Diseases of the peritoneum and intestines Flashcards
Where is the normal route of lymphatic drainage?
Right ventral diaphragm - through small holes channels that eventually anastamose with thoracic duct
What do mesothelial cells produce?
A polysaccharide that acts as low-viscosity lubricant
What are four potential responses of mesothelial cells to irritation?
- Hypertrophy, hyperplasia, metaplasia > cuboidal columnar shape
- Produce plasminogen activator
- Phagocytosis
- Slough, releasing inflammatory mediators and increasing local vascular permeability and neutrophil chemotaxis
What does the plasminogen activator mesothelial cells produce do?
Converts plasminogen> plasmin, which lyses any leaked fibrin to protect against adhesion formation
If the source of irritation is not cleared and mesothelial cells slough into the peritoneal cavity, what events occur past 3-4 days?
- Granulation tissue forms across opposed surfaces
- More mesothelial cells differentiate from sub-serosal mesenchyme to repair the peritoneal surface
1 + 2 = adhesion formation
What are two factors that favor adhesion formation?
- Sepsis
- Presence of foreign material
- Hypoxia
Define internal hernia
Displacement of viscera through a normal of abnormal hole within the peritoneal cavity without the formation of a hernial sac (rare_
Define external hernia
Herniation of viscera within a sac past the boundary of the abdominal wall
What does an external hernia consist of?
Hernial sac + herniated viscera + hernial ring
Give two examples of internal hernias
- Herniation through epiploic foramen
2. Herniation through hole in omentum or mesentery
What compound can be responsible for blue-black discolouration of tissue post mortem?
Sulphmethaemoglobin
What sort of hernia could pregnancy predispose to?
Ventral abdominal hernia
What sort of hernia might patent umbilical ring predispose to? What is the usual consequence?
Umbilical hernia
Usually fine as hernial ring is wide enough
Why do inguinal hernias occur?
Because the deep inguinal ring remains patent in adult males following the descent of the testes
What is an indirect inguinal hernia?
Herniation of viscera through the deep inguinal ring into the inguinal canal
May evolve into scrotal hernia if continues past vaginal ring
What is a direct inguinal hernia?
Viscera pass subcutaneously outside the inguinal canal and sit in the submucosa. More prone to strangulation
What is the most common type of diaphragmatic hernia? Which part of the diaphragm usually tears in small animals compared to horses?
Acquired pleuroperitoneal diaphragmatic hernia usually due to trauma
Muscular part is more usual in small animals
Tendinous part more usual in horses
What are five potential consequences of abdominal trauma?
- Septic peritonitis due to perforation of GIT
- Bruising or laceration of viscera
- Rupture of hollow organs
- Herniation of viscera
- Leakage of blood, urine, bile, inflammatory exudate into abdominal cavity
What is a common parasite that encysts in the peritoneal cavity of sheep?
Cysticercus - taenid tapeworm
Define ascites
Accumulation of excess non-inflammatory fluid in peritoneal cavity (transudate or modified transudate)
What are the two major mechanisms for ascites to develop?
- Obstruction of peritoneal fluid drainage e.g neoplasm at RV diaphragm or sternal lymph nodes
- Overproduction of peritoneal fluid e.g increased permeability of blood vessels due to endotoxaemia or renal failure, hypoalbuminaemia, increased hydrostatic pressure as in R sided CHF or cirrhosis
Name four pathologies that can result in peritonitis.
- Uroperitoneum
- Bile in thorax > septic peritonitis due to detergent action
- Intraperitoneal injection of medication including antibiotics
- Pancreatic necrosis
What is a chylothorax?
Chylous ascites due to leakage of chyle from ruptured lymphatic channel > mild granulomatous peritonitis
Describe how FIP infection causes peritoneal effusion.
- Viral ag-ab complexes are phagocytosed by macrophages and deposited into walls of blood vessels
- Complement is activation, neutrophils emigrate and local inflammation increases blood vessel permeability
- Peritoneal and pleural effusion with high protein
What are the four types of fat necrosis ?
- Enzymatic fat necrosis - pancreatitis
- Focal or multifocal fat necrosis - obesity
- Yellow fat disease - lots of polyunsaturated fats and low vitamin E in diet > ROS damage and ceroid lipofuschin accumulation
- Massive fat necrosis in cattle