Hyperlipaemia

Question 1

What is hyperlipaemia? What is the difference with hyperlipidaemia?

Answer 1

• Hyperlipaemia - Defined as serum triglycerides >5 mmol/L with grossly lipaemic plasma
• Hyperlipidaemia - increased triglycerides but <5mmol/L WITHOUT grossly lipaemic blood or fatty infiltration of liver

Question 2

Why does hyperlipaemia occur?

Answer 2

• Negative energy balance -> Increased calories out compared to calories in
• See increased mobilisation of fat
• Leads to increased triglycerides in blood
• See low glucose and depleted glycogen stores
• Increased lipolysis of adipose tissue -> fatty acids released into blood
• Liver converts fatty acids to ATP (via tricarboxylic cycle) or back to triglycerides (stored in liver or released into blood as VLDL)
  
  • Ponies and minis are very efficient at secreting VLDLs and have larger diameter VLDLs with greater triglyceride concentrations
• If triglyceride synthesis exceeds VLDL synthesis then see hepatic lipidosis -> hepatic failure +/- rupture

Question 3

What hormones are involved in hyperlipaemia?

Answer 3

**Hyperlipaemia **
- increases hormone sensitive lipase - important for increasing lypolysia and free fatty acids
- Reduces lipoprotein lipase whereas we would want it to increase because it reduces lypolysis and puts triglycerides back into lipid tissue

Insulin would be very helpful in hyperlipaemia
* Inhibits hormone sensitive lipase
* Reduces lipolysis
* Activates lipoprotein lipase
* Stimulates gluconeogenesis

But we often see
**Insulin resistance **
* EMS
* Ponies
* Reduced sensitivity in donkeys
* Steroids, catecholamines, ACTH oppose insulin

Azotaemia
- Inhibits lipoprotein lipase
- can see hyperliapaemia secondary to kidney disease

Question 4

What are risk factors for hyperlipaemia?

Answer 4

• More common in miniature horses, donkeys and ponies
• Obesity and stress are precipitating factors
• May have recent history of weight loss
• Increased risk if pregnant or lactating
• Underlying disease very common eg colitis, parasites, PPID, sepsis

Question 5

What clinical signs are associated with hyperlipaemia?

Answer 5

• Inappetance KEY
• Others -> icterus, weakness, depression, recumbency
• Can develop hepatic failure and colic

Question 6

How is hyperlipaemia diagnosed and monitored?

Answer 6

• Triglycerides
  
  • Normal triglycerides <1mmol/L although can be higher in healthy donkeys and pregnant pony mares
  • Hyperlipaemia - >5 mmol/L with grossly lipaemic plasma
  • Hyperlipidaemia - 1- 5mmol/L without lipaemic plasma
• May have increased liver enzymes
• Abdo US - may have fatty infiltration of liver

Question 7

How should you treat hyperlipaemia?

Answer 7

• Need to provide calories
  
  • Enteral
    
    • Needs working GIT
    • Free choice (buffet to encourage them), syringed or NGT
  • Parenteral - when gastro tract isn’t working or when horses don’t tolerate getting tube fed
    
    • 50% dextrose +/- amino acids (5-10kcal/kg/day)
    • Monitor blood glucose
    • May need insulin
• Eliminate stress
  
  • Wean suckling foals
• Treat any other diseases
  
  • Analgesia important
  • Treat SIRS/sepsis
• Treat hepatic failure if present
• Increase triglyceride uptake
  
  • Heparin potentiates LPL but already at maximum

Question 8

What is the prognosis of hyperlipaemia?

Answer 8

• Mortality 60-100%
• Death often due to underlying disease
• Better outcomes in miniature ponies

Question 9

How can you prevent hyperlipaemia?

Answer 9

• Identify at risk BEFORE they become hyperlipaemic
• Provide adequate calories to hospitalised animals