Blood in Cat Urine: Causes, Symptoms & What to Do Next

Finding blood in your cat's urine, known medically as haematuria, is alarming for any owner. It's visible as pink, red, or rust-coloured urine in the litter tray or on surfaces where your cat has urinated. Sometimes the blood is obvious to the naked eye, other times it's only detected on urine testing as microscopic haematuria.

Blood in the urine is never normal, but it's also not always an emergency. The urgency depends on the underlying cause, how much blood is present, whether your cat can urinate normally, and whether there are other symptoms alongside it. As a vet, I see cats with bloody urine regularly, and while some cases are straightforward and resolve quickly with treatment, others require more extensive investigation.

This guide covers every cause of blood in cat urine, what to watch for, and when you need to see your vet urgently.

What Does Blood in Cat Urine Look Like?

Blood in urine can appear as:

• Pink or red-tinged urine: The most obvious sign, ranging from light pink to bright red
• Rust or brown-coloured urine: Older blood that has oxidised
• Clots or spots of blood: Sometimes visible as dark specks or strands in the litter tray
• Blood spots outside the litter tray: On carpets, bedding, or other surfaces if your cat is urinating inappropriately

In some cases, the blood is microscopic and only detectable on urinalysis. This is why routine urine testing is so valuable, particularly in older cats.

Common Causes of Blood in Cat Urine

1. Feline Lower Urinary Tract Disease (FLUTD)

FLUTD is an umbrella term for several conditions affecting the bladder and urethra, including idiopathic cystitis (inflammation with no clear cause), bladder stones, urethral plugs, and bacterial infections. It's one of the most common causes of bloody urine in cats, particularly in young and middle-aged animals. Other signs include frequent trips to the litter tray, straining to urinate, urinating outside the tray, and excessive licking of the genital area.

2. Urinary Tract Infection (UTI)

True bacterial UTIs are less common in young, healthy cats but become more frequent in older cats, diabetic cats, and those with kidney disease or immune suppression. Infection causes inflammation of the bladder lining, leading to bleeding. Other symptoms include frequent urination, straining, and strong-smelling urine. For a complete guide, read our article on cat UTI symptoms.

3. Bladder Stones (Urolithiasis)

Mineral crystals in the urine can aggregate into stones that sit in the bladder, irritating the lining and causing bleeding. The most common types in cats are struvite and calcium oxalate stones. Stones can cause intermittent bloody urine, difficulty urinating, and in severe cases, complete urethral obstruction, particularly in male cats. Diagnosis requires X-rays or ultrasound, and treatment may involve dietary management or surgical removal.

4. Idiopathic Cystitis (FIC)

Feline idiopathic cystitis is sterile inflammation of the bladder with no identifiable cause, though stress is thought to play a major role. It's the most common cause of FLUTD in cats under 10 years old. Episodes of bloody urine, straining, and litter tray avoidance come and go, often triggered by stressful events. Management focuses on environmental enrichment, stress reduction, and increasing water intake.

5. Urethral Plugs (Particularly in Male Cats)

A combination of mucus, crystals, and inflammatory debris can form a plug that partially or completely blocks the urethra. This is most common in male cats due to their longer, narrower urethra. Blood in the urine is often the first sign, followed by straining with little or no urine produced, crying out in pain, and rapid deterioration. A blocked urethra is a life-threatening emergency requiring immediate veterinary intervention.

6. Trauma

Physical injury from a fall, road traffic accident, or fight with another animal can cause bleeding in the urinary tract. Trauma is usually obvious from the history, and there are often other visible injuries. Internal bleeding may not be immediately apparent, so any cat involved in an accident should be checked by a vet even if they seem outwardly fine.

7. Kidney Disease

Chronic kidney disease can occasionally cause microscopic haematuria due to inflammation or secondary infections. It's more commonly associated with increased thirst and urination, weight loss, and reduced appetite. For more on increased drinking, see our guide on why cats drink more water.

8. Tumours

Bladder tumours, while uncommon in cats, can cause persistent bloody urine. Transitional cell carcinoma is the most common type and typically affects older cats. Diagnosis requires imaging and biopsy.

9. Clotting Disorders

Rarely, blood in the urine can be caused by a bleeding disorder such as poisoning with rat bait (anticoagulant rodenticide), liver disease affecting clotting factors, or inherited clotting defects. These cats usually show bleeding in multiple locations: gums, nose, under the skin, and in the urine.

10. Medications

Certain medications, particularly chemotherapy drugs and some anti-inflammatories, can irritate the bladder lining and cause haematuria. If your cat has recently started medication and develops bloody urine, inform your vet immediately.

When Is Blood in Cat Urine an Emergency?

