10/05/2025
Complete urinalysis includes:
Physical, chemical, and microscopic evaluation of urine and provides essential diagnostic information about urinary tract diseases as well as several systemic diseases.
Sample Collection Methods:
1- Voided sample collection: (ie, free catch from the floor or table or into a clean container, not recommend-ed). A voided sample (ideally midstream) should be collected with the patient urinating directly into a specifi-cally designed and tightly sealable container.
a) Drawn from voided samples on tabletop or floor : Easy to collect, preferable to no collection, Samples commonly contaminated with bacteria, debris, or disinfectants.
a) Free catch in clean container:
Non-invasive, restraint not required, often easy to obtain, Owners can usually obtain samples from their dog, avoids iatrogenic hematuria, satisfactory for routine screening.
Difficult to obtain in most cats, potential contamination, repeat urinalysis may be needed with sample obtained via cystocentesis, patient not always cooperative, not ideal for culture
2- Cystocentesis:
Cystocentesis (preferred) or sterile catheterization should be used when collecting a urine sample for cul-ture and susceptibility testing.
Iatrogenic trauma of a blood vessel with the cystocentesis needle can cause a false increase in hemoglo-bin as well as RBCs in sediment. Protein can be observed with significant blood contamination. Repeated sampling may be needed to determine whether an increase is true or due to collection.
little to no contamination from lower urinary tract; helps localize to bladder, ureters, or kidneys; often requires no sedation; reduced risk for iatrogenic infection compared with catheterization; easier than voided sample collection in cats and some dogs .
Requires some expertise; bladder should be identified and stabilized; iatrogenic, microscopic hematu-ria (usually, 1 hour.
Refrigerated urine should be brought to room temperature before analysis to avoid an incorrect diagno-sis, as decreased temperature can cause a false increase in USG measurement and artifactual amor-phous crystals in the urine sediment.
Delayed examination of urine, especially unrefrigerated samples, can cause numerous artifactual changes, including bacterial overgrowth (pathologic or contaminant); loss of bacterial viability; changes in color; decreased bilirubin, glucose, and ketone concentrations; deterioration of casts and cells; disso-lution of crystals; and increased odor, turbidity, and pH.
2. Urinalysis with appropriate interpretation of Reagent Strips:
Strips are inexpensive, easy to use, and provide rapid results.
Some reagent strip pad assays (eg, USG, leukocyte esterase, nitrites, urobilinogen) are unreliable in vet-erinary species because they are generally manufactured for use in humans.
Leukocyte presence is better determined via sediment evaluation.3 A refractometer provides more reliable readings of USG.
Dip vs Drip Method for Reagent Strips:
There are contradictory viewpoints on whether reagent strips should be used via the dip or drip meth-od.
The dip method consists of briefly submerging the reagent strip in urine .
The drip method consists of directly pipetting urine onto each reagent pad
Analysis should be performed per manufacturer instructions for accurate results.
The dip method is the only method described in manufacturer guidelines and is preferred.
Dipping the stick in the urine allows for more uniform wetting of the reagent pad
Dripping urine on the pad may be more practical when only a small sample volume is available.
Some reagent pads are designed to absorb urine from the side rather than the top; dipping therefore ensures adequate exposure of the reagents to urine.
3- Patient History During Interpretation:
Patient history (e.g., diet, drugs) can affect urinalysis results and should be reviewed when abnormal or unexpected findings are identified.
Diet (e.g., beets, vitamin C, blackberries, rhubarb, carrots, vitamin B, food coloring) can alter urine col-or; pigmenturia may affect the results of reagent strip test pads and should be considered when reading results.
Urine pH is highly dependent on diet. Alkalinuria is expected in healthy herbivores, whereas aciduria is expected in carnivores and herbivores on a milk diet.
Effect of Medications on Urinalysis Results:
Prescription or over-the-counter drugs can also alter urinalysis findings.
Administration of fluids or diuretics may falsely decrease USG.
Dissociative anesthetics (eg, ketamine) can cause glucosuria and hyposthenuria, whereas false-negative reactions of blood (heme), bilirubin, and glucose may occur when vitamin C (ascorbic acid) is present.1
Conclusion:
As with all diagnostic assays, reliable results depend on the quality and appropriateness of the sample and assessment technique. Appropriate sample collection method, volume, timing, and technique, as well as awareness of patient history, can help ensure effective and efficient patient care.
