Dog - Hypocalcaemia - Eclampsia or Milk Fever

What is hypocalcaemia?

Hypocalcaemia means low circulating blood calcium. It is most commonly seen with eclampsia, or so-called milk fever, which may occur in bitches at any time during lactation or sometimes immediately before they whelp. However hypocalcaemia can occur due to other causes.

Why is calcium important?

Calcium is one of the most important minerals in bone. It is also of major importance in the transmission of nerve impulses and in muscle contraction.

How is low blood calcium diagnosed?

A simple blood test will reveal the total amount of circulating calcium (normal 2-3 nmol/l). Approximately 40% of this is free calcium whereas the remainder is bound with certain circulating proteins, mainly albumin, and is unavailable for use by the body.

What causes hypocalcaemia?

By far the most common cause is during lactation when milk production may make such a demand on circulating blood calcium that it falls to a dangerously low level and eclampsia develops. This involves muscle trembling and twitching, a stiff gait, panting and ultimately convulsions and death. This is an emergency situation and immediate treatment is required with special intravenous calcium supplements.

There are also other causes of low blood calcium:

1. Reduced intestinal absorption of calcium due to the lack of Vitamin D or inadequate dietary intake.
2. Chronic renal failure. This is a complicated process involving loss of both phosphate and calcium.
3. With some dogs acute pancreatitis can lead to hypocalcaemia as a secondary complication.
4. Low blood albumin. Provided the free calcium in the blood is unaffected, this is usually without symptoms (asymptomatic). If the low blood albumin (hypoalbuminaemia) is due to actual albumin loss a symptomatic hypocalcaemia may be evident. This occurs in certain kidney diseases (e.g. nephrotic syndrome) and bowel problems (e.g. protein losing enteropathy).