Urinalysis remains one of the most valuable, cost-effective, and accessible diagnostic tools available to veterinarians. Urine samples can reveal early indicators of disease affecting the kidneys, urinary tract, and other organ systems. However, because urine is a particularly sensitive and unstable biological sample, proper collection, storage, and shipping are important to ensure accurate diagnostic results.
This article outlines the key considerations for veterinarians and clinic staff when collecting and submitting urine samples to the Texas A&M Veterinary Medical Diagnostic Laboratory, TVMDL, including best practices for sample handling, preferred collection methods, and common pitfalls to avoid.
Why urinalysis matters
Urinalysis is considered a standard component of routine testing. When interpreted alongside a chemistry profile, it provides a more complete picture of renal and metabolic health.
A well-preserved urine sample can offer valuable diagnostic insight into:
- Urinary tract infections
- Urothelial carcinomas
- Diabetes mellitus
- Kidney disease and proteinuria
- Urolithiasis
- Hematuria and urinary tract bleeding
- Evidence of systemic toxicity or poisoning
Urine stability and shipping considerations
Urine deteriorates rapidly after collection due to its fluctuating pH, bacterial growth, and chemical instability. Many cellular elements including urinary casts, red blood cells, and epithelial cells begin to break down within hours of collection. To preserve sample integrity, consider the following:
Ship samples promptly after collection.
- Cellular components may degrade within 3-6 hours after collection.
- Samples older than three days can be unreliable.
- Overnight shipping is strongly recommended.
- Delays increase the likelihood of bacterial overgrowth and false results.
Keep samples cold but not frozen.
- Refrigeration slows cellular degradation and bacterial growth.
- Freezing can rupture cells and alter sediment.
- Use cold packs during transport.
Urine collection methods
The method of urine collection may greatly influence test interpretation. TVMDL receives samples obtained through several approaches, each with its own diagnostic implications:
| Collection Method | Description | Diagnostic Value and Notes |
|---|---|---|
| Cystocentesis | Sterile needle punctures directly into the bladder. | Preferred method for most diagnostic purposes. Minimizes contamination. Provides the most accurate bacterial culture results. |
| Catheterization | Insertion of a sterile catheter through the urethra. | Useful for targeted diagnostics (e.g., neoplasia). More invasive and less common. |
| Free catch | Sample ideally caught midstream during urination. | Convenient and acceptable alternative when cystocentesis is not possible. May contain external contaminants. |
| Voided (not by free catch) | Urine collected from surfaces or litter. | Not recommended. Often contaminated with environmental bacteria or debris. Usually leads to false positives. |
Sample volume, containers, and labeling
Volume requirements
- Preferred volume: 3-5 mL
- Minimum acceptable volume: 1.5 mL
Container recommendations
- Use sterile, leak-proof containers designed for biological fluids.
- Avoid thin or flexible plastic jars prone to leakage.
- Ensure tight seals on tubes and containers and securely wrap samples for transport.
Labeling and documentation
Proper labeling ensures accurate testing and reporting. Always include:
- Animal ID
- Collection date and time
- Collection method
Common submission errors
The most frequent issues encountered by TVMDL staff when receiving and testing urine samples stem from improper collection or delayed submission. Common mistakes include:
- Contaminated samples (e.g., environmental debris, starch crystals from gloves, fibers from gauze, and litter).
- Delayed shipping or prolonged storage at room temperature
- Leaking containers
- Freezing the sample
- Submitting insufficient volume
For the most comprehensive evaluation of renal and systemic health, it is helpful to request a urinalysis alongside a chemistry profile. For equivocal findings, TVMDL may recommend further testing such as urine cytology or culture.
Maximizing the diagnostic value of urinalysis
Urinalysis is a simple yet powerful diagnostic tool in veterinary medicine. Prompt submission, sterile collection, and storage of urine samples can significantly improve diagnostic reliability and patient outcomes.
Veterinarians are encouraged to contact TVMDL to discuss complex cases or other inquiries. Collaboration between clinics and TVMDL enhances clarity and contributes to accurate, actionable diagnostic insights.
To learn more about urinalysis and TVMDL’s diagnostic services visit tvmdl.tamu.edu or call the College Station laboratory at 1.888.646.5623.
