Medicine Lecture 5th year 23-10-2017 Dr.Osamah Muwafk
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PARTURIENT PARESIS (MILK FEVER)
A disease of cattle, sheep, and goats occurring around the time of
parturition and caused by hypocalcemia and characterized by weakness,
recumbency, and ultimately shock and death.
Etiology:
1. A depression of the levels of ionized calcium in tissue fluids
2. Imbalance between calcium output in the colostrum and influx of
calcium to the extracellular pool from intestine and bone
3. The onset of lactation results in a sudden large demand on the calcium
homeostasis.
4. cow producing 10 kg of colostrum (2.3 g of Ca/kg) will lose 23 g of
calcium in a single milking
Epidemiology:
1. The disease occurs most commonly in high-producing adult lactating
dairy cattle
2. Mature dairy cows are most commonly affected in the 5-10-year age
3. Most prepartum cases occur in the last few days of pregnancy and
during parturition but rare cases occur several weeks before calving
4. Most cases occur within the first 48 h after calving and the danger
period extends up to about the 10th postpartum day
5. Starvation for 48 h also causes severe depression of serum calcium
levels
6. Pregnant beef cattle fed on poor-quality roughage
7. In sheep, the disease commonly occurs in outbreaks in groups of ewes
exposed to forced exercise, long-distance transport, sudden
deprivation of food and grazing on oxalate-containing plants or green
cereal crops.
8. A high Body condition score (BCS) increases the risk of milk fever
9. Feeding more than 100 g of calcium daily during the dry period
Prepartum diets high in phosphorus anion-cation dietary difference
exerts a strong effect
Medicine Lecture 5th year 23-10-2017 Dr.Osamah Muwafk
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Economic Importance:
1. Milk fever relapses
2. Downer cow complications
3. Dystocia and reproductive disease
4. Retained placenta
5. Metritis
6. Milk production
7. Mastitis
8. Displacement of abomasum
9. Ketosis
10. Body weight losses
11. Culling
Pathogenesis:
1- Plasma calcium concentration is normally maintained between 2.1 and
2.6 mmol/L (8.5 -10.4 mg/dL).
2- Almost all dairy cows will experience subclinical hypocalcemia, <1.8
mmol/L (7.5 mg/dL ) within 24 h after calving.
3- In some cows, the hypocalcemia is more severe, <1.25 mmol/L (5
mg/dL).
4- Neuromuscular dysfunction.
5- Atony of skeletal muscle and plain muscle.
6- Depression of frequency and amplitude of rumen contractions
7- Hypophosphatemia and variations in levels of serum magnesium also
occur.
Clinical Findings:
- Cattle:
Three stages of milk fever in cattle are commonly recognized and
described.
A- Stage 1:
1- Cow is still standing.
2- Brief stage of excitement and tetany with hypersensitivity and muscle
tremor of the head and limbs.
Medicine Lecture 5th year 23-10-2017 Dr.Osamah Muwafk
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3- Disinclined to move and does not eat.
4- There may be a slight shaking of the head, protrusion of the tongue,
and grinding of the teeth.
5- The rectal temperature is usually normal to slightly above normal.
6- Stiffness of the hindlegs is apparent, the animal is ataxic and falls
easily and, on going down, the hindlegs are stuck out stiffly.
7- respond quickly to calcium therapy.
B- Stage 2:
1- Prolonged sternal recumbency.
2- Consciousness is usually depressed; the cow has a drowsy appearance
3- lateral kink in the neck or the head turned into the flank.
4- When approached, some of these cows will open their mouths, extend
their head and neck and protrude their tongues, which may be an
expression of apprehension and fear in an animal unable to stand.
5- The tetany of the limbs present in the first stage is not present and the
cow is unable to stand.
6- The muzzle is dry, the skin and extremities cool, and the rectal
temperature subnormal (36-38°C, 97-101)
7- There is a marked decrease in the absolute intensity of the heart
sounds and an increase in rate (about 80 bpm) .
8- The arterial pulse is weak and the venous pressure is also low, making
it difficult to raise the jugular veins.
9- The respirations are not markedly affected, although a mild forced
expiratory grunt or groan is sometimes audible.
10-
The eyes are usually dry and staring, the pupillary light reflex is
incomplete or absent and the diameter of the pupil varies from normal
to maximum dilatation.
11-
Ruminal stasis and secondary bloat are common and
constipation is characteristic.
