Liver Flashcards
Why does the horse have continuous bile flow into the duodenum
horses do not have a gall bladder
what are the function of the liver
Metabolic, secretory, excretory & storage
- Protein metabolism - AA delivered from the GIT to liver
- AA catabolism
- Lipid metabolism
- detoxification
- mononuclear phagocyte system
- Vit A,D, B12, cu, Fe
Why is it difficult to pick up liver failure in the early stages of disease
Varies greatly and are often non-specific
Hepatic insufficiency
- inability of the liver to maintain adequate normal function
Most functions are not impaired until 80% functional hepatic mass it lost making it very diffcicult to pick up disease in the early stages
What are the main clinical signs seen with hepatic disease in horses
weight loss Deppression anorexia Icterus/jaundice Hepatic encephalopathy signs of abdominal pain colic
what are some of the less common CS of hepatic disease
Photosensitisation Fever; inflammation +/- infection haemorrhage: typically only seen in end stage liver disease ascites or oedema Diarrhoea Bilateral laryngeal paralysis
Describe the aetiology of Hepatic encephalopathy
Not the primary disease it is a clinical manifestation of a disease
Complex clinical syndrome - CS result in neuronal inhibition
Severity of neurological signs corresponds to degree of hepatic dysfunction but not type or reversibility of hepatic disease
What are the 5 different proposed mechanism for hepatic encephalopathy
- Gastrointestinal derived neurotoxins (increased plasma ammonia)
- Altered amino acid metabolism
- Augmented GABA activity in the brain (diazepam contraindicated as enhances the effect of GABA)
- Increased permeability of the blood brain barrier
- Impaired CNS energy metabolism
What are the liver enzymes that can be used to detect Hepatobiliary
Gamma-glutamyl Transferase (GGT)- most sensitive indicator for liver disease
- Microsomal membrane protein found in epithelial cells of the biliary tract, renal tubules, mammary gland and pancreas
- Increased in blood GGT - specific for cholestasis - increase in urinary GGT = damage to renal tubular epithelial cells
what is an indicator of hepatobiliary leakage
AST - not specific for liver disease (can be very high your muscle trauma)
- Cystolic enzyme present in all cells in body
- Highest concentration in skeletal muscles & hepatocytes but also found cardiac mycocytes, erythocytes and enterocytes
Increases are non specific for liver disease
SDH - cytosolic enzyme released during acute hepatocellular necrosis or changes in hepatocyte membrane permeability
==> increases in blood are highly specific for hepatocellular injury
what is the most common cause of indirect reacting Hyperbilirubinaemia
unconjugated bilirubin - albumin bound
the most common cause is anoerexia
Liver failure
Haemolytic anaemia
what are the 3 most common reason for unconjugated bilirubin increase
increased in production
decrease hepatic uptake
decreased conjugation of bilirubin
increased conjugated bilirubin (direct reacting)
intrahepatic cholestasis
Extrahepatic bile duct obstruction
what are the the common causes of increased conjugated bilirubin
Liver failure
cholestheiasis
cholangiohepatitis
Blood ammonia
Very good indicator of liver functions
Toxic by product of amino acid metabolism produced in all tissues and by microflora in the GIT
Absorbed by hepatocytes and used to synthesise non essential AA - converted into urea in hepatocytes = BUN (excreted by kidneys)
Increased plasma ammonia = reduced liver function
Great in principle need a good lab to run often not possible
Serum bile acid
Produced and excreted by hepatocytes from cholesterol
Most sensitive and specific test of liver function: hepatic blow flow, removal from circulation, conjugation, excretion
Increases within 24-48 hours of onset of liver disease- highest in biliary obstructed liver disease
where is the liver located on your right side
9-14 intercostal space mid abdoen
surrounded by vital structures
where is the liver located on your left side
4-7th intercostal space ventral
on ultrasound liver should be hyopechoic (blacker) compared to the spleen
what are the principles of treatment of liver disease
Supportive care - aim to maintain patient until liver regenerated and regains function
antimicrobirals - often due to cholestasis
hepatic encpehalopathy
Nutritional suport
Antiinflammatories
what types food should be given to a horse with liver disease
Diet high in branches chains of amino acids and readily digestible CHO in multiple small feedings
Minimise intake of proteins and aromatic AA= avoid lucerne hey & legumes
what is the prognosis for horses with liver disease
Liver has significant ability to regenerate (fibrosis =poorer prognosis)
depends on severity and duration of underlying disease
Trend of decreasing bile Acids & GGT = better prognosis
What is the aetiology of theilers disease
Acute hepatic necrosis, serum hepatitis
Sporadic cause of acute and rapidly progressing hepatic failure (2-7 days)
How do you diagnose theilers disease
History of equine-origin biological admin 4-10wks prior (TETANUS)
HistopathOLOGY - centrilobular to midzonal hepatocellular necrosis
What is the difference b/w primary and secondary hepatic lipidosis
1- no underlying disease present
2- secondary to any other concurrent disease process = more common (any disease that results in negative energy balance)
what are the clinical signs of hepatic lipidosis
Often acute onset ==> hepatic +/- renal dysfunction
Initial signs are mild and vague - high index of suspicion in susceptible breeds and circumstances
initial - depression, lethargy, inappetance, icterus
mild to progressive - reluctance to move
late - hepatic failure, recumbent, altered mentation
