Pathology Of The Liver And Pancreas Flashcards
List the key functions of the liver
Protein synthesis - clotting factors and albumin
Metabolism - detoxification (e.g. ammonia)
Excretion and digestion - bilirubin and bile
Nutrition - regulation of fat and carbs
Describe the normal level of oxygen of the liver.
Poorly oxygenated
Describe the blood supply to the liver
75% from Portal vein (w/ nutrients)
25% from Hepatic artery (w/ oxygen)
Describe a liver lobule
2mm diameter
Hexagonal
Bounded by several portal tracts - portal vein, hepatic artery, bile duct
Describe the flow of blood in the liver
From branch of portal vein and branch of hepatic artery on periphery of lobule
Mix on way to central vein
Blood moves from outside of lobules into the centre
Describe the flow of bile in the liver lobule
Bile is produced in canaliculi
Flows in the opposite direction to blood in the bile ducts
What are the three hepatic zones?
- Periportal (centroacinar)
- AROUND THE OUTSIDE - Midzonal
- middle - Centrilobular (periacinar)
- IN THE MIDDLE
What hepatic zone is where most injuries occur?
Centrilobular (periacinar)
Which zone is most poorly oxygenated and is most affected by ischaemia?
Centrilobular
Which zone has the highest P450 cytochromes?
Centrilobular
Describe the histology of the portal vein.
Big, thin walled
Describe the histology of the hepatic artery
Smaller, thicker wall
Describe the epithelial lining of the bile duct
Tall, cuboidal columnar epithelium
Describe the shunt observed in a congenital PSS.
Usually single
To vena cava, azygous vein, renal vein
Describe the shunt observed in an acquired PSS.
multiple thin-walled shunts
How can an acquired shunt occur?
Secondary to fibrosis in older animals
How can a PSS affect the liver?
Causes atrophy
What other effect can a PSS have?
HE
Ammonia - neurotoxic
What congenital/developmental disorders can affect the liver?
Congenital cysts Displacements Tension lipidosis Capsular fibrosis - fibrous tags (e.g. equine liver capsule) Telangiectasis - focal sinusoidal Melanosis
INCIDENTAL LESIONS
Define telangiectasis
Dilation of the capillaries causing them to appear as small red or purple clusters, often spidery in appearance
Seen on the skin or the surface of an organ
How can you tell if a liver is enlarged?
Rounded edges
Cutting through might tell you why e.g. if congested
What can cause a vacuolar hepatopathy?
Anything with swelling and vacuolation of the hepatocytes.
Water- hydropic, Fat - lipidosis, glycogen - glycogenosis
Describe the typical distribution seen with a vacuolar hepatopathy
Usually zonal or diffuse
Describe the features of hydropic change.
Common
Non specific
Reversible
What can cause vacuolar hepatopathy?
Hypoxia
mild toxic damage
Metabolic stress
What can cause glycogenosis?
Hyperadrenocorticism
Steroids
What dietary factors can result in lipidosis?
Obesity
Starvation
What physiological factors can cause lipidosis?
Increased energy demand e.g. lactation and pregnancy
What diseases can cause hepatic lipidosis?
Diabetes mellitus
Ketosis
Pregnancy toxaemia
How can abnormal hepatocyte function result in lipidosis?
Decreased FA complexing
Decreases LDLs
Describe the appearance of a liver with amyloidosis
Pale orange
Friable
Describe the histology of a liver with amyloidosis
Homogenous acidophilus material
Special stain - Congo red - fluorescence (green birefringence)
What animals are predisposed to hepatic amyloidosis?
Abyssinian/ oriental cats
What can cause amyloidosis?
Primary or secondary liver disease
Endocrinopathy
What can cause centrilobular necrosis?
Ischaemia/anaemia
Metabolic/toxic damage
What would a zonal necrosis pattern suggest?
Ischaemia,
Toxic damage
What would a random pattern of necrosis suggest?
