1
Q
Rumen tympany
A
aka bloat; accumulation of gas in the rumen
2
Q
frothy bloat
A
formation of stable foam - balance between pro and anti-foaming factors is upset
3
Q
Three causes of frothy bloat
A
- Primarily dependent on leguminous diets high in soluble protein (bloat inducing legumes, such as alfalfa and clover, are up to 4.5% soluble protein).
- Decreased saliva production; saliva has anti-acid and anti-foaming properties.
- Decreased rumen pH promotes formation of a stable foam from soluble proteins
4
Q
Free gas bloat
A
physical or functional defects affecting the esophagus, esophageal groove or vagus nerve can prevent eructation;
- Esophagus: obstruction by foreign bodies (apple) or by extra-esophageal compression (lymphosarcoma).
- Failure to eructate - lesion involving vagus nerve (abscess, chronic pneumonia) or localized reticuloperitonitis involving the left ventral wall of the reticulum (adhesions and pain interfere with the cardia clearing reflex)
5
Q
Traumatic reitculoperitonitis
A
aka hardware disease; penetration of the reticulum by a sharp foreign body
6
Q
Sequelae of Traumatic reitculoperitonitis
A
- Localized peritonitis with or without abscesses may involve the diaphragm, spleen, and liver.
- Foreign body penetration through the diaphragm causing traumatic reticulopericarditis.
- Adhesions or abscesses between reticulum and diaphragm causing omasal transport failure (indigestion), or chronic bloat.
- Adhesions or abscesses that cause decreased abomasal motility and impaction (indigestion)
7
Q
Acute carbohydrate engorgement leads to _____.
A
Rumen lactic acidosis
8
Q
How does acute carbohydrate engorgement lead to rumen lactic acidosis?
A
- Quantities of readily digestible carbohydrates are rapidly consumed
- Rumen flora produce excessive volatile fatty acids
- Rumen pH lowered
- Lowere rumen pH favors overgrowth of streptococci and lactobacilli that produce excessive amounts of lactic acid
- As volative fatty aicds and lactic acid levels increase rumen pH drops from normal pH of 5.5 - 7.5 to 5.0 - 4.0, causing acidosis
- The osmotic effect of fatty acids draws fluid from the circulation into the rumen
9
Q
The result of acute carbohydrate engorgement/rumen lactic acidosis:
A
- Dehydration, hypovolemia, acidosis, rumen atony, splashy rumen, and toxemia; bloat (frothy or free gas) may also occur
- Rumenitis appears as “matting” and loss of rumen papilli
- Areas of infarction may develop due to mycotic infection of rumen wall blood vessels
10
Q
Sequellae of acute carbohydrate engorgement/rumen lactic acidosis
A
- Opportunistic pathogens like Fusobacterium and fungi invade the rumen wall
- Mycotic infection of rumen wall and blood vessels
- This condition may occur subclinically.
- Bacterial transportation to liver causes abscesses in liver
11
Q
Vagal indigestion
A
- Damage of vagus nerve causes outflow dysfunction
- Abscesses, lymphosarcoma, traumatic reticuloperitonitis
12
Q
What kind of dogs are most at risk to gastric dilatation/volvulus?
A
large, deep-chested young dogs
13
Q
What has been hypothesized to predispose dogs to gastric dilatation/volvulus?
A
Delayed gastric emptying
14
Q
Describe gastric dilatation/volvulus in dogs
A
- Gas distended stomach contains fluid and ingesta mixed with frothy mucoid substrate.
- Gastric dilatation may be accompanied by volvulus with gastric ischemia/infarction
15
Q
Sequellae to gastric dilatation/volvulus in dogs
A
- Decreased VENOUS return via compression of caudal vena cava and portal vein leads to decreased cardiac output and hypotensive shock.
- Reduced function of the hepatic mononuclear phagocytic system allows endotoxins to accumulate.
