Food Animal Metabolic: Hypocalcemia "Milk Fever"

Question 1

What DZ along with hepatic lipidosis is known as a metabolic DZ of transition cows?

Answer 1

Hypocalcemia

Question 2

What is hypocalcemia?

Answer 2

LOW Ca2+ (N= 8-10mg/dL)

When a cow goes through parturition and is lactating it decreases the Ca2+ from -1 to +3 days postpartum.

• Challenges calcium homeostasis*
• Predisposes cows to periparturient disorders that are costly to dairy producers*

Question 3

Milk fever is known as a _____________.

Answer 3

Gateway Dz

Question 4

If i have decreased muscle fx it will :

If i have decreased feed intake it will:

If i have decreased immune fx it will:

Answer 4

increase mastitis, DA’s, METRITIS.

increase KETOSIS/FATTY LIVER DZ, DA’s

increase mastitis, RFM, METRITIS

Question 5

What classifies a cow as hypocalcemic and when?

Answer 5

Decreased Ca2+ <7.5mg/dL

More common in cows with uterine prolapse. Happens within 1st 7d postpartum (especially if cows with RFM if fed a prepartum anioni diet)

Question 6

What organs are affected by hypocalcemia?

Answer 6

Uterus (Normal fx is affected)

Abomasum

Rumen

NO APPARENT CS (NO PARESIS)

Question 7

How much more likely is a cow to develop LDA from having hypocalcemia?

Answer 7

4.8x

Question 8

For how long can a cow stay hypocalcemic post partum?

Answer 8

10-30% of fresh cows remain hypocalcemic up to 10 days postpartum.

Question 9

At what point are the majority of cows found to have hypocalcemia?

Answer 9

50% of cows found to have hypocalcemia at calving <7.5mg/dL

Question 10

What is the pathway for Ca2+ homeostasis?

Answer 10

Low Ca2+ in the blood →PTH released (this inhibits with normal to increased ca2+ levels)→activates vit D3 →increased intestinal Ca2+ absoprtion→stimulates osteoclasts→increased Ca2+ uptake from bone→enhance renal tubular Ca2+ resoprtion and decrease renal Ca2+ excretion

Question 11

T/F: Ca2+ is absorbed in the small intestine with the help of Ca2+ binding protein.

Answer 11

True

Question 12

Where to ionized protein bounds form?

Answer 12

the plasma

Question 13

T/F: Ionized Ca2+ is metabolically active form, and is not sensitive to changes in the blood pH.

Answer 13

False

Very sensitive to change in blood pH

Question 14

Which of the following statements is INCORRECT?

a. Low ionized calcium [] does increase PTH production and release
b. Hypocalcemia in cows commonly occur during the first 2 weeks post calving.
c. Normal total serum calcium in cows is from 8-10mg/dL
d. Ca2+ below 4mg/dL decreases the prognosis of the laterally recumbent and comatose clinical hypocalcemia cow

Answer 14

B. Hypocalcemia in cows commonly occurs during the first 2 weeks post calving.

Its actually 1-3 days post partum

Question 15

What are some risks and predisposing factors of Hypocalcemia?

Answer 15

Acute Ca2+ output in colostrum

Milk production (10kg of colostrum has 23g of Ca2+ which is 9x the amt in plasma)

Having >4 lactation cows (decreases Vit D3 gut receptors, decrease osteoclast)

Blood levels of Mg, Ca, PO4

hypomagnesemia

hypophophatemia

Malfx of Ca2+ homeostatic feedback

Question 16

T/F: Milk fever risk is the highest with prepartum dietary Ca at 1.35%.

Answer 16

True

Question 17

T/F: Preosteoclast to osteoclast activation takes 24-48 hours.

Answer 17

False

It takes 48-72hrs

Question 18

What is happening when there is hypomagnesemia?

Answer 18

Low levels of Mg impairs the release of PTH and interaction of PTH with target organs

Question 19

What is going on when there is hypophosphatemia?

Answer 19

Low levels of PO4 interferes with activation of Vit D by inhibiting acivity of renal 1-hydroxylase enzyme

Question 20

What happens when there is subclinical hypocalcemia?

Answer 20

Malfx of Ca2+ homeostatic feedback, so there is flux in intestinal absorption which leads to forestomach hypomotility (DA, ketosis).

