Calcium, phosphorus, magnesium, sodium and potassium disorders Flashcards
What diseases are associated with calcium?
- Milk fever
- Downer cow syndrome
- Enzootic calcinosis
What are some other names for milk fever?
- Hypocalcaemia
- Parturient paresis
- Calving paralysis
When does milk fever occur?
75% occur within 24 hours after calving
5% occur post-48 hours
How many dairy cows are affected by milk fever in the UK (%)?
4-9%
How many grams of calcium is needed for 12l of colostrum?
30g
How many grams of calcium is needed for 40l of milk?
80g
Which cows are mostly affected by milk fever?
Older cows, after their 3rd lactation
How is calcium homeostasis maintained?
- Parathyroid hormone
- 1,25-dehydroxyvitamin D3
- Calcitonin
Why does milk fever occur?
Due to a rapid increase in the demands of calcium post-partum (colostrum). The body takes 2-3 days to compensate and for the hormonal mechanisms to take effect.
How many clinical stages are there to milk fever?
Three
Describe the clinical signs of stage 1 of milk fever
- Standing but wobbly
- Brief stage of excitement
- Tetany with hypersensitivity
- Muscle tremor of head and limbs
- Disinclined to move
- Inappetence
- Protrusion of tongue
- Bruxism
- Hind limb stiffness, ataxia and falling
Describe the clinical signs of stage 2 of milk fever
- Sternal recumbency
- Lateral kink in neck (S-shape)
- Inability to stand
- Depressed, drowsy
- Dry muzzle
- Cool extremities
- Marked decrease in heart sound intensity but tachycardia
- Dry, staring eyes
- Ruminal stasis and bloat
- Relaxed anal reflexes
Describe the clinical signs of stage 3 of milk fever
- Lateral recumbency
- Unresponsive, almost comatose
- Completely flaccid movement of legs
- Marked depressed on rectal temperature
- Almost inaudible heart sounds
- Increased heart rate (>120bpm)
- Bloat
- Death due to shock and respiratory muscle paralysis
How can milk fever be further complicated?
- Aspiration pneumonia due to inhalation of rumen content
2. Pressure damage to nerves and muscles
What post-mortem signs will you see in milk fever?
- Fatty liver
2. Displaced abomasum
How do we diagnose milk fever?
- History and clinical signs
2. Calcium levels (serum) - <1.5mmol.l
What are the NORMAL levels of calcium?
2.2-2.8mmol.l
What is the MAIN differential for milk fever?
Ketosis - >24 hours post-partum
How do we treat milk fever?
- Calcium salts - IV - slow injection over 5-10 minutes
- 400ml of 40% (160ml) calcium borogluconate administration
- Magnesium and phosphorus
- SC calcium - to prevent relapse
How do we prevent milk fever?
- BCS of 2.5-3.5 at calving
- Low calcium levels in the dry period (<30g/d)
- Limit P levels to <45g/d
- Calcium drench (150g CaCl2 daily) in days before calving
What is downer cow syndrome and how is it linked to milk fever?
Ischaemic necrosis of muscles due to prolonged (>24 hours) recumbency in one position (e.g. during milk fever)
What is a massive negative prognostic indicator of downer cow syndrome?
Damage to the sciatic nerve
What would we see on a post-mortem of a downer cow?
- Extensive necrosis of the caudal thigh muscles
- Inflammation of the sciatic nerve
- Necrosis of muscle fibres
- Rupture of muscle fibres
What enzymes would be elevated in downer cow syndrome?
CK, AST and LDH
How do we prevent downer cow syndrome?
Manual movement of a cow that is in recumbency for prolonged periods
What is enzootic calcinosis?
Intoxication with calcinogenic plants, resulting in hypERcalcaemia
What plants are calcinogenic?
- Solanum malacoxylon
2. Trisetum flavescens
What causes calcinogenic plants to be toxic?
Produce a substance that mimics calcitriol, and so bypasses the conversion of 25-hydroxycholcalciferol to calcitriol in the kidneys, resulting in greater calcium absorption that required
What are the clinical signs of enzootic calcinosis?
