Liver & Biliary Flashcards
A diagnosis of multifocal random hepatocellular necrosis and inflammation should prompt the clinician or diagnostician to search for a potential _____ cause.
Infectious
What compound can lead to the accumulation of glycogen in the liver of dogs?
Glucocorticoids
What portion of the hepatic lobule is most susceptible to hypoxic injury?
Centrilobular
Some cases of canine chronic hepatitis are associated with_____________.
Copper
A young dog with a ravenous appetite, decreased muscle mass and fetid feces should be screened for which condition?
Exocrine Pancreatic Insufficiency
(EPI)
What is the term for end-stage liver disease?
Cirrhosis
Categories of Liver Disease
- Congenital/Inherited
- Traumatic
- Circulatory
- Metabolic/Nutritional
- Inflammatory
- Toxic
- Neoplastic/Hyperplastic
- Gallbladder lesions
True/False
The liver, biliary system, and pancreas all originate from endodermal endothelium of the duodenum.
True
True/False
The hepatic artery provides ~70% of afferent blood flow to the liver.
False
Portal vein supplies most blood flow to the liver
True/False
Blood in the liver flows from portal triads to central veins, while bile flows in the opposite direction.
True
Which species lack a gallbladder?
Horse, rat, elephant
How much does the liver weigh in carnivores?
3-4% bodyweight
How much does the liver weigh in small ruminants and pigs?
1-2% bodyweight
How much does the liver weigh in large herbivores?
1% bodyweight
The hepatic lobule consists of:
- central vein at center
- portal triads at periphery
- canaliculi draining bile
- centrilobar, midzonal, periportal regions
The hepatic acinus contains
- portal triad at the center
- central veins at the periphery
- canaliculi draining bile
- Zone 1 - Periportal region, HIGH oxygen, nutrients, toxins
- Zone 2 - Midzonal region
- Zone 3 - Centrilobular, LOW oxygen & nutrients, site of earliest fat storage & glycogen
- Cells in the liver arranged in plates
- 2 cells thick with canaliculi between and sinusoids at lateral surface
- Cytosolic and membrane bound enzymes are what are measured for signs of liver damage
Hepatocytes
What are the cytosolic leakage enzymes from hepatocytes?
- Alanine Aminotransferase (ALT) - liver specific in dogs/cats
- Aspartate Aminotransferase (AST) - Liver & muscle
- Sorbitol Dehydrogenase (SDH) - Liver specific large animals
What are the membrane-bound induced enzymes from hepatocytes?
- Alkaline Phosphatase (ALP) - dogs/cats
- Gammaglutamyl Transpeptide (GGT) - Liver and biliary
- Fixed macrophages in liver sinusoids
- Phagocytosis
- Innate immune system
- Contain iron and lipofuscin
- Macrophage foci and pigment granulomas common - indicate hepatocellular turnover
Kupffer Cells
- Hepatic lipocytes between sinusoids and hepatocytes in space of Disse
- Vitamin A metabolism
- Important in fibrosis - can develop into myofibroblasts
Stellate Cells
Ito Cells
- Stem cell precursors to biliary and hepatic epithelium
- Located at edge of portal region in the limiting plate
Oval Cells
Dysfunction of protein synthesis in the liver leads to
Edema, ascites, bleeding disorders
Dysfunction of bile metabolism & transport and bilirubin metabolism leads to
Photosensitization, hyperbilirubinemia
Dysfunction of liver drug metabolism leads to
Toxicities
Dysfunction of liver’s ability to convert NHS (ammonia) to NH4 (ammonium) and other toxins into safe metabolites leads to
Hepatoencephalopathy
Dysfunction of the liver’s storage of lipid and carbohydrate leads to
Hepatic Lipidosis
Causes of Hyperbilirubinemia
- Prehepatic - hemolysis, increased unconjugated bilirubin initially
- Hepatic - liver disease, increased both conjugated & unconjugated bilirubin
- Posthepatic - biliary obstruction, increased conjugated bilirubin
Can be primary or secondary cause of lesions on sun-exposed, poorly pigmented skin
Primary (Type 1)
* Liver incapable of excreting photodynamic compound
* Can result from ingestion of St. John’s Wort (Hypericum perforatum)
Congenital (Type 2)
* Hereditary defect in heme metabolism
Secondary (Hepatogenous, Type 3)
* Follows cholestasis in herbivores
* Accumulation of phylloerythrin (chlorophyll catabolite) or other photodynamic compound
Photosensitization
Reactions to Liver Injury
- Hydropic or vacuolar degeneration
- Glycogen accumulation
- Fatty change / lipidosis
- Storage disorders
- Necrosis
- Inflammation
- Bile stasis
- Reversible swelling of hepatocytes
- Excess water enters due to inactivation of membrane sodium pump
- May lead to necrosis
Hepatocellular Swelling / Vacuolar / Hydropic Degeneration
- Reversible hepatocyte swelling with clear cytoplasm
- Usually midzonal but can be diffuse, zonal, or individual cells
- Liver appears swollen, orange-red color
- Physiologic in neonates
- Occurs ONLY in dogs as result of glucocorticoids
- NOT associated with necrosis
Glycogen Accumulation
Steroid Hepatophathy
What is the granular accumulation inside of these hepatocytes that commonly leads to hepattopathy/hepatitis in dogs?
Copper
- Post-necrotic & post-inflammatory response with proliferation of fibroblasts and myofibroblasts (from Stellate Cells)
- Production of collagen
- Can result from necrosis, inflammation, hypoxia
- Almost always occurs with regeneration & bile duct hyperplasia
- Can lead to disruption of blood flow, portal hypertension, bile duct obstruction, chronic cholangitis (cats specifically)
Fibrosis
- Atrophy of adjacent hepatocytes and dilation of sinusoids due to accumulation of eosinophilic material in space of Disse
- Material is usually SAA
- Associated with inflammatory conditions
- Predisposed breeds - Chinese Shar-Pei, Abyssinian, Siamese, Oriental breed cats)
- Spontaneous or biopsy-induced liver rupture can occur
Amyloidosis