- Disseminated intravascular coagulation (DIC) develops in the presence of endotoxins, venous stasis, hypoxia and metabolic acidosis
16
Q
Abomasal displacement in cattle
A
- Post parturient condition in high producing dairy cows on high grain rations
- Hypocalcemia causes low muscle tone ⇒ Abomasal atony is believed to play a role in this condition⇒Abomasum becomes distended with gas and rises to right or left side.
17
Q
Abomasal displacement in cattle: LDA vs RDA
A
- LDA is not usually a cause of death
- RDA is life threatening
18
Q
Gastric distention is mainly seen in ______, and may be seen in _____.
A
mainly horses; may see in nonhuman primates
19
Q
Gastric distension results from…….
And can result in ……
A
- Gaseous distention of the stomach results from engorgement of grain or other palatable food
- Ileus develops
- May have reflux of intestinal content in horses with small bowel obstruction
- Can result in gastric rupture
20
Q
Acute gastritis is characterized as?
A
- Multifocal or diffuse.
- Characterized by hemorrhage, congestion and edema with damage or loss of surface epithelium
21
Q
Common causes of acute gastritis:
Common causes of acute abomasitis:
A
- Nonsteroidal anti-inflammatory drugs
- Toxic metabolites such as found in uremic dogs
- Acute abomasitis may be caused by clostridia, mycotic agents, parasites, and systemic viral infections
22
Q
Uremic gastritis is ______, and is most common in _____.
A
- Mineralization of basement membranes, glands, vessels, and interstitium of mucosa
- Most common in carnivores with chronic renal failure and uremia
23
Q
What disease does the common name “braxy” stand for?
A
- acute emphysematous abomasitis caused by infection with Clostridium septicum
24
Q
Chronic gastritis
A
- prolonged exposure to agents that cause gastritis or to other factors can result in chronic inflammation of the stomach
25
Hypertrophic gastritis: lesions - grossly and microscopically, cause
* Gastric mucosa is thrown into thick folds resembling convolutions of the brain.
* Diffuse or focal
* Microscopically--severe epithelial hyperplasia, and infiltrates of mononuclear inflammatory cells
* Cause is unknown, associated with protein losing gastropathy, diarrhea
26
Parietal cell hyperplasia leads to thickening of mucosa with ______ syndrome.
Zollinger Ellison Syndrome
27
Dog breeds susceptible to hypertrophic gastritis
* Basenji
* Beagle
* Boxer
* Bull terrier
28
* What is Chronic hypertrophic pyloric gastropathy?
* What kinds of dogs does it most commonly involve (small/large, young/old, male/female)
* Symptoms
* Cause
* Associations
* Gross lesions
* Is it neoplastic?
* Hypertrophy of mucosa or smooth muscle
* Small breeds of dogs, middle aged or older
* Males \>\>\>\>\> females
* Chronic vomiting, weight loss, gastric distention
* Non-neoplastic
* Unkown cause
* Commonly associated with inflammation in mucosa
* Enlarged mucosal folds
29
Eosinophilic gastritis:
* Description
* Lesions
* May be accompanied by?
* Cause?
* May predispose rottweiler's with this syndrome:
* Extensive fibrosis with eosinophil infiltration may cause flattening of gastric rugae and marked thickening of the stomach wall
* Focal or diffuse
* May be accompanied by arteritis
* Likley a hypersensitivity response to agents unkown
* May occur in a hypereosinophilic syndrome in rottweilers
30
Lymphocytic-Plasmacytic Gastritis
* Chronic gastritis and gastric ulcers have been associated with gastric infection by spiral-shaped microorganisms in the genus Helicobacter.
* Multiple species are affected including dogs, cats, ferrets and non-human primates
31
Gastric mucosal barrier consists of certain gastrointestinal defense mechanisms which cannot be defined on a strictly anatomic basis. They are characterized by a number of physiochemical processes which seek to ......
Anatomic components include:
* ....maintain normal mucosal function by limiting the back diffusion of H+ ions.
* Mucous layer, epithelial cells, and vasculature
32
Five components of gastric mucosal barrier
1. Gastric mucus
2. Regulation of intramural pH
3. Mucosal regeneration
4. Cytoprotective functions of prostaglandins
33
Components of the Gastric Mucosal Barrier:
Gastric mucus
* Thin layer adherent to the lipid membranes of surface epithelial cells.
