Metabolic disorders in cattle

- Pathogenesis of milk fever

At calving:

• Large amounts of calcium are removed in colostrum
• Blood calcium drops rapidly

Normally the body responds through:

• Increased Parathyroid hormone (PTH) → mobilizes calcium from bone
• Increased Vitamin D activation → increases gut absorption of calcium
• Increased renal calcium reabsorption

In milk fever:

• Tissue response to PTH is delayed
• Bone mobilization is slow
• Intestinal absorption is insufficient

Result:
Serum calcium drops below 5–7 mg/dl (normal 8-10 mg/dl)

Calcium is activator of acetylcholine which is essential mediator at the neuromuscular junction enhancing muscular contractility, therefore decreased Ca level causes:

• Neuromuscular dysfunction
• Muscle weakness
• Paresis
• Reduced smooth muscle contraction