Viral/ bacterial
What does a focally extensive pattern of necrosis indicate?
Bacterial cause
What does massive necrosis indicate?
Severe injury/ toxicity
E.g. hepatosis dietetics
What is hepatosis dietetica?
What species does it typically affect?
Selenium/vitamin E deficiency
Presentation: sudden death
PM - large areas of hepatic necrosis and haemorrhage
- gall bladder oedematous
PIGS - young - 3/4 months
What does ascites indicate about oncotic pressure?
REDUCED
When is cirrhosis seen?
End stage liver disease
How can RCHF affect the liver?
Passive venous congestion
Describe the gross pathology associated with passive venous congestion.
Enlarged,
Rounded edges,
Blood from cut surface
NUTMEG LIVER - enhanced lobular pattern
Describe the histology associated with passive venous congestion.
Hepatic venules and sinusoids congested
Centrilobular atrophic hepatocytes (DARK RED)
Periportal lipidosis (pale red)
What is cholangitis?
Inflammation of the bile ducts
Can be immune mediated or associated with infection
What species is associated with immune mediated cholangitis ?
Cats
What affect on the liver can salmonellosis in calves have?
Cholangitis
What broadly occurs in acute hepatitis?
Necrosis followed by inflammation
If the animal survives, what progression follows from acute hepatitis?
- Complete resolution by regeneration
- Repair by fibrosis and scarring
- Encapsulation by abscessation
- Persistence by granulomatous disease
What can cause viral hepatitis?
What animals are these seen in?
Adenoviruses
Herpesviruses
FIP
Young, unvaccinated animals
What does adenovirus cause in dogs?
Canine infectious hepatitis
What herpesvirus is associated with abortions in horses?
EHV-1
What (herpes)viral conditions are associated with abortions in cows, cats and pigs?
Infectious bovine rhinotracheitis
Feline viral rhinotracheitis
Aujeszky’s disease
What liver lesions would you expect to see in an aborted foetus from a herpes virus infection?
Pinpoint foci of necrosis
Intranuclear inclusions
Necrosis also seen in lungs, kidneys, spleen, adrenals
What are the routes of infection with bacterial hepatitis?
Direct extension from adjacent tissues
Haematogenous spread
Abscessation
What are the sources of haematogenous bacteria?
Portal vein from alimentary tract
Hepatic artery - if a bacteraemia
Umbillicus/umbilical vein
What animals tend to get liver abscesses?
Cows
What is the source of most liver abscesses in cows?
Umbilical infections (usually mixed bacteria)
From grain overfeeding - rumenitis
What can cause a bacterial hepatitis?
Fusobacterium necrophorum Clostridium novyi B Clostridium haemolyticum Clostridium piliformis Leptospirosis Salmonellosis Listeria
What causes Tyzzer’s disease?
What animals are particularly susceptible?
Clostridium pilformis
Mice (+rats, gerbils)(rodents)
Foals - 1-4 weeks old
Immunosuppressed dogs and cats
What causes bacilliary haemoglobinuria?
Clostridiumhaemolyticum
What causes bacillary necrosis?
Fusobacterium necrophorum
What causes Black disease (Infectious, necrotic hepatitis)?
Clostridium novyi type B
What is the source of fusobacterium necrophorum in bacillary necrosis:
- in neonates?
- in adults?
Neonates - UMBILICAL
Adults - RUMENITIS
Describe the gross pathology associated with fusobacterium necrophorum.
Multiple pale foci of necrosis throughout the liver
May develop into abscesses if the animal survives
What is seen on microscopy with bacillary necrosis?
Coagulation necrosis with bacteria at periphery
What animals tend to get black disease?
Sheep
Rarely horses and pigs
What precipitates Clostridium novyi B?
LIVER FLUKES
What clinical presentation is associated with clostridium novyi B infection ?
SUDDEN DEATH
What pathology is associated with black disease?
