6.2.3: Ketosis Flashcards
What does subclinical ketosis lead to an increased risk of?
- Clinical ketosis
- RFM
- LDA
- Metritis
- Lameness
- Mastitis
- Culling
- Death
When (and why) does Type I ketosis occur?
- Slightly later in lactation (e.g. 30 days post calving onwards)
- This is at peak lactation
- In the high yielding cow, it is difficult to provide enough energy for peak lactation
- Rarer nowadays as we have improved our rations for these cows
When (and why) does Type II ketosis occur?
- Around calving/early lactation
- Energy requirements increase faster than appetite can keep up
- Most common form of ketosis seen today
What type of ketosis is shown here?
Type II
Yield is increasing faster than food intake
What type of ketosis is shown here?
Type I
This cow is high-yielding and at peak lactation it is difficult to provide her with sufficient energy
This image shows the pathophysiology of which type of ketosis?
Type I
This image shows the pathophysiology of which type of ketosis?
Type II
Describe the pathophysiology of Type I ketosis
- Occurs due to underfeeding, seen at peak lactation
- There is a reduced supply of propionate (source material for gluconeogenesis) and therefore glucose
- There is incomplete oxidation of NEFAs in liver (due to low glucose) that leads to ketone body production
Describe the pathophysiology of Type II ketosis
- Occurs in hepatic lipidosis, early lactation (close to calving, NOT peak lactation)
- Excessive mobilisation of fat -> increased NEFAs
- Incomplete oxidation of NEFA (ketones) and excessive fat accumulation in the liver. There are now so many NEFAs that no matter how much glucose we have, the liver is overwhelmed and can’t keep up.
- Reduced gluconeogenesis (liver inefficient) and liver function
- Metabolic effect of all these NEFAs causes insulin resistance
Type II ketosis is more common in which kind of cows around calving?
Over-conditioned cows! This means there are more fat reserves to mobilise and overwhelm the liver
True/false: there is higher BHB in Type II compared to Type I ketosis.
True - higher in Type II, but probably not used that much clinically to distinguish between the two.
This may be due to the fact that the liver is less efficient.
How can we treat ketosis/hepatic lipidosis?
- Glucose precursor: oral propylene glycol
- Glucocorticoids are sometimes given in practice
- IV glucose can be given to resolve nervous ketosis signs, making the cow stable enough to tolerate a propylene glycol drench
Why can’t we give oral glucose to treat ketosis?
- Oral glucose will be utilised by rumen bacteria and so will not effectively reach the cow and address her NEB.
- Propylene glycol is a glucose precursor that is able to reach the liver and enter the TCA cycle, so the cow can thus obtain glucose.
Diagnostic testing for ketosis
- Blood -> cow-side ketone meter (BHB) or lab
- Urine -> ketone dipstick
- Milk -> Rothera’s reagent (turns purple if positive)
Diagnostic testing for hepatic lipidosis
- Look for ketones (as with ketosis)
- Blood NEFA
- Look for evidence of liver damage e.g. AST, GGT
- Assess fat in liver e.g. biopsy, necropsy