CS: Renal/ endocrine disease

Question 1

What is USG dependent on?

Answer 1

dehydration and azotaemia

Question 2

How does addison’s cause azotaemia?

Answer 2

Addison’s –> hyponatraemia –> hypovolaemia –> azotaemia

Question 3

ECK signs - hyperkalaemia

Answer 3

• flat P wave
• bradycardia (increased PR interval)
• tall T waves

Question 4

When is a USG of 1.020 adequate when a patient has severe azotaemia?

Answer 4

if hyponatraemia also present (as this makes it hard for kidneeys to concentrate urine appropriately)

Question 5

Indicators on biochemistry of renal damage

Answer 5

• high K
• low Na
• low Cl

Question 6

2 broad causes of azotaemia

Answer 6

= reduced GFR:
1. underperfusion (low USG)
2. not enough glomeruli (v concentrated urine/ high USG)
> differentiate via USG

Question 7

T/F: proteinuria doesn’t stop you concentrating urine

Answer 7

True

Question 8

Management - acute addisonian crisis

Answer 8

• Rapid infusion 0.9% saline (NaCl) for 2 hours at 8ml/kg/hr then reduce infusion rate
• IV glucocorticoids
  o Hydrocortisone sodium succinate (hydrocortisone)
  o 0.5mg/kg/hr at 1-2mg/ml IV
  o Start on oral tx once eating and drinking (usually within 36 hours)
  o Reduce infusion rate to 0.25mg/kg/ IV
  o Stop after further 24-48 hours
  o PERFORM ACTH STIM TEST BEFORE GIVING GLUCOCORTICOIDS
• IV glucose with saline if hypoglycaemic
• IVFT until electrolytes stabilised and animal eating
• Treat hyperkalaemia (overall not necessary)

Question 9

Chronic tx - Addison’s

Answer 9

• MC replacement: either fludrocortisone acetate OR desoxycorticosterone pivalate (DOCP)
• GC replacement (50% cases need this): prednisolone or cortisone acetate
  o Correct dose is 0.2mg/kg/24 hours (prednisolone has 5x activity of cortisol)
  o Use the least potent GC possible (= cortisone acetate) at 0.5mg/kg/12 h for 5 days and then 0.5mg/kg/24 hours
• Table salt to food daily until Na normal (no evidence)
• Prednisolone at times of stress
• Water ad lib

Question 10

How to monitor response to tx for an addisonian crisis?

Answer 10

• Should show rapid response to therapy (1-2 hours)
• ECG changes should resolve
• Na and K concentrations normalising
• Uraemia resolving
• Rehydration may unmask severe anaemia

Question 11

Px - addisonian crisis treated successfully

Answer 11

long-term outlook excellent as most dogs can be controlled with oral or injectable medications to replace the deficient hormones.