Urinalysis

Question 1

Obtaining a urine sample

Answer 1

Cystocentesis is the only sterile sampling technique - however, it is not uncommon to see some red blood cells

Question 2

Sample processing

Answer 2

Should be processed within 30 minutes of being collected, if that is not possible refrigerate for up to 12 hours (never freeze)

Question 3

Workflow

Answer 3

Whole urine - evaluate chemistry with dipstick - centrifugation - take 90% for USG - remaining 10% is microscopically evaluated

Question 4

Casts

Answer 4

cylindrical structures forming in the renal tubules that are a re marker of renal insult or dysfunction

THP is produced and secreted into urine by the thick ascending loop of Henle preventing crystallisation and defending against bacteria

THP does always precipitate into casts because of concentration, rate of flow and urine pH

Question 5

Hyaline casts

Answer 5

protein only
small numbers normal
large numbers = proteinuria

Question 6

Cellular casts

Answer 6

necrosis of epithelial cells
presence = renal tubular insult
possible after administration of nephrotoxic drugs
potential to degrade and become granular and waxy - suggesting chronic disease with reduce urine flow

Question 7

Calcium carbonate

Answer 7

normal finding in horses due to forming in alkaline pH

Question 8

Struvite

Answer 8

form in alkaline pH only
dietary factors or infections can create environment that allows formation