Metabolic Diseases

Question 1

Hypocalcaemia Occurence

Answer 1

• Jersey cow is of high risk
• normally recently calved or have a large volume of milk produceiton
• most within 12-24 hours of calving

Question 2

Milk fever (4)

Answer 2

• pearturient hypocalcaemia
• acute disease
• couple of days before- first week after calving
• availability of calcium rather than a true defiecency
• [Ca total]plasma falls below 2.0 mmol/l
• [CA ++]plasma falls below 1.1mmol/l

Question 3

Ca losses

Answer 3

• 1kg of colostrum uses up 2.5g Ca from blood
• dry period total Ca loss: 10-12g/day
• lactation: up to 70g/day in milk alone

Question 4

Milk fever risk factors

Answer 4

• Diet: reduced prepartum feed intake/low Mg intake
• genetics: heritability –> jerseys
• production: high production cows
• season: late summer and autumn
• fat cows have reduced feed intake after calving–> low Ca –> decreased rumen motility –> eat less (degradative cycle!)

Question 5

milk fever pathogenesis

Answer 5

• decreased smooth muscle contractility (vascular and GI)
• decreased cardiac contractility
• decreased skeletal muscle contractility
• decreased neurotransmitter function
• decrease in apocrine gland function

Question 6

Milk fever effects

Answer 6

• muscular weakness
• decrease GI motility
• decreased thermoregulation
• CV collapse
• death

Question 7

Milk fever CS (13)

Answer 7

• apprehension
• tremor
• abnormal gait
• cold ears
• dry muzzle
• rumen stasis
• rumen tympany
• hypothermia
• dry scant faeces
• brady/tachycardia: fluttery heart
• recumbency
• grunting respiration
• hyperglycaemia (interferes with insulin release)

Question 8

Milk fever associated conditions

• at calving
• after calving

Answer 8

At calving:

• dystocia
• still births
• RFM
• uterine prolapse

After calving

• ketosis
• fat cow syndrome
• hepatic lipidosis
• abomasal displacement

Question 9

Priorities in treating hypocalcaemia

Answer 9

• bloat then confirm Dx then Ca
• ca then deliver dead calf
• control haemorrhae then Ca
• re position the Ca

Question 10

CS not associated with milk fever

Answer 10

• agalactia
• pyrexia
• diarrhoea

Question 11

Hypocalcaemia in ewes

Answer 11

• demand exceeds availibility

caused by:

• transport
• movement
• sudden off feed
• oxalates
• snow
• sudden exertion

Question 12

Hypocalcaemia and osteodystrophy

Answer 12

• energy and protein intake allows for high growth rates bu Ca intake is relatively inadequate
• chronic sporadic disease occurring in groups of animals
• cattle on cereal or grass hays with low ca and high grain diet containing high protein and low ca
• poor mineralisation of bones with metaphyseal thickening
• soft and pliable bones with pathological fractures

Question 13

Hypocalcaemia and osteodystrophy

CS

Answer 13

• poor growth rates and inappetence
• thickening of metaphyseal regions of long bones
• dental pitting and gum deformity
• lameness
• recumbancy

Question 14

Transit tetany

• when
• causes

Answer 14

• when cows/ewes in late pregnancy are moved long distances by rail or lorry
• heavy feeding before transport (24 hours off feed during transport)
• unlimited feed, water and exercise after loading

Question 15

Tx of milk fever

Answer 15

• Ca replacement (slow IV over 10-15 minutes –> need adequate restraint)
• supplement with glucose/dextrose and Mg
• symptomatic
• remove calf for 12-24 hours and do not strip udder
• correct positioning of cow will facilitate standing after treatment
• Ca replacement can cause arrhythmias and death –> auscultate whilst administering

Question 16

Evidence of response to tx

Answer 16

• sweat beads on muzzle
• steam rising from coat
• eructation
• tremor
• standing
• cardiac changes can be difficult to interpret

