangulating large colon volvulus Right dorsal colitis Mural infarction
Large colon tympany basics and risk factors
Gas colic dt excessive fermentation Most common diseases of the large colon and most common cause of colic in the horse Bowel distension and pain Risk factors: - Cribbing - Recent change in exercise program - Ineffective deworming regimen - Hx of travel - High carb diet
Large colon tympany Dx and Tx
Dx: rectal exam
- Gas distension without tight bands
- Need to rule out other differentials
Typically respond rapidly to conservative therapy: analgesics and temporary withholding of food
Large colon impaction basics and risk factors
Second most common disease of the large colon
Impaction can be caused by feed, sand, and gravel
Tends to occur in places where the diameter of the GIT changes dramatically
- Pelvic flexure
- Junction of the right dorsal colon and transverse colon
Risk factors:
- Decreased water intake
- Poor dental care
- Recent change in exercise regimen
- Insufficient deworming regimen
- Recent travel
- High carbohydrate diet
Large colon impaction Dx and Tx
Most frequently Dx on rectal exam
Medical management: oral, IV fluids, analgesics, oral laxatives, temporarily withholding feed
Early/mid impactions typically respond to medical management within 24-48h
Large impactions often require Sx
- Uncontrollable pain, deteriorating cardiovascular status, lack of progress with medical management, bowel compromise
Large colon sand impaction
Major risk factor is feeding on the ground in regions with sandy soil
Insufficient roughage diet
Build-up is typically slow, may show few clinical signs other than transient diarrhea
Dx via rads or fluoroscopy
May be able to auscultate sand rubbing along the ventral abdomen
Rupture a major concern
Enterolithiasis
Primarily struvite crystals and magnesium ammonium phosphate
- Primary enteroliths more common in California and Florida
Ingested FB can act as nuclei for formation of enteroliths
Come in different shapes and sizes
- Single enteroliths tend to be spherical
- Flattened surfaces are highly suggestive of multiple enteroliths
Can cause acute, persistent colic OR intermittent low grade colic (ball valve effect) dt intermittent obstruction
Most commonly located in the right dorsal colon, transverse colon, and small colon
Sometimes diagnosed on rads
Treatment is always surgical***
Large colon displacement/volvulus
Volvulus (colonic torsion) may be non-strangulating (<270) or strangulating (>360)
- If 360, may also be described as right dorsal displacement or left dorsal displacement/ nephrosplenic entrapment
- Torsion most commonly occurs at or proximal to the cecocolic ligament (must be palpated to determine direction for correction)
- NSE can cause strangulation
Nephrosplenic entrapment
Large colon is displaced dorsally and to the left and becomes stuck in the nephrosplenic space
Diagnosed by rectal exam and/or abd US
- Spleen and left kidney cannot be imaged adjacent to each other
Often, impaction is also present
Medical management:
- Phenylephrine (10-20mg) to shrink spleen and jogging
- Rolling (requires general anesthesia and lots of help)
Assess correction via rectal palpation and/or US
Right Dorsal Displacement
Initiated by retropulsive movement of impacted pelvic flexure and migration of the large colon to the right
Large colon located between the cecum and the body wall
Abd pain may be acute and moderate, or mild and intermittent
Cannot palpate pelvic flexure on rectal exam, may feel bands going up and to the right
May be able to resolve medically (IV fluids, analgesia) or may require Sx correction
Level of pain/response to pain meds determining factor
Large Colon Volvulus
Most painful and devastating GI dz Exact pathophysiology unknown Risk factors: - Broodmares - Recent parturition - Diet changes - Recent access to lush pasture Usually clockwise direction as viewed from behind the horse - Palpation intra-op to confirm
Large colon volvulus sequence
Pathology linked to colonic wall devitalization via ischemia and/or congestion
Fluid sequestration in the lumen
Bacterial translocation and massive endotoxin release into systemic lymphatics and vasculature
Septic/endotoxic shock
Early referral and prompt Sx significantly improves prognosis
Small colon lesions
Non-strangulating obstructions: - Fecal impaction (or meconium impaction in foals) - Enterolith - Fecolith - Phytobezoar/trichobezoar - Atresia coli Vascular lesions: - Intramural hematoma - Mesocolic rupture - Nonstrangulating infarction Strangulating lesions can also occur, similar to SI
Small colon impaction
Most commonly reported lesion of the small colon
Risk factors:
- Poor dentition
- Poor quality hay
- Lack of water
- Parasites
- Submucosal edema
- Motility problems
Salmonella risk? 0-25% incidence of positive cultures reported from small colon impactions
Typically a diffuse impaction rather than a focal
Medical or surgical treatment depending on extent and duration
Meconium impaction
Neonates
Failure to pass colonic contents accumulated during digestion
Progressive abdominal distension and pain
Persistent straining can lead to patent urachus and/or ruptured bladder
Perssistent impaction requires fluid support and warm, lubicant-based enemas
Medical management is generally effective, surgery rarely required
Small colon fecalith
Isolated intraluminal impaction Chronic focal intraluminal pressure can compromise the bowel wall - Infarction or rupture May be difficult to palpate rectally Miniature horses prone to this condition Surgical treatment is always required
Causes of rectal tears
Iatrogenic - most common Enemas Meconium extraction via forceps Misdirection via breeding Spontaneous tears
T/F: rectal tears are one of the most common causes of lawsuits against equine veterinarians in the US
True!
