Liver Flashcards
While 1/3 of the blood coming into the liver is clean blood from the hepatic artery, the other 2/3 of incoming blood is from the ______ _____.
Portal vein
*Dirty blood. Drains the abdominal viscera.
Not oxygenated.
What vessel is located in the center of each liver lobule?
Central vein
Which acinar zone is closest to the portal triad, and has the most oxygen and nutrients available, but is most susceptible to direct acting toxins?
Zone 1 (periportal)
Which acinar zone is most susceptible to hypoxia and indirect acting toxins?
Zone 3 (periacinar or centrilobular)
*Zone 3 is responsible for detoxification using Cp450 enzymes. Detox often activates toxins, leading to damage of the hepatocytes in this zone.
What are the reversible hepatocellular changes?
ADAPTATION: atrophy and hypertrophy
DEGENERATION: vacuolar change
What can cause the reversible change seen in the liver specimen on the right?
Malnutrition/Starvation
*This is atrophy. Nuclei are the same size as the normal liver on the left, but cytoplasm is reduced.
Injury and hypoxia leading to water uptake in hepatocytes causes which reversible change?
Hydropic degeneration (vacuolation)
Necropsy on a dog with Cushings Disease reveals an enarged, pale tan liver. Histopathology shows swollen hepatocytes with feathery cytoplasm. What is the pathogenesis?
This is glycogenosis.
Presence of glucocorticoids increases hepatic gluconeogenesis. Plasma glucose levels are increased, which triggers liver glycogen storage.
*Also seen in animals with Diabetes Mellitus and glycogen storage diseases
What are the mechanisms that would cause a liver to look like this?
This is hepatic lipidosis
- Increased supply of FFAs (mobilization from adipose: pregnancy, diabetes, food restriction)
- Impaired processing of FFAs within the hepatocyte (decreased use, problem with apoprotein/triglyceride pairing to make lipoprotein)
- Decreased lipoprotein secretion (heart failure, hepatotoxins)
Migration of Fascioloides magna in an Ox liver is an example of what pattern of necrosis?
Focal/Multifocal
*This pattern can also be seen with infection (Salmonellosis) and trauma, and is accompanied by inflammation (hepatitis)
A cat presents to your clinic weak, icteric, and hyperventilating. He dies on the exam table, and the owner requests necropsy. Tissue samples are taken and sent for histopathology. The liver sample shows periacinar (zone 3) necrosis. What is a likely cause of this pattern of necrosis in house cats?
Acetominophen toxicity
*This pattern can also be seen in animals who have died slowly (hypoxia in zone 3), or with passive congestion of the liver.
The red and yellow zonal pattern of Nutmeg Liver is commonly seen with what disease?
Chronic passive congestion due to CHF
Mulberry heart disease of swine, caused by Vit E/Selenium deficiency, causes what pattern of hepatic necrosis?
Massive: involves hepatocytes of the entire lobule
As long as the liver has a blood supply, free drainage of bile, and reticulin scaffolding, it is able to regenerate. The type of regeneration pictured is caused by what type of injury?
Repetitive/Sustained injury
*nodular regeneration with constricting bands of fibrous tissue
Histopathology on a liver is shown below. What is this response to injury?
Biliary hyperplasia
*Tortuous biliary channels. Increased profiles on cut section.
Histo on a liver specimen shows collagen deposition in the Space of Disse, caused by repeated injury. What is an implication of hepatic fibrosis?
Decreased blood filtration in the liver
*Bridging fibrosis is more likely to impair liver function byt segregating sections of the liver and cutting off blood supply.
Necropsy is performed on a 9 year old Labrador that died at home. The liver is pictured. What are the features you would expect to see in a liver like this?
This is an end stage liver (Cirrhosis)
- Disruption of architecture of entire organ
- Nodular regeneration
- Fibrous “bridging” scars
- Formation of shunts due to increased pressure in the portal vein
Liver sample on an icteric dog. According to the photo, what is the cause of icterus in this patient?
Cholestasis
(bile duct obstruction:post-hepatic)
If we can see icterus grossly in a patient, what is the extent of the liver injury?
Diffuse
*Focal injury will cause local cholestasis, but will not cause jaundice. Healthy parts of the liver will clear the bilirubin.