C- Stage 3:
1- lateral recumbency.
2- The cow is almost comatose and although the limbs may be stuck out
3- there is complete flaccidity on passive movement and the cow cannot
assume sternal recumbency on its own.
Medicine Lecture 5th year 23-10-2017 Dr.Osamah Muwafk
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4- In general, the depression of temperature and the cardiovascular
system are more marked.
5- The heart sounds are almost inaudible and the rate increased up to 120
bpm.
6- the pulse is almost impalpable and it may be impossible to raise the
jugular veins.
7- Bloat is usual because of lateral recumbency.
8- Without treatment, a few animals remain unchanged for several hours
but most become progressively worse during a period of several hours
and dye quietly from shock in a state of complete collapse.
- Concurrent hypomagnesaemia:
1- Mild to moderate tetany and hyperesthesia persisting beyond the first
stage suggests a concurrent hypomagnesaemia.
2- There is excitement and fibrillary twitching of the eyelids and tetanic
convulsions are readily precipitated by sound or touch.
3- The heart and respiratory rates are increased and the heart sounds are
much louder than normal.
4- Without treatment death occurs during a convulsion.
Concurrent hypophosphatemia:
1- With a concurrent hypophosphatemia, the clinical findings are typical
of milk fever which responds to calcium therapy in all respects except
that the cow is unable to stand after treatment.
Sheep and goats:
1- The disease in pastured ewes is similar to that in cattle.
2- The early signs include a stilty, proppy gait and tremor of the shoulder
muscles.
3- Recumbency follows, sometimes with tetany of the limbs.
4- Response to parenteral treatment with calcium salts is rapid, the ewe
is normal 30 min after a SC injection.
5- Death often occurs within 6-12 h if treatment is not administered.
Medicine Lecture 5th year 23-10-2017 Dr.Osamah Muwafk
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Clinical Pathology:
1- Total serum calcium levels are reduced to below 8 mg/dL (2.0
mmollL), usually to below 5 mg (1.2 mmol/L) and sometimes to as
low as 2 mg (0.5 mmol/L).
2- Cows 5.2 ± 1.2 mgldL (1.30 ± 0.30 mmol/L), ewes 4.6 ± 1.5 mg/dL
(1.15 ± 0.37 mmollL), goat does 3.8 ± 0.6 mg/dL (0.94 ± 0.15 mol/L).
3- Serum inorganic phosphorus levels are usually depressed to 1.5-3.0
mg/dL (0.4S-0.97 mmoI/L).
4- Serum magnesium levels are usually moderately elevated to 4-5 g/dL
(1.65-2.06 mmol/L) but in some areas low levels may be encountered,
especially in cows at pasture
5- Blood glucose levels are usually normal, although they may be
depressed if ketosis occurs concurrently
6- Serum muscle enzymes Prolonged recumbency results in ischemic
muscle necrosis and increases in the serum muscle enzymes creatine
phosphokinase (CPK) and aspartate aminotransferase (AST) or
SGOT.
Necropsy Findings:
There are no gross or histological changes unless concurrent disease is
present.
Differential Diagnosis:
1- Downer cows following milk fever
2- Carbohydrate engorgement
3- Hypomagnesaemia tetany(grass tetany)
4- Severe toxemia (acute diffuse peritonitis, coliform mastitis)
5- Fat cow syndrome
6- Physical injuries
7- Acute hypokalemia
8- Bovine spongiform encephalopathy
Medicine Lecture 5th year 23-10-2017 Dr.Osamah Muwafk
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Treatment:
1- Cows found in lateral recumbency (third stage) should be placed in
sternal recumbency until treatment is available.
2- Placement of rubber or other mats under the cow or transportation of
the cow to a piece of pasture with a dense sward on it.
3- Calcium borogluconate of a 25 % solution is the usual treatment.
4- An initial dose a large cow (540-590 kg) requires 800-1000 mL of a
25% solution and a small cow (320-360 kg) 400-500 Ml, over a
period of 15 min.
5- In sheep and goats, the recommended amount is 15-20 g IV with an
optional 5-10 g Sc.
6- Composite solutions containing calcium, magnesium, phosphorus and
glucose given orally.
7- The heart should be auscultated throughout the intravenous
administration for evidence of gross arrhythmia, bradycardia, and
tachycardia.
8- giving half the dose intravenously and half subcutaneously prevent
relapses.
