Controlling hypocalcaemia

Question 1

what is the main hormone that controls calcium levels

Answer 1

PTH triggers calcitrol release from kidneys- acts to try and increase absorption

Question 2

list 4 effects of hypocalcaemia in cows

Answer 2

Increased neuromuscular irritability.
Decreased smooth muscle contraction.
Decreased skeletal muscle contraction.
Reduced cardiac muscle contractility

Question 3

Which of the following act to increase blood calcium?
a) Calcitonin & Thyroxine
b) Parathyroid hormone & Aldosterone
c) Parathyroid hormone & Calcitrol
d) Calcitonin & Aldosterone

Answer 3

C- Parathyroid hormone & Calcitrol

Question 4

Which of the following cows is most at risk?
a) Heifer, calved today
b) 4th parity cow, calved today
c) High yield 2nd parity cow, 30 days in milk
d) Heifer, late gestation

Answer 4

b- 4th parity cow, calved today

Question 5

what are the risk factors for hypocalcaemia in cows

Answer 5

Age - older cows have reduced calcium reserves
Amount of milk producing
Breeds
BCS>4
C-section/ dystocia

Question 6

Based on the clinical signs, which down cow is most likely to have hypocalcaemia?
a) Constipation, ruminal bloat
b) Thrashing limbs, hyperaesthesia
c) Sunken eyes, diarrhoea
d) Lame. Unable to weight-bear on one leg

Answer 6

A

Question 7

List 7 clinical signs of hypocalcaemia

Answer 7

weakness
S-bend neck
rumen atopy
GI stasis
poor uterine involution
slightly increased HR
poor contractility

Question 8

Which of these additional treatments would you give after treating with IV calcium?
a) Sub-cut Ca & Phos
b) Oral Ca bolus & NSAID
c) Sub-cut Ca & NSAID
d) No additional Tx

Answer 8

B

Question 9

describe treatment plan to hypocalcaemia

Answer 9

400ml 40% calcium borogluconate slowly IV- over 5-10mins

Question 10

why shouldn’t you give IV calcium too quickly

Answer 10

risk of hypercalcaemic relapse.
Reverses physiological mechanisms.
Halts PTH release and triggers calcitonin secretion due to surplus in blood.

Question 11

what do you want to see after treating milk fever cow with IV calcium

Answer 11

Eructation
defecation
urination
standing within ~20-30 mins

Question 12

Which of the following methods may help reduce the incidence of milk fever on a herd level?
a) Increase Ca & Na at calving
b) Decrease Ca & Na at calving
c) Increase Ca & K in dry period
d) Decrease Ca & K in dry period

Answer 12

D- helps to get the PTH to already start mobilising

Question 13

what additional treatment can you give milk fever cow other than IV calcium

Answer 13

Subcut Ca
Oral Ca
NSAID
Phosphorus- not key but commonly in preparations with Ca

Question 14

what happens in dry cows getting high Ca diets

Answer 14

reduce absorption from the diet and excrete excess
Once calved- She cannot meet Ca demand as the mechanisms are already down-regulated- takes longer to mobilise

Question 15

why does restriticing Ca in dry period reduce milk fever

Answer 15

Limiting Ca prior to calving, up-regulates PTH mechanisms
Starts resorption from bone, increases dietary absorption etc,
Over 2-3 weeks cow is better prepared for increased demand.

Question 16

what level should you reduce Ca to in dry period diets to reduce MILK FEVER

Answer 16

Reduce dietary calcium to ~100g Ca/day.

Question 17

how does age increase the risk of hypocalcaemia in cows

Answer 17

older cows have reduced calcium reserves and their response mechanisms are slower

Question 18

what is DCAB

Answer 18

dietary cation-anion balance

Question 19

how does a DCAB diet help reduced hypocalcaemia incidence

Answer 19

blood pH is lowered and a slight acidosis occurs, this increases PTH function and means cows can mobilise calcium better

Question 20

how do we achieve a DCAB diet

Answer 20

decrease sodium and potassium (cations) and increase chlorine and sulfide (anions)

Question 21

if doing DCAB why do we have to be careful with silage

Answer 21

grass silage has variable amounts of ions

Question 22

how does hypocalcaemia lead to an increased risk of LDAs

Answer 22

rumen and digestive tract motility is reduced and this leads to an increased risk

Question 23

how does hypocalcaemia lead to an increased risk of ketosis

Answer 23

rumen and digestive tract motility is reduced, this leads to decreased DMI and this leads to an increased risk

Question 24

how does hypocalcaemia lead to a decreased milk yield

Answer 24

recued feed intake and reduced calcium levels leads to decreased milk production

Question 25

how does hypocalcaemia lead to an increased risk of mastitis

Answer 25

due to the lowered immune function and the lack of smooth muscle function

Question 26

how does hypocalcaemia lead to an increased risk of retained placenta and metritis and therefore a lower fertility

Answer 26

due to lowered uterine motility and decreased involution