Pathology of the liver and pacreas Flashcards
Portosystemic shunt
congenital or acquired
portal blood bypasses the liver
Portosystemic shunt - congenital
shunting into vena cava, azygos or renal vein
usually a single communication between the vessels
portosystemic shunt - acquired
shunts secondary to fibrosis in older animals
multiple thin-walled shunts
Congenital cysts
most are biliary
can be multiple
displacements
congenital or acquired
tension lipidosis
focal areas of subcapsular fatty change
may relate to local ischaemia
usually the tip where it touches the diaphram
capsular fibrosis
fibrous tags are common on the surface of the liver in older horses
telangiectasis
foci of sinusoidal dilatation
cats + cattle
Circulatory disorders - passive venous congestion - presentation
usually associated with right-sided heart failure acute or chronic
Circulatory disorders - passive venous congestion - gross pathology
liver enlarged with rounded borders and oozes blood on cut surface
enhanced lobular pattern (‘nutmeg liver’)
Circulatory disorders - passive venous congestion - microscopy
hepatic venules and sinusoids engorged
periacinar areas are congested with atrophy of hepatocytes (red colour)
periportal areas undergo fatty change (pale colour)
common pigments
melanin
haemosiderin
bile
liofuscin
vacuolar hepatopathies
degenerative
hydropic change is common, non-specific and reversible
glycogen accumulation (glycogenosis) occurs in
hyperadrenocorticalism
multifocal to diffuse swelling and vacuolation of hepatocytes
enlarged pale liver in severe cases
vacuolar hepatopathies - causes
hypoxia, mild toxic damage and metabolic stress
lipidosis - causes
dietary factors: obesity and starvation
incr energy demand
disease (e.g. diabetes mellitus, ketosis and pregnancy toxaemia)
abnormal hepatocyte function that prevents fatty acids
complexing with proteins to form low density lipoproteins
Abnormal deposits and accumulations - lysosomal storage diseases
inherited deficiencies of lysosomal enzymes – neuro disease
macrophages containing stored material accumulate at multiple sites (liver, lymph nodes, central nervous system)
diagnosed by liver biopsy or post mortem examination
Abnormal deposits and accumulations - amyloidosis
substance deposited under the endothelium + basement membranes of a variety of tissues - renal glomeruli, islets of Langerhans in the pancreas + liver
primary, secondary or endocrine-associated
amyloidosis - gross appearance
Liver pale, enlarged and friable – prone to rupture
amyloidosis - microscopic appearance
homogeneous acidophilic material that shows green birefringence when stained with Congo red
Necrosis of the liver - causes
ischaemia
toxic damage
nutritional deficiencies
microbial infection
necrosis - patterns
Random: e.g. EHV-1 or salmonellosis
Zonal: e.g. ischaemia or toxic damage
Massive: e.g. hepatosis dietetica
Fibrosis of the liver - Patterns of fibrosis
Periacinar fibrosis
Biliary fibrosis
Post-necrotic scarring
Cirrhosis
Periacinar fibrosis
fibrosis surrounds central vein
chronic passive congestion
Biliary fibrosis
accompanying inflammation
centred on the portal triads
Post-necrotic scarring
following massive necrosis
cirrhosis
extensive fibrotic lesions
end stage liver
may be concurrent nodular regeneration
hepatitis - define
Inflammation of the liver parenchyma
ften caused by infection
cholangitis - define
Inflammation of the bile ducts
may be immune-mediated or associated with infection (e.g. salmonellosis in calves)
cholangiohepatitis - define
Inflammation of parenchyma and bile ducts
progression of hepatitis
necrosis, succeeded by inflammation If the animal survives then progression is: Complete resolution by regeneration Repair by fibrosis and scarring Encapsulation by abscessation Persistence by granulomatous disease
viral hepatitis
Adenoviruses
Herpesviruses
Coronaviruses
generally occurs in young +/or unvaccinated
Infectious canine hepatitis
highly infectious disease of young dogs
long-term shedding in urine
tropism for endothelium (widespread haemorrhages, particularly on serosal surfaces) and hepatocytes
lymph nodes and tonsils enlarged and reddened, sometimes haemorrhagic
recovering animals may show an immune-mediated uveitis with corneal opacity
Herpesviruses cause which diseases
Equine Viral Rhinopneumonitis
Infectious Bovine Rhinotracheitis
Feline Viral Rhinopneumonitis
Aujezsky’s disease
herpesvirus infections
Liver lesions occur in aborted fetuses or neonates
pinpoint foci of necrosis with intranuclear inclusion bodies
Necrosis also occurs in lungs, kidneys, spleen and adrenal glands
Feline infectious peritonitis
Enteric coronavirus mutates to cause systemic vasculitis and effusions in cats
Pyogranulomatous lesions in multiple organs including the liver
‘wet’ (effusive) or ‘dry’ (granulomatous) forms
Bacterial hepatitis - Routes of infection - direct extension
from disease in adjacent tissues
Bacterial hepatitis - Routes of infection - haematogenous
via the umbilical vein from infected umbilicus
via the portal vein from the alimentary tract
via the hepatic artery in bacteraemias and septicaemias
Bacterial hepatitis - Routes of infection - hepatic abscessation
is particularly common in cattle
from umbilical infections - usually mixed bacteria
from rumenitis caused by overfeeding with grain
Bacillary necrosis - caused by which bacteria
Fusobacterium necrophorum
Bacillary necrosis - aetiology
Umbilical infection in calves
Rumenitis in adult cattle
Bacillary necrosis - gross pathology
Multiple pale foci of necrosis throughout the liver
may develop into abscesses if the animal survives
Bacillary necrosis - microscopy
coagulative necrosis with bacteria at periphery
Infectious necrotic hepatitis