Typical response to calcium borogluconate:
1- Belching
2- Muscle tremor, particularly of the flanks and often extending to the
whole body
3- Slowing and improvement in the amplitude and pressures of the pulse
4- Increase in the intensity of the heart sounds
5- Sweating of the muzzle
6- Defecation.
Medicine Lecture 5th year 23-10-2017 Dr.Osamah Muwafk
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DOWNER COW SYNDROME:
(Non-Ambulatory Cows with Non-Progressive Neurological Findings)
It is a complication of the recumbency associated with milk fever. A delay
of 4 h or more in that treatment of cows with milk fever may result in
ischemic necrosis of the muscles of the pelvic limbs. Traumatic injury to leg
muscles at the time of parturition or when the cow is unsteady and falls
during the first stage of milk fever will also result in the inability of the cow
to stand following treatment of milk fever.
Etiology:
1- Complication of milk fever (Ischemic necrosis of the large muscles of
in cows which remain recumbent 4 h or more ).
2- Injuries to the musculoskeletal system are also common as a result of
cows 'spread-eagling' their hind limbs.
3- Dystocia due to an oversized calf may result in extensive edema of the
pelvic tissues and vulva, and failure of the cow to stand following
parturition.
Pathogenesis:
1- Prolonged recumbency of 4 h or more results in varying degrees of
ischemic necrosis of major muscles of the hind limbs, particularly the
semitendinous muscle and muscles caudal to the stifle. Prolonged
compression of the muscle leads to tissue anoxia, cell damage and
inflammation which causes swelling; the swelling causes a further
increase in pressure which limits tissue perfusion and leads to a
detrimental cascade of events.
Clinical Findings:
1- May occur independently, or follow apparent recovery after treatment
for milk fever.
2- Unable to stand after 24 h and after two treatments are classified as
downers.
3- cow usually bright and alert.
Medicine Lecture 5th year 23-10-2017 Dr.Osamah Muwafk
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4- the cow eats and drinks moderately well.
5- The temperature is normal.
6- the heart rate may be normal or elevated to 80-100 bpm.
7- Respirations are usually unaffected.
8- Defecation and urination are normal.
9- Some affected cows may make no
10-
effort to stand. Others will make frequent attempts.
11-
frequent attempts to stand result in 'creeping' along the ground
with both hindlegs in a partially flexed position and displaced
posteriorly.
12-
About 50% of downer cows will stand within 4 days or less if
cared for properly.
Complications in the Downer Cow Syndrome:
1- Coliform mastitis.
2- decubitus ulceration, especially over the prominences of the hock and
elbow joint.
3- traumatic injuries around the tuber coxae caused by the hip slings are
common.
Clinical Pathology:
1- The CPK and AST levels are usually markedly elevated by 18-24 h
after the onset of recumbency and continue to elevate within the next
few days.
2- The proteinuria may persist for several days or be absent within a few
days .
Necropsy Findings:
1- Hemorrhages and edema of the skin of traumatic origin are common.
2- hemorrhages and degeneration of the medial thigh muscles.
3- Hemorrhages around the hip joint with or without rupture of the
ligamentum teres.
Medicine Lecture 5th year 23-10-2017 Dr.Osamah Muwafk
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Differential Diagnosis:
The other common causes of prolonged recumbency.
Treatment:
1- If the prognosis is favorable, the clinician should inform the owner
about the nature of the treatment which will be necessary and its
duration which may be several days of supportive care and therapy,
and should outline the costs which will be incurred.
2- Fluid and electrolyte therapy, The use of parenteral solutions
containing potassium, calcium, magnesium, and phosphorus.
3- Bedding and clinical care.
4- Assisted lifting to aid standing (Body slings, A water flotation tank).
Medicine Lecture 5th year 23-10-2017 Dr.Osamah Muwafk
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HYPOMAGNESEMIC TETANY
(Lactation Tetany, Grass Tetany, Grass Staggers, Wheat Pasture Poisoning):
Etiology:
1- Cattle grazing lush pastures that have insufficient magnesium to meet
dietary requirements.
2- Loss of magnesium in the milk during lactation.
3- Pastures that contain high concentrations of potassium and nitrogen,
impair absorption of magnesium in the rumen.
4- Young rapidly growing grass is low in sodium and high in potassium,
can result depress the Na:K ratio in the rumen fluid, causing
impairment of magnesium absorption.
