What are the 3 hepatic zones?
PERIPROTAL/CENTROACINAR - around portal triads MIDZONAL
CENTRILOBULAR/PERIACINAR - bordering the hepatic venules
How wide is a classic lobule?
What is the origin of a PSS?
CONGENITAL - shunting into VC, azygous or renal vein. Usually a single communication between the vessels. ACQUIRED - shunts secondary to fibrosis in older animals, multiple thin-walled shunts (see image)
List some other congenital and develipmental disorders of the liver
-Congenital cysts -Displacements -Tension lipidosis -Capsular fibrosis -Telangiectasis
Where are congenital cysts found?
Biliary mainly in cats (also dogs and pigs), can be multiple
Example of a displacement
What is tension lipidosis?
focal areas of subcapsular fatty change (may relate to local ischaemia)
What is capuslar fibrosis?
fibrous tags are common on the surface of the liver in older horses (due to migrating parasites or foci of non-spetic peritonitis)
What is tealngiectasis?
foci of sinusoidal dilatation (cats and cattle)
This image shows capsular fatty change and telangiectasis.
What type of a disorder is passive venous congestion?
a circulatory disorder
Presentation - passive venous congestion?
acute or chronic usually associated with right-sided heart failure
Gross pathology -passive venous congestion? 2
liver enlarge with rounder borders and oozes blood on cut surface, enhanced lobular pattern (nutmeg liver)
Microscopy - passive venous congestion? - 3
hepatic venules and sinusoids engorged; periacinar areas congested with atrophy of hepatocytes (red); periportal areas undergo fatty chage (pale colour)
List 4 disorders of pigmentation. Which one does this image show?
MELANIN - congenital (lambs and calves) HAEMOSIDERIN - chronic passive venous congestion) BILE - obstructive jaundice LIPOFUSCHIN or CEROID - ageing.
Image shows haemosiderin (blue strikes)
What are vacuolar hepatopathies?
A degenerative disease. Hydropic change is common, non-specific and reversible. Glycogen (glycogenosis) accumulation occurs in HAC. Multifocal to diffuse swelling and vacuolaton of hepatocytes. Enlarged pale liver in severe cases (steroid hepatopathy). See images
Causes of vacuolar hepatopathies - 3
Hypoxia, mild toxic damage and metabolic stress
4 broad causes of hepatic lipidosis (fatty liver)
Dietary, increased energy demand, disease, abnormal hepatocytes function that prevents FAs complexing with proteins to form low density lipoproteins.
Lysosomal storage disease - overview and diagnosis
-OVERVIEW: inherited deficiencies of lysosomal enzymes cause neurological disease. Macrophages containing stored material accumulate at multiple sites (liver, LNs, CNS). -DIAGNOSIS: liver biopsy or PME
What happens in amyloidosis?
Substance depositied under th enedothelium and basement membranes of a variety of tissues including the renal glomeruli, islets of langerhans in the pancreas and the liver.
Broad causes - amyloidosis - 3
Primary, secondary or endocrine related
Gross appearance - amyloidosis
liver pale, enlarged, and friable
Microscopic appearance - amyloidosis
Homogenoeous acidophilic material that shows green birefringence when stained with congo red
When can liver necrosis occur? 4
Following ishaemia, toxic damage, nutritional deficiencies, microbial infection
3 different patterns of necrosis = ? What is this image an example of ?
RANDOM - EHV-1 or salmonellosis ZONAL - ischeamie or toxic damage MASSIVE - hepatosis dietetica,
The image shows periportal necrosis.
4 patterns of liver fibrosis = ? What does the image show?
PERIACINAR - surrounds central vein, chronic passive congestion BILIARY - 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.
The image shows biliary fibrosis.
Inflammation of the bile ducts, may be immune mediated (cats) or associated with infection (salmonellosis in calves)
Cholangiohepatitis - define
Inflammation of parenchyma and bile ducts
Inflammation of the liver parenchyma (often caused by infection)
Outline the progression of necrosis - 4
Acute hepatitis generally involves 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
3 causes of viral hepatitis.
