NADIS disease bulletins are written specifically for farmers, to increase awareness of prevalent conditions and promote disease prevention and control, in order to benefit animal health and welfare.

Farmers are advised to discuss their individual farm circumstances with their veterinary surgeon.

Fatty Liver Syndrome

What is Fatty Liver?

Fatty liver syndrome is the accumulation of fat within the cow's liver. The dairy cow does not normally store fat in the liver, so fatty liver does not occur when a cow increases its body condition and puts fat on its back. Fatty liver occurs as a result of the cow breaking down too much fat for the liver to process properly, the broken down fat products are then converted back to fat in the liver to prevent them becoming toxic. Thus the liver becomes fat when the cow is losing condition, the more loss in condition the more fat in the liver. Fatty liver syndrome (> 20% fat) reduces liver function, depresses appetite and milk yield, increases the risk of diseases such as RFM, metritis and mastitis, reduces fertility, and when severe (when it is usually called fat cow syndrome) can lead to death. Once it is deposited in the liver, the concentration of fat in the liver does not fall until the cow gets into positive energy balance, which can be over ten weeks after calving, particularly if the fatty liver is severe. Fat cows (>BCS 3.5) are much more prone to fatty liver

Causes of Fatty Liver --

Fatty liver, ketosis and displaced abomasum are closely interconnected. Cows which have one of these conditions are much more likely to get another.

The most important cause of fatty liver is negative energy balance

Clinical Signs

High incidence of diseases such as milk fever, ketosis, mastitis after calving

Reduced fertility

Rapid weight loss after calving particularly in cows that were fat at calving

Reduced milk yield (often on a herd basis)

Diagnosis

Clinical signs

Blood samples: increased NEFA (free fatty acids), increased ketones (such as beta-hydroxy butyrate), increased liver enzymes

Liver biopsy: this the best diagnostic test

Treatment

Use the same treatment as for ketosis: Glucose, propylene glycol, corticosteroids

However treatment is often ineffective

Prevention is far more important

Prevention and control

Fatty liver occurs because of too much fat breakdown after calving. This occurs primarily in cows that are too fat at calving. Therefore ensuring that cows calve at a body condition score between 2.5 to 3.0 will significantly reduce the risk of fatty liver. Cows should be dried off at a body condition score of 2.5 to 3.0 and maintain their body condition during the dry period. Any alteration of body condition score is best done during mid to late lactation

Richard Laven PhD BVetMed MRCVS