Equine GI Sx I

Question 1

T/F: colic is a disease

Answer 1

False; it is a symptom

Question 2

Possible sources of colic

Answer 2

GIT
Hepatic system
Urinary system
Reproductive system
Peritoneum
Anything in the abdomen

Question 3

4 sources of pain

Answer 3

Stretch (distension)
Tension
Inflammation
Infarction

Question 4

Things that may present like colic

Answer 4

Myositis
Pleuropneumonia
Laminitis
Ataxia
Dementia

Question 5

T/F: Horses do NOT have a gallbladder

Answer 5

True, meant to be continuous grazers

Question 6

SI anatomy

Answer 6

Duodenum: 1m
Jejunum: 17-28m
Ileum: .7m
Ileum more muscular and has antimesenteric bans -> connects to dorsal band of cecum via ileocecal fold
Vascular arcades
- Major jejunal vessel
- Arcuate vessel
- Vasa recta

Question 7

Cecun anatomy

Answer 7

4 bands (teniae)
- Dorsal and medial go to apex
- Dorsal band -> ileocecal fold
- Lateral band -> cecocolic fold
Ileocecal valve
Cecocolic valve

Question 8

SI anatomy

Answer 8

3.5m long
Long, fatty mesentery
Wide, muscular antimesenteric band
Transverse mesocolon attached to root of mesentery
Attached to duodenum via duodenocolic ligament

Question 9

Stomach lesions

Answer 9

Ulcers
Impaction
Neoplasia
Gastric outflow obstruction
- Pyloric stenosis
- Pyloric mass
Risk of rupture secondary to ulcers, impaction, or other obstructions

Question 10

Gastric ulcer basics and Dx

Answer 10

Adults: Off feed (especially grain), low grade colic, poor performance, bruxism
Foals: Colic (rolling on back), ptyalism, bruxism
Hx of chronic or high-dose NSAIDs
Dx via gastroscopy or based on empirical response to Tx
Can cause rupture- Dx at laparoscopy or necropsy

Question 11

Gastric ulcer location and Tx

Answer 11

Typically occurs in non-glandular squamous epithelium
- Margo plicatus, lesser curvature
- Few defences against exposure to HCl
NSAIDs inhibit production of protective prostaglandins
Reported in foals as young as 2d
- Subclinical in healthy foals
Tx: Antacids, Sucralfate, H2 antagonist, omeprazole

Question 12

Gastric impactions basics

Answer 12

Occurs secondary to ingestion of:
- Excessive amounts of dry, fibrous material
- Feeds that swell, such as wheat, barley, and sugar beet pulp
- Materials that form a mass, such as persimmon seeds or mesquite beans
Dental disease increases risk of all impactions
CS may be acute/severe or mild/chronic
May be the primary lesion or an incidental finding at Sx

Question 13

Gastric impaction Dx

Answer 13

Suspect impaction when the stomach is large on US (past 14th rib), but little reflux obtained or when the reflux consists primarily of feed; endoscopy

Question 14

Gastric impaction Tx

Answer 14

Lavage via NG tube
- May take a long time
- Diet coke for persimmon phytobezoars
- Can monitor progress via endoscopy
NPO until impaction cleared
Risk of gastric rupture

Question 15

SI strangulation

Answer 15

Volvulus
Epiploic foramen entrapment
Pedunculated lipoma
Intussusception
Mesenteric rents
Inguinal/scrotal or umbilical hernia
Gastrosplenic ligament incarceration
Mesodiverticular band (vitelline anomaly)

Question 16

SI mechanical/functional obstructions

Answer 16

Ileal impaction
Muscular hypertrophy of the ileum
Ascarid impaction
Duodenitis-proximal jejunitis (proximal enteritis)
Neoplasia
Gastroduodenal obstructions
Intestinal inflammation and fibrosis

Question 17

Epiploic foramen entrapment

Answer 17

Epiploic foramen is the 4cm opening into the omental bursa
Margins:
- Dorsal/craniodorsal - caudate lobe of the liver (near vena cava)
- Cranioventral - portal vein
- Ventral - gastropancreatic fold
May or may not present with typical CS of strangulating SI lesion

Question 18

Epiploic foramen entrapment location and complications

Answer 18

Majority occur from left to right
Involvement:
- Ileum alone 20%
- Ileum and jejunum 70%
- Jejunum alone 30%
Cribbing predisposing factor
Fatal hemorrhage from rupture of portal vein a possible Sx complication
Decreased long-term survival

Question 19

Pedunculated lipoma incidence

Answer 19

Fatty tumor suspended on a mesenteric pedicle
- Single or multiple
Causes a strangulating obstruction when the pedicle wraps around intestine
- length of stalk, not size of tumor, determines risk for strangulation
Older horses at greatest risk
- Mean age of affected individuals 14-19y
Other risk factors include breed (Arabian) and sex (geldings)
Affected horses are not necessarily overweight

Question 20

Pedunculated lipoma location and Tx

Answer 20

90% of lipomas in SI, 9% in small colon
Affected segment may be short or extensive
Once identified, must cut stalk
- May or may not be able to exteriorize lipoma
Resection/anastomosis
Post-op complications common, post-operative ileus (POI)

