Milk fever, postparturient hypocalcemia, or parturient paresis is a disease, primarily in
dairy cattle
Dairy cattle (also called dairy cows) are cattle bred for the ability to produce large quantities of milk, from which dairy products are made. Dairy cattle generally are of the species ''Bos taurus''.
Historically, little distinction was mad ...
but also seen in
beef cattle
Beef cattle are cattle raised for meat production (as distinguished from dairy cattle, used for milk production). The meat of mature or almost mature cattle is mostly known as beef.
In beef production there are three main stages: cow-calf operat ...
and non-bovine
domesticated animals
This page gives a list of domesticated animals, also including a list of animals which are or may be currently undergoing the process of domestication and animals that have an extensive relationship with humans beyond simple predation. This includ ...
, characterized by reduced blood
calcium
Calcium is a chemical element with the symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar ...
levels (
hypocalcemia). It occurs following
parturition, at onset of
lactation, when demand for calcium for
colostrum
Colostrum, also known as beestings or first milk, is the first form of milk produced by the mammary glands of mammals (including humans) immediately following delivery of the newborn. Colostrum powder is rich in high protein and low in sugar and ...
and
milk production exceeds the body's ability to mobilize calcium.
"
Fever" is a misnomer, as
body temperature
Thermoregulation is the ability of an organism to keep its body temperature within certain boundaries, even when the surrounding temperature is very different. A thermoconforming organism, by contrast, simply adopts the surrounding temperature ...
during the disease is generally not elevated. Milk fever is more commonly seen in older animals (which have reduced ability to mobilize calcium from bone) and in certain breeds (such as
Channel Island
The Channel Islands ( nrf, Îles d'la Manche; french: îles Anglo-Normandes or ''îles de la Manche'') are an archipelago in the English Channel, off the French coast of Normandy. They include two Crown Dependencies: the Bailiwick of Jersey, ...
breeds).
Clinical signs
The clinical signs of milk fever can be divided into three distinct stages:
Stage 1
Cows are mobile but show signs of
hypersensitivity
Hypersensitivity (also called hypersensitivity reaction or intolerance) refers to undesirable reactions produced by the normal immune system, including allergies and autoimmunity. They are usually referred to as an over-reaction of the immune s ...
and excitability such as
restlessness,
tremors,
ear twitching, head bobbing, and mild
ataxia
Ataxia is a neurological sign consisting of lack of voluntary coordination of muscle movements that can include gait abnormality, speech changes, and abnormalities in eye movements. Ataxia is a clinical manifestation indicating dysfunction of ...
.
If not treated, symptoms usually progress to stage 2.
Stage 2
Cows can no longer stand and present in sternal
recumbency.
Tachycardia, weakened heart contraction and peripheral pulses. Cows appear dull, have dry muzzles, cold extremities and a lower than normal body temperature. Smooth muscle
paralysis can cause
bloat, and the inability to urinate or defecate. Cows often tuck their heads into their flanks.
Stage 3
Lateral recumbency, muscle
flaccidity
Flaccid paralysis is a neurological condition characterized by weakness or paralysis and reduced muscle tone without other obvious cause (e.g., trauma). This abnormal condition may be caused by disease or by trauma affecting the nerves associat ...
,
unresponsiveness to stimuli, and loss of consciousness progressing to
coma
A coma is a deep state of prolonged unconsciousness in which a person cannot be awakened, fails to respond normally to painful stimuli, light, or sound, lacks a normal wake-sleep cycle and does not initiate voluntary actions. Coma patients exhi ...
. Heart rate can approach 120 bpm, with peripheral pulses becoming undetectable. If untreated, progression will continue to death.
Cause
During the dry period (late gestation, non-lactating), dairy cattle have relatively low calcium requirements, with a need to replace approximately 30 g of calcium per day due to utilization for fetal growth and fecal and urinary losses. At parturition, the requirement for calcium is greatly increased due to initiation of lactation, when
mammary
A mammary gland is an exocrine gland in humans and other mammals that produces milk to feed young offspring. Mammals get their name from the Latin word ''mamma'', "breast". The mammary glands are arranged in organs such as the breasts in prima ...
drainage of calcium may exceed 50g per day.