* Protects against luminal pepsin and provides a mixing barrier for surface neutralization of H+ ions by HCO3- ions secreted from the underlying epithelium
34
Components of the gastric Mucosal Barrier:
Regulation of Intramural pH
* Normal mucosal blood flow ensures adequate oxygenation and energy substrates
* provides a pool of HCO3- ions and a means of disposal of back diffused H+ ions
35
Components of the gastric mucosal barrier:
Mucosal Regeneration
* Gastric epithelium has a high proliferation rate which enables continual replacement of shed cells and restitituion of epithelial integrity following acute damage (providing the basement membrane remains intact)
36
Components of Gastric Mucosal Barrier:
Cytoprotective functions of prostaglandins
* Prostaglandins are saturated, oxygenated fatty acids found in almost every mammalian cell.
* Prostaglandins of the E type occur in copious amounts in the gastrointestinal system in general.
* Current evidence indicates that prostaglandins play an important role in maintaining integrity of the gastroduodenal mucosa by virtue of their antisecretory and cytoprotective properties
* Protective effects of prostaglandins:
* Decrease gastric acid secretion
* Increase mucus and bicarbonate secretion
* Increase mucosal blood flow
* Enhance cell regeneration
37
Breakdown of the gastric mucosal barrier
* The gastric mucosal barrier can be disrupted in any number of situations that permit back diffusion of H+ ions, especially when the ability to neutralize or remove H+ ions from the mucosa also is impaired.
* Back diffusion of H+ ions triggers a series of events that ultimately increases the amount of acid entering the surface epithelial cells and subepithelial tissues
38
Acute hemorrhagic gastritis ⇒ ______ ⇒ \_\_\_\_\_\_\_
Acute hemorrhagic gastritis ⇒ gastric erosions ⇒ multiple small acute peptic ulcers
39
Acute gastric erosions and ulcers:
* Factors that may be involved in pathogenesis:
* These factors lead to:
* Irritation by drugs - NSAID's cause direct epithelial toxicity and inhibit prostaglandin synthesis
* Excess acid secretion via hypergastrinemia
* Reflux of bile and duodenal contents into the stomach
* Mucosal ischemia - caused by shock or hypotension (trauma, sepsis, burns, hypothermia) is likely an extremely important factor. Hypoxemia compromises integrity of the protective surface barrier and allows back-diffusion of acid through the damaged mucosal surface
Reduced effectiveness of the normal intact gastric mucosal barrier via direct injury to epithelial cells, back-diffusion of acid and pepsin and reduced mucosal perfusion or ischemia causes gastric mucosal damage that can progress to acute gastric ulcers.
40
Chronic Gastric Ulcers
* Description
* Location
* How do they differ from acute ulcers?
* Usually solitary and may occur at any level of gastrointestinal tract (esophagus, stomach, duodenum) exposed to the action of acid-peptic juices
* Most occur in the pyloric antrum and proximal duodenum
* Chronic ulcers differ from acute ulcers because they are usually solitary and have a predilection for specific locations in the stomach and duodenum
* There appears to be overlap in the pathogenesis of chronnic and acute ulcers as far as casues and role of decreased mucosal resistance to injury
41
Gastric/Duodenal Ulcer Disease in Small Animals
Describe pathogenesis of each clinical conidtion:
1. Cirrhosis
2. Chronic Renal failure
3. Mast Cell Tumor
4. Gastrinoma
5. Chronic Pancreatitis
6. Gastric neoplasms
1. Uncertain (multifactorial)
2. Vascular/toxic metabolic products?
3. Hiastmaine stimulates H+ secretion, vascular dilation
4. Gastrin stimulates H+ secretion
5. Decreased bicarbonate in pancreatic juices
6. Neoplastic cell infiltrates
42
Gastric/Duodenal Ulcer Disease in Large Animals
Describe the anatomic area selected and the pathogensis for each animal listed:
1. Foals \<4 months
2. Adult horses
3. Young Cows
4. Swine
1. Foals - stomach and duodenum - unkown/stress, NSAID's
2. Adult horses - squamous area, often asymptoamtic - unclear/NSAIDs
3. Young cows - abomasum - uknown (seen during postpartum period)
4. Swine - esophageal area of stomach - multifactorial (finley ground pelleted ration; hot weather)
43
Pyloric Stenosis
* Associated with ....
