Liver Infectious diseases

Question 1

What are the different infectious agents that can damage the liver?

Answer 1

• Viruses
  
  • Hepatocyte necrosis and lymphocytic inflammation
• Bacteria
  
  • Inflammation and secondary hepatocyte injury
• Fungi
  
  • Chronic granulomatous inflammation
• Parasites
  
  • Inflammation due to adult and migrating forms

Question 2

What viruses can affect the Liver?

Answer 2

• Canine adenovirus-1 (infectious Canine Hepatitis)
• Herpesvirus infections in neonates
  
  • most species have a specific herpesvirus
• Rift Valley Fever / Wesselbron Disease
  
  • Mosquito-borne transboundary disease
• Hepadnavirus (woodchuck hepatitis virus)
• Systemic calicivirus of cats

Question 3

What herpesviruses affect the liver?

Answer 3

• These are NOT liver-specific, can involve the liver as part of a multisystemic process
  
  • Canine herpesvirus 1
  • Feline herpesvirus 1 (Feline viral rhinotracheitis)
  • Bovine herpesvirus 1 (infectious bovine rhinotracheitis)
  • Equine herpesvirus 1 (Equine viral rhinopneumonitis)
  • Suid herpesvirus 1 (pseudorabies)
  • Thee viruses are abortigenic, causing fatal viremia/multisystemic disease in fetal or neonatal animals
    
    • Multifocal hepatic necrosis is a prominent lesion
    • Most sever before neonates are thermoregulatory competent

Question 4

What is Infectious canine hepatitis (ICH)?

Answer 4

• An important canine infectious disease caused by canine adenovirus-1
  
  • Considered a “core” vaccine component (DA2PP)
  • CA-2 provides protection against ICH
• The virus has affinity for hepatocytes and endothelium
  
  • Hepatocyte necrosis and endothelial injury leading to activation of coagulation
    
    • Signs include those of hepatic disease, often with terminal vascular collapse (DIC)
    • Post-infection type III hypersensitivity can cause corneal edema

Question 5

What Bacteria can cause Clostridial hepatitis?

Answer 5

• C. hemolyticum
• C. novyi
• C. piliformis

Question 6

What bacteria causes hepatic abscesses?

Answer 6

• Fusobacterium necrophorum
• Trueperella pyogenes

Question 7

What bacteria causes salmonellosis?

Answer 7

• s. typhimurium
• others

Question 8

What Bacteria cause leptospirosis?

Answer 8

L. interogans (Various serotypes

Question 9

What is Infectious Necrotic Hepatitis?

Answer 9

• Black Disease
• A disease of sheep caused by Clostridium novyi
• Lesions are characterized by multiple necrotic foci in the liver
  
  • Latent spores in the liver are activated by injury (often migrating larval flukes)
  • Anaerobic environment allows local bacteria growth and toxin production
• Peracute death often occurs due to toxemia

Question 10

What is Bacillary hemoglobinuria?

Answer 10

• Disease of predominately cattle caused by Clostridium hemolyticum
  
  • Lesion: A single, large necrotic focus of hepatic parenchyma
    
    • The pathogenesis is similar to Cl. novyi infection in sheep
  • Toxemia, with hemolytic anemia and hemoglobinuria are seen

Question 11

What is Tyzzers disease?

Answer 11

• Infection of rodents and some domestic species by Clostridium piliformis
  
  • Disease is most common in young foals
  • Lesion: Multifocal hepatic necrosis and inflammation with intracellular organisms
  • Fatalities are common with acute hepatic failure

Question 12

What are hepatic abscesses?

Answer 12

• Most common in ruminants
  
  • Trueperella pyogenes and Fusobacterium necrophorum are the most common causes
  • Theses often occur as a sequel to rumenitis or traumatic reticulitis
• Less common in other species
  
  • Hepatic abscesses in other species are often due to naval infection or bacterial emboli
    
    • Corynebacterium pseudotuberculosis
    • Others

Question 13

What is the pathogenesis of ruminant liver abscesses?

Answer 13

1. High-grain feeding
2. Acidosis
3. Rumenitis
4. Bacteria into Portal blood
5. Abscesses in the liver

Question 14

What is happening in this liver?

