Sudden Decrease in Serum Calcium Levels That Occurs in the Production of Colostrum and Milk in Early Stages of Lactation

  • Also known as milk fever or parturient paresis
  • Can be clinical or subclinical
    • Cows with subclinical do not show clinical symptoms
    • The only way to detect subclinical hypocalcemia is to analyze blood for the concentration of calcium within the first one to two days after calving

Three Stages

Stage 1:

  • Signs of hypersensitivity and excitability
  • Mildly ataxic
  • Fine tremors over the flanks and triceps
  • Ear twitching and head bobbing

If calcium therapy is not instituted, cows will likely progress to the second, more severe stage.

Stage 2:

  • Unable to stand but can maintain sternal recumbency
  • Anorexia, confusion, dry muzzle, subnormal body temperature and cold extremities
  • Auscultation reveals low heart rate and decreased intensity of heart sounds; peripheral pulses are weak, and smooth muscle paralysis leads to GI stasis
  • Inability to urinate
  • Cows often tuck their heads into their flanks – if the head is extended, one may see an S-shaped curve to the neck.

Stage 3:

  • Progressive loss of consciousness to the point of coma
  • Unable to maintain sternal recumbency, complete muscle flaccidity, unresponsive to stimuli and severe bloat
  • Heart rate approaching 120 bpm and undetectable peripheral pulses

If untreated, cows in stage 3 may only survive a few hours.

cows grazing

Differential diagnoses:

  • Toxic mastitis
  • Toxic metritis
  • Other systemic toxic conditions
  • Traumatic injury (stifle injury, coxofemoral luxation, fractured pelvis, spinal compression)
  • Calving paralysis syndrome (damage to the L6 lumbar roots of sciatic and obturator nerves)
  • Compartment syndrome: condition characterized by insufficient blood supply due to increased pressure to tissues that results in pain, decreased ability to move or numbness

Treatment Options

  • IV injection of a calcium gluconate salt, although SC and IP routes are also used. A general rule for dosing is 1 g calcium/45 kg (100 lb) body weight. Calcium is cardiotoxic, so calcium-containing solutions should be administered slowly (10-20 min.) while cardiac auscultation is performed.
  • Oral calcium avoids the risks of cardiotoxic adverse effects and may be useful in mild cases of parturient paresis.

Diet modifications to face the increased calcium demand1:

  • Low calcium diets: To be effective, diets must provide less than 20 g of available calcium.
  • Low potassium forages/diets: Decrease the likelihood of clinical hypocalcemia but not the incidence of subclinical hypocalcemia.
  • Feeding anionic salts for 21 days: Prevent clinical (a five-fold reduction) and subclinical hypocalcemia. Many commercially available anionic mineral- or protein-based supplements are available for use in formulating these diets.
  • Oral sources of calcium: In the form of calcium chloride in gel or paste forms, many oral supplements are absorbed within 30 minutes after administration and blood calcium concentration is increased for four to six hours.
  1. Amaral-Phillips, D. 2016. Subclinical Hypocalcemia, or Milk Fever in Dairy Cows. https://articles.extension.org