Forestomach, Abomasum & Stomach Diseases in Animals

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Questions and Answers

Which of the following is the primary function of the rumen in ruminants?

  • Main fermentation vat, creating VFAs for energy (correct)
  • Starting the digestion process
  • Initiating contractions in the digestive system
  • Water and electrolyte balance

What type of epithelium lines the forestomach?

  • Transitional epithelium
  • Simple columnar epithelium
  • Ciliated pseudostratified columnar epithelium
  • Thick keratinizing stratified squamous epithelium (correct)

What is the purpose of the diverse microflora and alkaline pH in the forestomach?

  • To aid in the secretion of digestive enzymes
  • To prevent colonization and multiplication of pathogens (correct)
  • To produce volatile fatty acids
  • To facilitate water absorption

In ruminants, what is traumatic reticulopericarditis commonly caused by?

<p>Ingestion of sharp metallic objects (B)</p> Signup and view all the answers

What is the primary cause of primary tympany (frothy bloat) in ruminants?

<p>Too much dietary protein (B)</p> Signup and view all the answers

What is the result of proteins creating small bubbles in the rumen?

<p>Prevention of eructation, leading to bloat (D)</p> Signup and view all the answers

What is the consequence of damage or compression of the vagus nerve in the context of ruminal tympany?

<p>Abnormal motility leading to secondary tympany (C)</p> Signup and view all the answers

What is the only reliable indicator of antemortem bloat?

<p>Bloat line (C)</p> Signup and view all the answers

What type of bacteria thrive in the rumen when lactic acidosis occurs?

<p>Lactobacillus and Streptococcus (D)</p> Signup and view all the answers

What is the primary cause of death in animals suffering from rumenitis and lactic acidosis?

<p>Dehydration (D)</p> Signup and view all the answers

What is the primary mechanism by which bacteria reach the liver and lungs, leading to abscess formation in bacterial rumenitis?

<p>Portal circulation (A)</p> Signup and view all the answers

Which of the following is a common fungal species involved in mycotic rumenitis?

<p>Mucor, Absidia, Rhizopus, Aspergillus (A)</p> Signup and view all the answers

What is the primary outcome of vessel invasion in cases of mycotic rumenitis?

<p>Thrombosis and infarcts (D)</p> Signup and view all the answers

True or False: An animal undergoing lactic acidosis experiences an increase in pH.

<p>False (A)</p> Signup and view all the answers

Which of the following outcomes is more closely associated with 'Bloat' than 'Lactic Acidosis'?

<p>Inability to eructate (C)</p> Signup and view all the answers

Which of the following is NOT generally an etiology of abomasitis?

<p>Prion infection (B)</p> Signup and view all the answers

Which parasite species is a voracious blood sucker that can lead to anemia and hypoproteinemia in infected animals?

<p>Haemonchus spp. (A)</p> Signup and view all the answers

What pathological change is associated with Ostertagia ostertagi infections, leading to impaired digestion?

<p>Loss of parietal and chief cells (D)</p> Signup and view all the answers

What are bracken fern poisonings strongly associated with in cattle

<p>Squamous cell carcinoma (C)</p> Signup and view all the answers

In monogastric animals, which region of the stomach is lined by squamous epithelium?

<p>Cardia (C)</p> Signup and view all the answers

Which cells in the fundus of the monogastric stomach produce hydrochloric acid (HCl)?

<p>Parietal cells (A)</p> Signup and view all the answers

Which cells secrete gastrin?

<p>Tubular glands (A)</p> Signup and view all the answers

What is the role of gastric mucus cells in protecting the stomach lining?

<p>Secreting bicarbonate and mucus (C)</p> Signup and view all the answers

What is the function of prostaglandin E2 in the gastric mucosal barrier?

<p>Stimulates mucus secretion and inhibits acid secretion (D)</p> Signup and view all the answers

Gastric Dilation and Volvulus is most common in what kind of animal?

<p>Deep-chested dogs (B)</p> Signup and view all the answers

What is the direction of the stomach rotation associated with Volvulus?

<p>Clockwise (B)</p> Signup and view all the answers

Why might splenic displacement occur in dogs with GDV?

<p>Due to compression of the caudal vena cava and portal vein (D)</p> Signup and view all the answers

What is meant by the term, 'Torsion'?

<p>The stomach twists on its long axis without obstructing the gastro-esophageal junction (A)</p> Signup and view all the answers

Gastric dilation and rupture in the horse most frequently results from:

<p>Excess Fermentable Carbohydrates (A)</p> Signup and view all the answers

Bruxism is a sign of gastrointestinal discomfort. What is bruxism?

<p>Grinding one's teeth (C)</p> Signup and view all the answers

Which domestic animal species is most prone to gastric ulcers associated with finely ground feed?

<p>Pigs (D)</p> Signup and view all the answers

In horses, where do gastric ulcers most frequently form?

<p>Margo plicatus (B)</p> Signup and view all the answers

What condition is the use of NSAIDs closely associated with?

<p>Gastric Ulcers (D)</p> Signup and view all the answers

Most common cause for an animal to have deposition of minerals in their stomach?

<p>Uremic gastritis (C)</p> Signup and view all the answers

Which of the following is the most common gastric neoplasm in cats?

