Icterus in Horses

Question 1

What is important to remember about a horses biliary system? How does this affect bile acid analysis?

Answer 1

They have no gall bladder and thus secrete bile acid constantly. Therefore there is no need to take two measurements for bile acids.

Question 2

How common is pre-heatic icterus in horses?

Answer 2

Relatively uncommon

Question 3

What can cause heamolysis in horses?

Answer 3

Neonatal isoerythrolysis
EIA
drugs
Toxins
Autoimmune HA

Question 4

What are common hepatic reasons for icterus in horses?

Answer 4

ANNOREXIA, acute hepatocellular disease

Question 5

What is uncommon post-hepatically in horses?

Answer 5

Shunts

Question 6

When should one think about liver disease in an icteric horse?

Answer 6

When it is still eating, not a foal and not pale.

Question 7

What are the main clinical signs of liver failure in horses, are they specific?

Answer 7

Depression and annorexia - non specific

Colic - hepatocellular swelling, biliary obstruction (often will see a mild colic)

Weight loss

Question 8

What is a cardinal sign of HE in horses?

Answer 8

Head pressing

Question 9

What is the cause of photosensitization in icteric horses?

Answer 9

Phylloerythrin is no longer conjugated and excreted by the liver. Cells are then more responsive to UV

Question 10

What needs to be done to diagnose liver disease?

Answer 10

Clinical signs
Bloods
Ultrasound
Biopsy

Question 11

What tests are specific for the liver?

Answer 11

Increased bile acids
Increased SDH
Increased GGT

Question 12

Why is abdominal ultrasound not that helpful in diagnosing liver disease?

Answer 12

It can only view ~20% of the liver as most of the liver is covered by lung tissue.

Question 13

What can findings from a hepatic biopsy be used for?

Answer 13

Dx, Px, Treatment

Question 14

What are the general principles of liver disease treatment in horses?

Answer 14

Suportive - maintain liver until regeneration. If fibrosis is severe this is less likely :

• Fluids/Acid base
• Glucose
• ABs????
• Anti-inflammatories

Question 15

What are the priniciples of HE treatment?

Answer 15

• Sedate
• Mannitol/hypertonic saline - brain oedema
• Oral lactulose - limitis ammonia absorption
• Oral BCAAs (no evidence of efficacy)

Question 16

What antiinflammatories can be used in liver disease? What should be remembered with corticosteroid use?

Answer 16

NSAIDs
DMSO
Cortico - link between these and laminitis
Pentoxifylline

Question 17

What is the pathogenesis of Pyrolizidine alkaloid toxicity?

Answer 17

Meabolized by liver to toxic pyrrole derivatives . These are antimitotic and xlink DNA and bind to nucleic acid and proteins within hepatocytes. Cells cant divide and become megalocytes which will die and fibrose.

Question 18

What can cause cholelithiasis?

Answer 18

parasites
Ascending biliary infection/inflammation
Biliary stasis

Question 19

What clinical signs are strongly suggestive of cholelithiasis?

Answer 19

Fever+Icterus+Colic

Question 20

How is cholelihiasis diagnosed?

Answer 20

Liver enzyme activity, ggt, shd, ast

Ultrasound (maybe)

Biopsy

Question 21

How is cholelithiasis treated?

Answer 21

Antimicrobials
Suportive care
DMSO
Anti-inflammatoris
Others

Question 22

When should hyperlipeamia be strongly suspected?

Answer 22

Obese pony breeds/ minature horses.

Question 23

What causes hyperlipaemia?

Answer 23

Negative energy balance

Question 24

How does hepatic lipidosis differ in horses compared to cats?

Answer 24

Horses very good at producing TGs and these are over produced so build up

Question 25

How can HL be diagnosed?

Answer 25

Breed
History
Clinical signs
Serum TGs
(liver biopsy)

Question 26

What are the principles of hyperlipaemia treatment?

Answer 26

1.Reverse te NEB
2.Treat hepatic disease
3.Eliminate stress/primary disease treatment
4. Inhibit fat mobilisation (insulin)
5.Increase uptake by peripheral tissues
(heparin - although likely that lipoprotein lipase is already maximally active)