EIM 12-14 GI/Liver/Urinary Flashcards
hepatic changes with DPJ
hepatocellular vacuolization
cholestasis
inflammatory infiltrate
biliary hyperplasia
suspected causative agent of DPJ
Salmonella spp or Clostridium spp
—can be isolated from culture of gastric reflux.
—Fusarium spp (causative agent of bovine interdigital necrobacillosis) also suspected
alimentary lymphosarcoma primarily affects horses aged
2-4
alimentary lymphosarcoma
lymphocytosis is rare
prognosis is poor
granulomatous enteritis
Standardbreds are overrepresented
Affected horses are 1-6 years, majority <3
+/- scurfy skin, severe lesions rare
Clinical signs include severe wasting, edema, variable appetite, depression, and occasional slight fever
Diarrhea is infrequent
proliferative enteropathy
L. intracellularis has a tropism for crypt epithelium
Infected cells proliferate far more rapidly than uninfected cells
L. intracellularis enters cell in membrane-bound vacuole, but eventually escapes vacuole and found free in cytoplasm
Lesions are most commonly found in ileum and terminal jejunum, but may be found in duodenum
Which serovar of Salmonella is the most pathogenic in horses?
Group B Salmonella enterica var. Typhimurium
What is the most common isolate type of Clostridium perfringens from healthy and diarrheic horses of all ages?
C. perfringens type A is the most common clostridial isolate from healthy and diarrheic horses of all ages.
C. perfringens types A, B, C, and D have all been associated with hemorrhagic enteritis in foals younger than 10 days of age, with type C being the most common cause in North America.
The primary toxin produced by C. perfringens type A is α-toxin (phospholipase C), virulent strains of type A may also produce enterotoxin
What are the more common toxins produced by Clostridium difficile?
Toxin A (enterotoxin) and Toxin B (cytotoxin), Toxin A’s role in the pathophys is more clear than Toxin B (in terms of equine diarrhea)
C. difficile toxin A is an enterotoxin that induces an inflammatory response with hypersecretory diarrhea
Preliminary diagnosis of equine intestinal clostridiosis caused by C. perfringens is based on the isolation of greater than what # of colony forming units (CFU) of C. perfringens type A per gram of feces (in horses with consistent Hx and CS)
> 100
Which life stage of Strongylus vulgaris is primarily responsible for the parasite’s pathogenicity in the equine abdomen?
L4
Fourth-stage larvae migrate through the mucosa and submucosa into the large intestinal vasculature - causing mural edema, hemorrhage, and infiltration of inflammatory cells of the bowel, and possible ischemia or acute infarction
arsenic toxicosis: CS
Acute hemorrhagic colitis with severe mural edema and mucosal ulceration.
Profuse hemorrhagic diarrhea and abdominal pain.
Later, cardiac arrhythmias, pulmonary edema, acute renal failure, and neurologic deficits (ataxia and stupor) may develop.
arsenic toxicosis: DX
measuring blood and urine arsenic concentration, but these tests may not be diagnostic. Post-mortem diagnosis is confirmed by measuring arsenic concentrations in liver and kidney samples. History of exposure and clinical signs remain the primary means of diagnosis.
hydrolyzed by colonic bacteria to SCFAs, such as butyrate, which represent a major energy source for colonocytes
Psyllium
PGE2
Increases Cl secretion, decreases neutral NaCl absorption
Vasoactive Intestinal Peptide
Increases cAMP-mediated NaCl secretion
Endotoxin
Increases Na absorption, Increases cell membrane permeability
Interferon-gamma
Decreases tight junctions and causes increase in cell membrane permeability
IL-1
Increase PGE2
H1
Increases Cl secretion via Ca-mediated pathways
endotoxin and prostaglandins affect large intestinal motility by:
creating less coordinated contractions.
the most important lps receptors are:
CD14 and TLR4
Which two intracellular processes control colonic secretion?
Cyclic nucleotide (cAMP, CGMP) and calcium system
The proximal 2/3 of the esophagus is
skeletal muscle
Why are horses are risk of gastric rupture
The mechanical and vagal mechanisms that promote lower esophageal sphincter tone prevent spontaneous decompression of the stomach, which along with a lack of a vomiting reflex in the horse, increases the risk of gastric rupture during episodes of severe distention.
Common site for esophageal obstruction in the horse
Esophageal obstruction occurs most commonly at sites of natural narrowing of the esophageal lumen, such as the cervical esophagus, the thoracic inlet, base of the heart, or the terminal esophagus
food should be withheld for what amount of time following esophageal obstruction?
24-48 hrs
The rate of re-obstruction may be as high as 37%.
Depending on the duration of the obstruction and the degree of trauma or dilation, the risk of re-obstruction is high for 24 to 48 hours or longer.
Esophageal disorders including megaesophagus, esophageal diverticulum, and esophageal rupture appear to be more common in
young Friesian horses, suggesting the possibility of a genetic predisposition in this breed.
Esophageal strictures may resolve with conservative management within
60 days
A foal presents with salivation, esophageal dysphagia, and swelling of the cervical esophagus. What can cause this presentation?
A: congenital stenosis B: persistent right aortic arch C: esophageal duplication cysts D: intramural inclusion cysts E: idiopathic megaesophagus
Isolated equine parietal cells respond maximally to which stimuli:
Histamine - released by mast cells and ECL-like cells in the gastric gland.
Gastric acid secretion by parietal cells is primarily inhibited by
somatostatin, which is released by fundic and antral D cells.
actions of sucralfate
A: adherence to ulcerated mucosa
B: enhanced PGE synthesis
C: stimulation of mucous secretion
D: promotes healing via concentration of growth factor at affected sites
The most common clinical sign of horses with intestinal neoplasia
Weight loss
primary caecal impactions
typically consist of impacted, relatively dry faecal material and there is a gradual onset of abdominal pain over a number of days reminiscent of the development of a large colon impaction
secondary caecal impactions
develop when a horse is being treated for a separate problem, and tend to have very fluid contents
caecal impaction - DX
based on rectal palpation of a firm, impacted or fluid-filled caecum. The hand will be unable to move completely dorsal to the impacted viscus due to the caecum’s attachment to the dorsal body wall
Just like urolithiasis in small ruminants, feeding alfalfa hay and decreased dietary proportions of pasture grass have been consistently identified as risk factors in horses with ____
enterolithiasis
Enteroliths are usually found in the
RIGHT DORSAL and TRANSVERSE colons
Enteroliths are mineralised masses typically composed of
ammonium magnesium phosphate
STRUVITE
alfalfa hay contains 6X the daily requirement of ____
Mg
The ascending colon is freely moveable except for the
RVC AND RDC
Development of large colon displacement
- feeding of large concentrate meals contributes to initiation by increasing the rate of passage of ingesta, allowing a greater percentage of soluble CHO to reach the large intestine
- increased rate of fermentation and amount of gas and VFAs produced
- production of large amounts of VFAs stimulates the secretion of large volumes of fluid into the colon
pelvic flexure usually not palpable