Seek emergency veterinary care if your cat:

• Is straining to urinate but producing nothing or only drops (particularly male cats, this suggests obstruction)
• Is crying out in pain when trying to urinate
• Has a distended, hard abdomen
• Is vomiting, lethargic, or collapsed alongside bloody urine
• Has not urinated at all in 12-24 hours
• Has profuse bright red blood with clots

A blocked urethra is life-threatening. Waste products build up rapidly, leading to kidney failure, heart arrhythmias, and death within 48-72 hours if untreated. For more on recognising emergencies, read our guide on cat medical emergencies.

When Should I Call the Vet (Non-Emergency)?

Contact your vet within 24 hours if your cat:

• Has blood in their urine but is otherwise urinating normally
• Is making frequent trips to the litter tray
• Is urinating outside the litter tray for the first time: read our guide on why cats stop using the litter tray
• Is excessively licking their genital area
• Has had blood in their urine for more than 24 hours

Even if your cat seems otherwise well, blood in the urine always warrants investigation. For more on recognising illness in cats, see our overview of cat symptoms and when to act.

How Is Blood in Cat Urine Diagnosed?

Your vet will start with a full physical examination, including palpation of the abdomen to check the bladder. They'll then typically recommend:

• Urinalysis: To confirm blood, check for crystals, bacteria, white blood cells, and measure urine concentration
• Urine culture: If infection is suspected, to identify the bacteria and guide antibiotic choice
• Blood tests: To assess kidney function and rule out systemic conditions
• Imaging (X-ray or ultrasound): To look for bladder stones, tumours, or other structural abnormalities

In many cases, a combination of urinalysis and imaging will identify the cause.

Treatment for Blood in Cat Urine

Treatment depends entirely on the underlying cause:

• Bacterial UTI: Antibiotics (typically 7-14 days)
• Bladder stones: Dietary dissolution (for struvite stones) or surgical removal
• Idiopathic cystitis: Pain relief, stress reduction, environmental enrichment, increased water intake
• Urethral obstruction: Emergency catheterisation under sedation or anaesthesia, hospitalisation with fluid therapy
• Trauma: Supportive care, pain relief, possible surgery depending on severity

Most cases of bloody urine respond well to treatment, though idiopathic cystitis tends to recur, requiring long-term management.

How to Prevent Bloody Urine in Cats

• Encourage water intake: Use water fountains, offer wet food, add water to meals
• Reduce stress: Maintain routine, provide hiding spots, use pheromone diffusers
• Keep litter trays clean: Scoop daily, wash regularly, provide one tray per cat plus one extra: see our guide on how many litter trays you need
• Maintain a healthy weight: Obesity increases FLUTD risk
• Monitor regularly: Check the litter tray daily for changes in urine colour, frequency, or volume

How Litter Sense Helps You Detect Blood Early

Litter Sense changes colour when it detects blood in your cat's urine, often before you'd notice it visually. This gives you the chance to seek veterinary care early, before symptoms worsen. Catching urinary problems in their early stages makes treatment more effective and less invasive.

To learn more about how this works, read our complete guide on how Litter Sense monitors cat health.

Frequently Asked Questions

Can blood in cat urine go away on its own?

Sometimes. Mild cases of idiopathic cystitis can resolve without treatment within a few days. However, you can't tell what's causing the blood without veterinary examination. Bacterial infections, stones, and obstructions won't resolve on their own and require treatment. It's always safer to get it checked.

Is blood in cat urine painful?

Yes, in most cases. Conditions causing bloody urine, particularly cystitis, UTIs, and stones, are painful. Affected cats often strain, cry out when urinating, and lick themselves excessively. Pain relief is an essential part of treatment.

How much does it cost to treat blood in cat urine?

Costs vary widely depending on the cause. A straightforward UTI treated with antibiotics might cost £100-200 including consultation and medication. Imaging, hospitalisation for a blocked urethra, or surgery for bladder stones can cost £500-2,000 or more. Pet insurance typically covers unexpected urinary problems.

Can stress cause blood in cat urine?

Yes. Stress is a major trigger for feline idiopathic cystitis, which causes inflammation and bleeding in the bladder. Moving house, new pets, changes in routine, or even a dirty litter tray can trigger an episode.

Why do male cats get blocked more than females?

Male cats have a longer, narrower urethra that tapers at the end, making it more prone to blockage from crystals, mucus, or inflammatory debris. Female cats can still develop cystitis and bloody urine, but complete obstruction is far less common.

Should I change my cat's diet if they have blood in their urine?

Possibly. Diet can play a role in managing bladder stones and idiopathic cystitis. Your vet may recommend a prescription urinary diet to dissolve struvite stones or reduce crystal formation. Always follow veterinary advice rather than changing food independently.