Urine sampling and urinalysis

State 5 pros to free catch sampling

1. quick

2. easy

3. non involved/traumatic to patient

4. allow to get first thing in morning

5. sample post available

state 4 cons of free catch samples

1. contamination from ground/environment

2. owners may use anything to catch it

3. disinfectants may contaminate sample

4. not useable for culture

State 5 pros of litter tray sampling

• easy

• cheap

• non-invasive

• stress free

• ideal for basic urinalysis in rabbits (if trained)

state 4 cons of litter tray sampling

• indoor cats only?

• how old is sample?

• contamination

• multi-cat household - can’t guarantee who’s urine it is

State 4 pros for floor sampling

• very easy

• cheap

• non invasive

• stress free

state 4 cons for floor sampling

• how long has it been left?

• contamination

• multi-pet household

• not suitable for bacteriology

what is the expressed sample?

• technique for expressing the bladder to collect a sample of urine - needs assistance but can train owner

state 4 pros to expressed sample collection

1. easy wtih training

2. cheap

3. not too invasive

4. fresh sample

state 8 cons of expressed sample collection

• possible painful

• can cause trauma

• abdominal muscles

• intestines

• possible bladder rupture

• contaminate external genitalia

• need a helper and reasonably full bladder

• difficult in large/uncooperative patients

for which animals is catheterisation easiest?

• male dogs

in which species/gender may we not use catheterisation?

• females

• cats

2 uses of catheters?

• diagnostic

• therapeutic

what size catheter do we want for male dogs?

• 3.5-12f (french)

describe the application of a catheter into a male dog (8)

1. choose correct catheter

2. clip hair, clean penis and flush prepuce

3. use sterile gloves and lubricant

4. extrude penis (assistant)

5. approximate length needed from urethral orifice to pelvic brim

6. introduce catheter into urethra in sterile manner

7. advance until urine flows

8. remove or secure as needed

what may we have to do to a tom can penis to cannulate?

• straighten with one hand whilst extruding

what type of catheter can we use for tom cats?

• catheter

• stylet

• sleepy sam

what size catheter do we want for our cats?

• 3.5f

how do we extrude the penis of a tom cat?

• dorsal and caudal pressure

what do we do for the first few ml of urine taken from a tom cat?

• discard it

how do we catheterise a bitch?

• ventral recumbency - straight body

• flush vaginal vault

• sterile gloves and lubricant

• use a speculum to visualise ventral wall of vagina to identify ureter joining vestibule

how do we perform a blind catheterisation of a bitch?

• use finger to palpate uethral papillae at pelvic brim

• beware of the blind ending ventral vault

how do we catheterise the queen?

• same theory as for the bitch - can use otoscope to visualise the tract - not as easy to palpate however

what size catheter for the queen?

• 3-3.5f

give 4 pros to catheterised sample collection

• easy in male dog

• diagnostic and therapeutic

• not very invasive

• fresh sample

state 6 cons of catheterised samples

• possible painful

• can cause trauma to urethra/bladder

• iatrogenic ascending infections

• sample contamination from lower urinary tract

• sedation/GA

• difficult in females

how is blind cystocentesis performed?

• sterilise the sampling field

• palpate bladder with non-dominant hand + slight caudal pressure

• insert needle into sterilised area, caudally angled aiming for neck of the bladder at 30-45 degree angle

what can we use to guide our needle with blind cystocentesis?

• ultrasound

why do we need to aim for the neck of the bladder with blind cystocentesis?

• bladder will shrink and retract caudally, therefore if needle is cranial it could cause you to puncture through to the abdomen

3 pros of blind cystocentesis?

• diagnostic and therapeutic

• no lower tract contamination

• fresh and immediate sample

can we do blind cystocentesis conscious?

• yes

state 8 pros to blind cystocentesis

• possibly painful

• can cause trauma

• could rupture bladder

• could hit other organs

• iatrogenic haematuria

• needs skilled operator

• difficulr in large patients/small bladder

state 6 pros to ultrasound guided cystocentesis

• diagnostic and therapeutic

• no lower urinary tract contamination

• fresh and immediate sample

• safer than blind cystocentesis

• easier to hit small bladder

• can gain information on bladder appearance at same time

state 7 cons of ultrasound guided cystocentesis

• possibly painful

• can cause trama

• possible rupture bladder

• iatrogenic haematuria

• requires operator skill

• sedation/GA

• need additional helper

what can ultrasound guided cystocentesis cause in rabbits

• urine leakage → peritonitis

why do we NOT do blind cystocentesis in the rabbit

• high risk of punturing caecum!

why do we not sample any mass in a bladder via cystocentesis/FNA?