- Stiffness and shifting limb lameness
- Distal limbs become straight, slow, stiff and awkward
- Abnormal gait - short strides
- Shallow, diaphragmatic breathing
- Extended head and neck
- Tachycardia and heart murmurs
- Weakness, weight loss, listlessness
What post-mortem lesions are associated with enzootic calcinosis?
- Degeneration and calcification of soft tissues
- Emaciation
- Excess fluid in thoracic and abdominal cavities and pericardium
- Calcification of bicuspid valves
- Mineral deposits on pleura, lungs, kidneys, ligaments and tendons
- Capsular thickening of articular cartilages
How do we diagnosis enzootic calcinosis?
- History and clinical signs
- Post mortem lesions
- High plasma calcium and phosphorus
How do we treat enzootic calcinosis?
No treatment
What conditions are associated with low phosphate levels?
- Hypophosphataemia
- Rickets
- Osteomalacia
- Post-parturient haemoglobinuria
What causes hypophosphataemia?
Low dietary levels of phosphate
What is the function of phosphate?
Component of phospholipids, phosphoproteins, nucleic acids and ATP
What is the normal plasma concentration of phosphorus?
1.3-2.6mmol.l
Where is the majority of phosphorus found in the body?
Bones and teeth
How is phosphorus metabolism regulated?
PTH - secreted during calcium stress
What are the two types of hypophosphataemia and their blood levels?
Acute - 0.3-0.6mmol.l
Chronic - 0.6-1.3mmol.l
When is acute hypophosphataemia seen?
Late gestation due to accelerated growth of foetus (or twin pregnancy) or at the onset of lactation
What are the clinical signs of acute hypophosphataemia?
Recumbency, but cow seems fine and is able to eat
What are the clinical signs of chronic hypophosphataemia?
- Failure to grow
- Inappetence
- Pica
- Lethargy
- Decreased milk yield
- Decreased fertility
How do we treat hypophosphataemia?
Increase phosphate levels in feed and IV phosphorus
What is the aetiology of post-parturient haemoglobinuria?
- Low phosphate levels in ration
- Ingestion of haemolytic agents - rape seed
- Phosphorus deficient soils
When does post-parturient haemoglobinuria most commonly occur?
2-4 weeks following parturition in dairy cows
Usually in 3-6th lactation in high producers
Most common with selenium deficiency
What is the pathogenesis of post-parturient haemoglobinuria?
It is characterised by development of peracute intravascular haemolysis and anaemia with potentially fatal outcome
What are the clinical signs of post-parturient haemoglobinuria?
- Haemoglobinuria - dark red urine
- Inappetence
- Sudden weakness and staggering
- Decreased milk yield
- Pale mucous membranes
- Anaemia and jaundice
- Dehydration
What are the post-mortem lesions seen in post-parturient haemoglobinuria?
- Thin blood
- Icterus
- Swollen liver
- Bladder filled with red urine
How do we diagnose post-parturient haemoglobinuria?
- CBC - anaemia
- Heinz body formation
- Low P in blood
How do we treat post-parturient haemoglobinuria?
- Blood transfusion
- Fluid therapy - supportive
- 60g sodium acid phosphate in 300ml of distilled water IV then SC
What are other names for hypomagnesaemia?
- Hypomagnesaemic tetany
- Grass tetany
- Grass staggers
What is the maintenance dose of magnesium?
3mg/kg BWT
What is the lactational requirements of magnesium?
120mg/kg
What is the cause of grass staggers?
- Reduced food intake during lactation
- Pasture low in magnesium (e.g. grass)
- High pasture nitrogen - reduces magnesium absorption
- Stress
- High moisture content - decreases absorption
What are the plasma magnesium levels found in grass staggers?
- Cattle - <0.5mmol.l
- Sheep - <0.2mmol.l
- CSF - <0.4mmol.l
When do clinical signs develop during grass staggers?
