Ketosis

Question 1

Describe the pathogenesis of ketosis

Answer 1

Cow in negative energy balance (often reduced DMI towards the end of pregnancy)
Cow mobilises body fat reserves (NEFAs to the liver)
Most fatty acids that enter the liver are partially oxidised to form acetyl-CoA, which can enter the TCA cycle, but during prolonged fasting acetyl- CoA is converted to ketone bodies.
Fatty liver syndrome - cow cannot fully metabolise this amount of fatty acids, so fat storage occurs in the liver. There is not enough glucose so fat mobilisation continues.

Question 2

Which cows are at highest risk of ketosis?

Answer 2

All dairy cows in first six weeks after calving
Risk increases with parity
Cows with a high BCS (over/= 3.75/5)
Management factors (insufficient access to feed)
Lactating cows with subclinical ketosis (high serum BHB) are at greater risk of developing clinical ketosis
Some specific genetic markers have been identified

Question 3

Clinical signs of ketosis

Answer 3

Sudden milk drop/failure to increase milk production in early lactation
Reduction in appetite especially concentrate portion
Form dung/constipation
Normal/subnormal temperature
Pear drop smell on breath (acetone)
Sometimes neuro signs e.g. agitation/vocalisation/manic licking
Lethargy
Empty-appearing abdomen

Question 4

Differentials for ketosis

Answer 4

LDA/RDA
Mastitis
Metritis
Digestive disorders
All of these can occur with clinical/sub clinical ketosis

Question 5

Treatment for ketosis

Answer 5

Drench with propylene glycol
300ml/day for 3-5 days
Propylene glycol = precursor of glucose
Treatment aim is to re-establish normoglycaemia and reduce serum ketone bodies

Question 6

Prognosis and expected response to treatment for ketosis

Answer 6

Both good

Question 7

How to control/ prevent ketosis

Answer 7

Can test for NEFAs (indicator of fat mobilisation)
Can actively test blood/milk in early lactation
Ensure good dry matter intake to reduce negative energy gap
Selectively cull cows with a history of metabolic disease

Question 8

How to diagnose ketosis?

Answer 8

Based on clinical signs
Measurement of ketone body concentrations via blood/milk/urine
Blood BHB measurement (>1.2mmol/L indicates hyperketonaemia)
Elevated ketone body concentration indicates disease severity regardless of whether clinical signs are observed

Question 9

Autopsy findings - Ketosis

Answer 9

Ketosis is unlikely to result in death but it is a risk factor for increased severity/poor recovery from other conditions e.g. DA correction, metritis
PM findings: excessive body fat esp on omentum and kidneys; pale, swollen, friable liver
Histopath findings: confirmation of fatty liver