* Interferes with ....
* Causes.....
* Narrowing of pylorus/thickening of pyloric area
* Interference with gastric emptying
* Projectile vomiting
44
Gastric Parasites - Equine
* Gastrophilus intestinalis* vs *Gastrophilus nasalis*
* Both produce these lesions:
* Gastrophilus intestinalis
* Bots - fly larvae attach to the stratified squamous portion of the gastric mucosa
* Gastrophilus nasalis
* Bots - fly larvae attach to the glandular portion of the gastric mucosa
* Both produce 1-2 mm ulcers at attachment site
45
Gastric Parasites - Equine
*Draschia megastoma*
* Filarid worm found in 2.5 - 3.0 cm diameter noduels (brood pouch) on the margo plicatus
* Focal or multifocal granulomatous gastritis in horses
* Eggs released through pore, pass out in feces, consumed by fly larvae that are the intermediate hosts
* Not usually associated with clinical signs
46
Gastric Parasites - Ruminants
* Ostertagia* sp.
* Acute vs Chronic
* Infest cattle and buffalo
* Reside in the mucosa
* Ingest blood products
* Acute - hemorrhagic inflammation
* Chronic - loss of glands, fibrosis of the mucosa; achlorhydria (low production of gastric acid) and unthriftiness
47
Gastric Parasites - Ruminants
*Haemonchus contortus*
* Blood sucking nematode that infests small ruminants
* Reside on the surface of the gastric mucosa
* Releases anti-coagulant causing hemorrhagic in abomasum - usually in sheep
48
Gastric Parasites - Cat
* Ollulanus tricuspis*
* What types of lesions does it cause?
* Mild gastritis that can lead to fibrosis of the mucosa
49
Gastric Parasites - Cat
* Gnathostoma* sp.
* What types of lesions does it cause?
* Granulomatous masses in submucosa (5 cm or more in diameter)
50
Gastric Parasites - Pigs
## Footnote
*Hyostrongylus rubidus*
* Thin sow syndrome
* Gastric mucosa is thickened, catarrhal, cobblestoned
* Mucus metaplasia of parasitized and adjacent glands
* Formation of submucosal lymphoid follicles
51
Gastric Tumor:
Leiomyoma
* Benign
* Smooth muscle tumor
* Clinically significant when they obstruct gastric inflow or outflow
52
Gastric Tumor:
Adenomatous polyps
* Benign
* Epithelial tumors of the gastric mucosa in dogs
* May cause vomiting
53
Gastric Tumor:
Adenocarcinoma
* Malignant
* Occur most often in the dog and cat; chow dogs appear to have an increased risk
* Causes vomiting and weight loss
* Pyloric antrum often involved
* Ulceration and thickening of the stomach wall is common - this may result in a flask-shaped stomach
* Metastases occur in the regional lymph nodes, lungs, and other organs
54
Gastric Tumor:
Lymphosarcoma
* Malignant
* Stomach of the dog and cat
* Abomasum of bovine
* Nodular or diffuse infiltrates of neopasltic lymphoid cells can infiltrate all layers of the stomach and may produce gastric ulcers
55
Gastric Tumors:
Squamous Cell Carcinoma
* Malignant
* Large cauliflower-like or ulcerated mass in the squamous part of the stomach in the horse
* Transmural infiltration with implatnation of the peritoneal surface is common
* Often metastasize widely before detection
56
Gastric Tumors:
Leiomyosarcoma
* Malignant counterpart of leiomyoma (smooth muscle tumor)
* Tumor cells are more undifferentiated and mitotic activity is greater
* Invasion of adjacent structures and metastasis may occur
Special Pathology - GIT
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