Pathology of Alimentary Tract 2 (Ruminant Forestomachs/ Glandular stomach)

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Doctorate Pathology (Systems Pathology) Mind Map on Pathology of Alimentary Tract 2 (Ruminant Forestomachs/ Glandular stomach), created by melian.yates on 12/05/2013.

Created by melian.yates over 5 years ago
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Pathology of Alimentary Tract 2 (Ruminant Forestomachs/ Glandular stomach)
1 Ruminant Forestomachs
1.1 Forestomachs: Rumen, Reticulum, Omasum
1.2 Note: Postmortem putrfactive changes occur rapidly (Gas distension, Sloughing of mucosa)
1.3 Functional Disorders
1.3.1 Bloat (Ruminal Tympany) Failure to expel fermentation gases Pathogenesis: Primary: "Frothy bloat" Due to formation of stable foam in Rumen (follows ingestion of excess high protein lucerne/clover or high concentrate, low roughage diet Secondary: Mechanical/functional obstruction of oesophagus (oesophageal stricture) -> accumulation of gas Vagus indigestion (Traumatic reticuloperitonitis, liver abscess, chronic suppurative bronchopneumonia) Recurrent laryngeal nerve & Vagus nerve => Vagal function => Reduced Rumen Motility Neoplasia (Lymphoarcoma, Papillomas) Overdistension of Rumen & Reticulum with fermentative gases Increased intra-abdominal pressure Congestive heart failure Compression of diaphragm Resp. failure "Bloat line" cranial to thoracic inlet Reduced return of blood flow to heart Blood is dark (Hypoxic) & clots poorly Congestion, Oedema & subcutaneous haemorrhage of head & neck tissues
1.3.2 Runminal Acidosis (Grain overload) Ruminitis may develop => allow thromboemboli to travel to the Liver => Hepatic abcessation Histologically: Microvesicles containing mainly neutrophils occur in the epithelium of the rumen papillae May be focal erosions/ulcerations Damaged mucosa may be colonized by fungi (e.g. Mucor/Rhizopus/Absidia app.) or bacteria (e.g. Fusobacterium necrophorum)
1.4 Inflammation
1.4.1 Traumatic Reticulitis "Hardware disease" Ingestion of sharp objects (e.g. wire, nails) 1) Fall to floor or reticulum => Insignificant 2) Contractions force foreign body into wall of reticulum: => Mild suppurative or Granulomatous reticulitis +/- Peritonitis Localized => Adhesions 3) Foreign body penetrates Cranial wall (rumen contractions) : => Acute Peritonitis, Local Fibrous adhesions => Penetrates Diaphragm (Fibrinopurelent pleurisy, pneumonia, pericarditis) Fusobacterium, Actinomyces spp. Inflammatory process around Reticulum (may) => vagus indeigestion & ruminal stasis => Purulent fluid build up => Cardiac Failure
1.4.2 Ruminitis (Bacterial or Mycotic) Bacterial Lactic Acidosis Opportunistic pathogens (Take advantage of acidotic lesions & other disturbances of rumen flora) Mechanical Injury to Rumen Ex. Traumatic Reticuloperitinitis Damage to Rumen wall => Infiltration of bacteria (GI colonizers) Fusobacterium necrophorum, Trueperella pyogenes, Actinobacillus lignieresii Mycotic Abx, Lactic Acidosis Vascular invasion -> Thrombosis -> Infarction Haematogenous -> Placentitis -> Abortion Mucor/Rhizopus/Absidia Gross: Multiple, dark red areas of swollen paillae, Coagulative necrosis of papillae, Serofibrinous exudate Histologically: Coagulative necrosis of papillae, marked neutrophil infiltrate Thromboembolic spread => Form areas of coagulative necrosis & abscesses in Liver
1.5 Neoplasia
1.5.1 Papillomatosis Bovine papillomavirus type 4 Usually pedunculated structures in Reticulum/Rumen of Cattle
1.5.2 Squamous cell carcinoma Thought to develop from papillomas in Cattle in association with ingested carcinogens in Bracken Fern
2 Pathology of the Glandular Stomach & Abomasum
2.1 Physical Disturbances
2.1.1 Obstruction Foreign body Bones, stones, hair/wool balls (trichobezoars), plant material (phytobezoars) Pyloric Stenosis Dogs, Foals, Cats Congenital Hypertrophy of Pyloric muscle => Delayed Gastric emptying & persistent vomiting/regurgitation Acquired Following healed ulcers (foals) Functional Obstruction Dysautonomia Feline dysautonomia Equine Grass sickness Vagal indigestion (Cattle) End-stage liver disease (Equine) Horses DON'T vomit! Stomach will rupture before they vomit