<p>Lymphoma (A)</p> Signup and view all the answers

A relative diffuse, soft tan/white homogenous thickening +/- nodules of the stomach is associated with which condition?

<p>Lymphoma (C)</p> Signup and view all the answers

Which benign smooth muscle neoplasm is also common in the GIST: Interstitial cells of Cajal?

<p>Leiomyoma (C)</p> Signup and view all the answers

Which of these characteristics is LEAST likely pertaining to Leiomyosarcoma?

<p>Does not metastasize (A)</p> Signup and view all the answers

A horse has squamous cell carcinoma. Where would we expect the lesion to be?

<p>Pars esophagea (A)</p> Signup and view all the answers

Uremic gastritis is most likely to be diagnosed in which animal?

<p>Dog (C)</p> Signup and view all the answers

What is the role of Enteroendocrine cells?

<p>Produce serotonin (C)</p> Signup and view all the answers

In ruminants, what is the omasum primarily responsible for?

<p>Electrolyte balance (D)</p> Signup and view all the answers

Which of the following processes primarily occurs in the rumen?

<p>Main fermentation, producing VFAs for energy (A)</p> Signup and view all the answers

What is the primary role of the reticulum in the ruminant digestive system?

<p>Initiating contractions to aid in digestion (B)</p> Signup and view all the answers

Which component of the ruminant stomach is considered the 'glandular stomach' and is where digestion starts?

<p>Abomasum (A)</p> Signup and view all the answers

What is the main function associated with the omasum?

<p>Water and electrolyte balance (B)</p> Signup and view all the answers

What kind of protection does the thick keratinizing stratified squamous epithelium of the forestomach provide?

<p>Mechanical (A)</p> Signup and view all the answers

What characteristic of the normal forestomach helps prevent pathogen colonization?

<p>A diverse microflora and alkaline pH (A)</p> Signup and view all the answers

Which of the following represents a primary cause of disease in the rumen?

<p>Too much gas (bloat) (B)</p> Signup and view all the answers

What is 'hardware disease' in ruminants most commonly associated with?

<p>Perforation of the reticulum by ingested metal objects (C)</p> Signup and view all the answers

Excess dietary protein in ruminants can lead to which condition?

<p>Frothy bloat (A)</p> Signup and view all the answers

Which of the following is a potential consequence of damage or compression of the vagus nerve in ruminants?

<p>Secondary tympany (A)</p> Signup and view all the answers

What is the key post-mortem finding that suggests bloat occurred before death?

<p>Bloat line (B)</p> Signup and view all the answers

Dehydration is the result of water being sucked into the rumen. What causes this influx of water?

<p>Increased osmotic pressure due to D-lactate production (A)</p> Signup and view all the answers

What is the primary reason animals die from rumenitis and lactic acidosis?

<p>Dehydration (B)</p> Signup and view all the answers

Which route does bacteria take to reach the liver and lungs in cases of bacterial rumenitis, leading to abscesses?

<p>Portal circulation (D)</p> Signup and view all the answers

What is a key pathological consequence of vessel invasion in mycotic rumenitis?

<p>Thrombosis and infarcts (A)</p> Signup and view all the answers

Which factor is associated with abomasal ulcers in feedlot cattle?

<p>Stress related to weaning and transport (B)</p> Signup and view all the answers

In cases of parasitic abomasitis, what is the primary pathogenic mechanism of Haemonchus contortus?

<p>Voracious blood sucking (B)</p> Signup and view all the answers

An animal presents with submandibular edema and anemia. Which parasitic infection is more closely associated with this presentation?

<p><em>Haemonchus spp.</em> (D)</p> Signup and view all the answers

In cattle, what pathological change in the abomasum is caused by Ostertagia ostertagi infections?

<p>Loss of parietal and chief cells (C)</p> Signup and view all the answers

Which of the following viruses can cause abomasitis primarily in cattle as part of a more systemic disease?

<p>Bovine Viral Diarrhea Virus (D)</p> Signup and view all the answers

Which of the following best describes the pathogenesis of Gastric Dilation-Volvulus (GDV)?

<p>Increased intra-abdominal pressure causes splenic torsion and decreased venous return to the heart (D)</p> Signup and view all the answers

What causes elevated acid secretion in small animal patients with Gastric Ulcers?

<p>Increased serum gastrin (rare, seen in gastrinomas) (D)</p> Signup and view all the answers

What condition in horses does not commonly cause gastric ulcers?

<p>Lower performance (A)</p> Signup and view all the answers

What is the main component found in the stomach of dogs with Uremic gastritis?

<p>Calcium deposits (C)</p> Signup and view all the answers

What is the most common result of Gastrointestinal stromal tumors (GIST) and leiomyosarcomas?

<p>GIST: Interstitial cells of Cajal (within tunica muscularis) (B)</p> Signup and view all the answers

What is the primary source of volatile fatty acids (VFAs) in the rumen?

<p>Fermentation of food by microorganisms (B)</p> Signup and view all the answers

Which epithelium type lines the rumen, reticulum, and omasum?

<p>Stratified squamous epithelium (D)</p> Signup and view all the answers

In 'hardware disease', which organ is typically perforated first by ingested foreign bodies?