- Recognize the problem
- Communicate adequately
- Treat the problem appropriately
Risk factors for rectal tears
Small horses, especially Arabians Horses that are straining Horses with colic Repeated rectal palpations Stallions and geldings Inadequate restraint and lubrication***
Dx of rectal tears
Blood on rectal sleeve Loss of resistance Careful palpation and colonoscopy Signs of colic, peritonitis, and endotoxemia Physical examination, abdominocentesis
Grading rectal tears
1: Involves mucosa and submucosa
2: Involces muscular layers, but mucosa and submucosa are intact
3: Involves the mucosa, submucosa, and muscle (can still contaminate environment though contained)
4: Involves all layers, gross contamination of the abdomen
Nonsurgical management for grade 3 or lower tears
Food deprivation Gentle manual evacuation of rectum Broad spectrum antibiotics Flunixin meglumine Laxatives and laxative diet
First aid for more severe tears
Address endotoxemia and peritonitis:
- Broad-spectrum antimicrobials (potassium penicillin and gentamicin and metronidazole)
- Antiinflammatory and anti-endotoxic medications (flunixin meglumine)
- IV fluids
Temporary rectal packing in horses that are being referred to a hospital for definitive treatment
- Can be life-saving, but is technically challenging
Suture repair of rectal tear
Ideal when fresh Easiest when to close anus Techniques - Instrument suturing - Blind direct suturing - Deschamps needle Can combine with bypass procedure
Bypass procedure
Indicated for grade 3 or 4 tears
Colostomy or rectal liner +/- colon evacuation
Goals:
- Reduce fecal contamination from grade 3 tears
- Prevent fecal peritonitis from grade 4 tears
Loop colostomy
2-incision technique
Loop of small colon
- arms sutured together
Stoma made in antimesenteric band
Gravity prevents feces from entering distal portion
Can be reversed
Flush water through distal portion of small colon to prevent atrophy
Rectal liner
Palpation sleeve glued to 5cm diameter x 7.5cm long rectal prolapse ring with holes for suture loops
Ventral midline incision -> nonsterile assistant passes lubricated ring and liner through rectum to surgeon who sutures it in place cranial to the tear
Pelvic flexure enterotomy, flush small colon
Rectal liner will be passed in 9-12d as sutures are absorbed
Complications: sleeve tearing, retraction of sleeve into rectum uncovering tear, formation of rectoperitoneal fistula
Prognosis for rectal tears
Excellent if tear lends itself to conservative management (>80%)
Guarded to fair if surgical correction is attempted (<60%)
Many horses with severe tears are euthanized without a repair attempt
Summary
Large colon lesions are the most commonly encountered causes of GI related colic
- Tympany, impaction
Impactions (regardless of location) frequently respond to conservative mgmt if caught early enough, but may require surgical correction if large/chronic or causing unremitting pain
Focal obstructions (enteroliths, fecaliths) always require surgical intervention
Care in diagnosis of large colon displacement/volvulus
- Nephrosplenic entrapment or right dorsal displacement may be able to be managed medically, but volvulus needs to be taken to surgery as soon as possible for the best possible prognosis
More summary
Bowel rupture is a particular concern in the cecum, large colon, and small colon
- may be secondary to gas distension and/or solid impaction (often both)
Rectal tears are one of the top reasons for litigation against equine veterinarians
- Use caution when performing a rectal exam on a “high risk” horse
Low grade rectal tears tend to do well with conservative management; surgical treatment options are available for higher grade tears, but euthanasia is frequently elected
