are usually retained in the circulation and are not filtered through the glomerulus
into the urine, however in dog urine concentraof protein of 0.5 gA are normal. Most
of this protein (which is mainly albumin) originates from the kidney itself and the
lower urinary tract and has not been filtered through the glomeruli. Care is needed
in interpreting protein concentrations in urine because this can be affected by the
dilution effects of polyuria.
Test strips are commonly used in veterinary practice and
these are more sensitive to albumin than to other proteins. A more useful measure
is 24-hour urinary protein loss but this requires collection of all voided urine
over a 24 hour period which is not practical without access to a metabolism
cage. Normal urine protein loss can be up to 30 mg/kg body
weight per day.
Excessive concentrations of protein in urine (above 10
g/l) are the result of renal
disease (various types - but mainly chronic renal failure or glomerular disease),
inflammatory disease, hyperproteinaemia (renal threshold is 100 g/l plasma protein),
haemorrhage, haemaglobinaemia or myoglobinaemia.