Hypocalcemia, Hypomagnesemia, DCAD Flashcards
Maintenance requirement for calcium
13g
T/F: Ca demand increases dramatically at the start of lactation
True
Which sucks b/c dry matter intake is down so def not getting it from the diet
If a cow is unable to take calcium in through her diet, where is she gonna try and get it from?
Plasma pool, extra cellular fluid, bone
What are the three ways the cow can control Ca?
- SI: when Ca is low, Ca binding protein is stimulated by vitamin D to increase absorption
- Bone: PTH promotes resorption by osteoclasts in bone
- Kidney: PTH promotes conservation
T/F: Hypocalcemia at parturition is attributable to PTH deficiency
False - Cows actually have higher concentrations of PTH
T/F: Milk fever occurs most commonly within 24h after calving
True
EARLY clinical signs of milk fever
Mild excitement, tetany, tachycardia, hyperthermia
Classic clinical signs of milk fever
Sternal recumbency, depression
Flaccid paralysis
Tachycardia
Hypothermia
Atonic rumen, bloat, constipation
Dilated, unresponsive pupils
LATE clinical signs of milk fever
Comatose
75% die w/o treatment
What should a normal fresh cow’s calcium levels be?
> 8mg/dL
What other clinical pathology changes might we see in a cow with milk fever?
Hypophosphatemia
Hypermagnesemia
Hyperglycemia - steroid influence
Milk fever treatment
8-12g calcium IV SLOWLY and monitor HR
Usually 500mL of a 23% Ca gluconate solution
How can we prevent milk fever?
- Maintain appetite and intake around parturition
- Avoid high K diets in dry period (thought to inhibit absorption of Ca)
- CaCl drench/tube at calving
Creeper cows are
Hypophosphatemic
T/F: to treat hypophosphatemia you should give 1-2 500mL bottles of CMPK
False - CMPK contains phosphite which won’t increase plasma P
Need to give phosphate - fleet enema IV or oral NA phosphate/dical phosphate
Where is most magnesium absorbed?
Rumen and LI
A cow has no endocrine regulation of Mg, meaning if they are low, they have no way of mobilizing magnesium from within the body. Where must cows get most of their magnesium?
Rely on daily intake
Diet usually meets requirements
What are the two kinds of hypomagnesemia?
Winter tetany: late gestation/early lactation
Grass tetany: lactating cows on lush spring or fall pasture
Why does lush spring pasture cause grass tetany?
High concentrations of potassium decrease the absorption of Mg from the rumen
High K in diet, fertilizer used on pasture
Clinical signs of hypomagnesemia
- Acute death
- Grass tetany: belligerent, ataxic, muscle tremors, protrusion of nictitans membrane, salivation, bruise, seizures, urination…DDX? Rabies
- Winter tetany: Alert down cow, “can almost get up”
How can we diagnose hypomagnesemia?
Normal serum Mg: 1.8-3.0mg/dL
Grass tetany: Mg <1.5mg/dL
Winter tetany: low Mg and low Ca
Can use blood, ocular fluid, CSF, or urine
Treatment for hypomagnesemia
IV Ca Mg solutions
Oral or enema
Recommended to follow IV treatment w/ oral supplementation as relapses are common
How can we prevent hypomagnesemia?
Supplement gestating and lactating beef cows w/ 10-20g of Mg/day
T/F: We can alter acid base status of the animal with the amount of cations and anions in the diet
True
Can you give an example of how a mineral salt can influence the pH of an animal?
MgCl - Acidifier
MgSO4 - Cathartic
MgOH - Alkalinizer
Can add Mg to the animal in multiple ways, but the effect on the animal will be different
If we feed an excess of cations, we are making the cow more _________
Alkalotic
If we feed or treat with an excess of strong anions, we can make a cow ___________
Acidic
How does acidifying cows lower the risk of hypocalcemia?
Counteract high K diets
Lower blood pH enhances receptivity of PTH receptor
