Equine GI Sx I Flashcards
T/F: colic is a disease
False; it is a symptom
Possible sources of colic
GIT Hepatic system Urinary system Reproductive system Peritoneum Anything in the abdomen
4 sources of pain
Stretch (distension)
Tension
Inflammation
Infarction
Things that may present like colic
Myositis Pleuropneumonia Laminitis Ataxia Dementia
T/F: Horses do NOT have a gallbladder
True, meant to be continuous grazers
SI anatomy
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
Cecun anatomy
4 bands (teniae) - Dorsal and medial go to apex - Dorsal band -> ileocecal fold - Lateral band -> cecocolic fold Ileocecal valve Cecocolic valve
SI anatomy
3.5m long
Long, fatty mesentery
Wide, muscular antimesenteric band
Transverse mesocolon attached to root of mesentery
Attached to duodenum via duodenocolic ligament
Stomach lesions
Ulcers Impaction Neoplasia Gastric outflow obstruction - Pyloric stenosis - Pyloric mass Risk of rupture secondary to ulcers, impaction, or other obstructions
Gastric ulcer basics and Dx
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
Gastric ulcer location and Tx
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
Gastric impactions basics
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
Gastric impaction Dx
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
Gastric impaction Tx
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
SI strangulation
Volvulus Epiploic foramen entrapment Pedunculated lipoma Intussusception Mesenteric rents Inguinal/scrotal or umbilical hernia Gastrosplenic ligament incarceration Mesodiverticular band (vitelline anomaly)
SI mechanical/functional obstructions
Ileal impaction Muscular hypertrophy of the ileum Ascarid impaction Duodenitis-proximal jejunitis (proximal enteritis) Neoplasia Gastroduodenal obstructions Intestinal inflammation and fibrosis
Epiploic foramen entrapment
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
Epiploic foramen entrapment location and complications
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
Pedunculated lipoma incidence
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
Pedunculated lipoma location and Tx
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)
Intussusception involvement
Jejunum-ileum Jejunum-jejunum Ileum-ileum Ileum-cecum Cecum-colon Small colon
Intussusception clinical presentation
Acute form: sudden onset, progressively severe abd pain
Subacute form: Anorexia, depression, intermittent colic
Intussusception Dx
Transabdominal palpation Rads US** Sx** Necropsy
Intususception possible causes
Heavy ascarid burden Enteritis Tapeworm infestation Abrupt dietary change Abnormal motility
Intussusception Tx
Sx!
Most will require some form of resection/anastomosis
Rarely, can manually reduce
Inguinal/scrotal hernia
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
Umbilical hernia
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
Ileal impaction
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
Ascarid impaction
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
Dx of Ascarid impaction
Characteristic thick-walled eggs on fecal float
US exam may show mass of parasites within intestine
May reflux adult parasites
Sx/necropsy
Tx of ascarid impaction
Sx if obstructed
Analgesics and lube
Prognosis and prevention of ascarid impaction
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
Duodenitis-proximal jejunitis (proximal enteritis)
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
Obstruction/strangulation vs. proximal enteritis
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
Obstruction/strangulation vs. Prox enteritis
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
Summary
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