<p>Reticulum (B)</p> Signup and view all the answers

Rumen atony, or stasis, is most commonly associated with dysfunction of which cranial nerve?

<p>Vagus nerve (CN X) (B)</p> Signup and view all the answers

What is the underlying cause of primary tympany (frothy bloat) in ruminants?

<p>Formation of stable foam that traps gas in the rumen (D)</p> Signup and view all the answers

In frothy bloat, the stable foam formation is primarily attributed to:

<p>The chemical composition of proteins in certain legumes (A)</p> Signup and view all the answers

The 'bloat line' observed post-mortem in the esophagus of a ruminant that died from bloat is characterized by:

<p>A sharp line separating congested cranial esophagus from pale distal esophagus (B)</p> Signup and view all the answers

Rumen acidosis is primarily caused by the overgrowth of which type of bacteria in the rumen?

<p>Gram-positive lactic acid-producing bacteria (B)</p> Signup and view all the answers

Dehydration in animals with rumen acidosis is primarily due to:

<p>Water influx into the rumen due to increased osmotic pressure (D)</p> Signup and view all the answers

Hepatic abscesses in ruminants are a common sequela to rumenitis and lactic acidosis because bacteria typically reach the liver via the:

<p>Portal circulation (C)</p> Signup and view all the answers

In mycotic rumenitis, fungal invasion of blood vessels leads to which primary pathological outcome in the rumen mucosa?

<p>Ischemic necrosis and infarct formation (A)</p> Signup and view all the answers

Haemonchus contortus parasitism in the abomasum primarily causes disease through which mechanism?

<p>Blood loss leading to anemia and hypoproteinemia (D)</p> Signup and view all the answers

Ostertagia ostertagi infection in cattle leads to 'Moroccan leather' appearance of the abomasal mucosa due to:

<p>Mucous neck cell metaplasia and hyperplasia (C)</p> Signup and view all the answers

Bracken fern poisoning in cattle is most strongly associated with the development of which type of neoplasia in the forestomach?

<p>Squamous cell carcinoma (C)</p> Signup and view all the answers

In monogastric animals, the region of the stomach lined by squamous epithelium is the:

<p>Cardia (D)</p> Signup and view all the answers

Which cells in the fundic glands of the monogastric stomach are responsible for producing hydrochloric acid (HCl)?

<p>Parietal cells (B)</p> Signup and view all the answers

Gastrin, which stimulates hydrochloric acid production, is secreted by cells located primarily in which region of the monogastric stomach?

<p>Pyloric antrum (D)</p> Signup and view all the answers

Prostaglandin E2 (PGE2) plays a crucial role in gastric mucosal protection by:

<p>Stimulating mucus secretion and inhibiting acid secretion (A)</p> Signup and view all the answers

Gastric Dilation and Volvulus (GDV) in dogs is primarily a life-threatening condition due to:

<p>Compression of the vena cava and circulatory shock (A)</p> Signup and view all the answers

In Gastric Dilation Volvulus (GDV), splenic displacement is a common occurrence. Why does the spleen often become displaced in GDV?

<p>The rotation of the stomach during volvulus often carries the spleen along (B)</p> Signup and view all the answers

Gastric dilation and rupture in horses is most frequently a secondary condition resulting from:

<p>Obstruction in the small intestine or ileus (B)</p> Signup and view all the answers

Bruxism, a clinical sign sometimes associated with gastrointestinal discomfort, is best described as:

<p>Teeth grinding (C)</p> Signup and view all the answers

In horses, gastric ulcers most commonly develop in which region of the stomach?

<p>Non-glandular (squamous) mucosa (D)</p> Signup and view all the answers

The use of Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) is a significant risk factor for gastric ulcers because NSAIDs:

<p>Inhibit prostaglandin synthesis, reducing mucosal protection (D)</p> Signup and view all the answers

Uremic gastritis, associated with chronic kidney disease, is characterized by deposition of what substance in the stomach mucosa?

<p>Calcium deposits (C)</p> Signup and view all the answers

A diffuse, soft, tan-white thickening of the stomach wall, often with nodules, is most suggestive of which type of gastric neoplasm?

<p>Lymphoma with neoplastic lymphocytes (D)</p> Signup and view all the answers

Gastrointestinal stromal tumors (GISTs) originate from which cell type within the stomach wall?

<p>Interstitial cells of Cajal (A)</p> Signup and view all the answers

Which characteristic is LEAST typical of a leiomyosarcoma in the stomach?

<p>Benign biological behavior with slow growth (C)</p> Signup and view all the answers

In a horse diagnosed with squamous cell carcinoma of the stomach, where would the lesion most likely be located?

<p>Non-glandular region, pars esophagia (D)</p> Signup and view all the answers

Uremic gastritis is most commonly encountered in animals suffering from:

<p>Chronic renal failure (B)</p> Signup and view all the answers

Enteroendocrine cells in the stomach mucosa are primarily responsible for:

<p>Releasing hormones like gastrin (C)</p> Signup and view all the answers

Which of the following conditions is more likely to result in epistaxis (nosebleed) as a secondary complication in ruminants?

