Icterus Flashcards
Define Icterus
Hyperbilirubinaemia - excess bilirubin in the blood
Newly formed _______ bilirubin is ______ and binds to _____
unconjugated - insoluble - albumin
What do hepatocytes conjugate bilirubin with to make it water soluble?
Glucuronic acid
What is the main cause of pre-hepatic icterus?
Haemolysis - conjugation and uptake of bilirubin into liver overwhelmed
What is the main cause of hepatic icterus?
Poor uptake - conjugation and excretion of bilirubin in hepatocytes overwhelmed
What is the main cause of post-hepatic icterus?
Cholestasis
What GIT signs give you a clue towards icterus?
Vomiting, diarrhoea, acholic (white) faeces, melaena (dark sticky faeces), ascites (abdominal effusion)
What Neurological signs give you a clue towards icterus?
Personality change, head pressing, ptyalism (excessive saliva), head pressing, disorientation, seizures, stupor
What Renal and Urinary changes give you a clue towards icterus?
PU/PD, stranguria (difficulty urinating), bilirubinuria
Give an example of differential diagnosis for pre-hepatic icterus in small animals
Immune Haemolytic Anaemia - Babesia infection - Toxins
Give an example of differential diagnosis for hepatic icterus in cats
Suppurative cholangiohepatitis - Lymphocytic plasmacytic hepatitis - Hepatic lipidosis - Feline infectious peritonitis - Toxins - Neoplasia
Give an example of differential diagnosis for hepatic icterus in dogs
Acute liver disease - Leptospirosis - Chronic hepatitis - Neoplasia
Give an example of differential diagnosis for post-hepatic icterus in small animals
Pancreatitis - Neoplasia - Cholelithiasis (stones in bile duct)
How would you differentiate between pre-heptic and hepatic icterus?
Packed Cell Volume (PCV) test and Total Solids (TS)
Pre = low PCV, normal TS
Hepatic = normal PCV, low TS (IF albumin production affected)
How would you differentiate between hepatic and post-hepatic icterus?
Imaging - X-rays, radiographs, ultrasound
Liver _____ elevations are common in small animals, mostly _____ ______ to hepatocytes
Enzyme - reversible damage
Name the significant liver enzymes
ALT (specifically liver) - AST (present in muscle and intestines) - AP (biliary duct cells)
What would idicate liver failure on a chemistry profile?
Low albumin - low cholesterol - low glucose - low BUN (blood urea nitrogen)
What is usually elevated in liver failure or portosystemic shunts?
Bile acid levels
What is hepatic encephalopathy? Give a clinical sign of it
NH3 and aromatic AA go directly into blood and exposed to the CNS - neurological problems or urate stone formation
What is the pathogenesis of hepatic encephalopathy?
Increased ammonium in blood - decreased ability to convert uric acid to allantoin in liver so more urate excreted in urine
In horses, what protein is responsible for unconjugated bilirubin uptake?
Ligandin
How come sometimes animals with liver failure don’t show any obvious clinical signs?
Liver has a large capacity for regeneration
In horse photosensitization, _______ (photodynamic agent) is formed by gut bacteria, absorbed and conjugated by the _____
Phylloerythrin - Liver
How can liver dysfunction cause photosensitization?
Increased levels of phylloerythrin cause UV light to be absorbed more efficiently causing damage and necrosis to non-pigmented areas
Give an example of three substances that will go up in a horses bloodwork when they have liver disease
Bile acids - SDH - GGT
When would bile acids increase in the blood of a horse?
Anorexia and obstructive disease
When does SDH increase in a horses bloodwork?
Acute liver disease
When does GGT increase in a horses bloodwork?
During Cholestasis
How can the diet of a hepatic encephalopathy horse be altered for treatment?
High carbohydrate and limited protein - enough to maintain so as not to cause malnutrition
How does ragwort cause hepatic disease in horses?
Pyrrolizidine alkaloids metabolised by liver to toxic pyrrole - these are antimitotic causing megalocyte production and fibrosis in hepatocytes
Give 5 examples of acute hepatitis in horses
Theiller’s disease - Tyzzer’s disease (bacterial) - Toxins - Viral (equine herpesvirus) - Parasitic (migration)
What is Tyzzer’s disease caused by? What does it do to the liver?
Clostridium piliformis - multifocal hepatitis and enteritis
How can you diagnose choleithiasis in horses?
Liver enzyme activity (increased GGT, SDH, AST) - Ultrasound - Biopsy
What is hyperlipaemia commonly caused by?
Negative energy balance - stress, disease, pregnancy, lactation
What is the pathogenesis of hyperlipaemia in horses?
Increased fatty acid production because of negative energy balance = greater Triglyceride production in liver
