Oliguria & Anuria in Cats: Vet Guide 🐱🚨 2025

By Dr Duncan Houston BVSc, veterinarian & founder of Ask A Vet.

Oliguria (markedly decreased urine output) and anuria (little or no urine production) are emergency signs of critical illness—most commonly tied to acute kidney injury or urinary obstruction. Without rapid action, cats can succumb within hours to days. This guide helps you:

• 🔍 Understand definitions & thresholds
• 🧬 Learn common causes
• 🚨 Spot clinical signs early
• 🧪 Navigate diagnostics & treatment
• 💊 Support recovery & prognosis
• 🤝 Use Ask A Vet telehealth for vet-level guidance fast

🔍 What Are Oliguria & Anuria?

Oliguria is a urine output of < 0.5 mL/kg/hr or <500 mL/day; Anuria is < 100 mL/day, effectively no urine production :contentReference[oaicite:2]{index=2}.

These are symptoms—not diseases—indicating serious underlying issues in the kidneys or urinary tract :contentReference[oaicite:3]{index=3}.

🧬 Common Causes

• Prerenal: dehydration, hypovolemia, shock, heart failure – reduces kidney blood flow :contentReference[oaicite:4]{index=4}.
• Renal/intrinsic: acute kidney injury—e.g., toxins (NSAIDs, lily ingestion), infections, ischemia, medications (aminoglycosides) :contentReference[oaicite:5]{index=5}.
• Postrenal: urinary obstruction (uroliths, urethral plugs), bladder rupture, strictures :contentReference[oaicite:6]{index=6}.

🚨 Clinical Signs

• Minimal or no urine output (monitor via litter clumps or catheter)
• Straining or attempts to urinate
• Vomiting, lethargy, anorexia, dehydration
• Abdominal pain, distended bladder
• Signs linked to underlying cause (e.g., pale mucous membranes, hypotension)
• Rapid deterioration without fluid therapy—watch for edema, pulmonary congestion

🧪 Diagnostic Workflow

1. History & physical: recent fluid loss, toxin exposure, trauma, urinary attempts
2. Measure urine output: use catheter if unclear :contentReference[oaicite:7]{index=7}.
3. Blood and chemistry panel: kidney values (creatinine, BUN, SDMA), electrolytes, acid-base, potassium, hydration
4. Urinalysis: concentration, sediments, crystals
5. Imaging: abdominal ultrasound/X-ray for obstruction, bladder size, kidney structure :contentReference[oaicite:8]{index=8}.
6. Scan bladder wall and urethra: via ultrasound or cystoscopy, especially with obstruction

🛠 Treatment & ICU Management

1. Restore Perfusion & Hydration

• IV isotonic fluids (e.g., LRS, Plasma‑Lyte); if hyperkalemia present use 0.9% saline :contentReference[oaicite:9]{index=9}.
• Monitor carefully—stop fluids if high risk of overload during anuria/oliguria :contentReference[oaicite:10]{index=10}.

2. Diuretics & Renal Replacement

• Furosemide IV (0.5–2 mg/kg) to jump‑start urine :contentReference[oaicite:11]{index=11}.
• Mannitol 0.5–1 g/kg IV if volume overloaded; avoid if dehydrated :contentReference[oaicite:12]{index=12}.
• In resistant cases consider renal replacement therapy (hemodialysis, peritoneal dialysis) where available :contentReference[oaicite:13]{index=13}.

3. Treat Underlying Cause

• Obstruction: relieve with catheter, surgery, or lithotripsy
• Sepsis or pyelonephritis: IV antibiotics targeting urinary pathogens
• Toxin removal: chelation or activated charcoal if ingestion suspected
• Support for AKI: gastroprotectants (famotidine, omeprazole) and antiemetics (ondansetron, maropitant) :contentReference[oaicite:14]{index=14}.

📆 Monitoring & Prognosis

• Monitor “in vs out” hourly; adjust fluids accordingly :contentReference[oaicite:15]{index=15}.
• Watch electrolytes closely—treat hyperkalemia/hypokalemia as needed
• Recheck kidney values daily
• Bladder drainage via catheter continuous in obstruction cases
• Fluid status assessment to prevent edema or pulmonary overload
• Prognosis: better if urine appears within 6 hr; guarded if persistent anuria without dialysis :contentReference[oaicite:16]{index=16}.

🏠 Home Care & Follow-Up

• Continue fluids if prescribed; switch to SQ or oral as appropriate
• Strict monitoring of appetite, urination, hydration, and weight
• Follow-up labs: renal panel and electrolytes weekly for 2–4 weeks
• Maintain catheter care with hygiene and proper technique :contentReference[oaicite:17]{index=17}.
• Dietary therapy: renal-support diets to ease kidney workload

🤝 Ask A Vet Telehealth Support

• Initial guidance for monitoring urine output & fluid balance
• Assist with calculating fluid volumes and adjusting IV rates
• Help coordinate diagnostics or imaging
• Support electrolyte management and medication adjustments
• Sustain follow-up during home recovery—vital signs, hydration, diet

✅ Key Takeaways

• Oliguria (< 0.5 mL/kg/hr) and anuria (< 100 mL/day) are RED FLAGS requiring rapid intervention
• Causes span prerenal, renal, postrenal—each demands targeted treatment
• Aggressive fluid therapy and diuretics may restore urine; otherwise dialysis may be lifesaving
• Prognosis depends on cause, timing, and response—urine within 6 hrs improves chances
• Close monitoring, follow-up, and telehealth support optimize recovery

📞 Final Thoughts

Oliguria and anuria in cats signal emergency. Swift, informed action—including fluids, diagnostics, treating root causes, and leveraging Ask A Vet’s telehealth support—can rescue kidney function and stabilize your cat. Don’t wait—early care saves lives. 🐱❤️

Need help calculating fluid needs, monitoring urine output, or pacing recovery? Visit AskAVet.com and download the Ask A Vet app for expert guidance anytime!