<p>Rumen acidosis (C)</p> Signup and view all the answers

Differentiating between antemortem and postmortem gastric rupture in a horse during necropsy relies heavily on identifying:

<p>Evidence of tissue reaction (hyperemia, edema) at the rupture margins (B)</p> Signup and view all the answers

In the context of gastric ulcers in dogs, which of the following paraneoplastic syndromes is associated with hypersecretion of gastric acid due to histamine release?

<p>Mast cell tumor (A)</p> Signup and view all the answers

Which of the following statements accurately contrasts adenocarcinoma and lymphoma as gastric neoplasms?

<p>Adenocarcinomas often induce a desmoplastic response, whereas lymphomas are usually homogenous and soft. (C)</p> Signup and view all the answers

A feedlot steer presents with lethargy, dehydration, and abdominal distension. Necropsy reveals a rumen with watery contents, mucosal hyperemia, and hepatic abscesses. Which of the following is the most likely primary diagnosis?

<p>Rumenitis and lactic acidosis (B)</p> Signup and view all the answers

A dog presents with hematemesis and melena. Endoscopy reveals a deep gastric ulcer. Further investigation for paraneoplastic syndromes would be most warranted if which of the following clinical findings were also present?

<p>Palpable cutaneous mass and episodic flushing (D)</p> Signup and view all the answers

Consider a scenario where a cow is grazing on lush alfalfa pasture and suddenly develops severe abdominal distension and respiratory distress. What is the most appropriate immediate intervention?

<p>Administer mineral oil via stomach tube to break down foam (A)</p> Signup and view all the answers

A horse presents with acute onset of severe abdominal pain, gastric reflux, and marked gastric distension on nasogastric intubation. Which of the following diagnostic procedures would be LEAST helpful in determining the underlying cause?

<p>Gastric biopsy to evaluate mucosal inflammation (C)</p> Signup and view all the answers

What is the primary function of the forestomach in ruminants?

<p>Microbial fermentation of plant fibers (B)</p> Signup and view all the answers

Which of the following best describes the epithelium lining the rumen and reticulum?

<p>Keratinized stratified squamous epithelium (D)</p> Signup and view all the answers

What is the significance of volatile fatty acids (VFAs) produced in the forestomach?

<p>They serve as the primary energy source for ruminants. (A)</p> Signup and view all the answers

In ruminants, 'hardware disease' primarily affects which part of the forestomach?

<p>Reticulum (C)</p> Signup and view all the answers

Which of the following is a common consequence of traumatic reticulopericarditis in cattle?

<p>Heart failure (D)</p> Signup and view all the answers

Primary tympany (frothy bloat) in ruminants is mainly caused by:

<p>Stable foam formation preventing eructation (D)</p> Signup and view all the answers

In frothy bloat, what component of the diet is most likely responsible for the stable foam formation?

<p>Legume proteins (A)</p> Signup and view all the answers

Secondary tympany (gas bloat) is often associated with:

<p>Physical or functional obstruction of eructation (B)</p> Signup and view all the answers

Damage to the vagus nerve can lead to which type of ruminal tympany?

<p>Secondary tympany (B)</p> Signup and view all the answers

The 'bloat line' in the esophagus is a post-mortem finding characteristic of:

<p>Antemortem bloat (C)</p> Signup and view all the answers

Rumen acidosis is primarily caused by the overproduction of:

<p>Lactic acid (C)</p> Signup and view all the answers

In rumen acidosis, dehydration occurs due to:

<p>Water influx into the rumen due to osmotic pressure (D)</p> Signup and view all the answers

Hepatic abscesses in ruminants are a common sequela to rumenitis because bacteria gain access to the liver via the:

<p>Portal circulation (B)</p> Signup and view all the answers

Mycotic rumenitis is characterized by fungal invasion of:

<p>Blood vessels in the rumen mucosa (D)</p> Signup and view all the answers

Which volatile fatty acid (VFA) production process is essential for ruminant energy and occurs primarily in the forestomach?

<p>Fermentation (D)</p> Signup and view all the answers

An abrupt dietary change in ruminants is most likely to disrupt which aspect of forestomach physiology, potentially leading to disease?

<p>Microbial flora balance (B)</p> Signup and view all the answers

In 'hardware disease', a metallic foreign body is most likely to penetrate which compartment of the ruminant stomach first due to its anatomical position?

<p>Reticulum (D)</p> Signup and view all the answers

What is the primary pathophysiological mechanism by which ruminal tympany (bloat) leads to death in ruminants?

<p>Cardiorespiratory compromise from diaphragmatic pressure (D)</p> Signup and view all the answers

The 'bloat line', a distinct demarcation in the esophagus, is a crucial post-mortem indicator of antemortem bloat. Which description accurately characterizes the cranial portion of the esophagus relative to the distal portion at this line?

<p>Cranial esophagus is hyperemic, distal is pale (C)</p> Signup and view all the answers

In rumen acidosis, the influx of water into the rumen is primarily driven by:

<p>Increased osmotic pressure due to fermentation products (B)</p> Signup and view all the answers

Hepatic abscesses are a common sequela to bacterial rumenitis because bacteria gain access to the liver primarily via the:

<p>Portal vein from the rumen submucosa (D)</p> Signup and view all the answers

Haemonchus contortus primarily causes disease in the abomasum through which of the following mechanisms?

