Lecture 8: Abnormal Conditions of Equine Large Intestine Flashcards
What is included in large intestine
Cecum, large colon, small colon, rectum
Where is the cecum located
Between small intestine and large colon on right side
What are the three parts of the cecum
- Base- most dorsal
- Body- 4 longitudinal bands
- Apex- narrow blinded end directed cranially
What are the two primary functions of the cecum
Water absorption, microbial digestion
What is the most common pathological condition of the cecum
Cecal impaction
What is the fatality rate in cecal impactions and why
43%, due to rupture
What are some causes of cecal impactions
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
How do you diagnose cecal impactions
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
What does the rectal exam reveal for cecal impaction
- Tension in ventral cecal band
- Lack of sacculations due to increased filling
- Can’t pass hand dorsally
Is BW normal or abnormal in cecal impactions
Normal
What are some characteristics of type 1-mechanical cecal impactions
Causes: Firm, dry or doughy ingesta
Location: base or body
Impaction indented with fingers
Cecal wall does not feel thickened
Normal peritoneal fluid
What are some characteristics of type 2 cecal dysfunction
- Cecum is tightly distended with gas and ingesta
- More painful
- Higher heart rate
- May be endotoxin
How do you tx type 1 mechanical cecal impactions
Soften ingesta to allow cecal contractions to empty cecal contents into right ventral colon
How do you tx type 2 cecal dysfunction
Surgical- decompression, typhlotomy and evacuation, cecal bypass- cecocolic anastomosis
What are the medical treatments in cecal impactions
- Withhold feed
- IV fluids
- Oral laxatives via NG tube
- Psyllium
- Walking and limited controlled grazing to stimulate motility
- Analagesics
What analgesics do you need to have caution with in cecal impactions
Xylazine, detomidine, butorphanol
When should surgery be considered for cecal impactions
- No improvement on rectal palpation for 24-36hrs
- Systemic deterioration (increase HR)
- Increase pain
- Cecum feels tight enough to rupture
What is the large colon composed of
Dorsal and ventral colons connected by short mesentery
Describe the order through the large colon
- Right ventral colon
- Sternal flexure
- Left ventral colon
- Pelvic flexure
- Left dorsal colon
- Diaphragmatic flexure
- Right dorsal colon
What are some abnormal conditions of large colon
Tympany, impaction, sand, enteroliths, nephrosplenic displacement, right dorsal displacement, volvulus
What is the most commonly reported colic in horses
Large colon tympany
What is large colon tympany
Gas colic, spasmodic colic
What causes large colon tympany
Excessive gas fermentation, resulting in distention and pain
What are some risk factors for large colon tympany
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
How do you diagnose large colon tympany
- Acute pain +/- visible abdominal distention
- Rectal palpation- moderate to severe gas distention of large colon
What are some differentials for large colon tympany
Large colon displacement, large colon torsion, ileus, impending colitis, small colon obstruction
What is treatment for large colon tympany
Withhold food, analgesics
If you suspect large colon tympany but horse does not respond to analgesics what is a more concerning differential
Large colon volvulus
What is the most frequent type of simple obstruction
Large colon impaction
What are some risk factors for large colon impaction
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)
What medications can cause large colon impactions
Atropine and morphine
What is most common site of large colon impaction
Pelvic flexure
Then right dorsal colon > transverse colon
What are some differentials for large colon impaction
Large colon displacement +/- right dorsal colon impaction
What is the treatment for large colon impaction
Withhold feed, fluid therapy, NSAIDS, cathartics (magnesium sulfate, mineral oil)
What are some indications for referral and surgery for large colon impactions
Uncontrollable pain, deteriorating cardiovascular status, abnormal changes in peritoneal fluid
What is the surgical procedure for large colon impactions
Pelvic flexure enterotomy and evacuation
What are some complications from surgery for large colon impaction
- Intraoperative rupture of large colon
- Post-op diarrhea
- Incisional drainage/infection
- Septic peritonitis
What are some risk factors for large colon sand impaction
- Insufficient roughage /fiber in diet
- Access to sand
How can sand colic be determined
- Sand ausculted in ventral abdomen caudal to xyphoid