Answer 14

• Hepatic abscess
• C pseudotuberculosis
• Multifocal suppurative hepatitis

Question 15

What is leptospirosis?

Answer 15

• Mainly due to serogroups of Leptospira interrogans
• Acute leptospirosis can cause centrilobular hepatic necrosis due to hemolysis and hypoxia
• Special effects on hepatocytes are poorly defined
  
  • Rounding and “disassociation” of hepatocytes is described
• L. grippotyphosa has been incriminated as a precipitating cause of some cases of chronic-active hepatitis

Question 16

What is Histoplasmosis?

Answer 16

• Mainly dogs and cats
• Systemic fungal infection caused by Histoplasma capsulatum
• Primary infection usually occurs in the lungs followed by systemic spread
  
  • Liver
  • Spleen
  • Lymph nodes
  • Intestine

Question 17

What parasites affect the liver?

Answer 17

• Many Larvae spend all or part of their life cycle in the liver
  
  • Tapeworm cysts
  • Ascaris suum
  • Stephanuris dentatus
  • Strongylus ap.
• Lesions vary from parasitic cysts to focal hepatitis to fibrosis

Question 18

How do cestodes affect the liver?

Answer 18

• Migrating immature forms of tapeworms can encyst in the livers of intermediate hosts
• Taenia hydatigena can encyst in liver of various species

Question 19

What is hepatic coccidiosis?

Answer 19

• A disease predominately in weanling rabbits caused by Eimeria stiedae
  
  • Ingested coccidia migrate to the bile ducts to continue their life cycle
  • Infection causes cholangiohepatitis with fibrosis and bile duct hyperplasia and dilation
  • Affected rabbits are thin and often develop ascites

Question 20

What is a Fasciola hepatica infection?

Answer 20

• This is common liver fluke of ruminants
  
  • Lesion:
    
    • Migrating larvae induce focal necrosis and eosinophil infiltrate
    • Adults induce fibrosing cholangiohepatitis
      
      • Adult flukes reside in the bile ducts
  • Chronic disease results in debilitation and GI distrubance
  • Migrating larvae can induce clostridial disease

Question 21

What is a Fascioloides magna infection?

Answer 21

• This is the large liver fluke of ruminants
  
  • Lesion;:
    
    • Migrating larvae induce focal necrosis and eosinophil infiltrate
    • Adults induce focal hepatitis
      
      • Adult flukes reside in the parenchyma
  • Chronic disease results in debilitation and GI disturbance
  • Migrating larvae can induce clostridial disease

Question 22

What are other causes of fascioliases?

Answer 22

• Dicrocoelium dendriticum
  
  • Lancet fluke of ruminant
• Metorchus conjunctus
  
  • The common liver fluke of dogs and cats
  • Opisthorcid flukes have been associated with neoplasia in some species

Question 23

How does Aflatoxin toxicity affect the liver?

Answer 23

• Cause:
  
  • Toxins produced by Aspergillus sp (Mainly A. flavus)
• Lesion:
  
  • Acute - centrilobular hepatic necrosis and/or lipidosis
    
    • Most common in pig, dogs, avians
  • Chronic - hepatic necrosis, fibrosis, biliary hyperplasia and megalocytosis
• Effects vary widely based on species and dose
  
  • Dogs, pigs, and avians are most susceptible

Question 24

What are the affects of Aflatoxicosis?

Answer 24

• Necrosis
• Lipidosis
• Cholangiolar hyperplasia
• Portal fibrosis
• Nodular regeneration

Question 25

What is Pyrrolizidine alkaloid toxicity?

Answer 25

• Cause:
  
  • Alkaloids produced by a wide variety of plants (senecio, Crotalaria, Heliotropium among others)
• Lesion:
  
  • Acute - centrilobular hepatic necrosis
  • Chronic - hepatic necrosis, fibrosis, biliary hyperplasia, and megalocytosis
• Effects vary widely based on species and dose
  
  • Pigs and horses are most susceptible

Question 26

What is blue green toxicity?

Answer 26

• Most common in late summer/early fall
  
  • Anabaena, Aphanixomenon and Microcystis
• Dying algae release preformed toxins into water that are ingested by livestock, dogs, cats
• Results in centrilobular to massive hepatic necrosis
  
  • Survivors often develop chronic liver disease
  • Signs are diarrhea and recumbency
• Some blue/green algae produce neurotoxins

Question 27

What is Xylitol toxicity?