<p>Blood loss leading to anemia and hypoproteinemia (B)</p> Signup and view all the answers

The 'Moroccan leather' appearance of the abomasal mucosa is a characteristic lesion associated with infection by which parasite?

<p><em>Ostertagia ostertagi</em> (D)</p> Signup and view all the answers

In monogastric animals, the region of the stomach lined by squamous epithelium and most susceptible to ulceration due to acid exposure is the:

<p>Cardia (A)</p> Signup and view all the answers

Which cells in the fundic glands of the monogastric stomach are responsible for producing hydrochloric acid (HCl) necessary for digestion?

<p>Parietal cells (C)</p> Signup and view all the answers

Prostaglandin E2 (PGE2) plays a crucial role in maintaining the gastric mucosal barrier by:

<p>Stimulating mucus secretion, inhibiting acid secretion, and regulating blood flow (D)</p> Signup and view all the answers

In dogs with Gastric Dilation Volvulus (GDV), splenic displacement often occurs concurrently due to:

<p>Anatomical attachment of the spleen to the greater curvature of the stomach (C)</p> Signup and view all the answers

Gastric dilation and rupture in horses is most frequently a secondary condition, most commonly resulting from:

<p>Obstruction of the small intestine or ileus (A)</p> Signup and view all the answers

Bruxism, as a clinical sign associated with gastrointestinal discomfort in animals, is best described as:

<p>Teeth grinding (A)</p> Signup and view all the answers

Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) are a significant risk factor for gastric ulcers because they directly inhibit the synthesis of:

<p>Prostaglandins (A)</p> Signup and view all the answers

Uremic gastritis, associated with chronic kidney disease, is characterized by the deposition of which substance in the gastric mucosa?

<p>Calcium (A)</p> Signup and view all the answers

A diffuse, soft, tan-white thickening of the stomach wall, often with nodules, in a cat is most suggestive of which type of gastric neoplasm?

<p>Lymphoma (A)</p> Signup and view all the answers

Gastrointestinal stromal tumors (GISTs) and leiomyosarcomas of the stomach primarily originate from which layer of the stomach wall?

<p>Muscularis externa (B)</p> Signup and view all the answers

In a horse diagnosed with squamous cell carcinoma of the stomach, where would the lesion be most likely located, considering the stomach's unique anatomical divisions?

<p>Non-glandular squamous mucosa near the margo plicatus (C)</p> Signup and view all the answers

Flashcards

Rumen

Main fermentation vat in ruminants, creating VFAs for energy.

Reticulum

Starts the contractions of the rumen.

Omasum

Likely balances water and electrolytes in ruminants.

Abomasum

Glandular stomach in ruminants where digestion starts.

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Trichobezoars

Hairballs that form in the ruminant stomach.

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Phytobezoars

Plant balls consisting of excess indigestible roughage.

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Hardware Disease

Nails and wires that perforate the reticulum.

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Bloat (Ruminal Tympany)

Gas accumulation in the rumen

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Primary Tympany

Frothy bloat due to excessive protein in the diet

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Secondary Tympany

Bloat due to vagal nerve damage or obstruction.

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Rumenitis

Inflammation of the rumen.

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Grain Overload

Excessive carbohydrate fermentation, decreasing pH.

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Lactobacillus and Streptococcus

Bacterial species that produce D-lactate and increase osmotic pressure.

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Consequences of Grain Overload

Dehydration, lactic acidosis, and rumenitis.

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Bacterial Rumenitis

Mucosal injury leads to invasion of resident flora

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Mycotic Rumenitis

Ruminal acidosis leads to mucosal injury, then fungal invasion

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Abomasitis

Inflammation of the abomasum.

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Haemonchus

Parasitic abomasitis caused by blood-sucking parasites.

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Ostertagia

Ostertagia ostertagi in cattle and Ostertagia circumcinta in small ruminants

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Forestomach Neoplasms

Tumors in the forestomach linked to ingesting bracken fern

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Fundus

Contains parietal cells that produce HCl and chief cells that produce pepsinogen

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Gastric mucosal barrier

Gastric mucus cells secrete bicarbonate and mucus = buffering gastric acid

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Gastric Dilation and Volvulus (GDV)

Gastric dilation and rotation causes venous return blockage.

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Gastric dilation and rupture in horses

Excess fermentable carbohydrates or cold water

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Gastroduodenal ulcerations

Increased gastric acid and/or mucosal damage.

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Gastric ulcers in small animals

Local disturbances or trauma damages the surface.

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Gastric Ulcers in pigs

Finely ground food. Common with Perforation

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Gastric Ulcers in Horses

Common with squamous part of the stomach in horses

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Abomasal ulcers in cattle

Associated with stress. Common in the pyloric region

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Gastritis

Inflammation of the stomach

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Uremic gastritis

Mostly in canines with severe kidney conditions

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Lymphoma in stomach

Relative diffuse, soft tan/white, homogenous thickening +/- nodules

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Forestomach Function

Break down fibers and produce volatile fatty acids.

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Two Key Forestomach Diseases

Bloat and ruminal acidosis.

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Order of Digestion

Rumen, reticulum, omasum, abomasum.

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Normal Rumen Bacteria

Anaerobic, mostly gram-negative.