-ADENOVIRUS - canine infectious hepatitis (ICH) -HERPESVIRUS - EHV-1, IBR, feline viral rhinotracheitis/rhinopneumonitis, equine viral rhinopneumonitis Aujeszky's disease -CORONAVIRUS - FIP Generally in young or unvaccinated animals
How is infectious canine hepatitis spread?
Long-term shedding in urine of canine adenovirus 1 (CAV-1) virus particles
Effects of CAV-1 on tissues?
Tropism for endothelium (widespread haemorrhages, particularly on serosal surfaces and hepatocytes), LNs and tonsils are enlarged and reddened, sometimes haemorrhagic, immune-mediated uveitis with corneal opacity
Describe the lesions seen with herpesvirus infections
Liver lesions occur in aborted foetuses or neonates - pinpoint foci of necrosis with intranuclear inclusion bodies. Necrosis also occurs in lungs, kidneys, spleen and adrenal glands.
How does FIP cause pathology?
enteric coronavirus mutates to cause systemic vasculitis and effisions in cats. Presents as 'wet' effusive or 'dry' granulomatous forms.
Describe the lesions - FIP
Pyogranulomatous lesions develop in multiple organs including the liver. The image shows pale lesions which are pyogranulomas. You can also see sticky yellow material which is the fibrin sticking to the organ surfaces.
3 broad routes of bacterial hepatitis infection. Examples.
-DIRECT EXTENSION (from disease in other tissues) -HAEMATOGENOUS (via umbilical vein, PV or hepatic artery in bacteraemias and sepsis) -HEPATIC ABSCESSATION (especially common in cattle, from umbilical infections - usually mixed bacteria, from rumenitis caused by overfeeding with grain).
Cause of bacillary necrosis in cattle
Fusobacterium necrophorum. The image shows in bottom half a pal foci of necrosis that may become an abscess. In the upper half of the image is a large thrombus indicating bacteria reached the liver via the blood.
What causes Black Disease/Infectious Necrotic Hepatitis in sheep (rarely horses or pigs)?
Clostridium novyi type B. The image shows a region of necrosis/bacteria (right) and also a region of inflammation/haemorrhage (left).
Cause of cattle and sheep haemoglobinuria
Clostridium haemolyticum - you can see a large necrotic focus in the liver.
What is Tyzzer's disease caused by?
Clostridium piliforme (Bacillus piliformis)
In the image you can see an area of liver necrosis. The bacteria colonies have been stained with a silver stain giving a wheat sheaf appearance.
Which animals do you see Tyzzer's disease in?
Laboratory rodents (occasionally foals, puppies or kittens)
Which species typically gets leptospirosis?
Dogs. In this image a silver stain has been used to label the bacteria black.
Which salmonella species do calves suffer from?
S. dublin. In histopathology you can see necrotic foci with mononuclear inflammatory cells around it.
Describe Fusbacterium necrophorum/bacillary necrosis in cattle (gross pathology and microscopy)
Calves - umbilical infection. Adults - rumenitis GROSS PATHOLOGY - multiple pale foci of necrosis throughout liver, may develop into abscesses if animal survives. MIRCROSCOPY - coagulative necrosis with bacteria at periphery.
What often precipitates black disease?
Pathology of black disease (infectious necrotic hepatitis)
extensive s/c venous congestion (black disease) and oedema, fibrinous peritoneal, thoracic and pericardial fluid, characteristic pale foci of necrosis (containing bacteria) surrounded by a rim of haemorrhage
What is Clostridium haemolyticum/ bacillary haemoglobinuria similar to?
Pathogenesis similar to black disease - severe anaemia, jaundice, haemoglobinuria. Pathology - large necrotic focus in the liver and haemoglobin staining of the kidneys
Other than lab rodents, which species may get Tyzzer's disease?
May affect foals (1-4wo) and immunosuppressed dogs/cats.
What is a 'wheat sheaf' appearance
Seen in Tyzzer's disease (Clostridium piliforme/Bacillus piriformis). It is the appearance of colonies when stained witha silver stain
Clinical signs - leptospirosis
Haemolytic anaemia, widespread haemorrhages, icterus. hepatocyyte dissociation (results in cholestasis) and haemosiderin accumulation (secondary to haemolysis)
Gross pathology and microscopy - salmonellosis
GROSS PATHOLOGY: Severe, often haemorrhagic inflammation in the ileum, pale foci of necrosis in the liver called 'paratyhoid nodules'. MICROSCOPY - foci of necrosis, mixed mononuclear inflammatory cell infiltrate
When do you see liver parasites?
