Urinalysis

Question 1

what can we test with a urine sample?

Answer 1

glucose
crystals
blood
infection
kidney function

Question 2

what are the different types of urine collection?

what do we need for them?

Answer 2

free catch/manual expression
- kidney dish
- gloves
- sample pot and pipette

cystocentesis
- long needle and suitable syringe
- ultrasound for insertion

urinary catheter
- sterile gloves
- sterile lube
- catheter - rigid for temporary, foley for long term
- collection set

Question 3

what is normal urine output?

Answer 3

1-2 ml/kg/hr

cats - 18-25mls/kg/day
dogs - 20-40mls/kg/day

Question 4

what considerations need to be made when collecting a free catch sample?

Answer 4

if obtaining from dogs make sure you get midflow
- avoid skin cells, bacteria already in the tract
- not possible with cats as use katkor

try to get the first sample of the day
- more concentrated and likely to find abnormalities

always take samples before starting any treatment
- as can impact results

can be useful to collect along side other tests
- allow for comparable results

Question 5

what are the advantages and disadvantages of free-catch sampling?

Answer 5

Advantages
- easy
- can be done by anyone - including owners
- can measure urine output throughout day
- least stressful

Disadvantages
- not a sterile sample so can’t culture
- contaminated with hair
- higher risk of urine contamination to person sampling
- cats dislike different litter
- dogs can be urine-shy

Question 6

what are the advantages and disadvantages of manual expression sampling?

Answer 6

Advantages
- good for neurological patients - avoid UTIs and scolding
- can be done consciously
- non-invasive
- can measure urine output throughout the day

Disadvantages
- requires skill
- difficult in obese and very tense patients - high muscular tone/refusing can cause burst
- unsuitable if coagulopathic - bleeding risk
- can cause bladder rupture - especially if blocked
- non-sterile sample

Question 7

what are the advantages and disadvantages of cystocentesis sampling?

Answer 7

Advantages
- sterile sample - can be cultured
- quick
- can be emergency help for blocked cats

Disadvantages
- only a veterinary surgeon can perform
- can cause trauma to other organs
- if diseased bladder - uroabdomen (bladder walls don’t contract down properly causing leaking into abdomen)
- may require a sedation - uncomfortable

Question 8

what are the advantages and disadvantages of short term catheterisation sampling?

Answer 8

Advantages
- can completely empty bladder
- can obtain sterile sample
- can be done by a nurse or vet
- infection is less likekly

Disadvantages
- may require sedation
- difficult to place in bitches
- can cause urethral damage
- risk of introducing infection

Question 9

what are the advantages and disadvantages of indwelling catheterisation sampling?

Answer 9

Advantages
- ideal for measuring urine output over a long period of time
- good for patients with infectious urine to contain it (eg lepto or cytotoxic drugs)
- can take a sterile sample
- allow to drain bladder if blocked

Disadvantages
- risk of introducing infection
- invasive
- may require sedation
- risk of patient interference - kink/twist or remove

Question 10

how should you store urine samples?

Answer 10

plain urine tube
- all samples run within 24hours

boric acid tube
- all samples run after 24 hours
- prevents bacterial overgrowth

Question 11

when using urine samples for diagnosis what do you need to consider?

Answer 11

patient history
- any clinical signs observed, changes in output and appearance
urinalysis
physical examination
- abdominal palpation - firm in bladder? stones?

definitive diagnosis
- ultrasonography urine tract
- radiography
- contrast radiography

Question 12

what is involved in a crude assessment of urine?

what can different variations tell us?

Answer 12

colour
- light yellow = normal, low concentration - unless dehydrated as renal failure
- yellow = normal, normal concentration
- amber = normal, high concentration - can be bilirubinuria (caused by liver damage or breakdown of RBCs)
- red = haematuria or haemoglobinuria (acute breakdown of RBCs)
- brown = myoglobin (muscle damage), methaemoglobin or bilirubinuria (caused by liver damage or breakdown of RBCs)

smell
- noticeable bad smell
- highly concentrated
- bacterial infection
- toxins

amount
- 0.5-1ml/kg/hr = oliguria - not ideal but monitor
- <0.5ml/kg/hr = anuria - kidneys failed
- >2ml/kg/hr = polyuria - acute renal injury/start of renal disease

turbidity
- normal varies between species
- dogs = clear
- cats = slightly cloudy
- guinea pugs = cloudy
- abnormal = turbid

Question 13

what are the advantages and disadvantages of dipsticks?

Answer 13

advantages
- rapid results
- non-invasive
- good early indicator

disadvantage
- no animal specific - some tests no useful for animals
- not reliable for SG
- timings can be hard to follow

Question 14

what can pH on a dipstick tell us?

Answer 14

dogs and cats usually have slighly acidic urine

alkaluria can be caused by urease-producing bacteria

pH level also impact crystal production
- cystines = acidic
- struvite = alkaline

Question 15

what can protein on a dipstick tell us?

Answer 15

detects albumin
a large amount has to be present to have a positive result
- large amounts of protein leaking from the kidneys
- late-stage kidney failure

Question 16

what can glucose on a dipstick tell us?

Answer 16

renal threshold is >18g/l in dogs and >24g/l in cats

if test is positive very likely to be diabetic

Question 17

what can ketones on a dipstick tell us?

