Milk Fever of Cows - Hypocalcemia

Milk fever, also known as Parturient paresis, is an acute and afebrile disease of mature cows, occurring a few days before, or mostly just after calving. It is common in imported high yielding dairy cows, especially Jersey and Friesian. Milk fever is not commonly reported in the indigenous stock.

Beginning of lactation of a cow results in the sudden loss of calcium into milk. Serum calcium levels decline from a normal of 10-12 mg/dL to 2-7 mg/dL. The nutritional status of the cow in the dry period is known to influence the risk of the disease. Diets low in dry matter such as lush pastures and diets with high calcium during dry period can predispose the cow to milk fever. Low magnesium in the diet hinders absorption of calcium and hence is predisposing to milk fever. The disease is more risky in cows after third calving and is rare in calving heifers.

Signs

• The first sign of the disease is loss in appetite followed by slight drop in temperature.
• Milk fever usually occurs within 72 hr of parturition. 
• The disease can contribute to dystocia, uterine prolapse, retained fetal membranes, metritis, abomasal displacement, and mastitis.

There are 3 stages of milk fever;

Stage 1; Cows are able to walk, but show signs of hypersensitivity and excitability. They may be mildly lacking coordination and have fine tremors over the flanks and triceps, and display ear twitching and head bobbing. Cows may appear restless, shuffling their rear feet and bellowing. Dull eyes and shivering, constipation is a common feature and sometimes a goose-stepping gait is seen.

Stage 2; Cows are unable to stand but can maintain sternal recumbence. Cows are anorectic, and have a dry muzzle, subnormal body temperature, and cold extremities. Auscultation reveals an abnormally fast resting heart rate and decreased intensity of heart sounds. Peripheral pulses are weak. Smooth muscle paralysis leads to gastrointestinal stasis, which can manifest as bloat, failure to defecate, and loss of anal sphincter tone. An inability to urinate may manifest as a distended bladder on rectal examination. Cows often tuck their heads into their flanks, or if the head is extended, an S-shaped curve to the neck may be noted.

Stage 3; Cows lose consciousness progressively to the point of coma. They are unable to maintain sternal recumbency, have muscle flaccidity, unresponsive to stimuli, and can suffer severe bloat. As cardiac output worsens, heart rate can approach 120 bpm, and peripheral pulses may be undetectable. If untreated, cows in stage 3 may survive only a few hours.

Treatment

 If the cow is found to be lying on her side or lateral recumbence, she should be immediately propped on to her chest–sternal recumbence. Otherwise she is liable to get bloat or inhale stomach content with the risk of developing aspiration pneumonia.

Slow intravenous infusion of 400 ml of 20% calcium borogluconate should be administered as soon as possible while cardiac auscultation is performed as Calcium is cardiotoxic. If it is impossible, try the same volume by subcutaneous injection. If any disturbance or abnormality in a normal rhythmic pattern of heart rate develops, administration should be stopped until the heart rhythm has returned to normal. Give in several sites and massage the sites of injection to disperse the solution.

Response to treatment is seen by the cow belching, snapping and opening her  eyelids, breathing deeply, passing dung and sitting up. Even if the cow appears to be unconscious give intravenous calcium. Even cases which look hopeless can recover. The calf should be removed and the cow not milked for 24 hours. If the calf is allowed to access the cow or milking is carried out, the cow may well go down again.

On day two milk half the estimated volume from each quarter and feed this to the calf, and  following  day three  milk normally.

Cow with Milk fever & Big Calf

Prevention and Control

• Feed the cow with the correct levels of nutrients from the late pregnancy to peak lactation.
• Feed diets with the right dry matter content such as offering additional hay in combination with lush pasture.
• Feed balanced mineral supplement which appreciates the inter-relationship between calcium and magnesium. Oral administration of 50g of soluble calcium results in 4g calcium being absorbed into the circulation.
• Administration of vitamin D3 and its metabolites is effective in preventing milk fever. Large doses of vitamin D  given in the feed for 5-7 days before parturition, reduces the incidence.