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Reticulum Appearance

Honeycomb pattern.

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Omasum Appearance

Long, thin folds like pages of a book.

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Abomasum Appearance

Smooth with some folds, glandular.

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Causes of Forestomach Disease

Foreign bodies, motility problems, flora imbalance, pH changes and mucosal damage.

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Hardware Disease Definition

Rupture of the reticulum by a wire or nail.

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Hardware Disease Complication

Traumatic reticulopericarditis.

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Bloat Line

Congestion of the cranial esophagus and pale distal esophagus.

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Frothy Bloat Cause

Legumes rich in high-quality protein promote stable foam formation.

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Eructation Requirement

Free gas in the dorsal sac.

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Secondary Bloat Causes

Esophagus or cardia obstruction, or vagal nerve damage.

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Bloat Pathophysiology

Distended rumen compresses the lung and vena cava, leading to death.

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Rumen Acidosis Pathogenesis

Excessive carbohydrate fermentation leads to lactic acid production and increased osmotic pressure.

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Consequences of Ruminal Acidosis

Dehydration and metabolic acidosis.

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Bacteria Related to Rumenitis

Fusobacterium necrophorum and Trueperilla pyogenes.

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Liver Abscess Pathogenesis

Damage to the ruminal mucosa, invasion of bacteria liver, hepatic abscesses.

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Mycotic Rumenitis Lesions

Areas of infarcts in the rumen due to thrombosis caused by fungi.

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Cause of Primary or Frothy Bloat

Pro-foaming diet, legumes, alfalfa, clover, red and white clovers

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What could cause secondary bloat

It could be by a mechanical obstruction in the esophagus or cardia.

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Cause of Vegal Indigestion

Lesions in the pharynx, travels along the neck and esophagus.

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Function of Gastrin

The cells secrete gastrin, and the gastrin stimulates secretion of the acid gastric.

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Effect of Mast Cell Tumors

Tumors secrete histamine, stimulate gastric acid causing ulcers.

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Causes of Ulcers

Local disturbances or trauma to the mucosal epithelium barrier.

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Study Notes

  • The lecture covers diseases of the forestomach and abomasum, emphasizing pathology terms, pathogenesis, gross lesions, clinical signs, and differential diagnoses.
  • The main functions of the forestomach are to break down fiber and produce volatile fatty acids (VFAs) for energy, a process carried out by bacteria, protozoa, and some fungi.
  • Key forestomach issues include bloat and chemical rumenitis (ruminal acidosis).
  • Gram-negative bacteria typically predominate in the rumen, but ruminal acidosis results in the death of the gram-negative bacteria, leading to an overgrowth of gram-positive bacteria

Ruminant Stomach Anatomy Review

  • Esophagus leads to the rumen, then to the reticulum, omasum, and abomasum.
  • The spleen is typically attached to the rumen.

Rumen

  • Characterized by mucosal folds and papillae.

Reticulum

  • It has a honeycomb pattern on the mucosa.

Omasum

  • has long, thin folds resembling pages of a book.

Abomasum

  • It resembles a normal glandular stomach with some folds and is lined by columnar epithelium.

Etiopathogenesis of Rumen Issues

  • Issues include foreign bodies (wires, nails), motility problems, imbalance of ruminal flora, abrupt diet change, pH changes, and loss of mucosal lining integrity (ulcers).
  • Vagus nerve damage can cause motility problems (rumen atony).
  • Imbalance of ruminal flora is often associated with dietary changes, which kill good bacteria and allow bad bacteria to proliferate.

Foreign Bodies

  • Hairballs (trichobezoars) and plant balls (phytobezoars) are usually incidental findings
  • Nails and wires can perforate the reticulum, diaphragm, and pericardium
  • Reticulopericarditis results in chronic, active infection of the pericardial sac
  • Lead poisoning from batteries or paints can cause necrosis of the gray matter of the brain (polioencephalomalacia).
  • Traumatic reticulopericarditis is diagnosed via finding the foreign body, or a scar in the reticulum.
  • Fibrin (yellow, friable material) covering the heart indicates a chronic active infection of the pericardial sac and epicardial surface, leading to heart failure.

Bloat (Ruminal Tympany)

  • This can cause death via cardiorespiratory arrest due to pressure on the diaphragm and compressed lung or cardiogenic shock with decreased venous return due to compressed vena cava.
  • Severe cases can cause distension on both sides of the animal.

Primary Bloat

  • Dietary protein, especially from legumes like alfalfa and clover, can cause primary or frothy bloat.
  • Proteins create stable foam that prevents eructation by blocking the cardia and trapping gas in bubbles

Secondary Bloat

  • Secondary tympany or gas bloat is caused by obstruction from foreign bodies or tumors, or damage to the vagus nerve.
  • Vagal nerve damage or compression, caused by abscesses or inflammation, can lead to vagal indigestion and secondary bloat (ruminal atony and bloat).

Identifying Antemortem Bloat

  • Reliable indicator of antemortem bloat is the bloat line which causes congestion of the cranial esophagus and a pale distal esophagus.

