Hypocalcaemia / Milk fever

Hypocalcaemia, or milk fever, occurs in cattle, sheep and goats. It is most common in high producing or dairy-cross cows and in milking goats. Clinical signs develop when serum calcium levels fall below a critical level (hypocalcaemia).

Affected animals are initially excited or agitated with muscle tremors, then go down and are unable to rise.

Conditions when hypocalcaemia is likely to occur

• property history of hypocalcaemia
• in cows greater than five years old, in does greater than four 4 years old and in ewes
• late pregnancy and also after calving in dairy cows
• high producing and dairy-cross cows
• cows with a history of hypocalcaemia
• alkaline diets high in sodium and potassium, and low in sulphate and chloride
• low calcium intake after calving and high intake before
• low roughage intake
• heavy grain feeding of sheep
• fat cows with a fat score of 3.5 or greater.

Identification and diagnosis

Clinical signs that would lead you to suspect hypocalcaemia include:

• tetany, unable to rise, dry muzzle
• ewes cast after handling, often with hind legs behind
• response to treatment with calcium borogluconate
• blood samples can also be collected to determine serum calcium levels

Prevention

An integrated approach to prevent hypocalcaemia should consider the following:

• avoiding over-fattening cows
• ensuring constant access to feed during calving
• avoiding grazing high-risk pastures as per grass tetany
• feeding hay before calving. Using the Health Cost Benefit Calculator to determine the cost-benefit of the this option
• keeping calcium intake to less than 50g/day before calving
• feeding as much calcium as possible after calving. Clover-dominant pasture is one way to do this
• avoiding handling of heavily pregnant ewes
• lowering the herd/flock age structure as older cows, does and ewes are higher risk.