السبت، 6 يوليو 2013

Milk fever


Milk fever (Milk fever, post-parturient hypocalcemia, or parturient paresis)

Milk  fever, post-parturient hypocalcemia, or parturient paresis is a  disease, usually of dairy cows, characterized by reduced blood calcium  levels.

It is most common in the first few days of lactation, when demand for calcium for milk production exceeds the bod...y's ability to mobilize calcium reserves.

"Fever"  is a misnomer, as body temperature during the disease is usually below  normal. Low blood calcium levels interfere with muscle function  throughout the body, causing general weakness, loss of appetite, and  eventually heart failure.

Hypocalcemia is more common in older  animals (who have reduced ability to mobilize calcium from bone) and in  certain breeds (such as Jersey cattle).

Hypocalcemia, like milk fever, occurs occasionally at any time during the lactation or pregnancy and in many mammalian species.


*Clinical symptoms:-
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In  mild cases, the animal seems quite normal, but has difficulties  standing. If the cow succeeds in rising, she staggers, and will very  soon fall. The cow's appetite can be maintained at that stage. Body  temperatures are from 37 to 38.5°C (normal range 38-38.5°C).

This stage, referred to as "first degree", corresponds to calcemiae of 55 to 75 mg/l.

In  typical cases, the cow's head is in a so-called self-auscultation  position. Mydriasis is often present. The heart can be slow or  arrhythmic. The body temperature is 35 to 37°C. In that stage, referred  to as "second degree", calcium levels in the blood are of 30 to 65 mg/l.

In  advanced cases, the cow is lying on its side, seeming dead. The body  temperature can go as low as 32°C. This is the 3rd degree, with calcemia  as low as 20 mg/l.


*Treatment:-
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Treatment  generally involves calcium injection by intravenous, intramuscular or  subcutaneous routes. Before calcium injection was employed treatment  comprised inflation of the udder using a pneumatic pump. Inflation of  the udder worked because the increased pressure created in the udder  pushed the calcium in the udder back into the bloodstream of the cow

Intravenous  calcium, though indicated in many cases, is potentially fatal through  "heart blockade", or transient high calcium levels stopping the heart,  so should be administered with care.

n unclear cases of downer  cows, intravenous calcium injection can lead to diagnosis. The typical  reaction will be a generalized tremor of the skeletal muscles, and  sometimes cardiac arrhythmia. Defecation, urination and eructation are  frequent during the treatment, due to pharmacological effect of calcium  on the smooth muscles. In stage I and II, The cow can stand up  approximately 10 minutes after the end of the intravenous injection. But  in stage III, it may take two or three hours. If the cow is in stage  III and lying on its side, it is important to put the cow in a sternal  position or else risk aspiration.

The prognosis is generally  good, even in advanced cases. However, some cows can relapse the  following day, and even a third time the day after.


*Prevention:-
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Proper  dietary management will prevent most cases of milk fever. This  generally involves close attention to mineral and fiber levels in the  pre-calving diet as well as improving cow comfort to eliminate other  problems that may interfere with appetite and so trigger hypocalcemia.

Oral administration of a dose of a calcium salt in a gel have been advised by some veterinarians.