Answer 27

• An artificial sweetener (alcohol sugar)
  
  • Ingestion causes a rapid release of insulin (hyperinsulinemia and hypoglycemia)
    
    • There is weakness, ataxia, seizures, and hypokalemia
  • Small amounts can cause acute centrilobular to massive hepatic necrosis
    
    • Injury is presumed to be due to depletion of ATP

Question 28

How does Carprofen (Rimadyl) affect the liver?

Answer 28

• Non-steroidal anti-inflammatory drug
  
  • Rarely it can cause hepatotoxicity
    
    • Nearly 25% of cases occur in Laborador retrievers
    • Hepatic lesions are centrilobular necrosis
  • Signs include vomiting, icterus, hypoalbuminemia, and hyperbilirubinemia
  • Other effects can include GI disorders, neurological, renal, or skin disease

Question 29

How does Acetaminophen toxicity affect the liver?

Answer 29

• Cats and to a lesser extent, dogs are affected
  
  • Cats are less efficient at conjugating activated xenobiotics
  • Cats have a relative deficiency of glucuronyl transferase
• Centrilobular to massive hepatic necrosis
• Affected dogs can have facial edema

Question 30

How does copper toxicity affect the liver of sheep?

Answer 30

• Copper accumulates to high levels without apparent clinical signs
  
  • Hepatic injury results in copper release
    
    • Hepatotoxins or hypoxia can trigger release
    • Excess copper or decreased molybdenum in the ration predisposes to disease
  • There is copper induced hemolytic anemia

Question 31

How does copper toxicity affect the liver of dogs

Answer 31

• Occurs in a variety of breeds
  
  • Most common in bedlington and west highland white terriers
  • Due to a mutation in the COMMD1 gene
• Excess copper increases hepatocyte turnover along with progressive necrosis, inflammation, and fibrosis (“end-stage liver”)
  
  • Canine chronic hepatitis
• Clinical signs are those of hepatic failure
  
  • Wasting, ascites, neurologic signs
  • Copper-induced hemolysis may occur in some cases

Question 32

What is Iron toxicity?

Answer 32

• Most common in baby pigs given iron dextran injections
  
  • Neonatal nutritional supplements containing excess ferrous fumarate as an iron source have caused toxicity in foals
• Lesion: centrilobular to massive necrosis
  
  • Iron catalyzes oxidation reactions
• Clinical signs include apathy and coma

Question 33

What is Hepatosis dietetica?

Answer 33

• A disease of pigs attributed to vitamin E / Selenium deficiency
  
  • Lack of antioxidants leads to hepatic necrosis
  • Hepatic injury (necrosis) can be massive
• Signs:
  
  • GI problems
  • Icterus
  • Collapse
• The heart and skeletal muscles can also be affected
  
  • Mulberry heart disease
  • White muscle disease

Question 34

What is Canine Chronic hepatitis?

Answer 34

• A condition characterized by progressive, self-perpetuating (Chronic-active) hepatic necrosis, lymphoplasmacytic inflammation, fibrosis and regenerative hyperplasia
• Often etiologically non-specific
  
  • original insult could be infectious, toxic, or immunologic
  • Idiopathic chronic hepatitis
• Some cases have identifiable underlying causes
  
  • Copper-associated
  • Vascular malformations
  • Infection
    
    • Adenovirus-1 or Leptospira spp. among others
• Signs are those of chronic hepatic failure

Question 35

What are the possible causes of Canine Chronic Hepatitis?

Answer 35

• Leptospirosis
• Infectious canine hepatitis
• Copper toxicity
• Various other hepatotoxins (Drugs, aflatoxin, etc)
• Immune mediated

Question 36

What are chronic changes associated with Canine Chronic Hepatitis?

Answer 36

• Architectural distortion
• Chronic inflammation
• Cholestasis
• Portal fibrosis (often extending into the lobule)

Question 37

What is Idiopathic acute hepatic disease of horses?