Inflammation of the Rumen (Rumenitis)

  • Grain overload causes excessive carbohydrate fermentation, which lowers pH, kills protozoa, and allows proliferation of Lactobacillus and Streptococcus
  • This leads to D-lactate production, increasing osmotic pressure, resulting in water influx and rumen atony and mucosal damage.
  • Animals can die of dehydration due to water drawn into the rumen.
  • Ruminal scars and mucosal damage may develop in survivors

Bacterial Rumenitis

  • Resident flora, such as Fusobacterium necrophorum and T. pyogenes, invade injured mucosa due to ruminal acidosis.
  • Bacteria can be transported to the liver via the portal circulation, resulting in hepatic abscesses, and subsequently to the lungs, causing pulmonary abscesses, hemorrhage, and epistaxis.

Mycotic Rumenitis

  • Mucosal injury from ruminal acidosis facilitates fungal invasion.
  • Fungi invade vessels, causing thrombosis and infarcts.
  • Common fungi include Mucor, Absidia, Rhizopus, and Aspergillus.
  • Fungi go specifically to the vessel walls, leading to inflammation and obstruction of blood supply and causing areas of ischemia

Lactic Acidosis

  • Lactic Acidosis or Grain Overload results in severe dehydration and is lethal
  • If the animal recovers, a sequel can be hepatic abscesses and not pancreatic
  • Diets high in grain cause the disease and not altafa
  • increased protozoa in the rumen does not result in lactic acidosis

Main Rumen Problems:

  • Lactic Acidosis and Bloat

Abomasitis

  • Bacterial causes are Clostridium septicum (Braxy)
  • Parasitic causes are Hemonchus contortus and Ostertagia
  • Fungal causes are chronic ulceration or sepsis in calves
  • Viral causes are part of systemic diseases like IBR, BVD, and MCF in cattle, or blue tongue in sheep

Parasitic Abomasitis: Haemonchus

  • H. contortus impacts sheep and H. placei impacts cattle
  • Parasite attaches to mucosa as voracious blood suckers, causes anemia and hypoproteinemia, leading to edema.
  • Female parasites have a "barber's pole" appearance due to the pale tan reproductive tract and dark red digestive tract filled with blood.

Parasitic Abomasitis: Ostertagia

  • Most prominent characteristic is Moroccan Leather
  • Parasite resides in the abomasal glands, causing metaplasia of epithelial cells, replacing parietal and chief cells with mucous cells
  • Affects parietal and chief cells responsible for digestion of proteins and production of hydrochloric acid
  • Thickening of the mucosa results in a cobblestone or Moroccan leather appearance
  • Leads to impaired digestion, hypoproteinemia, diarrhea due to maldigestion and malabsorption, chronic weight loss, and is often untreatable.

Forestomach Neoplasms

  • Bracken fern poisoning causes squamous cell carcinoma in cattle
  • Ruminal papilloma is associated with bovine papilloma virus 4
  • Squamous cell carcinoma can obstruct the cardia leading to secondary bloat.

Stomach Anatomy in Monogastrics

  • divided into the cardia, fundus, and pyloric region
  • Cardia abuts the esophageal region and is lined by squamous epithelium
  • Fundus contains parietal cells, which produce HCL, and chief cells, which produce pepsinogen; lined by columnar mucus cells
  • Pyloric region contains tubular glands that secrete gastrin
  • Horses have a non-glandular stomach lined by stratified squamous epithelium, susceptible to ulcers

Gastric Anatomy and Histology

  • Low luminal pH destroys ingested pathogens, resident bacterial flora can't be cultured by conventional methods
  • Parietal cells produce rennin to coagulate milk protein, intrinsic factor for vitamin B12 absorption, and hydrogen chloride (HCI)
  • Chief cells produce zymogen and pepsin for digestion
  • Enteroendocrine cells produce serotonin, gastrin, somatostatin, endothelin, histamine
  • Mucus cells produce bicarbonate and a protective layer
  • Activation of pepsinogen requires hydrochloric acid and is affected by decreased production of hydrochloric acid

Gastric Mucosal Barrier

  • Gastric mucus cells secrete bicarbonate and mucus to buffer gastric acid
  • A thick mucus layer prevents bacterial attachment
  • Prostaglandin E2 stimulates mucus secretion, inhibits acid secretion, and regulates blood flow; inhibited by NSAIDs
  • HCI kills most organisms
  • IgA prevents attachment

Gastric Dilation and Volvulus (GDV)

  • GDV is common in deep-chested dog breeds
  • Often linked to exercise following ingestion to large meals, water intake, and air
  • Spleen may twist
  • Compression of the caudal vena cava and portal vein leads to shock
  • This is a life-threatening emergency

Gastric Dilation-Volvulus (GDV) Details

  • Constriction of blood outflow and decreased venous return
  • Increases intra-abdominal pressure
  • Reduced perfusion of intra-abdominal organs
  • Pressure on diaphragm makes respiration compromised
  • Reduced cardiac output and circulatory shock
  • In volvulus, the stomach rotates 180-270 degrees clockwise on its mesenteric axis
  • Obstruction of both the esophagus (which affects eructation and vomiting) and the pylorus (affecting outflow) leads to hypovolemic shock, cell hypoxia, and poor tissue perfusion

Pathogenesis of GDV

  • Dilation involves gas or fluid accumulation from bacterial fermentation, aerophagia, or gastric secretions. Obstruction affects eructation, vomiting, and outflow, leading to hypovolemic shock, cell hypoxia, and poor tissue perfusion.