Due to this large increase in demand for calcium, most cows will experience some degree of hypocalcemia for a short period following
parturition as the metabolism adjusts to the increased demand. When the mammary drain of plasma calcium causes hypocalcemia severe enough to compromise
neuromuscular
A neuromuscular junction (or myoneural junction) is a chemical synapse between a motor neuron and a muscle fiber.
It allows the motor neuron to transmit a signal to the muscle fiber, causing muscle contraction.
Muscles require innervation to ...
function, the cow is considered to have clinical milk fever.
Mechanism
In normal calcium regulation, a decrease in plasma calcium levels causes the
parathyroid glands to secrete
parathyroid hormone (PTH), which regulates the activation of
Vitamin D3 in the
kidney. These two compounds act to increase blood calcium levels by increasing absorption of dietary calcium from the
intestine, increasing renal tubular reabsorption of calcium in the kidney, and increasing resorption of calcium from bones.
It has been found that tissue is less responsive to
parathyroid hormone prepartum, compared to postpartum. It is believed that hypocalcemia causing milk fever is due to a lower level of responsiveness of the cow's tissues to circulating parathyroid hormone.
The resultant decreased plasma calcium causes hyperexcitability of the
nervous system and weakened muscle contractions, which result in both tetany and
paresis
In medicine, paresis () is a condition typified by a weakness of voluntary movement, or by partial loss of voluntary movement or by impaired movement. When used without qualifiers, it usually refers to the limbs, but it can also be used to desc ...
.
Prevention
Diet
Proper
dietary management will prevent most cases of milk fever. This generally involves close attention to mineral and
fiber levels in the diet prior to calving, as well as improving cow comfort to eliminate other problems that may interfere with appetite (and so trigger hypocalcemia). General advice is to restrict calcium intake before calving, as this leads to the parathyroid gland stimulating the release of calcium from bones.
Calcium Salts
A synthetic analogue of
25-hydroxycholecalciferol
Calcifediol, also known as calcidiol, 25-hydroxycholecalciferol, or 25-hydroxyvitamin D3 (abbreviated 25(OH)D3), is a form of vitamin D produced in the liver by hydroxylation of vitamin D3, vitamin D3 (cholecalciferol) by the enzyme vitamin D 25- ...
can be given by injection in the days leading up to calving, although the timing of this
prophylaxis
Preventive healthcare, or prophylaxis, consists of measures taken for the purposes of disease prevention.Hugh R. Leavell and E. Gurney Clark as "the science and art of preventing disease, prolonging life, and promoting physical and mental hea ...
makes it difficult to use.
Oral administration of a dose of a
calcium salt in a gel has been advised by some veterinarians. An orally administered
bolus containing a much higher concentration of calcium than the injectable solutions can also be given so long as the cow is standing or sitting up. If the cow is lying 'flat out' then immediate intravenous therapy is required to avoid death.
Treatment
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. Cows are to be fed
jaggery
Jaggery is a traditional non-centrifugal cane sugar consumed in the Indian Subcontinent, Southeast Asia, and Africa. It is a concentrated product of cane juice and often date or palm sap without separation of the molasses and crystals, and can ...
along with the lime water mixture. In unclear cases of
downer cow
A downer is an animal, usually livestock, that cannot stand on its own and therefore is to be killed. A downed animal, one that is unable to stand, is not necessarily a downer. Causes
The animal's inability to stand may be caused by illness or ...
s, intravenous calcium injection can lead to
diagnosis. The typical reaction will be a generalized
tremor of the
skeletal muscles, and sometimes
cardiac arrhythmia
Arrhythmias, also known as cardiac arrhythmias, heart arrhythmias, or dysrhythmias, are irregularities in the heartbeat, including when it is too fast or too slow. A resting heart rate that is too fast – above 100 beats per minute in adults ...