Usually an incidental finding (except liver fluke).
What causes a milk spot liver'?
The parasite Ascaris suum in pigs
What are the signs that the animal has had parasites?
Fibrinous tags incidentally on the surface of the liver and adjacent diaphragm. Remnants of fibrous repair following egress of parasites from liver.
What does acute intoxication usually lead to? (3 examples
Widespread haemorrhages in the body due to excessive comsuption of the CFs in the damaged liver coupled with failure to produce these by the damaged liver. (blue-green algae, iron, cereals)
What does chronic intoxication usually lead to? (3 examples)
Continual ingestion of toxic compounds at low doses over a period of time. Evidence of regeneration and repair (e.g. fibrosis and biliary hyperplasia (ragwort, aflatoxins, copper). Certain drugs are also hepatotoxic (primidone, sulphonamides and paracetamol - cats)
When might you see inflammation of the gall bladder? 2
Salmonellosis and Infectious Canine Hepatitis
What are choleliths?
What may cause obstruction to the biliary tree?
-compression of the ducts by nearby inflammatory and neoplastic processes - commonest -parasites, sometimes choleliths - rare. The image shows gallstone obstruction.
Why is rupture of the bile duct serious?
the omentum is incapable of sealing even the smallest leaks
Result of bile duct rupture?
chronic inflammatory processes, if infected --> widespread peritonitis
Nodular hyperplasia - gross pathology and microscopy?
GROSS PATHOLOGY - spherical nodules in the liver, vary in colour from pale to dark or can be the same colour as the rest of the liver MICROSCOPY - cells are larger, may contain more glycogen, portal areas still visible within the mass, compression of adjacent normal tissue
Species principally affected by primary hepatic tumour s- 2
dogs and cats
primary hepatic tumour - derivation. How to differentiate?
usually hepatocytes (hepatoma or hepatocellular carcinoma) or biliary epithelium (most are cholangiocellular carcinomas) APPEARANCE - hepatocellular tumours may resemble normal parenhcyma (with haemorrhage or necrosis in malignant tumours) whereas cholangiocellular cacinomas are often white, firm and umbilicate.
Origin of haemangiosarcoma in the liver
Can be primary or metastatic. Other predilection sites are the spleen and right auricle of the heart. Prevalent in large breeds.
Is secondary neoplastic involvement of the liver common?
Yes - melanoma, carcinoma, sarcoma and lymphoma
List 4 pathologies of the exocrine pancreas
Developmental anomalies, pancreatitis, pancreatic hyperplasia, pancreatic neoplasia
What is pancreatic hypoplasia? What does it look like?
Developmental anomaly of the pancreas (GSDs and calves). Occurs at about one year of age. CLINICAL SIGNS - steatorrhoea and diarrhoea, loss of condition despite polyphagia, pot-bellied.
Presence of excess fat in faeces
Synonym for acute pancreatitis
Acute pancreatic necrosis
Clinical signs - acute pancreatitis
Shock and cardiovascular collapse, raised lipase and amylase levels, some cases subclinical
Gross findings - acute pancreatitis
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
Microscopy - acute pancreatitis
haemorrhagic oedema and necrosis affecting pancreas and peripancreatic fat
What is chronic pancreatitis? Appearance?
In dogs, often follows bouts of acute pancreatitis resulting in replacement fibrosis and atrophy. Leads to EPI (steatorrhoea and loss of condition). May be subclinical in cats and horses.
When might you see pancreatic hyperplasia?
Nodular hyperplasia is common in older dogs and (especially) cats - of no clinical significance
Gross appearance and microscopy - pancreatic hyperplasia
GROSS APPEARANCE - White lobules or plaques projecting from the surface. Don't distort adjacent tissue and aren't encapsulated. MICROSCOPY - similar to normal glandular tissue
What is pancreatic neoplasia? 2 types
-Adenoma - extremely rare. -Carcinoma - dogs and cats; highly invasive with metastases to the lvier, peritoneum, abdominal LNs, spleen, adrenals