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Module 21: Ruminant Production > Production Diseases: HypoCa, HypoMg, HypoP > Flashcards

Production Diseases: HypoCa, HypoMg, HypoP Flashcards

1
Q

when do hypoCa, hypoMg, hypoP occur during the dairy cow cycle

A
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2
Q

what are the functions of calcium

A

Essential mineral component of skeleton

Ionized calcium involved in muscle contraction, blood coagulation, enzyme activity, neural excitability and hormone secretion

98% of Ca is in skeleton

2% in extracellular fluid, around half bound to plasma protein (albumin) and around half ionized in soluble form

Must maintain ionized Ca in blood for normal nerve and muscle function

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3
Q

what is the total blood Ca in a normal adult cow

A

2.1-2.5 mmol/L

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4
Q

what occurs at the onset of lactation

A

degree of hypocalcemia 12-24h postpartum

calcium homeostasis mechanisms kick in and restore circulating levels

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5
Q

what are the calcium homeostasis mechanisms

A
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6
Q

what 3 hormones manage calcium homeostasis

A
  1. parathyroid hormone (PTH)
  2. 1,25-dihydroxyvitamin D
  3. calcitonin
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7
Q

how do the 3 hormones maintain blood calcium levels

A
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8
Q

what is the calcium status during the transition period

A
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9
Q

what is subclinical hypocalcemia total blood levels

A

1.38-2.0 mmol/L

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10
Q

what does subclinical hypocalcemia predispose the cow to

A

Increases risk of:

Ketosis

DA

Mastitis

Metritis

Fatty liver

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11
Q

what effect does subclinical hypoCa have on production

A

decrease fertility, milk yield, immunity

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12
Q

at what blood Ca level is milk fever

A

<1.4 mmol/L

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13
Q

when does milk fever occur

A

dystocia

still births

RFM

uterine prolapse

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14
Q

what is milk fever

A

clinical disorder

Availability of calcium rather than true deficiency

Life threatening to cow

Increases risk of other diseases (metabolic and infectious)

Age

Breed

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15
Q

what is the prevalence of milk fever

A

increasing prevalence as increasing lactation number

Up to 50% of herd could have subclinical hypocalcemia near parturition

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16
Q

what are the clinical signs of stage 1 of milk fever

A

Excitability

Nervous

Weak

Shift weight and shuffle hind feet

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17
Q

what are stage 2 milk fever clinical signs

A

Sternal recumbency

Moderate to severe depression

Partial paralysis

Lying down with head turned into their flank

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18
Q

what are stage 3 milk fever clinical signs

A

Lateral recumbency

Completely paralyzed

Bloated

Severe depression to coma

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19
Q

what are the general clinical signs of milk fever

A

Protrusion of tongue

Thermoregulation ability loss

Cutaneous circulation depressed — cold extremities (cold ears and dry muzzles)

Rumen stasis

Increased heart rate

Absence of PLR

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20
Q

how are stage 1 clinical signs of milk fever treated

A

Oral calcium

  • Calcium chloride 50g
  • Calcium propionate 75-125g
  • Calcium chloride + calcium sulphate fat-coated bolus

SC 23% calcium solution

  • Divided for at least 4-5 sites ~75ml each
  • May be ineffective in dehydrated cows
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21
Q

how are stage 2 and 3 milk fever cows treated

A

IV calcium (jugular vein)

  • 500ml of 23% calcium borogluconate (10g calcium)
  • 400ml of 40% calcium borogluconate (12g calcium)
  • Slow administration (5-10 min)

Sudden increase in heart rate

Arrhythmia

Stop!

If relapses 12-18h later then:

    • oral calcium: once the cow is alert and able to swallow + 12h later
  • Or SC calcium (may be ineffective in severe cases and dehydrated cows)

Palliative care! Down cow

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22
Q

what are early signs of treatment responsiveness to milk fever

A

Tremors

PLR

Wet muzzle

Eructation

Urination

Defecation

23
Q

how is hypoCa prevented using nutrition pre calving

A

Low-calcium diet at pre-partum (less 100g)

Nutritional antagonists/binders of Ca (zeolite)

Vitamin D supplementation

Assurance dietary magnesium supply (0.4%)

Slight acidification of blood reducing ratio of strong cations (Na+ + K+) to strong anions (Cl- + S2-) to increase PTH activity (DCAD diet) —> metabolic acidosis

  • Monitor urine pH (loss H+)
  • Decrease palatability

Calcium supplementation at calving

Monitor calcium in blood (24-48h post-partum)

24
Q

how is hypoCa prevented/controlled using good management

A

Avoid stress

No overcrowding

No group movement

Social factors

Feed management (low K silage)

Etc

25
Q

what are the risk factors of hypoMg

A

Older cows

  • Decrease ability to absorb dietary magnesium

Rapid changes of diet

  • Lush grass (moving fields)
  • Low fibre (straw can slow rumen transit)
  • Weather (rain leaching)
  • Diet restriction (inadequate supply/ration access)