- Observation of sand in feces
- AUS
What is medical treatment for large colon sand impaction
Remove horse from access to sand, rehydrate, laxatives, magnesium sulfate and/or psyllium
How is surgery performed for large colon sand impaction
Pelvic flexure enterotomy and evacuated
What site does sand like to sit, predisposed to rupture
Right dorsal colon
What is the pelvic flexure pacemaker
Contractions of longitudinal muscle layers shorten length of left colons and move pelvic flexure toward diaphragm followed by caudal movement towards pelvis during relaxation
What type of diet can cause large colon displacement
Increase carbs- excessive fermentation and gas distention
What is nephrosplenic entrapment/ left dorsal displacement
Left dorsal and left ventral colons migrate later to the spleen in dorsal direction until entrapped in nephrosplenic space
What age group is typically associated with nephrosplenic entrapment
Any age
How do you diagnose nephrosplenic entrapment
Transabdominal US- presence of gas filled colon dorsal to spleen, precludes imaging of left kidney
Rectal palpation- mainstay diagnosing this
What is medical treatment for nephrosplenic entrapment
Withhold feed, IV, phenylephrine- causes splenic contraction, rolling under GA, trocharization then lunge, therapeutic trailer ride
What drug can you give to treat nephrosplenic entrapment and what does it do
Phenylephrine- causes splenic contraction, lunge after administration
What is the surgical procedure for nephrosplenic entrapment
Standing flank laparotomy or ventral midline celiotomy
What is right dorsal displacement
Retropulsive movement of pelvic flexure with subsequent migration cranial
What is one of the most painful and devastating causes of colic
Large colon volvulus
Without intervention in large colon volvulus death occurs within hours, what is death due to
Hypovolemia shock, progressive cardiovascular collapse, poor pulmonary expansion
What horses have a higher prevalence for large colon volvulus
Broodmares
What are the risk factors for broodmares getting large colon volvulus
Recent patrurition, recent dietary changes, recent access to lush pasture
What is tx for large colon volvulus
Surgery
What needs to be done pre-operatively for large colon volvulus
Stabilization measures taken- fluids!
What is prognosis for large colon volvulus
Not great, mortality rates between 56%-65%
What are the pre-operative parameters that indicate poor prognosis for large colon volvulus
PCV >50%, rectal temp>102%, heart rate >80%
Where does the small colon sit
Caudo-dorsal quadrant of the abdomen
What is function of small colon
Contractile activity and circular muscles produce fecal balls
What are some simple obstructions of small colon
- Fecal impaction
- Enterolithiasis
- Fecaliths, phytobezoars, trichobezoars, meconium
What are some vascular lesions of small colon
Intramural hematoma, mesocolic rupture, nonstrangulating infarction
What are some strangulating lesions in small colon
Strangulating lipomas, intussception
What are some risk factors for enteroliths
- Geographic- CA and FL
- Breeds: Arabians and minis
- Feeding alfalfa hay
- <50% time spent outdoors
What is the most common site for enterolith obstruction
Small colon
What is prognosis for enteroliths
Excellent if no local necrosis of bowel
T or F: rectal tears are life threatening
True!
Where do most rectal tears occur
Dorsal aspect of rectum, oriented parallel to longitudinal axis of rectum
What are some signs indicating rectal tear
- Sudden release of pressure
- Direct palpation of abdominal organs
- Large amount of blood on sleeve/glove
- Hemorrhagic feces
What do you do once you suspect rectal tear
- Assess severity
- Inform owner
- Apply tx
- Contact liability insurance
What is the initial treatment for rectal tears
- Reduction of rectal activity- IV sedation, caudal epidural, lidocaine enema, buscopan
- Gentle fecal removal (after epidural)
- Treatment of septic shock and peritonitis with banamine and broad spectrum antibiotics
- Referral
What are some causes of rectal prolapse
Tenesmus from diarrhea, dystocia, intestinal parasites, colic, rectal tumor
What sex are rectal prolapses more common in
Females
What is the treatment for rectal prolapse
- Caudal epidural to reduce straining and facilities reduction
- Reduce mucosal enema with topical glycerin/ sugar/ magnesium sulfate / lidocaine
- Purse string suture
- With hold feed 12-24hrs
- Mineral oil via NG tube
Label 1-7
- Right ventral colon
- Sternal flexure
- Left ventral colon
4.pelvic flexure - Left dorsal colon
- Diaphragmatic flexure
- Right dorsal colon