Question 21

Intussusception involvement

Answer 21

Jejunum-ileum
Jejunum-jejunum
Ileum-ileum
Ileum-cecum
Cecum-colon
Small colon

Question 22

Intussusception clinical presentation

Answer 22

Acute form: sudden onset, progressively severe abd pain

Subacute form: Anorexia, depression, intermittent colic

Question 23

Intussusception Dx

Answer 23

Transabdominal palpation
Rads
US**
Sx**
Necropsy

Question 24

Intususception possible causes

Answer 24

Heavy ascarid burden
Enteritis
Tapeworm infestation
Abrupt dietary change
Abnormal motility

Question 25

Intussusception Tx

Answer 25

Sx!
Most will require some form of resection/anastomosis
Rarely, can manually reduce

Question 26

Inguinal/scrotal hernia

Answer 26

Most are indirect
- Intestine passes through vaginal ring into vaginal tunic
Direct hernias are more common in foals than in adults
- Intestine goes into SQ space adjacent to vaginal ring via fascia/musculature
In adults, typically acquired, irriducible, with a short segment of affected bowel
In foals, often congenital and reducible, with a long segment of affected bowel
Predisposed breeds: Standardbreds, Tennessee Walkers, Saddlebreds
Inguinal incision and midline celiotomy for irreducible strangulating lesions
- Unilateral castration recommended

Question 27

Umbilical hernia

Answer 27

Common to have bowel enter hernial sac through a large defect (reducible), rare to strangulate
Most common strangulating lesion involves only the antimesenteric wall of the ileum
- Parietal (Richter’s) hernia
Suspect parietal hernia when an umbilical hernia becomes nonreducible, large, turgid, edematous, and painful to palpation
En block resection of hernia and resection/anastomosis of affected bowel

Question 28

Ileal impaction

Answer 28

Most commonly primary condition of normal ileum
- Can be secondary to other ileal disease
Most common in southeastern US related to feeding coastal bermuda grass hay
Has also been associated with tapeworm infection
May be able to palpate rectally
If early in dz, can treat medically, but Sx often required

Question 29

Ascarid impaction

Answer 29

Parascaris equorum
- Roundworms
Predominantly affects foals <6mo, source is contaminated pastures, paddocks, stalls
Prepatent period 10-12wk
- Infective eggs can remain viable in contaminated soil for years
Can cause acute colic in 3 ways
- Heavy load of living parasites can cause intestinal obstruction, rupture, and/or peritonitis, intussusception
- Absorption of antigen can cause ileus -> impaction
- Rapid die-off after deworming can cause obstruction and/or rupture
. Commonly, affected foals have been administered dewormer within past 24h

Question 30

Dx of Ascarid impaction

Answer 30

Characteristic thick-walled eggs on fecal float
US exam may show mass of parasites within intestine
May reflux adult parasites
Sx/necropsy

Question 31

Tx of ascarid impaction

Answer 31

Sx if obstructed

Analgesics and lube

Question 32

Prognosis and prevention of ascarid impaction

Answer 32

Prognosis fair to guarded
- Horses with simple impactions more likely to survive Sx than those with volvulus or intussusception
- Poor long-term survival - in one study only 4/25 (16%) still alive 3yr post-op
Prevention
- If heavily parasitized, use a staged kill technique
- Half dose dewormer first
- 3 wk later give 2nd Tx

Question 33

Duodenitis-proximal jejunitis (proximal enteritis)

Answer 33

Hallmark of dz is large amounts of ng reflux
- >48L in 24h
Pain can vary from mild to severe and depression
Fundamentals of Tx:
- Frequent decompression via NG tube
- Medical mgmt to address electrolyte abnormalities, dehydration, etc.
- NPO until resolution of CS
Serious complications dt endotoxemia (including laminitis) can occur
HORSES WITH ENTERITIS MAY STILL REQUIRE Sx

Question 34

Obstruction/strangulation vs. proximal enteritis

Answer 34

SI obstruction can affect horses of any age, proximal enteritis rare in young horses <1.5y
Both can present initially with intense pain and then progress to depression
Horses with enteritis are sick- may have fever and leukocytosis or leukopenia
Color and odor of reflux may be similar, but usually volume is greater with enteritis

Question 35

Obstruction/strangulation vs. Prox enteritis

Answer 35

After gastric decompression, horses with enteritis usually improve in overall attitude and HR
On rectal palpation, strangulating lesions more likely to have tightly distended loops of SI
On US, enteritis more likely to be hypermotile, fluid-filled, moderately distended; strangulation more likely to be hypomotile, moderately to markedly distended
Peritoneal fluid in enteritis usually only has increased total protein, not cells; strangulating lesions more likely to have serosanguinous fluid

Question 36

Summary

Answer 36

Colic = abd pain
Anatomy drives many lesions
- Impactions @ change in diameter
- Free floating viscera prone to displacements, torsions, and incarceration
Strangulating lesions must always be managed Sx
Non-strangulating lesions are often managed medically, but Sx may be required in certain cases
- Severity/extent of lesion and pain level are the driving factors in this decision
It is easier to distinguish between strangulating and non-strangulating lesions than to determine what the cause of a strangulation is
- Definitive Dx generally not made until Sx/necropsy