When plasma Mg levesl drop to <0.35mmol.l
How does a low magnesium level affect the body?
Interferes with neuromuscular transmission and neurone activation
What are the forms of clinical grass staggers?
- Acute
- Chronic
- Calves - 2 weeks to 8 months
What are the clinical signs of acute grass staggers?
- Depression, dullness
- Throw head up and bellow
- Restlessness
- Galloping in a blind frenzy
- Fall and exhibit wild paddling convulsions
- Tetanic spasms
- Chewing
- Coma and death
What are the clinical signs of chronic grass staggers?
- Nervous and irritable
- Depressed appetite
- Decreased production
- Reduced gut motility
What are the clinical signs of hypomagnesaemia in calves?
- Hyperexcitability
- Muscle fasciculations
- Stiff gait
- Constant movement
- Ear flapping
- Convulsions, spasms, tetany and death
What are the differentials for grass staggers?
- Nitrate/nitrite intoxications
- Lead battery ingestion
- Infections - BSE, Aujeskys
How do we treat grass staggers?
- Slow IV Ca and Mg (5%) salts and SC Mg
- Mg enema
- Oral Mg - use stomach tube
How much Mg should go SC in grass staggers?
Cattle - 400ml 25%
Sheep - 40-50ml 25%
What causes hyponatraemia?
- Low oral intake of sodium
2. Increased renal losses - diuretics, intestinal losses (diarrhoea)
What is the function of sodium?
- Maintains ECF osmolality and water distribution between ECF and ICF
- Regulates acid-base balance
- Maintains neuromuscular functions and cell permeability
What are the clinical signs of low sodium?
- Neurological signs
- Hypovolaemia and hypotension
- Shock
- Anorexia
- Apathy, weakness
- Disturbances in rumen function - alkalosis
How do we diagnose hyponatraemia?
Serum sodium <136mmol.l
What causes sodium intoxication?
- Increased sodium retention
- Increased sodium intake
- Increased water loss or decreased intake
- Hypotonic water loss
What are the clinical signs of sodium intoxication?
- Increased thirst
- Hypersalivation
- Vomiting, abdominal pain and diarrhoea
- Nervous signs
- Coma
What are the post-mortem signs of hypernatraemia?
- Acute cerebral oedema
- Inflamed meninges
- Increased intra-cranial pressure
- Gastric irritation and haemorrhages
How do we diagnose hypernatraemia
Serum and CSF concentration of >160mmol.l
How do we treat hypernatraemia?
Immediate removal of salt and water. Then trickle feed water
What is the function of potassium in the body?
Determining resting membrane potential
What can cause hyperkalaemia?
- Increased dietary intake - mollasses
- Decreased excretion - anuria, metabolic acidosis
- Rapid IV administration of potassium
How is potassium controlled in the body?
By aldosterone - enhancing renal and salivary excretion and promoting resorption of sodium ions
What are the clinical signs of hyperkalaemia?
- Cramping
- Weakness
- Diarrhoea
- CNS signs - irritability and excitement
- Paralysis
- Cardiac failure - bradycardia - cardiac arrest
How do we diagnose hyperkalaemia?
Serum levels >6.5mmol.l
Na:K ratio <25:1
How do we treat hyperkalaemia?
0.9% NaCl IV to promote diuresis and NaHCO3 to correct acidosis
What causes hypokalaemia?
- Decreased intake
- CCS use - enhances GIT and renal losses
- Impaired absorption - abomasal displacement, ileus, diarrhoea, diuretics, etc
What are the clinical signs of hypokalaemia?
- Inappetence
- Atony of GIT
- Skeletal muscle weakness and muscle fasiculations
- Arrhythmias
- PU
- Recumbency
- Coma
How do we diagnose hypoakalaemia?
- Moderate - 2.5-3.5mmol.l
2. Severe - <2.5mmol.l
How do we treat hypokalaemia?
- Correct underlying imbalances
2. Potassium supplementation - SLOW
How much potassium should we give?
30-60g KCl at 12 hour intervals (MAX 240g per day)