GI - lower tract pathology Flashcards
What is the stomach wall called? What are the layers of the stomach wall?
Mucosa
Made up of the
Epithelium
Lamina propria
Muscularis mucosa
What cell secretes hydrochloric acid in the stomach?
Parietal cells
What cell secretes pepsin in the stomach?
Chief cells
(Chiefffff drinking Pepsi heheh)
What causes dilation of the stomach in horses?
Overconsumption of food
Ingesting large amounts of water
Secondary to GI obstruction, ilius, dysautomonia
What can gastric dilation lead to in horses?
Gastric rupture
What causes dilation and volvulus in dogs?
Cause not completely understood
Gastric distention, overfeeding, exercise after feeding
How does the stomach usually rotate during dilation and volvulus?
Usually clockwise (viewing from behind) from 180 to 360 degrees
How does the stomach change shape during dilation and volvulus?
Pylorus moves upwards and to opposite side, twisting oesophagus and SI over it
What are the potential consequences of GDV?
Gastric infarction
Gastric rupture
Circulatory shock - reduced venous return from portal vein and caudal vena cava
Cardiac arrhythmias
Death
What can cause stomach obstruction?
Displacements and volvulus
Foreign bodies
Impaction
Pyloric stenosis
What can cause pyloric stenosis?
Congenital - benign muscular pyloric hypertrophy
Secondary to neoplasia, inflammation, FBs
What can be associated with gastric ulceration?
Stress
Diet
NSAIDs
Neoplasia
Hypoxia
What are the features of gastric inflammation?
Hyperaemia
Thickening
Necrosis/erosion/ulceration
Haemorrhage
Fibrosis
What are the 4 different types of inflammatory cell infiltrate?
Lymphoplasmacytic
Eosinophilic
Neutrophilic
Granulomatous
What paraneoplastic effect increases acid secretion in the stomach?
Histamine release from mast cell tumours
What drugs cause decreased mucosal protection? How?
NSAIDs - inhibit prostaglandin production so less bicarbonate
What factors cause decreased mucosal protection?
Stress
Mucosal trauma
Ischaemia
What features do stomach neoplasms tend to have?
Are uncommon
Tend to be malignant
What is the most common gastric tumour in dogs?
Adenocarcinoma
What is the most common gastric tumour in cats?
Lymphoma
What is the most common gastric tumour in horses?
Squamous cell carcinoma
What do gastric adenocarcinomas look like?
Ulcerated craters or diffuse thickening in the gastric wall
What are the two types of functional obstruction of the intestines?
Paralytic ilius
Dysautonomia
What is paralytic ilius?
Inhibition of peristalsis secondary to otehr conditions - neurological feedback stops
What is dysautonomia?
Altered intestinal motility
What is an example of dysautonomia?
Grass sickness in horses
What causes functional obstruction in the colon?
Colonic inertia
What causes megacolon?
Conditions causing colonic hypomotility
What are the 3 different types of colonic inertia?
Idiopathic - old cats
Secondary to neuro disease
Secondary to prolonged colonic distention
What else can cause colonic obstruction other than colonic inerta?
Outlet obstruction - mechanical/physical
eg. , FBs, mass, pelvic fracture malunion, stricture
What problem would string cause if ingested?
Linear foreign body - causing intestinal obstruction by pleating/plication
What is it called when an animal is born without an anus?
Atresia - congenital occlusion
What mass can cause intestinal obstruction by strangulation?
Strangulating lipoma - pedunculated
How can septic peritonitis be caused without intestinal perforation?
Strangulation - ischaemia from mesenteric veins causes effusion of necrotic tissue fluid and blood into intestinal lumen
Anaerobes proliferation producing gas and toxins
What are the 4 types of intestinal displacement?
Hernia
Entrapment
Volvulus and torsion
Intussusception
What are the different kinds of hernia?
Umbilical
Diaphragmatic
Inguinal
Through natural or acquired foramina
What are the potential complications of hernias?
Intestinal obstruction
Intestinal strangulation
Incarceration - cant be returned through the hole
What species are prone to intestinal entrapment? What do they get?
Horses - gastrosplenic ligament entrapment (hole in ligament)
What is the definition of a volvulus?
Twisting of the intestine on its mesenteric axis (twisting around in half)
What is the definition of a torsion?
Twisting of a tubular organ along its long axis (wringing a sock)
What is insussusception?
When part of the intestine folds inside itself
What are the terms for which bit goes where in an intussusception?
The interssisceptum telescopes into the intessuscipiens
What are the consequences of an intussusception?
Partial/complete intestinal obstruction
Congestion, oedema, haemorrhage, necrosis etc.
What is the definition of diarrhoea?
Excess water relative to the proportion of dry matter within the faeces
What are the 4 mechanisms of diarrhoea?
Malabsorptive (osmotic)
Hypersecretory
Increased permeability/effusion
Altered motility
What most commonly causes malabsorptive diarrhoea?
Villus atrophy - reduces SA for absorption
What are some examples of causes of villus atrophy?
Attaching and effacing e coli
Rotavirus/parvovirus/coronavirus
What can cause hypersecretory diarrhoea?
Pathogens producing toxins that stimulate increased secretion
Endogenous substances - histamine, prostinoids (inflammation)
What can cause increased permeability/effusion diarrhoea?
Damage to mucosal integrity
Vascular damage
Inflammation
Hypoproteinaemia
What happens in increased permeability/effusion diarrhoea?
Conditions cause effusion of fluid and solutes/proteins from the mucosa into the intestinal lumen
How does inflammation cause an increased permeability/effusion diarrhoea?
Increased hydrostatic pressure
Impairs lipid drainage
How does vascular damage cause an increased permeability/effusion diarrhoea?
Leakage of plasma components into lumen
Or haemorrhage
How does damage to the mucosal integrity cause an increased permeability/effusion diarrhoea?
Altered tight junction increases permeability
How does altered motility cause diarrhoea?
Hypermotility and decreased gut transit time reduces ability to absorb water and digest nutrients
Where doe parvovirus infect to cause diarrhoea?
Enterocytes in crypts - cant renew epithelial layer of villi so they collapse
What disease can cause impaired lymphatic drainage so cause an increased permeability/effusion diarrhoea?
Lymphangiectasia
What is lymphangiectasia?
Obstruction of the lymphatics in the intestines
What are the consequences of lymphangectasia?
Dilation of lacteals (villi)
Malabsorption
Protein losing enteropathy
Lipogranulomatous lymphangitis - creamy nodular foci
What can cause lymphangectasia?
Mucosal inflammatory cell infiltrates
Intestinal neoplasia
Mesenteric lymph node disease
What is the name for inflammation of the rectal mucosa?
Proctitis
How is inflammatory bowel disease diagnosed?
Diagnosis by exclusion - idiopathic disease
What are the clinical signs/pathogenic changes of inflammatory bowel disease?
Clinical signs consistent with malabsorption or plasma loss from the gut wall
What are the most common intestinal tumours?
Adenocarcinoma - dogs
Lymphoma - cats
(same as in stomach)
What does adenocarcinoma of the intestine look like?
Annular thickening ofthe wall
Intraluminal mass protruding from the wall
Fibrosis and stenosis
What does lymphoma of the intestines look like?
Localised/diffuse
Cobblestone or granular appearance
Lymph node involvement
What cells line the peritoneal cavity?
Mesothelial cells
What are some potential consequences of peritonitis?
Paralytic ileus
Exudate
CV system affected - shock, death
Fibrinous adhesions - impaired motility
What is a tumour of the peritoneum?
Mesothelioma - of the mesothelium
What tumours can be retroperitoneal tissue tumours?
Lipomas