Question 17

Hypocalcaemia complications

Answer 17

• aspiration pneumonia
• downer cow sundrome
• mastitis
• recurrence
• abscesses

Question 18

Hypocalcaemia Px

Answer 18

• dietary cat anion difference (DCAD) diets
• limited Ca prepartum
• Vit D3 injection prepartum
• prophylactic Ca admin
• Mg intake 0.4% of DM

Question 19

DCAD What?? (5)

Answer 19

• bone reorption better in slightly acidic conditions
• acid pH favours increased Ca renal excretion
• high K, Na favour alkalinisation
• creates slightly acidotic condition on cattle prepartum by lowering Na ad K
• rations fed in last 2-3 weeks gestation

Question 20

DCAD considerations

Answer 20

• must have adequate Ca in diet (150g/day)
• problems with maintaining DMI due to unpalatable salt
• not suitable in heifers due to NEB
• require infrastructure to enable prepartum deeding
• high K pastures present problems with balance

Question 21

Mg

• functions (7)

Answer 21

• complex associated with bone
• acts on neuromuscular end plate
• neuromuscular irritibilty increases when [Mg]ecf falls
• ACh release increases
• ACh degradation reduces
• activator in many enzyme systems
• no specific humoral regulator for [Mg]plasma

Question 22

hypomagnesaemia

• normal (4)
• disease (3)

Answer 22

• virtually total reliance on dietary sources for requirements
• circulating poos =4.5g
• [Mg]plasma = 0.7=1mmol/l
• 12mg/kg Mg in milk

hypomagnesaemia when:

• [Mg]plasma = <2mmol/l
• clinical disease occurs within 24 hours of Ca fall although hypoMg has occurred for weeks/months

Question 23

hypomagnesaemia presentation (6)

Answer 23

• adult dairy cow recently calved
• milk fed calf
• adult store beef
• sheep mostly after lambing on improved pasture

all induced by some sort of trigger factor: reduced DMI, transport, bad weather, other diseases

• may and october peak due to differences in feed

Question 24

hypomagnesaemia risk factors

Answer 24

• tamporary decerase in DMI: snow/storms/starvation
• low [Mg]pasture in diet: rye grass (high in buttercups and clover rather than fast growing grass)
• fertilizers leading to reduced Mg in grass: hgih K
• high moisture content pastures:

Question 25

Mg absorption

Answer 25

best when Na:K =5
failure when Na:L <3

(it moves with Na)

Question 26

hypomagnesaemia CS

• peractue (4)
• acute/subacute (16)
• chronic/subclinical (6)

Answer 26

peracute:

• true sudden death
• found dead
• ground torn up
• damage to body: especially eyes and head

acute/subacute:

• suddenly stop grazing
• increased discomfort
• twitching/hyperaesthesia
• galloping, bellowing
• staggering
• rcumbancy
• tetanic spasm
• convulsions
• increased alterness
• nystagmus
• jaw chomping
• retracted eyelids
• ears pricked
• tachypnoea
• tachycardia
• pyrexia

chronic/sunclinical:

• prodromal
• poor appetite
• hyperaesthesia
• muscle tremors
• spontaneous resolution
• progression to clinical

Question 27

hypomagnesaemia in calves (4)

Answer 27

• 3-6 months
• when bucket fed
• single sucked
• milk is poor source of Mg

Question 28

hypomagnesaemia Dx

Answer 28

• epidemiology
• PM:
• -> lack of vindings
• -> [Mg]virteous within 48 hours [Mg]csf within 12 hours [Mg]plasma <2mmol/l

Question 29

hypomagnesaemia Tx

Answer 29

• MgSO4, 400ml 25% s/c –> multiple sites
• Ca borogluconate 400ml, 40% I/V, slowly and warmed
• if not up in 2 hours = poor prognosis
• sucler: keep calf close by to reduce stress

Question 30

hypomagnesaemia Px

Answer 30

• Mg salts in feed
• Mg bullers
• MgCl in water
• pasture and herd management