Can occur in up to 50% of cows

Question 21

T/F: Alkaline blood pH lowers Ca2+ mobilization

Answer 21

True

+DCAD favors alkalosis which leads to high K+ and Na+ in forage for dry cow diet.

(Na + K) - (Cl + S)= DCAD

Cations - Anions

Question 22

What are other aspects of having Alkaline blood pH that lowers Ca2+ mobilization?

Answer 22

Increased bound Ca2+ from ionized pool

Less efficient intestinal absorption

Decreased osteoclast receptor affinity for PTH

Question 23

What are some characteristics of having acidic pH increase blood Ca2+?

Answer 23

Increased plasma level activated Vit D3 will increase intestinal absorption.

Can cause calciuria which leads to increased PTH secretion.

Cause increaed affinity of osteoclast bone receptors for PTH which leads to Ca2+ mobilization from bone.

Question 24

What should a farmer do, if he knows his cow is pregnant?

Answer 24

Prepare the cow for Ca2+ shortage because when calving comes, will have full potential for Ca2+ availability.

Question 25

What are some clinical signs to be aware of when on a hypocalcemia case?

Answer 25

**Gradual loss of thermoregulation (COLD EXTREMETIES AND EARS)** *Due to decreased circulation* Physically: **DOWN,** kinked neck, decreased jaw/tongue tone **Flaccid paralysis** Suspended rumen contraction Decreaed anal tone **Full rectum** **Tachycardia** soft heart sounds decreased inotropy/CO due to decreaed venous returna nd weaker cardiac muscle Weak corneal reflex Semi-comatose state

Question 26

How would you dx hypocalcemia?

Answer 26

CS Hx Ionized blood levels \<1mmol/L or total Ca2+

Question 27

What is Stage 1?

Answer 27

standing decreased rumen fx subclinical Ca2+ \<7.5mg/dL

Question 28

What is Stage 2?

Answer 28

**Most likely call a VET at this stage!!!** Sternal recumbency Fights reactions and stimulations Bellowing, open tongue, shaking, anxious Bent neck → "S" or "Z", bloat, cold extremeties **5mg/dL \< Ca2+ \< 7.5mg/dL**

Question 29

What is Stage 3?

Answer 29

Comatose Unresponsive near death Ca2+ \< 5mg/dL

Question 30

How do you Tx hypocalcemia?

Answer 30

**IMMEDIATELY PARENTERAL IV Ca2+ THERAPY** Ca²⁺ gluconate less caustic than CaCl₂ Ca²⁺ borogluconatnt for hypocalcemia more soluble and stable soln. **Ca²⁺ replacement about 10g** *Give at a rate of 1g/min total ds=2g/100kg BW*

Question 31

What are favorable responses to hypocalcemia tx?

Answer 31

**Eructation** Tremors especially head and neck Decreased heart rate and increased sound intesity improved attitude they poop 25-30% will relapse, so retx with Ca²⁺ IV + SQ and consider giving Mg

Question 32

How would you prevent hypocalcemia?

Answer 32

Ca2+ gel at parturition Don't overfeed Ca2+, avoiding over conditioning and stress Give maintanence PO4 requiremnets and 100-125g Ca2+/day PO or inj Vit D prior to calving DCAD diet

Question 33

What should a DCAD diet include when treating hypocalcemia?

Answer 33

Want **5 to 10mEq/100g of DM** Anion salts...Bitter, a challenge with DMI Roughage low in Na and K *Add ammonium chloride the last few weeks before parturition. Start with 25g/d and increase to to 100g/d* ***Careful because anionic DCAD→metabolic acidosis→aciduria :(***

Question 34

What is considered subclinical treatment of hypocalcemia?

Answer 34

Ca2+ tx to restore blood Ca2+ and promote normal fx of Ca2+ dependent organs (IV or PO) *Cows with RFM, uterine prolapse, DA, inappetence*

Question 35

What precautions should you be aware of when treating hypocalcemia?

Answer 35

1. toxemic animals super sensitive to IV Ca2+ 2. Ca2+ sequestration in cows with ischemic muscle necrosis can develop **metastatic calcification of cardiac muscle** 3. do not use in cows with cardiac glycoside intoxication 4. **FAST CA2+ IV INFUSION CAN LEAD TO HEART FAILURE AND THEN DEATH!!!**

Question 36

Which breed is most susceptible to hypocalcemia?

Answer 36

**Jerseys!!!** more Ca2+ in colostrum, less intestinal Vit D3 receptors