Medicine Lecture 5th Stage 5-12-2017 Dr.Osamah Muwafk
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ACUTE HYPOKALEMIA IN CATTLE
ETIOLOGY :
Hypokalemia is most common in lactating dairy cattle and is secondary to
the following:
1. Anorexia resulting from clinical mastitis and retained placenta
2. Upper gastrointestinal obstruction, particularly left-displaced
abomasum, right-displaced abomasum, abomasal volvulus, and
abomasal impaction
3. Obligatory loss of potassium in milk (1.4 g potassium/L of milk)
4. Hyperinsulinemia secondary to hyperglycemia and transcellular shift
of extracellular potassium
5. Sympathetic nervous system activation
6. Aldosterone release in response to hypovolemia and the need for
sodium retention
7. Decreased whole-body potassium stores as a result of the relatively
low muscle mass in dairy cows
EPIDEMIOLOGY:
1. The potassium content of cattle has been estimated at approximately
2.2 g/kg BW
2. occurs commonly in lactating dairy cattle with prolonged inappetence
(>2 days)
3. occurs more commonly in lactating dairy cows than beef cows or
feedlot animals
4. Potassium excretion by the kidneys is via secretion by the distal
tubular cells
5. Aldosterone or other steroids with mineralocorticoid activity enhance
distal tubular secretion of potassium
6. common in lactating dairy cattle receiving one or more injections of
corticosteroids for ketosis
7. mineralocorticoid activity of isoflupredone enhances renal and
gastrointestinal (saliva and colon) losses of potassium
Medicine Lecture 5th Stage 5-12-2017 Dr.Osamah Muwafk
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8. Exogenous or endogenous insulin release secondary to hyperglycemia
following IV dextrose administration or corticosteroid administration
9. Calving cause whole-body depletion of potassium in healthy cattle
10. Early-lactation, negative energy balance; catabolism of intracellular
Glycogen,
potassium is bound to glycogen, potassium excretion in
urine
PATHOGENESIS
1. Potassium homeostasis in adult cattle is determined by the balance
between absorption of potassium from the gastrointestinal (GI) tract
and subsequent excretion by the kidneys and salivary glands.
2. Transport of potassium is passive in the small intestine and active in
the colon under the influence of aldosterone.
3. increasing potassium intake (specifically, increasing rumen
potassium concentration) will directly lead to increased potassium
absorption.
4. The most important hormone affecting renal and salivary potassium
excretion is aldosterone, which is released from the zona glomerulosa
of the adrenal gland in response to hyperkalemia and other factors.
5. At least 95% of whole-body potassium is intracellular.
6. skeletal muscle containing 60% to 75% of the total intracellular
potassium.
7. Marked changes in serum or plasma potassium concentrations alter
the resting membrane potential of cells
8. because the potassium gradient generated by Na-K ATPase is the
main cause for the negative electric potential across cell membranes.
9. Anorexia is thought to play an important role in the development of
hypokalemia in cattle because 24 to 48 hours are needed for the
mammalian kidney to adjust to a reduction in dietary potassium
intake.
10. Dehydration also plays an important role in hypokalemia via
aldosterone activation.
CLINICAL FINDINGS
Medicine Lecture 5th Stage 5-12-2017 Dr.Osamah Muwafk
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1) generalized muscle weakness
2) decreased gastrointestinal motility
3) depression
4) Severely affected animals are unable to stand or lift their heads from
the ground
5) Cows with severe hypokalemia (<2.0 mEq/L) are usually recumbent
and profoundly weak, appear flaccid, and lie in sternal or lateral
recumbency
6) They are unable to support the weight of their heads off the ground
and commonly hold their heads in their flanks
7) Profound weakness of the lateral cervical muscles may occur
8) Cardiac arrhythmias are often detectable on auscultation, and atrial
fibrillation may be present on electrocardiography
9) chronic potassium depletion in cattle include
a) anorexia
b) pica characterized by hair licking, floor licking, and
chewing of wooden partitions
c) rough hair coat
d) muscular weakness
e) irritability, paralysis and tetany
CLINICAL PATHOLOGY:
1) Skeletal Muscle Potassium Content
2) Plasma Potassium Concentration
3) Milk Potassium Concentration: decrease from 1.45 g/L to 1.28 g/L
4) Erythrocyte Potassium Concentration
5) Urine Potassium Concentration: normally (454 ± 112 mEq/L)
6) Salivary Potassium Concentration
NECROPSY FINDINGS :
- Necropsy of cattle with hypokalemia induced recumbency reveals the
presence of muscle necrosis in the pelvic limbs
TREATMENT
Medicine Lecture 5th Stage 5-12-2017 Dr.Osamah Muwafk
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1. Treatment of hypokalemia in lactating dairy cows should focus on
surgical correction of abomasal displacement
2. increasing the potassium intake by increasing dry matter intake or the
oral administration of KCl, and
3. correction of hypochloremia, alkalemia, metabolic alkalosis, and
dehydration
4. Inappetent adult cattle should initially be treated with 120 g of KCl
PO, followed by an additional oral treatment of 120 g KCl 12 hours
later, for a total 24-hour treatment of 240 g KCl (0.4 g/kg BW)
5. Palatable hay and propylene glycol orally are recommended