Hypomagnesemia

Question 1

What are the other names for hypomagnesemia?

Answer 1

1. Grass staggers.
2. Grass tetany.

Question 2

What is hypomagnesemia associated with?

Answer 2

1. Lush, growing pastures.
2. Silage.

Question 3

What is hypomagnesemia?

Answer 3

A metabolic disorder characterized by low body magnesium and low magnesium in the CSF.

Question 4

What animal and production stage is hypomagnesemia most commonly seen in?

Answer 4

1. Beef Cattle.
2. Growing calves (high Mg demands, milk only diet, secondary to scours).

Question 5

What is the etiology of hypomagnesemia?

Answer 5

1. Occurs when Mg intake does not meet demands of Mg required for maintenance and/or lactation.
2. Lush pastures low in Mg.
3. Periods of decreased food intake due to weather, stress, etc.

Question 6

What is the maintenance requirement for Mg?

Answer 6

3 mg/kg body weight.

Question 7

What is the lactation requirement for Mg?

Answer 7

120 mg/kg milk.

Question 8

What is the source of magnesium in the body?

Answer 8

There is not one, Mg must come from the diet.

Question 9

How is Mg absorbed in ruminants?

Answer 9

In the rumen from forages.

Question 10

What minerals in the diet decrease Mg absorption?

Answer 10

1. High K+ and N intake.
2. Low Na+ and P intake.

Question 11

What are rapidly growing grass high and low in?

Answer 11

K+, Mg.

Question 11

Soil high in _________ and/or fertilized with ______ and ________ increases the risk of grass tetany.

Answer 11

potassium, potash, and nitrogen.

Question 12

What cellular pathways is Mg necessary for?

Answer 12

1. ATPase requires Mg.
2. ATP formation is dependent upon Mg.
3. Regulating calcium channel function.
4. Cardiac excitability.
5. Neurotransmission.
6. Vasomotor tone.
7. Muscular contraction.

Question 13

Where is Mg found?

Answer 13

Primarily in cells, but 1% is found in the blood.

Question 14

What is Mg a co-factor for?

Answer 14

The calcium-ATP pump.
*Moves calcium into the sarcoplasmic reticulum.

Question 15

Which two minerals does Mg help transport across the cell membrane via active transport for nerve impulse conduction?

Answer 15

1. Ca.
2. K.

Question 16

When do clinical signs of hypomagnesemia occur?

Answer 16

When plasma calcium is also low.

Question 17

What condition can lush pastures cause in addition to hypomagnesemia?

Answer 17

Metabolic alkalosis.

Question 18

What are the signs of metabolic alkalosis?

Answer 18

1. Urine pH of >8.5.
2. Decreased mobilization of calcium stores.

Question 19

What are the signs of hypomagnesemia?

Answer 19

1. Acute death.
2. Hyperesthesia.
3. Twitching, erect ears.
4. Convulsions/seizures.
5. Hyperexcitable, aggressive.
6. Tetanic muscle spasms.
7. Recumbency.

Question 20

What condition do cows take shorter to recover from than hypomagnesemia?

Answer 20

Milk fever/hypocalcemia.

Question 21

What is the tx for hypomagnesemia?

Answer 21

1. IV infusion of Ca/Mg solution-Given slowly while the HR is monitored.
2. Minimize stimulation.
3. Mg sulfate SQ after IV infusion.
4. Quiet/calm for recovery.

Question 22

How is hypomagnesemia prevented?

Answer 22

1. Begin high Mg mineral supplement several weeks before turning cows onto lush, new pastures until pastures mature.
   *Give with a free choice supplement.

Question 23

How is hypomagnesemia prevented?

Answer 23

1. Supplement water w/ Mg.
2. Avoid K+ fertilizers.
3. Dress pastures with Mg-only effective in certain soil types.
4. Adequate shelter in inclement weather.