PATHOLOGY - Pancreatic Disease Flashcards
(69 cards)
Describe the anatomy of the exocrine pancreas
The pancreas consists of a central body with a right and left limb. The functional units of the exocrine portion of the pancreas consist of acini which contain acinar cells, and the pancreatic ducts which are lined with pancreatic duct cells
Describe the anatomy of the pancreatic ducts in the dog
The dog has a pancreatic duct and an accessory duct. The pancreatic duct is the smaller of the two and drains into the major duonenal papilla and the accessory duct drains into the minor duodenal papilla, both distal to the entry of the common bile duct
Describe the anatomy of the pancreatic duct in the cat
The cat has a singular pancreatic duct which merges with the common bile duct before entering the duodenum at the major duodenal papilla
What are the functions of the exocrine pancreas?
Production and secretion of pancreatic enzymes
Production and secretion of bicarbonate
Production and secretion of intrinsic factor involved in vitamin B12 (cobalamin) absorption
Production and secretion of antibacterial proteins
Which cells produce and secrete pancreatic enzymes?
Acinar cells
Which pancreatic enzymes are produced by the acinar cells?
Proteolytic zymogens (inactive precursors)
Amylase
Lipase
Which cells produce and secrete bicarbonate?
Pancreatic duct cells
What stimulates the production and secretion of bicarbonate by the pancreatic duct cells?
The pancreatic duct cells produce and secrete bicarbonate in response to secretin which is produced by the duodenum. The bicarbonate is secreted into the duodenum where it neutralises the acidic ingesta which has travelled from the stomach
What are the pancreas’ defence mechanisms against autodigestion?
- Proteolytic enzymes are synthesised as zymogens (inactive precursors)
- Zymogens are packaged into granules and released from the acinar cells via exocytosis
- Pancreatic secretory trypsin inhibitors are packaged into the zymogen granules to prevent premature activation of trypsinogen into trypsin
- Lipase and amylase are packaged within lysosomes to seperate them from the zymogen granules
What are the systemic defence mechanisms agaisnt the release of pancreatic enzymes into the bloodstream?
The plasma contains systemic anti-proteases which scavange any free pancreatic enzymes released into the circulation
Describe the pathophysiolgy of acute pancreatitis
Acute pancreatitis is described as acute pancreatic necrosis in pathology
Lysosomes containing amylase and lipase fuse with the zymogen granules, forming vacuoles. The enzymes within the lysosomes activate trypsinogen into trypsin and the vacuoles will rupture, releasing the trypsin into the acinar cells where they will activate other zymogens and cause pancreatic necrosis and autodigestion. Inflammatory mediators and cytokines will cause inflammation and exacerbate the necrosis. Systemically, the plasma anti-proteases will become overwhelmed resulting in systemic inflammatory response syndrome (SIRS) which can progress to disseminated intravascular coagulation (DIC)
What are the risk factors for acute pancreatitis in dogs?
Middle aged to old
Female
Breed
Obesity/hyperlipidaemia
Quantity and quality of dietary lipids
Drugs
Hyperadrenocorticism (Cushing’s disease)
Hypothyroidism
Hypercalcaemia
Underlying neoplasia
Which dog breeds are at increased risk of acute pancreatitis?
Yorkshire Terrier
Silky Terrier
Minature Schnauzer
Minature Poodle
Cocker Spaniel
Give an example of a drug which increases the risk of acute pancreatitis in dogs
Potassium bromide
What are the risk factors for acute pancreatitis in cats?
Abdominal trauma
Acute hypercalcaemia
Ductul reflux of duodenal contents
Organophosphate poisoning
What are the clinical signs of acute pancreatitis?
Anorexia
Vomiting
Diarrhoea
Abdominal pain
Lethargy
Dehydration
Pyrexia
Jaundice
(T/F) Patients with acute pancreatitis are more likely to present with diarrhoea than vomiting
FALSE. Patients with acute pancreatitis are more likely to present with vomiting than diarrhoea, so if a patient has diarrhoea with no vomiting, this should put pancreatitis lower on your differential diagnoses list
Why do cats more commonly present with jaundice due to acute pancreatitis than dogs?
Cats more commonly present with jaundice due to acute pancreatitis than dogs as the feline pancreatic duct merges with the common bile duct, so inflammation and necrosis of the pancreas can cause post-hepatic jaundice
How can you diagnose acute pancreatitis?
Assess history, signalement and clinical signs
Haematology
Biochemistry
Serum lipase and amylase
Trypsin-like immunoreactivity (TLI)
Pancreatic specfic lipase (PLI)
Diagnostic imaging
Pancreatic biopsy
What changes on haematology can indicate acute pancreatitis?
Inflammatory leukogram
What are the characteristics of an inflammatory leukogram?
Leukocytosis
Neutrophilia
± Left shift
What changes on biochemistry can indicate acute pancreatitis?
Increased liver enzymes (ALP and GGT tend to increase more than ALT and AST)
Hyperbilirubinaemia
Hypocalcaemia
Azotaemia (due to dehydration)
Electrolyte disturbances (due to clinical signs, i.e. vomiting)
Why does acute pancreatitis cause hypocalcaemia?
Acute pancreatitis can cause fat saponification as lipase is released which will break down the mesenteric fat surrounding the pancreas into fatty acids which can bind to calcium, reducing the free calcium in the bloodstream resulting in hypocalcaemia
What changes in serum amylase and lipase can indicate acute pancreatitis?
Increased serum amylase and lipase can indicate acute pancreatitis
If amylase and lipase are not increased, this reduces the likelyhood of acute pancreatitis