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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
what are the risk factors of hypoMg
**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
when does hypoMg occur
4-8 weeks postpartum beef cattle peracute cases sudden death
27
how does hypoMg lead to increase risk for milk fever
Decrease secretion parathyroid hormone Decrease tissue sensitivity to PTH Mg has no hormonal control
28
what is the plasma levels of Mg in a normal adult cow
Plasma: 0.80 to 1.0mmol/L CSF: ~1.0mmol/L
29
how is Mg homeostasis maintained
young calves: small intestine absorption adult: rumen * [Mg] in solution in rumen fluid * Mg transport mechanism (Na vs K)
30
when should you blood sample cows to monitor for hypoMg
Within 12 hours postpartum — periparturient cow status First week of lactation — lactating cow’s diet
31
at what plasma level does hypoMg tetany occur
Less than 0.5mmol/L
32
what does hypoMg tetany cause
Ataxia Tetanic muscle spasms Hyper excitability Hyperesthesia
33
when do seizures and convulsions occur in hypoMg
less than 0.4 mmol/L
34
what are the treatment options of hypoMg
Mg IV Mg + other macroelements Mg SC Mg enema
35
when should Mg IV be used
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
how is Mg and other macroelements IV + Mg SC used to treat hypoMg
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
how is Mg SC injection used to treat hypoMg
SC injection magnesium sulphate 50% solution (200ml — at least 4 injection sites)
38
how is Mg enema used to treat hypoMg
Rectal infusion of Mg salts Magnesium chloride — up to 5 tablespoonful in 250ml warm water
39
how often do relapses occur after hypoMg treatment
Relapses 12 to 24h later Assure dietary intake (40g) * Ex. concentrates
40
how is hypoMg prevented/controlled
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
what are the challenges with hypoP
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
what are the causes of hypoP
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
what are the normal serum levels in adult cattle
1.4-2.6 mmol/L
44
what are the normal serum levels in growing cattle
1.9-2.6 mmol/L
45
what are the considerations when blood sampling to measure levels of P
Site Anticoagulants Sample collection and processing Pre-sampling factors
46
what are serum levels of clinical cases of hypoP
serum \<0.5 mmol/L
47
when do acute hypoP cases occur in dairy
around parturition early lactation
48
when do chronic hypoP cases occur i
grazing animals in arid regions - low P soil content fast growing calves low P ration/milk
49
what are the clinical signs of acute hypoP
Muscle weakness Recumbency Intravascular hemolysis —\> downer cow syndrome, periparturient hemoglobinuria leads to: Downer cow syndrome Periparturient hemoglobinuria
50
what are the clinical signs of chronic hypoP
Bone demineralization Impaired fertility Anorexia Pica (abnormal eating) Poor growth or weight loss Impaired milk production
51
how are anorexic cattle treated for hypoP
Oral supplementation: * Sodium phosphate salts: 150 to 270g * Monopotassium phosphate * Monocalcium phosphate: 200 to 400g
52
how are recumbent cattle treated for hypoP
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
how is hypoP prevented/controlled
Grazing animals: * Fertilizing soil with P * Free access to high P minerals * Water supplementation

Module 21: Ruminant Production (21 decks)

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