This plant was found in a pasture in which several of the cows exhibited skin injury due to sun damage. Should you be worried about impaired liver function in the affected cows?
No. St John’s Wort (Hypericum perforatum) causes primary photosensitivity. The compounds (hypericin) are deposited unchanged into the skin after ingestion.
A Limousin calf presents with what looks to be photosensitization lesions on his face. What is the disease and pathogenesis?
Congenital erythropoietic protoporphyria
*enzyme deficiency resulting in the aberrant metabolism of heme
You are examining a cow who developed the following skin lesions after several days on pasture. Blood is taken and the cow has increased ALP and Bili. What is causing the skin problem in this cow?
Secondary Photosensitization
*Cholestasis increases phylloerythrin in the blood. Normally this plant metabolite is excreted in the bile. With cholestasis, it builds up and binds to the cells in the dermis.
You arrive at a farm to find a sheep with the following lesions. In addition to skin sloughing, there is a serous exudate and edema. What toxin is likely affecting the liver in this case?
Sporidesmin
*From Pithomyces chartarum fungus. Found on dead ryegrass in warm climates.
A client brings her dog in for behavioral changes and shows you this photo she took yesterday. Labwork indicates liver failure. What is causing the behavioral signs in this dog?
Hepatic encephalopathy
*Failure to clear ammonia from the blood, either due to hepatic failure or portocaval shunt bypassing the liver. When ammonia crosses the BBB it causes encephalopathy by causing edema and altering GABA activity.
Signs can range from dullness/blindness in sheep, to mania and frenzy in cattle and horses.
Hemorrhagic diathesis following surgery on a dog with liver failure. What is the cause of the bleeding?
Decreased coagulation factors leading to increased clotting time. Doesn’t usually cause hemorrhage unless there is increased demand for hemostasis (surgery).
Histopath on the kidney of a dog, showing bile pigment in the tubular epithelium. What is the disease name and cause?
Biliary nephrosis
Caused by acute liver failure (vasoconstriction leading to decreased GFR?)
An 8 year old dog presents with ascites, and labs show increased ALT and AST, and decreased Albumin. What is causing ascites in this patient?
Liver failure
*Restricted blood flow through an end stage liver leads to portal hypertension. Increased hydrostatic pressure causes ascites.
*Expect to see acquired postocaval shunts in these patients.
A 10 year old dog presents to your clinic with necrolytic dermatitis (erythema, crusting, ulceration) of the paw pads and other presure points. What are the characteristic lesions of the histo that point to liver failure as the pathogenesis?
- Parakeratotic hyperkeratosis (nucleated keratocytes)
- Epidermal swelling
- Basal cell hyperplasia
*Red, white, and blue lesion
A 9 month old Yorkie presents for poor growth, head pressing, and a suspected seizure. On physical exam you notice a distended abdomen. Labs confirm microcytic anemia, decreased BUN, Alb and Glu, and a urine sample reveals a USG of 1.008. You perform a bile acids test and the result is high. On radiology the liver appears small. A liver biopsy is performed and the histo is as pictured. What is your diagnosis?
Acquired portocaval shunt due to lack of portal veins.
*Note small hepatocytes, numerous tortuous arterioles, and bile ducts, but no portal veins in the “triad”.
What kind of congenital portocavl shunt is found in large breed dogs?
Intrahepatic
*persistent ductus venosus
What kind of portocaval shunt is found in small dogs?
Extrahepatic
*From portal to caudal vena cava or azygos vein
This portocaval shunt is found in what size dog breeds?
Large breed dogs
*Intrahepatic
This portocaval shunt is found in what kind of dog breeds?
Small breed dogs
*extrahepatic
Necropsy on a dog with a history of ascites and splenomegaly shows a thrombus in the portal vein. What acquired vascular disease is visible in this patient?
Acquired portocaval shunt
*prehepatic
Necropsy on a dog with cirrhosis. Is the acquired shunt pre hepatic, hepatic, or post hepatic?
Hepatic
*Decreased blood flow through end stage liver
What is the most likely cause of this condition?
Passive venous congestion due to congestive heart failure.
