Fungal Lower Urinary Tract Infections in Cats: Diagnosis and Treatment

By Dr Duncan Houston

Repeated litter-tray visits are distressing, whether the eventual diagnosis is bladder inflammation, stones or infection. Fungal infection is one uncommon possibility, especially in cats with other urinary or medical problems.

The first question is whether urine can pass. That matters more urgently than identifying which organism may be present.

Quick Answer

Fungal lower urinary tract infection can cause painful, frequent urination and blood in the urine, but those signs do not identify the cause. Candida species are among the organisms reported, and diagnosis requires an appropriately collected sample interpreted alongside the cat's condition. Straining with little or no urine, especially with vomiting or weakness, needs emergency care.

Why might a fungal infection develop?

Reported cases often involve predisposing problems such as prior antimicrobial treatment, urinary tract disease, catheterisation, diabetes or altered immune defences. A study of Candida urinary infections in dogs and cats found an association with recent antibacterial treatment, while feline numbers were small. Risk factors should not be mistaken for proof that a particular cat has a fungal infection.

Candiduria means Candida detected in urine. It does not automatically distinguish contamination, colonisation and clinically important infection. Sampling method, repeated findings, urinary signs and other test results help resolve that question.

How urgent are the signs?

What else is more likely?

Feline idiopathic cystitis, urinary stones, urethral plugs and bacterial infection can cause similar signs. Incontinence, constipation and behavioural changes may also confuse the history. A diagnosis of lower urinary tract disease describes a group of problems; it does not by itself establish infection.

Male cats are particularly vulnerable to urethral blockage, but any cat with doubtful urine output should be assessed promptly. Do not assume tray straining is constipation.

How is a fungal infection confirmed?

Urinalysis can identify inflammation, blood and possible yeast. Culture and organism identification may require specific laboratory instructions. A cleanly collected sample, often obtained directly from the bladder by the veterinary team, reduces uncertainty from contamination.

Bloodwork can assess kidney function, glucose and other relevant abnormalities. Ultrasound or other imaging may help investigate stones, bladder changes, obstruction or upper urinary tract involvement. A positive culture does not remove the need to look for a structural or metabolic problem that is sustaining infection.

Why does antifungal choice matter?

Antifungal drugs are not interchangeable. The organism's susceptibility and whether useful drug concentrations reach the urine are important. The Merck Veterinary Manual's fungal urinary treatment guidance identifies fluconazole as a usual choice for candidal cystitis, while individual cases require veterinary selection and monitoring.

Do not substitute a skin-infection prescription or assume itraconazole is equally suitable for a bladder infection. Treatment may also require addressing diabetes, reviewing unnecessary medications and managing a catheter or urinary abnormality. Never remove a catheter or stop prescribed immunosuppressive treatment yourself.

Clinical improvement is useful, but a follow-up plan may include repeat urine testing to assess whether the organism persists. Published feline evidence is limited, and treatment duration should be individualised rather than promised as a fixed short course.

When is this an emergency?

Go now if your cat repeatedly strains without producing urine, becomes weak, vomits or develops a painful abdomen. Do not press on the bladder, force water or wait for a sample before leaving. Call ahead and say that urinary obstruction is possible.

What should you do next?

1. Observe actual urine production and seek urgent help if it is uncertain.
2. Bring details of recent antibiotics, catheterisation and current medicines.
3. Ask what confirms infection and whether underlying disease has been assessed.
4. Give treatment exactly as prescribed and report poor appetite, vomiting or other new signs.
5. Complete the planned recheck and sample collection rather than relying only on tray behaviour.

Common mistakes

• Assuming every urinary episode is another infection.
• Giving antibiotics when a fungal problem is suspected without reassessment.
• Using human antifungals or leftover pet medication.
• Delaying care because a few drops of urine appeared earlier.

Can recurrence be reduced?

Manage established medical conditions, use antimicrobials only when indicated and follow veterinary catheter-care instructions. Fresh water, accessible clean trays and a suitable diet support urinary care, but they do not reliably cure a fungal infection. A prescription urinary diet should match the actual diagnosis.

Frequently asked questions

Is fungal cystitis common?

No. More common explanations for urinary signs must also be considered.

Does cloudy urine prove infection?

No. Appearance alone cannot identify bacteria, fungi or the underlying cause.

Can antifungal cream treat the bladder?

No. It is not an appropriate urinary treatment.

Why repeat a urine culture?

It can help clarify persistence or recurrence and guide the next decision.

Confirm the diagnosis, address what allowed infection to develop and treat doubtful urine output as urgent.

For help understanding your cat's health and preparing questions for your veterinary team, visit ASK A VET™. If your cat has emergency signs, contact an emergency clinic directly.