Canine Hematuria: Localizing the Bleed
A 6-year-old male castrated Boxer presents with a 2-week history of hematuria. Urinalysis: specific gravity 1.030, pH 7.0, protein 3+ (sulfosalicylic acid positive), RBC >100/hpf, no crystals, no bacteria on sediment exam. The urine is red throughout the stream. Serum biochemistry is normal; CBC shows mild neutrophilia. The clinician is unsure whether the bleeding is renal, bladder, or prostatic and asks how to localize it using laboratory data.
1. How do you use urinalysis and the pattern of hematuria to localize the source of bleeding?
Read the worked answer
Localization strategy:
- Bleeding throughout the stream suggests a source above the urethra (bladder, ureter, kidney) rather than distal urethra.
- Proteinuria with hematuria: protein 3+ on sulfosalicylic acid in a concentrated urine (SG 1.030) is significant. Hematuria alone can cause mild proteinuria, but 3+ suggests either glomerular protein loss or substantial hemorrhage. If proteinuria persists after hematuria resolves, consider glomerular disease.
- RBC morphology: dysmorphic RBCs and RBC casts indicate glomerular/renal origin; uniform RBCs favor lower tract. The sediment report should comment on this.
- No crystals or bacteria makes urolithiasis and bacterial cystitis less likely, though not excluded.
Next steps:
- Urine sediment for RBC casts - a cast confirms renal origin.
- Urine culture even without bacteria on sediment (occult infection).
- Imaging (ultrasound) to assess bladder wall, prostate, and kidneys - laboratory data alone cannot fully localize.
Conclusion: the data point to a bladder or renal source; prostatic origin is possible in an intact dog but this dog is castrated, lowering that probability.
2. If the sediment shows uniform RBCs and no casts, and ultrasound reveals a thickened bladder wall, how does that change your interpretation and what is the next step?
Read the worked answer
Reinterpretation: uniform RBCs without casts favor a lower urinary tract (bladder) source. A thickened bladder wall on ultrasound in a middle-aged Boxer raises concern for cystitis, polypoid cystitis, or transitional cell carcinoma (TCC).
Next steps:
- Urine culture - chronic cystitis can cause wall thickening; treat if positive.
- Cytology of a bladder wall sample (via catheter-assisted or ultrasound-guided aspirate) - but beware seeding if TCC is suspected; some clinicians prefer not to aspirate suspected TCC.
- Biopsy via cystoscopy for definitive diagnosis if a mass is seen.
- Check for proteinuria resolution after treating hematuria - persistent proteinuria would prompt glomerular workup.
Key judgment: do not stop at 'hematuria = cystitis.' In a breed predisposed to TCC (Boxers, Scotties), a thickened wall warrants histopathology, and the pathologist should recommend biopsy rather than empirical antibiotics alone. If culture is negative and hematuria persists, pursue cystoscopy.