Blood in Cat Urine: 5 Causes and When to Call a Vet

Blood in cat urine, called hematuria, is a sign of irritation or damage somewhere in the urinary tract, most often from cystitis, crystals, stones or infection. It matters for every cat owner because a male cat that strains and produces little or no urine can have a life-threatening blockage within 24 to 48 hours.

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Blood in cat urine at a glance:

• Short Answer: Hematuria means red blood cells are present in the urine, and it always needs a veterinary diagnosis.
• Most Common Causes: Idiopathic cystitis, bladder crystals and stones, urinary tract infection, urethral blockage, and tumors.
• Urgency: Same-day vet visit for any blood; emergency care if your cat strains without producing urine.
• What to Do at Home: Collect a fresh urine sample, boost water intake, and keep the litter box very clean.
• When to See a Vet: Immediately, because the cause cannot be identified by looking at the urine alone.

Common Causes of Blood in Cat Urine

Several conditions cause blood in cat urine, and in cats under 10 years old the most frequent one is a non-infectious bladder inflammation. Your vet sorts these out with testing.

Feline Idiopathic Cystitis

Idiopathic cystitis is sterile bladder inflammation with no identifiable cause, and it is the leading diagnosis in young to middle-aged cats with urinary signs. Stress, indoor-only living, and multi-cat households are well-known triggers.

Bladder Crystals and Stones

Minerals in concentrated urine can form crystals that scratch the bladder lining and grow into stones. Cats that drink little water and eat only dry food face a higher risk.

Urinary Tract Infection

Bacterial infections are less common in young cats but occur more often in seniors and in cats with kidney disease or diabetes. Infected cats often urinate small amounts again and again.

Urethral Blockage

Crystals or mucus plugs can block the narrow urethra, and this happens mainly in male cats. A blocked cat cannot empty its bladder, and toxins build up in the blood quickly.

Tumors, Trauma and Other Causes

Bladder tumors are uncommon and mostly affect older cats. Injuries, clotting disorders, and kidney problems can also put blood in the urine.

Signs to Watch For Along With Bloody Urine

Blood in cat urine rarely appears alone, and the companion signs help your vet narrow down the cause. Note each one before the appointment.

• Frequent trips to the litter box with only small amounts of urine
• Straining, crouching for a long time, or crying while trying to pee
• Peeing outside the box, often on cool surfaces like tile or the bathtub
• Constant licking of the genital area
• Hiding, irritability, or sudden changes in behavior (see why a cat may be suddenly hiding)
• Lethargy, vomiting, and loss of appetite

Emergency signs:

• Straining with no urine or only drops coming out
• Crying in the litter box, a hard painful belly, or a swollen bladder
• Vomiting, weakness, or collapse

These signs suggest a blockage, and your cat needs an emergency veterinarian right away. If you want more on this, our post on a cat urinating blood covers the emergency picture in detail.

How Vets Diagnose the Cause

Your veterinarian cannot tell the cause of hematuria by sight, so testing is the only reliable route. Most diagnoses start with a urine sample and a physical exam.

1. Physical exam: The vet feels the bladder and belly to check size, firmness, and pain.
2. Urinalysis: This checks urine concentration, pH, crystals, blood, and signs of infection.
3. Urine culture: This confirms bacteria and shows which antibiotic works.
4. Blood work: This screens kidney function and looks for diabetes or other illness.
5. X-rays or ultrasound: Imaging finds stones, thickened bladder walls, or tumors.

A clean cat urine collection kit with non-absorbent litter makes sampling much easier at home, and a fresh sample under about 12 hours old gives the most useful results.

Treatment and Home Care for Blood in Cat Urine

Treatment for blood in cat urine depends entirely on the diagnosis, so never start medicine on your own. Never give human pain relievers or leftover antibiotics, because many are toxic to cats.

• Infection: Your vet prescribes an antibiotic matched to the culture results.
• Idiopathic cystitis: Treatment centers on pain relief, more water, and stress reduction at home.
• Crystals and small stones: A prescription urinary diet can dissolve some struvite stones and prevent new ones.
• Large stones, tumors, or blockage: These may need catheter relief, fluids, or surgery.

Supportive care that helps recovery:

• Switch toward wet food, since canned diets are about 75 percent water and dilute urine.
• Offer a stainless steel cat water fountain to encourage drinking; see our guide to the best cat water fountain for easy cleaning.
• Scoop daily and use an unscented clumping litter, because a dirty box can make cats hold their urine. Our post on how often to clean a litter box sets a simple schedule.
• Add a cat calming diffuser and extra hiding spots if stress seems to be a trigger.
• Use an enzyme cleaner on accidents so the smell does not draw your cat back; see how to remove cat urine.

Reputable guidance on urinary conditions is available from Cornell Feline Health Center.

When to See a Vet and How to Prevent Repeat Episodes

Book a same-day appointment for any visible blood in cat urine, even if your cat acts normal. Cats hide pain well, and a mild-looking episode can hide stones or an early blockage.

Prevention habits that lower the risk:

• Keep fresh water in several spots around the house.
• Feed measured portions of wet food daily to keep urine dilute.
• Keep one litter box per cat plus one extra, in quiet places.
• Maintain a healthy weight, since obesity raises urinary risk.
• Schedule regular checkups, as covered in our post on regular veterinary check-ups for cats.

The VCA Animal Hospitals library has more detail on feline urinary disease.

Frequently Asked Questions

Blood in cat urine is always a reason to call your veterinarian, because causes range from simple cystitis to a life-threatening blockage. Collect a fresh urine sample, watch for straining, and book a vet visit today.