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Milk fever, what it is & how to prevent it.

Updated: Nov 20, 2023

sleeping cat

Milk fever, also called Eclampsia refers to the condition Hypocalcaemia (low blood calcium). Under normal conditions calcium is absorbed from food and stored in the bones for later use, a healthy balanced diet ensures there are plenty of stores available when needed with hormones responsible for maintaining balanced calcium levels in the blood. As the Bitch or Queen begins to produce milk her demand for calcium increases greatly, under normal conditions this would trigger the parathyroid gland to produce the parathyroid hormone which acts to draw calcium from the bones as needed to rebalance blood levels. If there is insufficient calcium available in the bones or insufficient hormone to extract the calcium then blood calcium levels will continue to drop, and symptoms of milk fever will present.

Initial signs that milk fever is developing may be a general loss of interest in the pups, restlessness or nervousness. Calcium is responsible for stabilising nerve and muscle cells, as levels drop the muscles contract continuously and muscle spasms develop throughout the body, without immediate intervention and treatment with IV calcium the pet is likely to slip into a coma with death the likely outcome.

To meet the needs of lactation the bitch or queen needs a good store of calcium in her bones which comes from a lifetime of a healthy diet, if these stores are not present then it would not be wise to use her for breeding as there are likely to be many other deficiencies and health issues stemming from the poor diet. If the owner insists on breeding from her then artificial supplementation will undoubtedly need to occur throughout lactation to meet her daily calcium needs and prevent milk fever.

For those on a healthy, balanced diet leading up to their pregnancy, with healthy calcium stores in their bones, minor adjustments to increase these stores during pregnancy are relatively straightforward with an increase in the ratio of digestible bones and supporting nutrients to provide a more nutrient dense growth diet. As the expected delivery date approaches, removing the digestible bones from the diet will result in a manageable drop in blood calcium levels and naturally trigger the parathyroid gland into action releasing the hormone, rebalancing blood calcium levels. With delivery of the puppies or kittens milk production begins, the parathyroid gland continues to work to stabilise blood calcium levels. To ensure the available stores are not depleted digestible meaty bones return to the diet within a few days of delivery. It is the combination of the parathyroid gland function the available calcium stores and the healthy nutrient dense post–delivery diet which will see the bitch or queen through lactation successfully.

A number of factors increase the risk of a Bitch or Queen developing milk fever, even for those with a lifetime on a balanced species appropriate diet. Demands for milk are very high, peaking when the youngsters are around 3-4 old, this is the time of greatest risk to the mum as her calcium needs are at their greatest. If she has had previous litters which have successively depleted her calcium stores and/or she is feeding a large litter, then she may not be able to cope with the high calcium demands at this time. Milk fever, or Hypocalcaemia, is a life-threatening condition which can progress quickly, if there are any concerns regarding the Bitch or Queens blood calcium levels a vet should be contacted immediately.

Dr Ian Billinghurst, Author

If you’re looking for an easy, well-informed read on nutrition, one author worth checking out is Dr Ian Billinghurst with chapters devoted to breeding specific nutrition, the above article is based on the text “Grow your pups with bones.”

The above is provided to inform only, animal breeding involves many complex issues and with an abundance of abandoned animals already available, adoption is recommended.


Billinghurst, I., 1998. Grow your pups with bones. Bathurst, New South Wales: Warrigal Publishing.

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