Contributors: Kathleen P Freeman

 Species: Canine   |   Classification: Lab Tests

Overview Sampling Tests Result Data Further Reading

Overview

  • Changes in chemical and physical characteristics of urine occur in many diseases and include urinary tract disease, hepatic disease, hematological disorders, endocrinopathy, neoplasia, musculoskeletal disease and hepatic encephalopathy.
  • These changes in characteristics can predict disease.
  • Therefore, used as a screening test in any ill patient.
    Always do complete urinalysis including sediment examination.

Uses

In combination

  • Diagnosis of diabetes mellitus.

Other points

  • Dipstick urine specific gravity should be ignored ( it is inaccurate for animal urine); use refractometer method.

Sampling

Source of Test Material

Quantity of Test Material

  • A few drops to 1 ml.
  • Standard volume of 4-5 ml preferred.

Sample Collection Technique

Cystocentesis

  • See technique Cystocentesis.
  • Use a 10 ml sterile syringe and a 1.5 inch 21-25G needle.
  • With the animal standing or in lateral recumbency, palpate and direct bladder towards abdominal wall.
  • Needle is introduced through abdominal wall. Direct needle point caudodorsally towards the bladder neck.
  • If bladder is less obviously palpable, place animal in dorsal recumbency and direct needle through midline in the bitch or lateral to the penis in the dog at the level of the last mammary gland. Direct needle caudodorsally.

Quality Control

Precautions

  • Trauma during collection may contaminate sample.
  • Delay between collection and analysis → less reliable results.
  • Sample standing for >30 minutes must be refrigerated (2-8°C).
  • Urine must be at room temperature before analysis.
  • Protect sample from bright light.

Timing of test

  • The composition of urine varies throughout the day.
  • Sample for screening test at any time of day.

Early morning sample

  • Advantage: concentrated with higher yield of cells, casts and bacteria.
  • Disadvantage: less likely to reveal hyperglycemic glucosuria than a 3 hour post-prandial sample. Cells may be degenerated.

Recently formed sample

  • Advantage: cytologic detail superior.
  • Disadvantage: may be insufficiently concentrated to evalute renal function as well as causing lysis of red and white blood cells.

Sample storage

  • Urine can be refrigerated at 2-8°C for a few hours (maximum 12 hours).
  • If sample is to be stored, divide into two containers, add preservative (boric acid tablet or 10% formalin) to one and refrigerate both.
  • The sample with preservative is for sediment examination. The sample with no preservative is for dipstick (chemical) analysis.
  • Specimen for bacteriologic culture should be in sterile container without preservative.

Sample transport

  • The longer the delay between collection and analysis, the less reliable the results.
  • Temperature above 8°C for longer than 30 minutes results in artefacts.
  • Must not transport without preservative.
  • Package according to Post Office regulations Transportation of diagnostic specimen.

Tests

Methodologies

  • Determine specifc gravity by refractometer.
    Dipstick specific gravity does not correlate well with refractometry.
  • Rapid, complete immersion of the dipstick with immediate shaking off of excess urine as well as holding the dipstick level is needed to avoid run-off between pads.
  • Compare the color change of dipstick to the reference range at the correct time.

Availability

  • Can be performed in-house by most veterinary practices.
  • All external laboratories.

Validity

Sensitivity

  • Low to high.

Specificity

  • Low to moderate.

Technique (Intrinsic) Limitations

  • Urine specific gravity reading on dipstick is unreliable.

Technician (Extrinsic) Limitations

  • Standardized approach for every analysis results in consistent findings and allows the technician to develop experience.

Result Data

Normal (Reference) Values

pH

  • 5.5-7.0.
    Some normal dogs may be outside this range.

Protein

Must interpret in conjunction with SG.
  • Myelomas will not cause a positive protein reaction on dipstick.
  • Normal ranges:
    Chemical determination is more accurate than dipstick estimates. Check all abnormal results by other methods.

Glucose

  • If SG <1.020: negative.
  • If SG >1.035: <30 mg/dl.
  • Urine protein:urine creatinine ratio <0.6.
  • Negative.

Ketones

  • Negative.

Bilirubin

  • If SG >1.020: trace.

Urobilinogen

  • Trace.

Blood

  • Negative.

Nitrite

  • Negative (unreliable in animals for screening for bacteria because of large number of false negative tests).

Errors and Artifacts

  • Not using fresh urine.
  • Outdated dipstick (beyond expiration date).
  • Incorrect storage of dipstick.
  • Urine not at room temperature.
  • Reading dipstick at incorrect time.
  • Using a collection technique other than cystocentesis.
  • Not being consistent in analysis (technique, timing, volume).

pH

  • Increase:
    • Sample standing open at room temperature for few hours (loss of CO2).
    • Furosemide Furosemide at therapeutic dose.
  • Decrease:

Protein

  • Increase:
    • Chlorhexidine Chlorhexidine.
    • Moisture on dipstick during storage.
    • Prolonged contact of dipstick with excessive amounts of urine.
    • Alkaline urine (>9).

Glucose

Ketones

  • Negative.

Bilirubin

Urobilinogen

  • Increase:
  • Decrease:
    • Prolonged exposure to light.​

Hematuria

  • Increase:
    • Trauma during sampling.
    • Contamination with vaginal/preputial secretion.
  • Decrease:
    • Hemolysis.
    • Hyposthenuric.
    • Very acid urine.
    • Very alkaline urine.

Nitrite

  • Increase:
    • Phenazopyridine.
  • Decrease:

Further Reading

Publications

Refereed papers

  • Recent references from VetMedResource and PubMed.
  • Brobst D (1989) Urinalysis and associated laboratory procedures. Vet Clin North Am Small Anim Pract 19 (5), 929-949.
  • McCaw D L, Fleming E J & Mikiciuk M G (1989) Interpreting the results of urinalysis - a key to diagnosing renal disorders. Vet Med 84 (3), 281-286.

Other sources of information

  • Kaneko J J (1997) Clinical Biochemistry of Domestic Animals. 5th edn. Eds: Harvey J W & Bruss M L. Academic Press, USA.
  • Duncan J R, Prasse K W & Mahaffey E A (1994) Veterinary Laboratory Medicine Clinical Pathology. 3rd edn. Iowa University Press, USA.