Hepatic Dr Yvorchuck

Question 1

What is the triad of CS for Cholelithiasis in the horse

Answer 1

Colic

Pyrexia

Icterus

Question 2

What is the triad of CS for Pyrrolizidine Alkaloid toxicity in equines

Answer 2

Fibrosis

Bile duct proliferation

megalocytosis

Question 3

what are bw changes seen in hepatic dysfunction in horses

Answer 3

on CBC:

• RBCs = mostly ACD*
• WBC = varies but expected to be elevated as almost alway some infectious component*

in acute dz = leukopenia likely

Fibrinogen = varies depending on timeline & severity

likely hyperfibrinogenemic (chronic)

on Chemistry:

• Glu = possibly hypoglycemic, often hyperglycemic*
• BUN = <10 considered significant for liver dysfunct.*
• Protein = rarely hypoalbuminemic or hypoproteinemic, may see hyperglobinemia d/t chron. inflammatory dz*
• Bilirubin = serum bile aciids (SBA) increased esp chronic/severs dz*

Liver enzymes = SDH, ALP, AST, GGT gives clues as to specific dz process

hepatocellular = SDH -> ACUTE, AST -> Chronic

biliary = ALP -> ACUTE, GGT -> Chronic

Question 4

what is the most useful indicators of liver injury

Answer 4

SDH, GGT & SBA

in the face of significant liver dz at least 1 of the 3 are elevated

SDH = acute liver

SBA = end stage liver

Question 5

what does GGT mean

Answer 5

ductal enzyme denoting biliary dysfunction

also involved in repair phase, not only cell dysfunct. & renal

Question 6

what does GGT elevations in urine indicate

Answer 6

that the GGT is of renal origin not liver (too big to pass through glomerulus)

Question 7

other than liver dysfunction what other reason might you see an incr in ALP in an equine

Answer 7

ALP is also a bone enzyme so it might be elevated in Young Growing horses!

Remember context when interp. BW!

Question 8

When interpreting SDH what is good to remember

Answer 8

That SDH returns to baseline in 3-5 days so can indicate point insult & if shows up again = new insult

Question 9

will horses likely have just hepatocellular or biliary dysfunction

Answer 9

No!

Very rare that will have one or the other exclusively - more likely to have both dz processes concurrently to some degree

Question 10

What should you suspect when you see a triad of CS referable to coagulation, nervous & cutaneous systems

Answer 10

Liver dysfunction

involvement of these 3 systems in a horse think LIVER!

usually not a single horse problem - more likely a “herd” issue think toxins

Question 11

what are 4 clincal presentations (problems) that can indicate liver dysfunction

Answer 11

1. Icterus
2. Hepatic encephalopathy
3. Photosenstization
4. Clotting disorders
5. w or w/o Colic

Question 12

Icterus

Answer 12

conjugated bilirubin causes more pronounce icterus than unconjugated

the pattern of bilirubin elevation helps differentiate b/t

Pre & post-hepatic hyperbilirubinemia

Question 13

how are total bilirubins measure

Answer 13

unconjugated (indirect) = calculated

conjugated (direct) = measured

Question 14

what is elevated direct bilirubin a highly specific indicator or

Answer 14

liver failure

if direct >/= 25% of total -> predominantly biliary disease

Question 15

how commonly is hepatic encephalopathy seen in liver dysfunction

Answer 15

80% of case

d/t accumulation of blood ammonia

must differentiate from idiopathic hyperammonemia:

rare complication of severe GI dz

Absence of markers of hepatic dz.

Question 16

Tx for hepatic encephalopathy

Answer 16

supplement BC AAs

Low protein diet

Question 17

photosensitization

Answer 17

white areas affected

tx symptomatically

Question 18

clotting disorders

Answer 18

not seen frequently compared to other signs

tends to be terminal in horses

PT increases first - shortest T_1/2

Question 19

CS of hepatic dz in horses

Answer 19

Colic - common

Behavior changes - aggression/depression

Ascites - very rare

Yawning

Question 20

how to classify liver pathology

Answer 20

consider acute v chronic = liver insult v liver failure

• liver damage/insult*
• more likely when pre-existing septic, hypoxic, neoplastic or metabolic conditon

increases in liver enzymes, normal liver function tests

• liver failure*
• rare in horse

increases in liver enzymes AND liver function tests

Question 21

most common liver pathology

cause(s)

Answer 21

hepatitis

• toxins: plants or feeds*
• infection*
• choleliths*

most common chronic cause:

megalocytic hepatopathy (PA toxicosis)

Question 22

Tx for liver dx

Answer 22

behavior:

sm.doses of alpha2 agonists if sedation necessary

avoid diazepam

correct acid base disturbances

decr enteric ammonia - neomycin or lactulose

• neomycin can mess up intes. flora use carefully

Decr hepatic workload

dietary mgmt:

• freq small feedings
• < 8% protein hay - no alfalfa
• supplement w/ folic acid, B vits & fat-soluble vits

antimicrobials:

• broad-spectrum
• Pen/Gen/Metro or Enro/metro
• TMS depending on c/s

Pentoxifylline for inflammatory a/o fibrosing liver dz

Question 23

Px for liver dz

Answer 23

dependent on dz

poor if:

low alb, incr glob or both

PT 30% longer than normal

lg incr GGT, ALP w/ norm or decr SDH w/ incr SBA

terminal signs: hemolytic crisis, encephalopathy w fibrotic liver