*Can also be caused by thrombosis of caudal VC in cattle
You are performing a necropsy on a cow and find these lesions on the liver. What is the pathogenesis?
Teliangiectasis: Dilation of the sinusoids
*Incidental finding in cattle and old cats
This liver is diffusely yellow, enlarged, friable, and greasy on cut surfaces. What disease processes can lead to this?
Feline hepatic lipidosis and equine hyperlipemia
Diabetes mellitus
Fatty liver disease of dairy cows and pregnancy toxemia of ewes
You arrive on a farm to examine a Shetland Pony who has been off feed for 2 days and is having diarrhea. The owner is very worried because she just foaled and is lactating. You note ventral edema in addition to a BCS of 8/9. You take blood for testing and the tubes appear as pictured. What complications can arise from this disease?
Severe fatty liver - rupture
DIC
Insulin resistance
*This is equine hyperlipemia. It is often seen in obese, pregnant or lactating mares.Serum/blood will appear milky due to increased triglycerides.
Abdominal xrays indicate heptomegaly and histology is as pictured. What is the likely pathogenesis?
Genetic defect in iron metabolism
*This is hemosiderosis: hemosiderin accumulation in hepatocytes and Kupffer cells. Can also be seen in piglets after receiving iron injections. Causes breakdown of hepatocytes and bridging fibrosis.
Necropsy on a Shar-Pei reveals a pale, enlarged and waxy liver. What disease did this dog have?
Familial AA amyloidosis
Liver histology of a cat with a history of chronic inflammation. You determine that the light pink areas indicate amyloid. What is the likely pathogenesis and why does this disease lead to reduced blood filtration?
Systemic reactive amyloidosis due to overproduction of amyloid A (part of an acute phase protein)
Amyloid accumulates in the Space of Disse, impeding the Kupffer cells from filtering the blood that passes through.
During a necropsy you find the liver as pictured, with multifocal and locally extensive lesions. How did the infection get to the liver?
Hematogenous route via the umbilical vein
*GI tract is another common route of bacterial entry to the liver
Liver of an owl with multifocal white spots disseminated throughout. You suspect herpesviral infection. What is the typical route of spread for infectious agents?
Hematogenous
Histolgy on the liver of a puppy shows necrosis and hemorrhage, but almost no inflammation. You also see intranuclear inclusion bodies. What is a likely etiology?
Canine herpes virus 1
*Equine herpesvirus 1 will have similar lesions in aborted foals.
Necropsy on a 6 month old foal with a history of respiratory symptoms shows disseminated abscesses in the liver. You suspect entry via the lungs. What is the causative agent?
Rhodococcus equi
Liver of a steer that died on the feedlot with a history of rumenitis, with multifocal abscesses and necrosis. What complications can arrise from this infection?
Embolism into hepatic vein to produce:
Thromboembolitis of the vena cava
Endocarditis
Pulmonary abscesses
*Fusobacterium necrophorum
Microabscesses such as these, with pinpoints of necrosis and neutrophils, can enter the liver through the GI tract via the portal vein. What bacterial species are you likely to find in a culture of this liver?
Salmonella spp
Liver of a lamb fetus with lesions of central necrosis surrounded by neutrophilic inflammation. These donut shaped lesions are caused by what pathogen?
Campylobacter fetus
Histology of a liver shows central areas of necrosis surrounded by macrophages. What is a likely etiology?
Mycobacterium spp
*granulomatous inflammation
Necropsy on a lab rat reveals a liver with lesions of necrosis and supperative inflammation. Histology is performed and you see intracellular bacteria. What is the likely disease?
Tyzzer’s
*Clostridium piliforme. Spread to the liver from the GI tract via the portal vein.
Necrotizing, supperative, or granulomatous hepatitis can be seen secondary to rumenitis. What is the causative agent?
Fungi
Aspergillus or Zygomycetes
Larval migration by what parasites causes fibrotic tracts in the livers of cattle and pigs?
Fasciola hepatica
Ascaris suum
*While still fresh, migration tracts will be full of eosinophils and hemorrhage.
What Cestodes cause larval cysts in the liver?
