MILK FEVER

Hawke's Bay Tribune, Volume XXIII, Issue 74, 9 March 1933, Page 5

MILK FEVER

SYMPTOMS AND CAUSES

HEAVY PRODUCING COWS AFFECTED, CALCIUM PHOSPHOROUS BALANCE UPSET.

The number of cases of milk fever which occur every year are considerable, and by knowing the cause of the condition, many farmers should be able to prevent or alleviate the cases occurring in their herds. The balance of piiosI phorus and calcium in the animal I body has a considerable bearing on the incidence of the disease. The first symptom of milk fever is usually some uneasiness on the part ef the cow. It may bellow, or while standing it may move uneasily from one bind foot to another (known as paddling the foot to another), whisk its tail, and will often lean on any sufficient support which happens to be at hand; it is unsteady m its gait, and may fall headlong forward to the ground; if it struggles to its feet again it stands with all four legs stuck out like props, and with limb muscles, especially the tendon of achilles (hamstring), tensed. Shivers may pass through the body, but no fever is present. Respirations are often hurried, and eventually the cow falls to the ground and remains there, usually lying on the sternum (breast bone) with the head up and often turned towards the flank, sometimes with the muzzle on the ground. Spasmodic contractings of the limb muscles continue, producing aimless movements, and often injury occurs to the cow as a result of her struggling, while the horns may be fractured from the wild movements of the head.

There is no real paralysis, though movements are in no way co-ordinated. The eyes are wild and staring, frequently reddened, and the pupil is dilated. In the final stages the animal becomes insensible and comatose, and quite unable to make any effective attempt to rise. The respirations become slow, deep and laboured, and very often gases, resulting from fermentation, collect in the rumen and cause interference to breathing by pressing on the diaphragm and distension of the Hanks (hoyen or bloat). Eructation cf stomach gases may bring up some of the ingesta, which may escape by the nostrils or may pass down to the lungs to cause a subsequent pneumonia. Milk secretion ceases, and sometimes the milk already in the gland becomes reabsorbed, so that the udder appears quite fiaccid. Constipation soon supervenes, and urine is not passed, but collects in the bladder, which consequently becomes distended. In the later stages the temperature becomes subnormal and the limbs and horns feel icy cold. The duration of the disease is very short, being in the more severe eases usually onlv two or three hours, but lasting as many days in less severe eases.

If left untreated the cow gradually sinks into still deeper coma, and 50 per cent, of such cases die usually without a struggle. Writing in the London “Live Stock Journal,” a veterinary expert points out that the mortality in untreated cases is very high, but by the adoption of appropriate treatment mortality is reduced to an almost negligible amount if the cases are seen early. In all eases care should be taken not to confuse with milk fever a condition known as post partem paralysis, which is simply a paralysis of the hindquarters unaccompanied by other symptoms, and occurs as a result of injury during parturition.

A cow during pregnancy supplies a very large amount of calcium to the foetus for the development of the young animal’s bones aud other tissues, and this alone acts as a considerable drain on the mother’s system, but is spread over a fairly lengthy period. At either a short time before or immediately after parturition milk secretion commences. Milk is very rich in calcium salts, and the first milk (colostrum) is specially so; further, a cow reaches her maximum milk production shortly after the commencement of lactation. It will thus be seen that lactation lays an enormous and sudden strain on the mother io provide calcium salts from her body, and if she be a

very high milk producer her body may be unable to respond sufficiently rapidly, and she herself suffers from insuffi. cient circulating blood calcium, evidenced by the production of symptoms of milk fever.

This explains why heavy producing dairy cows are most frequently affected (beef breeds are not often affected, and the disease is very rare if the ci w be allowed to suckle her calf). It also explains why the disease occurs soon after the commencement of lactation. If, however, milk production gradually increased over a considerable period the body would have time to accommodate itself to the demands by drawing on its reserves of calcium in its own hones. IHPis known from experiments that such withdrawal of the reserves of calcium from the mother’s body is more likely to occur during lactation even than during pregnancy. Cows grazed on pastures deficient in calcium and phosphorus are affected in a rather different way as a result of pregnancy and lactation; milk fever is not rendered thereby very much more frequent for the reason that the cows are usually not exceptionally high milk, producing animals (for high producers usually have their rations suitably supplemented). But even in these more mediocre animals the demand for calcium for the growth of the foetus and for milk production is still very considerable, and seeing that insufficient is obtained from the fodder, the required calcium is withdrawn from the mother’s skeleton, resulting in the production of osteomalacia, a scourge of many dairymen, and evidenced by lameness, brittle bones, frequent fractures, and the like. Milk fever is more likely to appear in circumstances where maximum milk production is brought about rapidly, that is, after the third to the seventh calvings, after an easy parturition and the pastures are particularly succulent, especially if she has had a previous dry period. Very fat and very poor animals seldom produce a very great volume of milk, and hence are not likely subjects.