Clin Med - Equine Liver

drraythe's version from 2016-03-15 11:37


Question Answer
What is different about the horse's hepatic system which czs some special things?THEY LACK A GALL BLADDER
*Bc horses lack a gall bladder, what are 3 hepatic quirks which would be ABNORMAL in other animals but are NORMAL in horses?(1) Continually secrete bile
(2) 10% of horses normally MILDLY icteric
(3) Plasma always yellow
If you see icterus, what are you thinking?PRE-HEPATIC
*What can happen if there is anorexia in a horse? Why?CAN BE ICTERIC...probably bc of reduced uptake of the bili
**How can you tell the difference btwn icterus from anorexia & pathological icterus? (2)(1) Bilirubin never > 6mg/dL if due to anorexia (if ↑er, bc of pathology)
(2) It will go away if they are fed
What can ammonia tell you about a horse?Unique for CS of equine liver dz! Bc it is normally produced in large volumes in the colon by bacteria & in a healthy horse is removed by the liver (so levels rise in liver dz)
What does head pressing tell you? (3 possible czs)Can indicate Hepatic encephalopathy, ↑ ammonia levels & maybe ataxia. (Pathophysiology unclear)
What does the liver metabolize, which if there is dz & it cant, lead to photosensitization?Phylloerythrin metabolism
Explain what Phylloerythrin is & does & what it says about the liverPhylloerythrin is ingested from normal plants in diet. Usually it is metabolized by the liver. If it isn't metabolized & eliminated due to liver dz, it builds up in the skin & czs photosensitization
Photosensitization happens when what happens, usually is seen where & looks like what?When there are photodynamic pigments in the skin (usually phylloerythrin that the liver was unable to metabolize/elim) & the damage usually occurs on areas w/ white or no hair. It appears as Erythematous, scaling, necrotic
How would you describe the lipid metabolism of a horse?ITS LIKE A CAT!
Hyperlipidemia can indicate...Liver dz
Who is most prone to hyperlipidemia?Miniature horses
(All breeds can be affected tho)
What can start the slippery slope of hyperlipidemia & what happens which might result in a FATALITY??Usually begins as a sequale to a 1° dz, or some other reason for a negative energy balance → leads to FAT MOBILIZATION → the liver is overwhelmed w/ fat = HEAPTIC LIPIDOSIS → Abnormal VLDLs produced bc of liver unable to handle it all → lipid accumulation in the blood → can be fatal
If you were worried about hyperlipidemia in mini horses, ponies & donkeys, what blood thing would you measure?Triglycerides are measured (cholesterol is useless tho) ((bc it's abnormal buildup of VLDL which is measured as a triglyceride not a cholesterol)
**For a HORSE, what is the BEST enzyme indicative of hepatocellular damage?SDH (L-sorbose 1-dehydrogenase)
**What is SDH? What is it good for? What must you be aware of?This is an ENZYME which is the BEST indicator for hepatocellular damage in horses (SDH wont rise for any other reason). (Shit! damn hepatic). It will be very ↑ in acute liver damage, but may ↓ in chronic. Also, note that it is very volatile so you need to run the test quickly
**What is GGT? What does it tell you?Enzyme which is the best indicator of cholestatic dz
**Which enzyme is the best indicator of cholestatic dz?GGT
What do AST & ALP tell you & what should you know about them?They are LESS SPECIFIC than SDH & GGT.....however, AST will indicate hepatocellular damage & ALP will indicate cholestatic damage
How accurate is fasting bile acids w/ a horse?Trick question-this is pointless, bc horses have no gall bladder!
What chem things can you measure which can indicate liver dz?Ammonia & triglycerides
What imaging can you use to explore liver dz?Can use ultrasound... NO RADS
How would you have to do a liver biopsy in a horse?Standing & under light sedation

Cases (Useful!!)

Question Answer
(icterus is usually present 1st where?)Vulva
***If a horse is like, crazy peeing orange, what dx test would you want to do 1st?CBC, serum chemistry panel & urinalysis (NOT Abdominocentesis or Liver ultrasound & biopsy)
When doing a urinalysis, what cant you do?Cant use test strip w/ horses
What should you know about moldy hay?Moldy hay can have aflatoxins, which is a Mycotoxin produced by various fungi (Aspergillus, Penicillium, Rhizopus, Mucor, Streptomyces..) that grows on grains, beans, grass, hay. The toxin is activated in the liver which it then damages
Explain how aflatoxin damages the liverToxin activated in liver → Binds enzymes
Prevents protein synthesis
alkylates DNA → hepatocytes also can't divide properly
Aflatoxicosis → is this usually an individual or herd prob?Herd-everyone's eating the same hay/pasture usually
Explain how aflatoxicosis CSs can varyBased on AMOUNT CONSUMED
Explain how acute, subacute & chronic aflatoxicosis presents(Depends on amount consumed!)
Acute = Hemorrhagic diarrhea, sudden death
UBACUTE = Hepatic failure, icterus, anorexia, weakness, tremors, abortion, death. Chronic = poor growth, ill thrift, liver damage
How do you dx aflatoxicosis?You test the feed-no such thing as a tox screen!!
What does Histopathology of aflatoxicosis look like?Centrilobularnecrosis
Biliary hyperplasia
Nodular regeneration
How do you Tx aflatoxicosis?Stop feeding them the mold, supportive
If you get an ultrasound of a horse liver & you see a HUGE biliary tree, All ducts distended & Multiple small calculi visible, what do you think?Cholelithiasis
Biliary calculi are usually made of what & affect what age of horse?Made of Calcium bilirubinate, Middle aged horses 6-15 years
CS of biliary calculi?Icterus
Weight loss
What lab tests would show up abnormal for a biliary calculi?GGT ↑!!
↑ bile acids
Non-septic peritonitis

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