5- Young grass fertilized with nitrogenous fertilizers has an increased
crude protein which is readily fermentable and leads to increased
ammonia concentrations impairs magnesium absorption in the rumen.
6- In wheat (cereal) pasture poisoning, the ingestion of abnormally large
amounts of potassium and low levels of calcium in the diet leads to
hypomagnesemia and also hypocalcemia.
7- Climatic conditions reduced serum magnesium levels in adult cattle
and sheep (cold, wet, windy weather with little sunshine and no access
to shelter or supplementary feed).
8- Diarrhea which decreasing the alimentary sojourn may also reduce
magnesium absorption.
Pathogenesis:
1- Decrease serum magnesium levels below 1 mg/dL (041 mmol/L)
normal levels in cattle of 1.7-3 mg/dL (0.70-1.23 mmol/L).
2- Muscular irritability, because magnesium has many influences on
impulse transmission at the neuromuscular system, including effects
on the release of acetylcholine, on the sensitivity of the motor end
plate, on the threshold of the muscle membrane and on activation of
the cholinesterase system.
Clinical Findings:
Medicine Lecture 5th year 23-10-2017 Dr.Osamah Muwafk
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A- Acute lactation tetany:
1- suddenly cease to graze,
2- adopt a posture of unusual alertness and appear uncomfortable.
3- twitching of the muscles and ears.
4- Hyperesthesia
5- gait becomes staggering
6- animal falls with obvious tetany of the limbs, which is rapidly
followed by clonic convulsions lasting for about a minute.
7- During the convulsive episodes there is: Opisthotonos,
Nystagmus, Champing of the jaws, Frothing at the mouth,
Pricking of the ears and Retraction of the eyelids.
8- Between episodes, the animal lies quietly but a sudden noise or
touch may precipitate another attack.
9- The temperature rises to 40-40.5°C (104-105°F) after severe
muscle exertion; the pulse and respiratory rates are also high.
10-
Death usually occurs within 5-1 h.
11-
The response to treatment is generally good if the animal is
treated early.
B- Subacute lactation tetany:
1- The onset is more gradual.
2- Over a period of 3-4 days, there is slight inappetence.
3- wildness of the facial expression.
4- Exaggerated limb movements.
5- Spasmodic urination and frequent defecation are characteristic.
6- milk yield are diminished and ruminal movements decrease.
7- Muscle tremor and mild tetany of the hindlegs and tail with an
unsteady, straddling gait may be accompanied by retraction of the
head and trismus.
8- Recover spontaneously within a few days or progress to a stage of
recumbency.
C- Chronic hypomagnesemia:
1- Many animals in affected herds have low serum magnesium levels
but do not show clinical signs.
2- A few animals do evidence a rather vague syndrome including
dullness, unthriftiness and indifferent appetite.
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3- In lactating cows, this may be the development of paresis and a
milk fever-like syndrome that is poorly responsive to calcium
treatment.
Clinical Pathology:
1- Serum magnesium concentrations.
2- Urinary magnesium concentrations.
3- Reduced in serum magnesium concentrations in seasonal subclinical
hypomagnesemia to between 1 and 2 mg/dL (0.41 and 0.82 mmollL)
but risk for tetany is not present until the level falls to below 1.2
mg/dL (0.49 mmoIlL) .
4- Urine magnesium concentrations below 1.0 mg/dL (0.4 mmol/L)
indicate a danger for tetany.
Necropsy Findings:
There are no specific findings.
Differential Diagnosis:
A- Cattle
1- Acute lead poisoning
2- Rabies
3- Nervous ketosis
4- Bovine spongiform encephalopathy.
B- Sheep
1- Hypocalcemia
2- Phalaris poisoning
3- Stagger' syndromes
Treatment:
1- IV administration of preparations containing magnesium or
magnesium and calcium.
2- A combined calcium-magnesium preparation (e.g. 500 mL of a
solution containing 25% calcium borogluconate and 5% magnesium
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hypophosphite for cattle, 50 mL for sheep) IV followed by a SC
injection of a concentrated solution of a magnesium salt.
3- IV chloral hydrate may be administered to reduce the severity of
convulsions during treatment with magnesium.
4- Magnesium solutions 200-300 mL of a 20% solution of magnesium
sulfate may be injected IV.
5- Feeding of magnesium-rich supplements.