• most common bladder mass is transitional cell carcinoma - metastatic - therefore risk of ‘seeding’ into abdomen

for TCC what can we do to confirm sample?

• endoscopy/cystoscopy or via urinary catheter

what method do we NOT use for sampling suspected TCC

• FNA

• cystocentesis

how soon should we analyse a urine sample?

• ideally within an hour

how long can we refrigerate urine for?

• 6-24 hrs

why can we not freeze urine

• due to ice crystals potentially damaging any cells present

what 3 appropriate ‘ideal’ containers can we use for collecting urine, why?

• plain tube - biochem or sediment analysis/imminent culture

• EDTA - prevents cellular degradation

• boric acid - holds bacterial population and cellular components static for up to 96 hours

what 4 quick observations can we make of a urine sample?

• colour

• turbidity

• odour

• debris

how may strongly coloured urine affect a dipstick test?

• may cause false positives but may also be pathology in of itself

which 4 readings should we disregard in dogs adn cats on a dipstick?

• leukocytes

• nitrites

• urobilinogen

• specific gravity

what 4 things may cause strongly coloured urine?

• marked haematuria

• haemoglobinuria

• myoglobinuria

  • bilirubinuria

how do we use a dipstick?

• wear globes

• apply one drip to each section

• tap off excess

• leave for the amount of time and hold in line with the bottle and read each measurement

what may the first strip in a dipstick test be?

• comparison strip - checks for staining

what should the level of blood be?

• negative!!

how should we distinguish between a positive blood sample on a dipstick being caused by blood or by haemoglobin?

• spin for PCV to distinguish

what should bilirubin be on a dipstick:

1. dogs

2. cats

1. can be up to 2+ and still normal

2. negative

what should the ketone level be, what is its limitation?

• level should be negative

• but only tests for oxaloacetate

what should glucose reading be?

• negative

why may we see trace protein on a male animals’ dipstick?

• if they’re intact - could be due to sperm

why may we have protein in the dipstick sample and blood?

• protein may be due to haemoglobin

  • false positives are common in cats

what should pH be of urine?

• 6-7

why may pH or urine vary for each animal?

• diet

• medications

how do UTIs often affect urine pH?

• cause it to increase (more alkaline)

how do we callibrate a refractometer?

• put distilled water onto the lens

• check the reading is 1.000

• alter line height as required

how do we read USG?

• place a sample of urine onto a dry refractometer

• look and see what it reads as

what value is considered hyposthenuria?

• 1.001-1.007 USG

what does hyposthenuria tell us?

• kidenys are actively diluting urine

what is isosthenuria?

• 1.008-1.012 USG

what does isosthenuria tell us?

• the kidneys are neither concentrating or diluting

what is hypersthenuria?

• 1.013-1.075+ USG

what does hypersthenuria tell us?

• actively concentrating urine

what should the USG be for:

1. dog

2. cat

1. 1.015-1.045

2. 1.035-1.060

what do we expect the USG of the following to be, if clinically dehydrated?

1. dog

2. cat

1. >1.030

2. >1.035

what do we do to visualise urine microscopically?

• agitate urine

• centrifuge - 1000-1500rpm for 3-5mins

• remove without agitating

• remove supernatant pellet at the bottom

• resuspend pellet in remaining urine by agitating

what stain do we use for visualising urine microscopically?

• Sedi stain

what are the 2 methods we can use to visualise urine microscopically?

• plains lides

• stain with Sedi stain

what do we determine as haematuria microscopically?

• up to 5RBCs and 5WBCs per HPF

What are these?

• RBCs - A

• WBCs - B

What are these?

• transitional cells

What are these?

• squamous cells - urethra and female genital tract

What is this?

• hyaline cast

What is this?

• cellular cast

what are casts?

• moulds of renal tubules

• mucoproteins ± cells

when are casts more likely to appear in urine?

• low pH

• low urine flow rate

• high USG

how many casts should be visible per low power field?

• 1 granular and 2 hyaline MAX

what may many casts indicate in urine?

• tubular damage

when do crystals form?

• if oversaturated in urine

what crystals are normally found inurine?

• calcium oxalate dihydrate

what crystal is an artefact or storage method?

• calcium oxalate dihydrate

what crystal is often indicative of altered urine pH?

• struvite

what crystals are often indicative of liver disease

• bilirubin

  • ammonium bi-urate

what crystals are often indicative of toxins/drugs

• ethylene glycol

• calcium oxalate monohydrate

Identify this crystal

• ammonium bi-urate

identify this crystal

• struvite

Identify this crystal

• bilirubin

Identify this crystal

• calcium oxalate monohydrate

what do lipid droplets indicate, in which species?

• in cats they indicate epithelial degeneration

what will pathogens in urine indicate?

• pathology