Extensive subcutaneous venous congestion and oedema
Fibrinous peritoneal, thoracic and pericardial fluid
Pale foci of liver necrosis (containing bacteria) surrounded by a rim of haemorrhage
What species get bacillary haemaglobinuria?
Cattle and sheep
What clinical sign is associated with bacillary haemaglobinuria?
Haemaglobin in urine - ‘red water’
Severe anaemia
Jaundice
What can be seen on PM with bacillary haemaglobinuria?
Focally extensive hepatic necrosis
Haemaglobin staining of kidneys
Describe the lesions seen in tyzzer’s disease
Liver filled with nodules of necrosis
Describe the histology of tyzzer’s
Wheat sheaf appearance of colonies with special stain
What infections tend to cause focally extensive/ abscessating lesions?
Bacteria
What clinical signs are associated with salmonellosis in calves?
Fever, dehydration, diarrhoea
Haemorrhagic ileitis
Pale pinpoint foci of necrosis in liver
Necrosis and mixed mononuclear cells
How can the nodules in the liver of a calf with salmonellosis be described?
Paratyphoid nodules
Which parasites of the liver are NOT incidental?
FLUKE
What causes ‘milk spot liver’ ?
Ascaris Suum
What causes fibrous tags on horse liver?
Strongyle migration
tags seen on liver surface and diaphragm
How does acute liver intoxication occur?
HAEMORRHAGE occurs ->
Increased consumption and decreased synthesis of clotting factors by damaged liver - Jaundice
E.g. blue-green algae, iron and cresols
How does chronic liver intoxication occur?
Continual low dose toxic compounds
Regeneration and repair - fibrosis and biliary hyperplasia
E.g. ragwort, aflatoxins (produced by moulds), copper
Drugs: primidone, sulphonamides, paracetamol (CATS)
What drugs can cause chronic liver intoxication?
Primidone - phenobarb analogue (anticonvulsant)
Paracetamol (CATS)
Sulphonamides
What infectious conditions cause cholecystitis (Gall bladder + extrahepatic bile duct)?
SALMONELLA
INFECTIOUS CANINE HEPATITIS
What can occur if the gall bladder /extrahepatic duct ruptures ?
BILE PERITONITIS
What would make you suspect that a liver nodule is an incidental finding?
If they look the same as the rest of the liver
In what animals is nodular hyperplasia common?
Older dogs
How do the cells appear in nodular hyperplasia?
Cells are larger. Contain more glycogen
Which animals tend to get liver neoplasms?
Dogs and cats
What primary tumours of hepatocytes can occur?
Hepatoma / hepatocellular carcinoma
What is the most common neoplasm of the biliary epithelium?
Cholangiocellular carcinoma
Describe the typical appearance of a cholangiocellular carcinoma.
White, firm and umbilicate (depression in the middle)
What hepatic neoplasm can be primary or metastatic?
Haemangiosarcoma
Where are primary haemangiosarcoma usually found?
Spleen
Right auricle
What tumours tend to metastasise to the liver?
Melanoma
Carcinoma
Sarcoma
Lymphoma
What breeds are predisposed to haemangiosarcoma?
Large dogs
What animals tend to get pancreatic hypoplasia?
GSDs
Calves
When do clinical signs of pancreatic hypoplasia tend to be seen?
Around a year old
What clinical signs are associated with pancreatic hypoplasia?
Diarrhoea + steatorrhaea
Loss of condition despite polyphagia
Pot bellied
Lack of abdominal fat
Define the term : steatorrhoea
Abnormally high levels of fat in faeces
What type of pancreatic neoplasia is most common?
Carcinoma
Describe a pancreatic carcinoma
Highly invasive Infiltrative with mets to: -liver -abdominal LNs - spleen - adrenals
How does chronic pancreatitis occur in dogs?
Acute pancreatitis
Replacement fibrosis and atrophy
EPI - steatorrhoea and loss of condition
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