3/3 Parathyroid Gland - Hypocalcaemia COMPLETE***

Question 1

Hypocalcaemia: State another name for Hypocalcaemia

Answer 1

milk fever

Question 2

Hypocalcaemia: What is calcium important for?

Answer 2

muscle contraction

Question 3

Hypocalcaemia: Generally, what are the effects of Hypocalcaemia? 4

Answer 3

decreased smooth muscle contraction
decreased skeletal muscle contraction
reduced cardiac muscle contractility
increase neuromuscular irritability

Question 4

Hypocalcaemia: Why does hypocalcaemia affect so many different systems? 3

Answer 4

skeletal muscle is affected so affects posture and gait
smooth muscle is affected so affects the GI tract and reproductive tract
cardiac muscle is affected so affects the heart and circulation

Question 5

Hypocalcaemia: Describe the cascade of events stemming from the effect on cardiac muscle 4

Answer 5

reduced force of contraction
reduced cardiac output
reflex tachycardia
peripheral vasodilation

Question 5

Hypocalcaemia: What clinical signs would you expect to see as a result of skeletal muscle being affected? 3

Answer 5

recumbency
weakness when attempting to stand
S bend in neck

Question 6

Hypocalcaemia: What clinical signs would you expect to see as a result of Smooth muscle being affected for the reproductive tract? 2
- What about for the GI tract?

Answer 6

poor uterine contraction leading to uterine inertia and dystocia
poor uterine involution so retained foetal membranes and metritis

reduced contractions and peristalsis so reduced rumen turnover, luminal bloat, luminal impaction, constipation

Question 7

Hypocalcaemia: Describe the cascade of events stemming form the effect on cardiac muscle 4

Answer 7

reduced force of contraction
reduced cardiac output
reflex tachycardia
peripheral vasoconstriction

Question 8

Hypocalcaemia: What usually causes Hypocalcaemia?

Answer 8

due to high calcium demand

Question 9

Hypocalcaemia: What factors contribute to high calcium demand? 4

Answer 9

milk production
colostrum production
late pregnancy
maintenance

Question 10

Hypocalcaemia: Detail the events following lactation and the bodies response to low calcium

Answer 10

calcium is lost through milk and colostrum
there is a decrease in ionised calcium in plasma
this is detected by the parathyroid gland
increase in PTH
PTH increases calcium reabsorption in kidney
PTH increases activity of enzyme converting inactive vitamin d to calcitriol
PTH acts on bone to obtain calcium
calcitriol increases intestinal absorption of calcium

Question 11

Hypocalcaemia: In dairy Cows, why do blood calcium concentrations not return to normal if all these mechanisms are in place? 2
- Why might they get metabolic alkalosis?

Answer 11

metabolic alkalosis at calving reduced response to PTH
insufficient magnesium reduced PTH secretion

due to increased dietary sodium and potassium leading up to calving

Question 12

Hypocalcaemia: What is the term given to describe involuntary muscular contractions?

Answer 12

tetany