GDV Risk Factors and Potential Sequelae

  • High-risk breeds are typically giant, deep-chested dogs: Great Dane, German Shepherd, Weimaraner, St. Bernard, Standard Poodle
  • Splenic displacement causes compression of the caudal vena cava and portal vein which obstructs venous return to the heart, causing blood to pool in other organs
  • Gastrointestinal outflow obstruction leads to fluid loss
  • Can result in portal hypertension, GI tract ischemia, hypovolemia, and systemic hypotension
  • Distended stomach can cause venous infarction, bacterial proliferation, and endotoxemia and fluid loss into the lumen

Gastric Dilation and Rupture in Horses

  • Primary gastric dilation and rupture results from excess fermentable carbohydrates via over grain consumption in excess
  • Secondary gastric dilation results from obstruction of the small bowel or of colic with ileus
  • Rupture can occur post-mortem from gas production, but antemortem ruptures feature hyperemia and edema at the margins.

Gastroduodenal Ulcerations

  • Caused by increased acid secretion and/or loss of mucosal integrity
  • Result in vomiting, pain, weight loss, salivation, bruxism, anorexia, hematemesis, melena, and anemia
  • Erosion is a partial loss of the mucosa and is not transmural
  • Ulcer is where the pathogen has moved through the muscularis to submucousal layers
  • Perforation is where it is transmural

Gastric Ulcers in Small Animals

  • Local disturbances or trauma to the mucosal epithelial barrier can cause damage
  • NSAIDs and corticosteroids causes epithelial damage
  • Decreased bicarbonate and mucus production
  • Elevated acid secretion caused by increased serum gastrin or histamine levels
  • Liver disease
  • Histamine into the blood binds to receptors on parietal cells and increasing HCL secretion.

Gastric Ulcers in Pigs

  • Result from finely ground feed
  • Pars esophagia area is where they form
  • Often fatal because Perforation, hemoabdomen and acute death are common

Gastric Ulcers in Horses

  • Very common
  • Ulcers can appear in margo plicatus
  • High performance, intensive management, and blister beetles
  • Ulcers in pars glandularis are less common
  • especially with NSAIDs
  • Can be associated with stress via recent transportation

Abomasal Ulcers in Cattle

  • Very common in feedlot cattle, in dairy associated with lactic acidosis
  • Associated with stress - weaning, transport
  • Most common in the pyloric region
  • Can be asymptomatic or lead to perforation and acute death

Gastritis

  • Gastritis is the inflammation of the stomach in general
  • Causes include uremic gastritis, mechanical gastritis from foreign bodies, and infectious gastritis
  • Infectious gastritis can be bacterial (Braxy), parasitic, or viral, but viral is rare

Uremic Gastritis

  • Mostly in dogs with severe kidney disease
  • Uremia damages blood vessels that induces vasculitis
  • The mucosal hyperemia, erosions, hemorrhage, and thickening of the stomach wall occur due to edema and calcium deposits
  • Diagnosed via thickening of the mucosa due to edema and mineral deposits.

Parasitic Gastritis

  • Gasterophilus bots can cause parasitic gastritis
  • These are a common finding in stomachs of horses, usually incidental

Gastric Neoplasia

  • There are is general 3 types: Epithelial, Mesenchymal and Round cell

Epithelial Neoplasia

  • Hyperplastic polyp/Adenoma
  • Adenocarcinoma (dogs > cats)
  • Squamous cell carcinoma (horses)

Mesenchymal Neoplasia

  • Leiomyoma/Leiomyosarcoma (dogs > cats)
  • Gastrointestinal stromal tumors (GIST) (dog > horses > cats)

Round Cell Neoplasia

  • Lymphoma (cats > cattle > horses > dogs)

Gastric Polyps/Adenomatous Polyps

  • Most common in pylorus of dogs
  • Exophytic and pedunculated benign nodules/masses
  • Can cause obstruction of the pylorus but usually is incidental

Gastric Adenocarcinoma

  • Most prevalent in dogs, rare otherwise
  • Its ulcerative, aggressive, and can be fibrotic
  • Locally aggressive, metastasize
  • Causes bleeding, anemia and melena

Squamous Cell Carcinoma

  • Most common gastric tumor in horses but still rare
  • Pars esophagea is non-glandular

Lymphoma

  • Most common gastric neoplasm in cats
  • Common in cattle with Bovine Leukemia Virus (retrovirus)
  • Causes multicentric tumors
  • Also causes lymphoma in heart, kidney, epidural space, retrobulbar
  • Relative diffuse, soft tan/white, homogenous thickening +/- nodules
  • Lymphoma is a sheet of lymphocytes

Gastrointestinal Stromal Tumor (GIST) and Leiomyosarcoma

  • GIST originates from interstitial cells of Cajal within the tunica muscularis
  • Leiomyosarcomas originate from smooth muscle fibers
  • Leiomyomas are benign as well and can be frequent
  • Both GIST and leiomyosarcoma can cause obstruction
  • Leiomyosarcomas do not metastasize
  • GIST metastasize more often

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