PU/PD

Question 1

Confirming pathological polydipsia

Answer 1

Dog over 100 mls and cat over 50 mls/ kg a day

Question 2

Primary polydipsia

Answer 2

“Want to drink”
Lesions causing excessive water intake → polyuria

Question 3

What causes primary polydipsia

Answer 3

Psychogenic causes (stress)**
Hyperadrenocorticism (behavioral, prominent sign)**
Hepatic encephalopathy
Hyperthyroidism**
Hypothalamic lesion affecting thirst receptors
Drug effect on thirst center (phenobarbitone)

Question 4

Primary polyuria

Answer 4

“Need to drink”
Lesions causing excessive urine production → polydipsia
Structural renal disease
Extra-renal disease causing renal dysfunction

Question 5

What are the 4 mechanisms of primary polyuria?

Answer 5

Primary renal: structural renal path.
Extra renal: reduced medullary hypertonicity, absent/ impaired ADH, osmotic diuresis

Question 6

Primary structural renal disease (# 1 polyuria)

Answer 6

Chronic kidney disease***
Pyelonephritis
Nephrocalcinosis (vit. D calcification)
Bilateral neoplasia (lymphoma)

Question 7

Reduced medullary tonicity causes (# 2 polyuria)

Answer 7

Hyponatraemia
↓ urea concentration
Endotoxemia
Hypercalcemia and hypokalemia

Question 8

Hyponatremia

Answer 8

Hypoadrenocoticism (addisons)
Profound gut sodium loss

Question 9

↓ urea concentration

Answer 9

ADH deficiency/ dysfunction
Liver disease

Question 10

Endotoxemia

Answer 10

Disrupts the medullary osmotic gradient

Question 11

Hypercalcemia and hypokalemia

Answer 11

Disrupts the Na-K pump in the ascending loop of Henle→ ↑ Na+ loss

Question 12

What can cause absent/ reduced/ dysfunctional ADH (# 3 polyuria)

Answer 12

Diabetes insipudis**
Hyperadrenocorticism (cushings)
Hypercalcemia** and hypokalemia
Pyometra
Pyelonephritis (E. coli)

Question 13

What does absent ADH cause?

Answer 13

↓ urea or water reabsorption
↓ urea concentration

Question 14

Osmotic diuresis causes (# 4 polyuria)

Answer 14

Glucosuria from diabetes mellitus and renal tubular defect
Active molecules in tubules not allowing resorption

Question 15

SG < 1.008

Answer 15

Actively diluted
Hyposthenuria

Question 16

Hyposthenuria

Answer 16

Patient can’t have structural renal disease (CKD, nephrocalcinosis or bilateral neoplasia)
Can have pyelonephritis (disrupting medullary gradient and impaired ADH)

Question 17

SG 1.008 -1.012

Answer 17

Urine neither diluted or concentrated
Isothenuria

Question 18

SG > 1.012

Answer 18

Urine concentrated but to some degree

Question 19

When is SG appropriate?

Answer 19

If <1.030 in dogs or 1.045 in cats in a dehydrated or azotemic patient

Question 20

SG and primary polydipsia

Answer 20

If no other CS, blood unremarkable and patient bright and happy
NOT USED IF PATIENT UNWELL