High levels of potassium and ammonia

Low levels of sodium

26
Q

when does hypoMg occur

A

4-8 weeks postpartum beef cattle

peracute cases

sudden death

27
Q

how does hypoMg lead to increase risk for milk fever

A

Decrease secretion parathyroid hormone

Decrease tissue sensitivity to PTH

Mg has no hormonal control

28
Q

what is the plasma levels of Mg in a normal adult cow

A

Plasma: 0.80 to 1.0mmol/L

CSF: ~1.0mmol/L

29
Q

how is Mg homeostasis maintained

A

young calves: small intestine absorption

adult: rumen

  • [Mg] in solution in rumen fluid
  • Mg transport mechanism (Na vs K)
30
Q

when should you blood sample cows to monitor for hypoMg

A

Within 12 hours postpartum — periparturient cow status

First week of lactation — lactating cow’s diet

31
Q

at what plasma level does hypoMg tetany occur

A

Less than 0.5mmol/L

32
Q

what does hypoMg tetany cause

A

Ataxia

Tetanic muscle spasms

Hyper excitability

Hyperesthesia

33
Q

when do seizures and convulsions occur in hypoMg

A

less than 0.4 mmol/L

34
Q

what are the treatment options of hypoMg

A

Mg IV

Mg + other macroelements

Mg SC

Mg enema

35
Q

when should Mg IV be used

A

Seizures + convulsions

IV sedation

  • Xylazine 0.05mg/kg

IV magnesium sulphate 20% (200-300ml)

Slow administration — cardiotoxicity

Respiratory distress

Excessive slowing or increase in heart rate —> stop admin

36
Q

how is Mg and other macroelements IV + Mg SC used to treat hypoMg

A

Seizures & convulsions:

IV sedation

  • Pentobarbitone 3mg/kg; xylazine 0.05mg/kg

IV magnesium sulphate (30ml 25% solution) combine with calcium borogluconate (400ml 40% solution)

  • Remaining 370ml of 25% magnesium sulphate SC (over at least 4 sites)
37
Q

how is Mg SC injection used to treat hypoMg

A

SC injection magnesium sulphate 50% solution (200ml — at least 4 injection sites)

38
Q

how is Mg enema used to treat hypoMg

A

Rectal infusion of Mg salts

Magnesium chloride — up to 5 tablespoonful in 250ml warm water

39
Q

how often do relapses occur after hypoMg treatment

A

Relapses 12 to 24h later

Assure dietary intake (40g)

  • Ex. concentrates
40
Q

how is hypoMg prevented/controlled

A

Potassium and sodium content in the diet

Molasses-based licks/buckets (Mg and Na)

Concentrates with Mg and Na

Water medicated with Mg salts

Intraruminal boluses containing Mg

Pastures dusted with calcined magnesite

Ensure adequate ration intakes!

41
Q

what are the challenges with hypoP

A

Not fully understood

Similar mechanisms and links with calcium homeostasis

Sometimes difficult to distinguish clinically in diary cows with hypocalcemia

Can be observed as complication in milk fever cases

42
Q

what are the causes of hypoP

A

Inadequate dietary P supply (diet or soil)

Excessive P losses

Compartmental P shifts (dextrose/insulin)

Combination of several mechanisms

  • Increased milk production
  • Decline of DMI
  • Increase glucose and cortisol at parturition
  • Renal losses
43
Q

what are the normal serum levels in adult cattle

A

1.4-2.6 mmol/L

44
Q

what are the normal serum levels in growing cattle

A

1.9-2.6 mmol/L

45
Q

what are the considerations when blood sampling to measure levels of P

A

Site

Anticoagulants

Sample collection and processing

Pre-sampling factors

46
Q

what are serum levels of clinical cases of hypoP

A

serum <0.5 mmol/L

47
Q

when do acute hypoP cases occur in dairy

A

around parturition

early lactation

48
Q

when do chronic hypoP cases occur i

A

grazing animals in arid regions - low P soil content

fast growing calves low P ration/milk

49
Q

what are the clinical signs of acute hypoP

A

Muscle weakness

Recumbency

Intravascular hemolysis —> downer cow syndrome, periparturient hemoglobinuria

leads to:

Downer cow syndrome

Periparturient hemoglobinuria

50
Q

what are the clinical signs of chronic hypoP

A

Bone demineralization

Impaired fertility

Anorexia

Pica (abnormal eating)

Poor growth or weight loss

Impaired milk production

51
Q

how are anorexic cattle treated for hypoP

A

Oral supplementation:

  • Sodium phosphate salts: 150 to 270g
  • Monopotassium phosphate
  • Monocalcium phosphate: 200 to 400g
52
Q

how are recumbent cattle treated for hypoP

A

slow IV injection of sodium phosphate salts (extralabel)

  • life-threatening hyperkalemia + oral supplementation

Slow IV injection:

  • Calcium hypophosphite (400ml)
  • 20% toldimphos (20ml)
  • Sodium glycerophosphate
53
Q

how is hypoP prevented/controlled

A

Grazing animals:

  • Fertilizing soil with P
  • Free access to high P minerals
  • Water supplementation

Module 21: Ruminant Production (21 decks)

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