Food Animal Metabolic: Hypocalcemia "Milk Fever" Flashcards
What DZ along with hepatic lipidosis is known as a metabolic DZ of transition cows?
Hypocalcemia
What is hypocalcemia?
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*
Milk fever is known as a _____________.
Gateway Dz
If i have decreased muscle fx it will :
If i have decreased feed intake it will:
If i have decreased immune fx it will:
increase mastitis, DA’s, METRITIS.
increase KETOSIS/FATTY LIVER DZ, DA’s
increase mastitis, RFM, METRITIS
What classifies a cow as hypocalcemic and when?
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)
What organs are affected by hypocalcemia?
Uterus (Normal fx is affected)
Abomasum
Rumen
NO APPARENT CS (NO PARESIS)
How much more likely is a cow to develop LDA from having hypocalcemia?
4.8x
For how long can a cow stay hypocalcemic post partum?
10-30% of fresh cows remain hypocalcemic up to 10 days postpartum.
At what point are the majority of cows found to have hypocalcemia?
50% of cows found to have hypocalcemia at calving <7.5mg/dL
What is the pathway for Ca2+ homeostasis?
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
T/F: Ca2+ is absorbed in the small intestine with the help of Ca2+ binding protein.
True
Where to ionized protein bounds form?
the plasma
T/F: Ionized Ca2+ is metabolically active form, and is not sensitive to changes in the blood pH.
False
Very sensitive to change in blood pH
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
B. Hypocalcemia in cows commonly occurs during the first 2 weeks post calving.
Its actually 1-3 days post partum
What are some risks and predisposing factors of Hypocalcemia?
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
T/F: Milk fever risk is the highest with prepartum dietary Ca at 1.35%.
True
T/F: Preosteoclast to osteoclast activation takes 24-48 hours.
False
It takes 48-72hrs
What is happening when there is hypomagnesemia?
Low levels of Mg impairs the release of PTH and interaction of PTH with target organs
What is going on when there is hypophosphatemia?
Low levels of PO4 interferes with activation of Vit D by inhibiting acivity of renal 1-hydroxylase enzyme
What happens when there is subclinical hypocalcemia?
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
T/F: Alkaline blood pH lowers Ca2+ mobilization
True
+DCAD favors alkalosis which leads to high K+ and Na+ in forage for dry cow diet.
(Na + K) - (Cl + S)= DCAD
Cations - Anions
What are other aspects of having Alkaline blood pH that lowers Ca2+ mobilization?
Increased bound Ca2+ from ionized pool
Less efficient intestinal absorption
Decreased osteoclast receptor affinity for PTH
What are some characteristics of having acidic pH increase blood Ca2+?
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.
What should a farmer do, if he knows his cow is pregnant?
Prepare the cow for Ca2+ shortage because when calving comes, will have full potential for Ca2+ availability.
What are some clinical signs to be aware of when on a hypocalcemia case?
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
How would you dx hypocalcemia?
CS
Hx
Ionized blood levels <1mmol/L or total Ca2+
What is Stage 1?
standing
decreased rumen fx
subclinical
Ca2+ <7.5mg/dL
What is Stage 2?
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
What is Stage 3?
Comatose
Unresponsive
near death
Ca2+ < 5mg/dL
How do you Tx hypocalcemia?
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
What are favorable responses to hypocalcemia tx?
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
How would you prevent hypocalcemia?
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
What should a DCAD diet include when treating hypocalcemia?
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 :(
What is considered subclinical treatment of hypocalcemia?
Ca2+ tx to restore blood Ca2+ and promote normal fx of Ca2+ dependent organs (IV or PO)
Cows with RFM, uterine prolapse, DA, inappetence
What precautions should you be aware of when treating hypocalcemia?
- toxemic animals super sensitive to IV Ca2+
- Ca2+ sequestration in cows with ischemic muscle necrosis can develop metastatic calcification of cardiac muscle
- do not use in cows with cardiac glycoside intoxication
- FAST CA2+ IV INFUSION CAN LEAD TO HEART FAILURE AND THEN DEATH!!!
Which breed is most susceptible to hypocalcemia?
Jerseys!!!
more Ca2+ in colostrum, less intestinal Vit D3 receptors