.
Defecation
Defecation (or defaecation) follows digestion, and is a necessary process by which organisms eliminate a solid, semisolid, or liquid waste material known as feces from the digestive tract via the anus. The act has a variety of names ranging fr ...
,
urination
Urination, also known as micturition, is the release of urine from the urinary bladder through the urethra to the outside of the body. It is the urinary system's form of excretion. It is also known medically as micturition, voiding, uresis, ...
and
eructation are frequent during the treatment, due to pharmacological effect of calcium on the
smooth muscles.
Prognosis
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.
[ (unpublished data)] Without treatment, between 60% and 80% of cows usually die,
although death rates as high as 90% have been recorded.
History
It is thought that milk fever has existed for a very long time in dairy cattle.
The first reports in veterinary literature can be traced to around 1793.
Early Theories
Early treatments involved
venesection
In medicine, venipuncture or venepuncture is the process of obtaining intravenous access for the purpose of venous blood sampling (also called ''phlebotomy'') or intravenous therapy. In healthcare, this procedure is performed by medical labor ...
, but this proved ineffective.
Potassium Iodide
In the late 1800s, Jurgens Schmidt proposed the use of an infused solution of
potassium iodide for treatment.
A follow-up study of this treatment by
Danish
Danish may refer to:
* Something of, from, or related to the country of Denmark
People
* A national or citizen of Denmark, also called a "Dane," see Demographics of Denmark
* Culture of Denmark
* Danish people or Danes, people with a Danish ance ...
veterinarians showed that 90% of cows recovered after use of the treatment,
compared with only 20-40% survival without.
A study in
Iowa showed that 76.5% of cows recovered after use of the treatment.
However, the premise of the Schmidt treatment was misleading, as later veterinarians used water alone to the same success rate.
Udder Inflation
In 1901, Anderson and Evers trialled a treatment of udder inflation with air, which reduced mortality rates to just 1%.
although with the added complication of
mastitis
Mastitis is inflammation of the breast or udder, usually associated with breastfeeding. Symptoms typically include local pain and redness. There is often an associated fever and general soreness. Onset is typically fairly rapid and usually occurs ...
.
Although this was an effective treatment (and is still used as a backup today),
it was not understood at the time why it worked, and remains the source of some debate. Some scientists believed that udder inflation could cause stimulation that then prevents calcium loss. Other scientists suggested that udder inflation prevented milk secretion, reducing calcium loss overall.
This may prevent calcium being taken from the blood plasma.
Later Theories
The true cause of milk fever was first suggested by Prof
John Russell Greig
John McDougal Russell Greig CBE FRSE MRCVS (September 1889-1 May 1963) was a Scottish veterinarian who was Director of the Moredun Research Institute from 1930 to 1954. He is noted for the development of several important animal vaccines: Enzoo ...
and
Henry Dryerre in March 1925,
at the
Moredun Research Institute
The Moredun Research Institute is a scientific research institution based at the Pentlands Science Park, in the Bush Estate area of Midlothian, Scotland. It conducts research into diseases of farm livestock and the promotion of animal health and ...
in
Scotland.
This idea was later confirmed experimentally by Little and Wright in May 1925.
By 1933, Pulles began treatments with
magnesium chloride and
calcium chloride
Calcium chloride is an inorganic compound, a salt with the chemical formula . It is a white crystalline solid at room temperature, and it is highly soluble in water. It can be created by neutralising hydrochloric acid with calcium hydroxide.
Ca ...
, which is the basis for modern pharmaceutical treatments.
References
External links
Prevention of Milk Fever University of Kentucky
Parturient Paresis in Cows (Milk fever, Hypocalcemia) The Merck Veterinary Manual
{{Commons category, Hypocalcemia in ruminants
Bovine diseases
Dairy farming