Echinococcus granulosus
Taenia hydatigena
You arrive on a farm to perform a necropsy on a recently deceased sheep. You immediately notice dark subcutaneous lesions. On inspection of the abdominal cavity, you notice that the liver has a 2cm diameter focus of necrosis, surrounded by hyperemia. This disease is likely secondary to what event?
Fluke migration
*Clostridium novyi type B (Black Disease) proliferates after an anaerobic event, producing necrotizing beta toxin.
Eimeria hepatic coccidiosis in a rabbit, forming a biliary pattern of hyperplasia and lymphoplasmacytic inflammation. Biliary patterns of infection primarily reach the liver through what route?
Ascending infection from the GI tract
*Can also be immune mediated
Necropsy on the liver of a cow shows “pipestem” lesions that contain dark, granular material. You diagnose cholangiohepatitis. What is the causative agent?
Fasciola hepatica
*mechanical irritation and obstruction of the bile ducts by mature flukes
Severely enlarged and fibrotic bile ducts in stray cats from St Kitts. What is the likely agent?
Platynosomum fastosum
PM exam of a Bedlington Terrier with a history of ill-thrift, ascites, and strange behavior reveals the liver as pictured, with regenerative nodules and fibrosis. What mechanism may have caused chronic hepatitis in this dog?
Increased hepatic copper concentration
*Hereditary Cu associated hepatopathy. Defect in ability to metabolize copper. Leads to hepatitis when concentrations reach more that 2000ppm.
A famer asks you to perform a necropsy on his horse. He states that the horse had received a serum injection of tetanus antitoxin 2 months ago, but was otherwise seemingly healthy until recently when he fell ill and was acting strangely. On PM exam you note petechiae, icterus, and ascites. The liver has a dish rag appearance, as pictured. What is your diagnosis?
Theiler’s Disease
*Equine serum hepatitis. Caused by pegivirus. Occurs 1-2 months after biological serum injections.
Liver cytology from a Bedlington Terrier, stained with Rhodanine. What disease process does this dog have?
Chronic hepatitis caused by inability to metbolize copper.
Liver histology on a young rhino that died suddenly. On necropsy the animal was icteric. Lab tests indicated hyperbilirubinemia and bilirubinuria. What caused liver necrosis in this animal?
Sterigmatocystin, a mycotoxin from feed contaminated with Aspergillus.
*Acute, zone 3 (periacinar/centrilobar) necrosis
Histology of a liver showing megalocytes (DNA replication without mitosis), and hepatic atrophy (liver becomes smaller as it gets larger). Grossly, there are regenerative nodules. What is the toxin?
Pyrrolizidine alkaloid
PM exam on a sheep who was found dead, with no history of illness. The carcass is yellow, spleen dark and engorged, there is a “gun metal” appearance to the kidneys, the liver is soft, swollen and orange, and hemoglobinuria is evident. What is the likely cause of sudden death?
Hemolytic crisis caused by Cu toxicity. Hemolytic anemia accelerates hepatocellular necrosis, causing Cu to enter the circulation at an even higher rate. Death in 6 hours.
Liver of a dog with a single, light brown, well demarcated and un-encapsulated nodule. Histology shows normal hepatocytes, but the acinar structures and portal triads are absent in the area. What is your diagnosis?
Hepatoma (benign)
“Hepatocellular adenoma”
On exploratory of a dog, you find the liver as pictured. There are poorly demarcated nodules, with hemorrhage and necrosis on cut surface. Considering the likely diagnosis, what is your next diagnostic test?
Thoracic radiographs
*This is hepatocellular carcinoma. It is malignant and tends to metastasize to the lungs. Spontneous rupture leads to hemoperitoneum.
Necropsy on a cat reveals a liver with multiple nodules that are firm, white, and umbilicated. You also find lesions in the lungs and lymph nodes. What is your diagnosis?
Cholangiocellular carcinoma
*More common in cats, while hepatocellular carcinomas are more common in dogs.
This neoplasm metastasized to the liver from the spleen via the portal vein.
Hemangiosarcoma
What is this PM change in a horse liver?
Capsular fibrosis caused by previous parasitic migration.
*In other species is a resolution of peritonitis
What is this PM change seen occasionally in cattle and horses?
Tension lipidosis. In areas of mesenteric attachment.