Answer 17

ketonuria is associated with diabetes mellitus in small animals

Question 18

what can bilirubin on a dipstick tell us?

Answer 18

dogs can breakdown haemoglobin into bilirubin in the kidneys

bilirubinuria could mean either liver disease or haemolysis

Question 19

what can blood on a dipstick tell us?

Answer 19

detects RBCs, haemoglobin and myoglobin
- so positive could mean haematuria, haemolysis or myoglobinuria

need to do further tests
- check plasma to determine haemoglobin or myoglobin
- check urine sediment

Question 20

what is urine specific gravity?

what can it tell us?

Answer 20

the weight of a volume of liquid to the weight of an equal volume of distilled water

hypersthenia = >1.025 - 1.040
- high concentration
- ideal/normal
- kidneys retain the correct water amount so function fine
- may be slightly dehydrated

isothenuria = 1.010 - 1.025
- same concentration as blood
- not ideal but monitor
- may be overhydrated
- could be start of kidney failure

hyposthenuria = <1.001 - 1.005
- kidneys not concentrating urine at all
- pure water
- likely kidney failure

Question 21

how do you prep a microscope slide for urinalysis?

Answer 21

spin urine sample in a centrifuge
- 2000 rpm for 5 mins

remove the supernatant and resuspend the sample

pipette sample onto slide and place cover slip

Question 22

what would RBCs in a sediment tell us?

Answer 22

<5 RBCs per field is normal

can be iatrogenic
- consider sample
- cysto and expression likely to have some

> 5 RBCs per field = haematuria
- some damage within urinary tract

Question 23

what would WBCs in a sediment tell us?

Answer 23

<5 WBCs per field is normal
- consider sample
- expressed or free catch likely to have few

> 5 WBCs per field = pyuria
- could mean inflammation, infection, trauma, neoplasia
- could also be due to contamination

Question 24

what would epithelial cells in a sediment tell us?

Answer 24

transitional cells
- normal - wall of bladder/urethra

squamous cells
- normal in free-catch or expressed samples

neoplastic - carcinoma

Question 25

what would casts in sediment tell us?
what are the different types?

Answer 25

Casts are a build-up of broken-down cells and/or material
some are normal with a few being fine but many suggest damage somewhere within the tract

types:
- myaline = few is normal
- epithelial = renal tubular disease
- granular = degenerated epithelial casts = few is normal
- waxy = degeneration of granular casts
- RBC = renal haemorrhage
- WBC = renal inflammation
- fatty = diabetes mellitus

Question 26

what would bacteria cells in a sediment tell us?

Answer 26

depends on sample type taken

if present with a cysto sample then there is an infection
- if in free-catch/express could just be contamination

you would then confirm with gram stains and aerobic culture to find out type of bacteria and an effective antibiotic

Question 27

what would yeast in a sediment tell us?

Answer 27

most likely due to contamination

but if seen in a cysto sample then suggest infection
- especially if on long term antibiotics and immunosuppressed

Question 28

what would fungal hyphae in a sediment tell us?

Answer 28

most likely caused by contaminants overgrowth

but could be Aspergillus terreus
- systemic infection where colonisation can occur in the renal pelvis

Question 29

what would parasitic ova in a sediment tell us?

Answer 29

Parasitic eggs present
could be parasites within the urinary bladder or kidney worms

if sample was free catch or expressed may be GI parasites contaminating sample (eg tapeworm eggs)
- so confirm with cysto sample

Question 30

what would lipids in a sediment tell us?

Answer 30

renal dysfunction

common
- often mistaken for RBCs
- esp. in feline samples

Question 31

what would sperm in a sediment tell us?

Answer 31

male or recently bred female

Question 32

what would plant material in a sediment tell us?

Answer 32

debris
sample is contaminated
sample voided

Question 33

what factors affect crystal formation?

Answer 33

Urine pH
Concentration of crystal-forming minerals
Urine temperature
Length of time between collection and examination

Question 34

what are the characteristics of a struvite?

Answer 34

favours alkaline and lower-temp urine

there’s a risk of uroliths forming - especially cats - only if dogs get a UTI

dogs = normal
cats = abnormal

shaped as a coffin

Question 35

what are the characteristics of cysteine?

Answer 35

favour acidic urine

no risk of uroliths forming

dogs = normal - especially male dogs and dachshunds, Newfoundlands, English bulldogs and Scottish terriers
cats = abnormal

caused by tubular defect in amino acid resorption

hexagon shaped

Question 36

what are the characteristics of calcium oxalate (dihydrate)?

Answer 36

favours acidic and alkaline urine and lower temperatures

form due to storage

theres a risk of uroliths forming - especially in mini schnauzers

dogs = normal
cats =normal

enveloped shape

Question 37

what are the characteristics of ammonium urate?

Answer 37

favours acidic urine

some risk of uroliths forming - more likely in Dalmatians

dogs = normal - especially with dalmations
cats = abnormal

sign of liver disease

irregular with spiky projections

Question 38

what are the characteristics of bilirubin in urine?

Answer 38

favours acidic urine

no risk of uroliths forming

dogs = normal
cats = abnormal

caused by bilirubinurea

yellow/brown needle-like shape

Question 39

what are the different types of uroliths?

Answer 39

struvite

calcium oxalate

urate