October 25th, 2023
Hypocalcemia (Milk Fever)
Milk fever is the common name used to describe hypocalcemia in cattle.
Only 1% of the total body calcium is in a form which is immediately available to the cow. Therefore, the cow is heavily reliant on the homeostatic mechanisms involved in regulating blood calcium levels. Parathyroid hormone (PTH), 1,25-dihydroxycholecalciferol (calcitriol) and calcitonin are the key hormones involved in the regulation of blood calcium levels. Immediately after calving, these homeostatic mechanisms are under increased pressure to release calcium from the skeleton and/or increase gut absorption to meet the high calcium requirements of the cow to produce colostrum/milk. These processes take 2-3 days to become fully active, and if these processes fail to meet the cow’s calcium demands in time, hypocalcemia will occur.
Hypocalcemia affects muscular contraction due to the requirement of calcium for membrane stabilization in peripheral nerves, release of acetylcholine at the neuromuscular junction and contraction of muscle cells.
Signs that may be observed in affected cattle include flaccid paralysis of skeletal muscles (resulting in recumbency), flaccid paralysis of smooth muscle (resulting in gut stasis and bloat) and cardiac muscle (reduction in cardiac output). In the early stages, cattle may show signs of stiffness, reluctance to move, and may sway laterally with incoordination and ataxia when forced to move. When in sternal recumbency, a lateral kink (S-bend) in the neck may be observed, and this may then progress to the head turned to the side and resting on the shoulder.
Uterine inertia due to lack of myometrial contractions may lead to dystocia and/or stillbirth and may result in uterine prolapse.
Diagnosis is achieved via clinical examination, pre-treatment blood calcium levels and response to treatment. The severity of the clinical signs are normally related to the severity of hypocalcemia.
Undertake a thorough clinical examination (especially udder, vaginal and rectal examination). It may be necessary to calve the cow, replace a prolapse and/or deal with severe bloat in addition to providing calcium supplementation!
Take a blood sample for measurement of calcium, magnesium and phosphorous levels.
Administer at least 400 ml of 40% calcium borogluconate solution by slow intravenous injection via the jugular vein using a flutter valve. Further calcium supplementation may be required depending on the severity of the case. Over treatment should be avoided and heart rate monitored for bradycardia associated with hypercalcemia.
The cow will need nursing care and may require analgesia as she recovers.
Prognosis is excellent with early intervention but becomes more guarded if treatment is delayed. Secondary factors associated with the downer cow may hinder recovery.
Farms suffering regular milk fever cases should revise their transition cow management and nutrition.
More Information Here
· Calcium and phosphorus metabolism: overview https://www.vetlexicon.com/treat/bovis/freeform/calcium-and-phosphorous-an-overview
· Down cow: overview https://www.vetlexicon.com/treat/bovis/freeform/the-downer-cow
· Lifting cows: overview https://www.vetlexicon.com/treat/bovis/freeform/how-to-lift-cows-safely
· Physiotherapy: overview https://www.vetlexicon.com/treat/bovis/freeform/cattle-physiotherapy
· Magnesium: overview https://www.vetlexicon.com/treat/bovis/freeform/magnesium-an-overview
· Ruminal bloat https://www.vetlexicon.com/treat/bovis/diseases
Content provided from Vetstream's Vetlexicon Bovis
Vetlexicon is the world’s largest peer-reviewed online clinical reference source. All our content is written and peer-reviewed by over 1,000 of the world’s leading veterinarians, ensuring relevance, accuracy and quality.