aka black disease Sheep (rarely horses or pigs) Migrating immature liver flukes often precipitate disease Animals found dead Post-mortem changes occur rapidly
Infectious necrotic hepatitis - caused by which bacteria
Clostridium novyi type B
Infectious necrotic hepatitis - pathology
extensive subcutaneous venous congestion (‘Black disease’) and oedema
fibrinous peritoneal, thoracic + pericardial fluid
characteristic pale foci of necrosis (containing bacteria) surrounded by a rim of haemorrhage
Bacillary haemoglobinuria - caused by which bacteria
Clostridium haemolyticum
Bacillary haemoglobinuria
Cattle and sheep
closely related to C. novyi and the pathogenesis is similar to black disease
Bacillary haemoglobinuria - pathology
Severe anaemia, jaundice, haemoglobinuria
large necrotic focus in liver + haemoglobin staining of kidneys
tyzzers disease - caused by which bacteria
Clostridium piliforme
Bacillus piliformis
tyzzers disease
disease of laboratory rodents
may affect foals + immunosuppressed dogs and cats
initial intestinal lesions can be hard to find at post-mortem exam
‘wheat sheaf’’ appearance of colonies when stained with a silver stain
leptospirosis
zoonosis
hepatic disease in dogs
multiple serovars involved
haemolytic anaemia, widespread haemorrhages and icterus
hepatocyte dissociation (results in cholestasis) and haemosiderin accumulation (secondary to haemolysis)
salmonellosis - clinical features
fever, dehydration and diarrhoea
salmonellosis - gross pathology
severe, often haemorrhagic, inflammation in the ileum
pale foci of necrosis in the liver called ‘paratyphoid nodules
salmonellosis - microscopy
Foci of necrosis
Mixed mononuclear inflammatory cell infiltrate
parasites of the liver
usually incidental findings (excluding liver fluke)
ascaris suum migration- ‘milk spot’ liver
strongyle migration in the horse
common to find fibrous tags incidentally on the surface of the liver and adjacent diaphragm
remnants of fibrous repair following the egress of the parasites from the liver
toxic liver disease - acute intoxication
causes widespread haemorrhages in the body due to excessive consumption of the clotting factors in the damaged liver coupled with failure to produce these
factors by the damaged liver
Examples are blue-green algae, iron and cresols
toxic liver disease - chronic intoxication
continual ingestion of toxic compounds at low doses over a period of time
there will be evidence of regeneration and repair of the damaged tissue i.e. fibrosis and biliary hyperplasia
Examples are ragwort, aflatoxins and copper
Certain drugs are also hepatotoxic
pathology of the gall bladder
Inflammation (cholecystitis) occurs in Salmonellosis and Infectious Canine Hepatitis
Hyperplasia of the mucosa is a common reaction to any irritation of this area
Gallstones (choleliths) may be found as an incidental finding
pathology of biliary tree - obstruction
occurs due to parasites, sometimes gall stones (choleliths) - rare
compression of the ducts by nearby inflammatory and neoplastic processes - more common
pathology of biliary tree - rupture of bile duct
serious as omentum is incapable of sealing even the smallest leaks
chronic inflammatory process; if infected widespread peritonitis
Nodular hyperplasia - gross
spherical nodules in the liver
vary in colour from pale to dark or can be same colour as rest of the liver
nodular hyperplasia - micro
cells are larger, may contain more glycogen
portal areas still visible within the mass
compression of adjacent normal tissue
Neoplastic disease of the liver: primary tumours
Principally dogs and cats
from hepatocytes (hepatoma or hepatocellular carcinoma)
or biliary epithelium (most are cholangiocellular carcinomas)
Hepatocellular tumours may resemble normal parenchyma (with haemorrhage or necrosis in malignant tumours)
cholangiocellular carcinomas are often white, firm and umbilicate
Neoplastic disease of the liver: metastatic tumours - Haemangiosarcoma
can be primary or metastatic in the liver
other predilection sites are the spleen and right auricle of the heart
prevalent in large breeds
Neoplastic disease of the liver: metastatic tumours - secondary tumours
secondary metastatic involvement of the liver is very common: includes melanoma, carcinoma, sarcoma and lymphoma
Pancreatic hypoplasia
developmental abnormality
German shepherd dogs and calves
occurs at about one year of age
Pancreatic hypoplasia - clinical signs
steatorrhoea (fat in faeces) and diarrhoea
loss of condition despite polyphagia
pot-bellied
Pancreatic hypoplasia - pathology
intestines distended by bulky fatty ingesta
lack of fat in the mesentery and abdomen
sparse pink pancreatic tissue
microscopy reveals hypoplastic acini
Acute pancreatitis - clinical signs
shock and cardiovascular collapse
raised lipase and amylase levels
some cases subclinical
Acute pancreatitis - gross
chalk-like areas of fat necrosis with local reddening around the pancreas
a small amount of blood-tinged fluid in the abdomen with fatty globules
Acute pancreatitis - micro
haemorrhagic oedema and necrosis affecting pancreas and peripancreatic fat
Chronic pancreatitis
often follows acute pancreatitis - replacement fibrosis and atrophy
leads to exocrine pancreatic insufficiency (steatorrhoea and loss of condition)
may be subclinical in cats and horses
Pancreatic hyperplasia
Nodular hyperplasia is common in older dogs and (esp) cats - of no clinical significance
Pancreatic hyperplasia - gross
white lobules or plaques projecting from the surface
don’t distort adjacent tissue + aren’t encapsulated
Pancreatic hyperplasia - micro
similar to normal glandular tissue
Pancreatic neoplasia
Adenoma - extremely rare
Carcinoma -highly invasive and infiltrative with metastases to the liver, peritoneum, abdominal lymph nodes, spleen, adrenals