2.1.2 Displacements of the stomach/abomasum Herniation of Stomach (through diaphragm) Congenital (Cats) Often associated w/ herniation of Liver Peritoneo-pericardial diaphragmatic hernia Acquired (Dogs, Cats) RTAs Displacement of GI tract into peritoneal cavity Abomasal Displacement (Cattle) Ventral & to left of Rumen (LDA) 85% of Displacements Partial obstruction of outflow Mild consequences: May not require surgery To right of Rumen (RDA) 15% of Displacements Acute dilation & volvulus Severe consequences: Usually require surgery Obstructs outflow from abomasum Normal location: Close to or just right of the ventral midline Constriction of blood vessels & trauma to vagus nerve resulting in abomasal distension w/ blood-stained fluid & gas, congested mucosa, infarction May rupture => Peritonitis, shock, death NOTE: Gastric rupture may be a PM event due to putrefactive gases (Look for evidence of haemorrhage & Peritonitis suggesting antemortem rupture Predisposing factors: Post-parturient Dairy Cows Change to grain concentrates in diet (Increased VFAs -> Affect motility) Hypocalcaemia (Abomasal atony)
2.2 Inflammation
2.2.1 Haemorrhagic/necrotizing Abomasitis Braxy Sheep/Cattle Acute abomastitis (Red, thickend, necrotic haemorrhagic mucosa Ingestion of frozen food in winter Devitalizes gastric mucosa Coagulative necrosis of mucosa & deeper structures w/ fibrin, oedema, haemorrhage & sometimes submucosal emphysema Clostridium septicum (Exotoxin)
2.2.2 Bacterial Gastritis & Gastric Ulceration Heliobacteriosis Dogs, Cats Helicobacter heilmannii, Helicobacter felis Chronic mucoid gastritis
2.2.3 Hypertrophic Gastritis/ Abomastitis Chronic hypertrophic gastritis (Dogs) Chronic retention of gastric fluid & bile reflux Marked mucosal thickening & convolution of rugae Histologically: Marked epithelial hyperplasia, loss of parietal/chief cells, dilation of mucous glands & mixed inflammatory cell infiltrates in lamina propria Parasitic Gastritis (Osteragiosis) Cattle: Ostertagia ostertagi Sheep: Teladorsagia circumcincta Acute Gastritis Hyperaemia & oedema Chronic Gastritis Nodules (encysted larvae) in abomasal mucosa, "Morocco leather" appearence Glandular hyperplasia, loss of parietal/chief cells, chronic inflammation associated w/ lymphocytes, plasma cells & eosinophils & larvae
2.2.4 Chronic Atrophic Gastritis (Dogs) Aetiology uncertain Mucosal thinning & loss of gastric glands, diffuse mixed inflammtory infiltrate in the lamina propria
2.3 Ulceration
2.3.1 Pathogenesis Hypersecretion of acid &/or impaired mucosal barrier => Mucosal barrier is disrupted -> Pepsin & acid cause Necrosis -> Erosion/ulcers (Erosion of underlying blood vessels -> Haemorrhage Causes: NSAIDs Corticosteroids (Stress) Viral infection (e.g. mucosal disease) Foreign bodies Intestinal obstruction (reflux of bile) Neoplasia Idiopathic (Local Trauma) (Local Ischaemia)
2.3.2 Dogs: NSAIDs, Mast cell tumor (Histamine => HCl hypersecretion), Pancreatic gastrinoma (Tumor derived from Islets -Pancreas -> Gastrin) Azotaemia, Cirrhosis, Bile reflux
2.3.3 Pigs (weaned growers & feeders): Finely ground grain concentrate diets - stratified squamous areas of stomach affected
2.3.4 Horses: Stress/ NSAIDs - stratified squamous epithelium at margo plicatus (adults & foals), glandular area (foals)
2.3.5 Cattle: Periparturient lactic acidosis, Abomasal impaction, displacement or torsion, Mucosal disease - Bleed & perforation
2.3.6 Heal by granulation & fibrosis or perforate
2.4 Neoplasia
2.4.1 Adenocarcinoma Malignancy of mucosal epithelium Most common gastric neoplasm in Small animals Locally aggressive & spreads via lymphatic vessels to lymph nodes, lung, liver Thickened, pale tissue, ulcerated of fungating
2.4.2 Squamous cell carcinoma Commonest gastric tumor in Horses Large cauliflower-like mass Metastases & transcoelomic spread
2.4.3 Leiomyoma/Leiomyosarcoma Smooth muscle neoplasms forming nodular masses Mainly Dogs
2.4.4 Lymphoma Diffuse infiltration of Neoplastic lymphocytes Dogs, Cats, Horses