(“serum hepatitis”, “Theiler’s disease”)

Answer 37

• Acute hepatic failure 4-10 weeks after receiving an equine serum product
  
  • Frequently tetanus anti-toxin
• Some cases occur without exposure to a serum product
  
  • Type III hypersensitivity
  • Theiler disease-associated virus
• Centrilobular to massive hepatic necrosis
• Acute disease is associated with anorexia, encephalopathy and icterus
  
  • more chronic forms may also occur
• Mortality is typically high
  
  • >50% for acute form

Question 38

What is Feline lymphocytic cholangitis?

Answer 38

• A syndrome of cats with an uncertain cause
• Lesion:
  
  • lymphoplasmacytic cholangitis and bile duct hyperplasia
• Affected cats are chronically icteric and unthrifty
• Possibly immune-mediated
• Lymphosarcoma is the major differential diagnosis

Question 39

What is Canine vacuolar hepatopathy?

Answer 39

• Relatively commonly diagnosed syndrome in dogs
  
  • Hepatocytes contain excess glycogen
• Associated with hyperadrenocorticism, exogenous corticosteroids, chronic stress, inflammation or neoplasia
• Prognosis depends on underlying cause
  
  • Most are relatively benign
  • Hepatocutaneous syndrome (“superficial necrolytic dermatitis”) is an exception, which is progressive and usually fatal
    
    • Vacuolar hepatopathy with hypo-aminoacidemia and superficial necrotic dermatitis
    • Usually associated with diabetes melitus

Question 40

What are the fatty liver syndromes?

Answer 40

• Bovine fatty liver
  
  • White liver disease o sheep/cobalt B12 deficiency
• Ketosis/pregnancy toxemia of ruminants
• Hepatocellular steatosis of ponies and donkeys
• Feline fatty liver syndrome

Question 41

What is feline fatty liver syndrome?

Answer 41

• A syndrome of overweight/obese cats
• Lesion: severe hepatic lipidosis
• Usually triggered by a stressful event that induces anorexia
  
  • Excessive fat mobilization results in formation of ketone bodies and dyshomeostasis of fat and carbohydrate metabolism
• Often need to feed through a gastric tube until the cats stars eating again

Question 42

What is Bovine fatty liver syndrome?

Answer 42

• Most common is periparturient period due to high energy demand
• Can be predisposed by anything resulting in anorexia
  
  • mastitis, metritis, parturient paresis, displace abomasum
• Most common in well conditioned animals (obese)
• Due to increased fat mobilization and sometimes decreased hepatocyte function (decreased lipoprotein formation and export)

Question 43

What is Ketosis?

Answer 43

• High energy needs (Glucose, fats, proteins) usually at peak lactation in cattle and periparturient in sheep
  
  • Pregnancy toxemia in sheep
• Ketosis is the result of formation of excessive ketones via excessive fat metabolism
  
  • Oxidation of esterified fatty acids (fatty acyl CoA) result in formation of ketones (acetoacetic acid and B-hydroxybutyric acid)
• Fatty liver due to high fat mobilization from peripheral tissues

Question 44

What is Pony/Donkey lipidosis

Answer 44

• Often in obese ponies, following stress or anorexia
• Often during periparturient period
• Hyperlipidemia

Question 45

What are Cholelithiasis?

Answer 45

• Gallstones
  
  • formed from constituents of bile
• Uncommon in domestic animals

Question 46

What is cholecystitis?

Answer 46

• Inflammation of the gall bladder
• Commonly infectious in origin
  
  • Salmonella enteritidis serotype dublin in cattle

Question 47

What is a gall bladder mucocele in dogs?

Answer 47

• Accumulation of thick, mucin-containing bile
  
  • Musus hypersecretion often with cystic mucosal hyperplasia
• Results in gallbladder stasis and bile duct obstruction
  
  • Decreased motility or dysmotility
• Expansion of the gall bladder can lead to necrosis, cholecystitis, bile peritonitis and infection
• Multiple predisposing factors
  
  • Age, endocrine disease, hyperlipidemia/hypercholesterolemia, dysmotility, cystic hyperplasia
• Genetic basis in some species
  
  • Shetland sheepdogs, Miniature schnauzers, Cocker Spaniel
  • Mutation in the ABCB4 (MDR3) phospholipase flippase transporter gene
• Clinically acute, but may have vague episodic symptoms for months
  
  • Vomiting, abdominal pain, icterus, diarrhea, fever, tachycardia/tachypnea
    *