Investigating PU/PD

Question 1

Whta is normal water intake in horse

Answer 1

20-30L/ day for a 500kg horse

Question 2

define polydipsia in horse

Answer 2

> 70-100ml/kg/day
7-10% body weight

Question 3

define polyuria in horse

Answer 3

> 50ml/kg/day (5%BWT)
Difficult to quantify!
24h urine collection impractical

Question 4

List 4 physiological causes of PU/PD in horses

Answer 4

Excessive dietary protein
Excessive salt consumption
Drug administration
high enviornmental temp

Question 5

List 3 drugs that can cause PU/PD

Answer 5

glucocorticoids
diuretics
a-2 agonists

Question 6

List 8 pathological causes of PU/PD

Answer 6

Apparent Psychogenic polydipsia (APP)
PPID (Equine Cushings’ disease)
Chronic renal failure (CRF)
Hepatic insufficiency
Sepsis/endotoxaemia
Renal medullary solute washout
Diabetes Mellitus (DM)
Diabetes Insipidus (DI)

Question 7

What is seen with Apparent Psychogenic Polydipsia (APP)

Answer 7

good BCS/ not azotaemic
Results in significant PU - often “flooded” stables

Question 8

what causes Apparent Psychogenic Polydipsia (APP)

Answer 8

Reflection of change diet (excessive salt consumption), stabling, management, environment, meds

Question 9

How to diagnose Apparent Psychogenic Polydipsia (APP)

Answer 9

by exclusion

Question 10

how to manage Apparent Psychogenic Polydipsia (APP)

Answer 10

restrict salt intake
restrict water intake

Question 11

Clinical signs of PPID

Answer 11

PU/PD
long curly coat
weight loss/ muscle wasteage

varied

Question 12

How to diagnose PPID

Answer 12

resting ACTH

Question 13

How to treat PPID

Answer 13

pergolide
dietary management

Question 14

what is neurogenic DI

Answer 14

central- inadequate secretion of ADH

Question 15

what is nephrogenic DI

Answer 15

Decreased sensitivity of epithelial cells on collecting ducts to circulating ADH

Question 16

List the broad steps in investigating PU/PD in horses

Answer 16

history
confirm presence of PU/PD
Blood tests
Urinalysis

Question 17

what does history help to rule out in ases of PU/PD

Answer 17

iatrogenic cause- e.g. change in diet, drugs, fluid therapy

Question 18

How do we confirm PU/PD in horse

Answer 18

Verification and quantification of water intake
Over 24h period, horse must be stabled
Might repeat over few days??

Question 19

if you see polycythaemia in cases of PUPD what does this suggest

Answer 19

Dehydration suggesting PU is the primary problem rather than PD eg. DI

Question 20

if urine Hypothosthenuric and horse had PU/PD what does this mean

Answer 20

USG <1.008 - kidney actively excreting water –> DI and APP

Question 21

if urine isothenuric in horse with PU/PD what does this mean

Answer 21

USG 1.008-1.014 - kidney neither concentrating or diluting –> CRF

Question 22

If urine Hypersthenuric in horse with PU/PD what does this mean

Answer 22

USG >1.014 – kidney able to concente –> Normal

Question 23

what does water deprivation test differentiate between

Answer 23

APP from DI
APP cases can concentrate the urine
DI cases cannot concentrate the urine

Question 24

when should you not perform water deprivation test

Answer 24

in azotaemic horses with renal compromise

Question 25

DEcsribe how to perform water deprivation test

Answer 25

1. Weigh horse
2. Check serum urea and creatinine are normal (if not DO NOT proceed)
3. Take baseline urine sample and measure SG (if >1.008, DO NOT proceed)
4. Keep horse stabled and remove water
5. Check serum urea and creatinine and USG q 6h and re-weigh

Question 26

List 5 reasons to stop water deprivation test

Answer 26

24h of water deprivation
5% reduction in body weight
Clinical signs of dehydration
Azotaemia develops
USG >1.020