Large colon

Question 1

What are the causes of large colon impactions?

Answer 1

Coarse feeds, poor dentition, inadequate mastication
Alterations in colonic motility, reduced water intake, sand and amitraz (a2agonist)

Question 2

2 sites of large colon impactions

Answer 2

Pelvic flexure and transverse colon
Motor centers to induce retention of food

Question 3

CS of ingesta impactions

Answer 3

Intermittent mild pain that worsens
Pulse 40-60 dpm
Mild dehydration
Pelvic flexure or ventral colon mass
Shock (devitalizedDx colon)

Question 4

Dx ingesta impactions

Answer 4

CS
Rectal exam (right side pelvic mass, gas distention of colon, normal exam)

Question 5

Medical tx of ingesta impactions

Answer 5

Mineral oil, oral fluids, IV fluids, analgesics (fluxenin meglumine), restricted oral intake

Question 6

Sx tx of ingesta impactions

Answer 6

Perform when deterioration of vital signs and changes in peritoneal fluid
Pelvic flexure enterotomy

Question 7

CS of sand impactions

Answer 7

Intermittent colic that responds to initial therapy
Recurs in a few days to weeks
Similar to ingesta signs

Question 8

How to dx sand impactions

Answer 8

Rectal exam: hard mass or sand (central midline and pelvic flexure)

Question 9

Medical tx for sand impactions

Answer 9

IV fluids
Mineral oil (lubricates intestinal tract, ↓ tympany)
Psyllium (propels the impaction)

Question 10

When is sx for sand impactions performed?

Answer 10

There’s unrelenting pain, palpable mass on rectum and changes in peritoneal fluid

Question 11

What kind of sx is done with sand impactions

Answer 11

Pelvic flexure colotomy and lavage
(transverse colon)

Question 12

Enteroliths

Answer 12

Common in FL, CA and midwest
Transverse, right dorsal and pelvic flexure most common sites
Made of Mg ammonium phosphate

Question 13

CS of enteroliths

Answer 13

Moderate abdominal pain
Lack of fecal production
Don’t pass mineral oil
Tympany in extreme cases

Question 14

Sx tx for enteroliths

Answer 14

Pelvic flexure colotomy- retrograde manipulation of stone and empty large colon
Second colotmy in dorsal colon

Question 15

Large colon displacements are due to…

Answer 15

Extensive movement of abdominal cavity
↑ abdominal content of weight
Excess gas production in the colon

Question 16

Most common forms of large colon displacements

Answer 16

Left dorsal displacement (nephrosplenic)
Right dorsal displacement
Retroflexion of the pelvic flexure

Question 17

CS of large colon displacements

Answer 17

Intermittent pain that worsens
Mild dehydration
Shock with devitalized colon

Question 18

Rectal exam of left colon displacement

Answer 18

Nephrosplenic entrapment
Spleen not against body wall
Can’t sweep kidney to spleen
Could have flexure (needs sx!)

Question 19

Rectal exam of right dorsal displacement

Answer 19

Left abdomen empty
Left colon lateral to cecum

Question 20

Retroflexion of pelvic flexure rectal exam

Answer 20

Left abdomen empty
Thick blind pouch

Question 21

Medical tx for left dorsal displacement (without flexure)

Answer 21

Short acting anesthetic
Rompun- ketamine
Right roll, hoist and hand, right roll

Question 22

What tx is best for mild to moderate colon distention (left colon dispacement)

Answer 22

Phenylephrine
Excitement evident during infusion then jog/ lunge for 30 minutes

Question 23

Sx tx for left dorsal displacements

Answer 23

If conservative methods fail and deteriorating condition
Large entrapment

Question 24

Volvulus of the large colon

Answer 24

Most devastating forms of colic
Bloodmares most commonly affected
Involve cecocolic ligament or cecal base
Ventral colon dives medially

Question 25

CS of volvulus of the large colon

Answer 25

Severe continuous abdominal pain HR >80 bpm Shock: delayed CRT, cyanotic mm, cold sweat, ↓ skin turgor

Question 26

Dx of Volvulus of the large colon

Answer 26

CS Rectal exam: severe distended large colon

Question 27

Tx of Volvulus of the large colon

Answer 27

Sx: early intervention → replace colon in normal position with colotomy (↓ transmural absorption) Transabdominal drain

Question 28

How to evaluate the colon for sx

Answer 28

Serosal color Presence of arterial pulsation Bowel wall thickness Hemorrhage from colotomy site Mucosal color

Question 29

Resection of the large colon (Volvulus of the large colon)

Answer 29

Damage extends beyond resection area 81% survival in horses with less than 50% resected 53% survival in horses with more than 50% resected

Question 30

Adaptive changes of a resected large colon

Answer 30

Prone to poor protein absorption ↑ fecal water losses

Question 31

Colopexy (Volvulus of the large colon)

Answer 31

Developed for recurrence of volvulus Left ventral colon to midline closure and 6 cm to the left of midline Done if WL and rupture of colon occurs

Question 32

Prognosis of Volvulus of the large colon

Answer 32

Early intervention: good Delayed: laminitis and shock