Blood in your cat’s urine: what it means and when it is urgent
Seeing pink urine or drops of blood in the litter tray is alarming, and rightly so, although the most common cause in young cats is not an infection but stress-related bladder inflammation. What matters is working out straight away whether the cat is passing urine properly, because in a male the difference is a matter of hours.
What it looks like
Haematuria, blood in the urine, shows up in several ways: clumps of litter stained pink or red, drops of blood on the edge of the tray or on the floor, pinkish or brownish urine if the cat pees outside the litter, or reddish traces around the genitals. It often comes with other lower urinary tract signs: going to the tray many times and passing little, straining, crying while urinating, licking the genitals a lot, or urinating outside the litter on cold, smooth surfaces such as the bath, the sink or the floor. Litters that change colour with pH or blood can give clues, but they are no substitute for a urine test.
First: is it urinating or not?
Before anything else, check whether the cat is really passing urine. Count the clumps in the litter: if there are normal-sized ones, it is urinating; if there are only tiny spots or nothing at all, or you see it crouching again and again without result, it may be blocked. In males, the urethra is long and narrow and blocks easily. A blocked cat can die within one or two days because the kidneys cannot get rid of potassium and toxins. If it is male and you are not sure it is urinating, if it is vomiting, subdued, hiding or has a painful belly, go to an emergency vet at once, whatever the time. In females, blockage is very rare, but blood in the urine still warrants a vet visit.
The most common cause: idiopathic cystitis
In cats under about ten years old, the most common cause of blood in the urine is feline idiopathic cystitis: inflammation of the bladder without infection or stones, closely linked to stress and to how the cat perceives its surroundings. It typically appears in young or middle-aged indoor cats that are overweight, eat only dry food and drink little, and it often coincides with change: a house move, a new cat, building work, conflict with another cat at home. Episodes usually improve within a few days with pain relief, but they tend to come back if nothing in the environment changes. The subject is covered in depth in the article on idiopathic cystitis.
Stones, crystals and infections
Urinary stones (uroliths) are the second cause. Two types dominate in cats: struvite, which can often be dissolved with a specific diet, and calcium oxalate, which does not dissolve and has to be removed if it causes problems. Crystals in the urine without a stone are not always a problem in themselves, but they can form urethral plugs in males. Bacterial urinary tract infections are uncommon in healthy young cats, but they become much more common in older cats, particularly those with kidney disease, diabetes or hyperthyroidism. That is why a “just in case” antibiotic in a young cat is usually a mistake, and in an older one it is best to confirm with a culture.
Other, less common causes
Trauma, such as a fall or a road accident, can damage the bladder or kidneys and cause blood in the urine, sometimes with few external signs. Bladder tumours are rare in cats but they do occur, mainly in older animals. Clotting problems, for example after eating an anticoagulant rat poison, cause bleeding in the urine and elsewhere (gums, faeces, small spots on the skin). Some kidney diseases can produce haematuria. And in entire females, vaginal bleeding can be mistaken for blood in the urine, although a female cat in heat does not normally bleed. The cat’s age and its other symptoms help the vet put the possibilities in order.
What the vet will do
The vet will feel the bladder to see whether it is full and hard (possible blockage) or small and inflamed. Urinalysis is the key test: specific gravity, sediment with crystals and cells, a dipstick and, if infection is suspected, a culture. Ideally the urine is collected directly from the bladder with a fine needle guided by ultrasound (cystocentesis), a quick, well-tolerated technique that avoids contamination. Ultrasound or X-rays look for stones, a thickened bladder wall or masses. In older cats, blood tests are added. If there is a blockage, the cat is sedated or anaesthetised to place a urinary catheter and is hospitalised on fluids.
What it costs in Spain in 2026
As a guide: consultation, €40 to €60; full urinalysis, €30 to €60; urine culture, €30 to €70; cystocentesis, €15 to €40; abdominal ultrasound, €70 to €150; X-rays, €60 to €120. A thoroughly investigated episode of cystitis with pain relief can cost €150 to €350. A veterinary urinary diet costs €25 to €60 a month. Unblocking a male cat with a catheter and two or three days in hospital usually costs €600 to €1,500, and can exceed €2,000 if there are complications or it has to be repeated; surgical removal of bladder stones, €500 to €1,200.
What not to do
Do not wait to see if it passes in a male cat that keeps going to the litter tray. Do not give it human painkillers: paracetamol is fatal to cats and ibuprofen or aspirin can damage their stomach and kidneys. Do not use antibiotics left over from other treatments: most young cats have no infection, and in older ones you need to know which bacterium is involved. Do not switch to a urinary diet on your own without knowing what type of crystals or stones are present, because each needs a different diet. And do not punish the cat if it urinates outside the litter: it hurts, and it is associating the tray with that pain.
Prevention: water, litter trays and less stress
Almost everything that protects a cat’s bladder is the same. Water: wet food for some or all of the diet, wide water bowls in several places around the home, fountains if it likes them. An ideal weight and daily play. Enough litter trays (the classic rule is one per cat plus one), large, very clean, in quiet spots and away from food. Less stress: hiding places, high spots, stable routines, duplicated resources if there are several cats, and changes introduced gradually. And, if the vet has diagnosed crystals or a particular type of stone, the diet they prescribe, kept up over time with regular urine checks.
If it keeps happening
Many cats with idiopathic cystitis have several episodes over their lifetime, especially in the first year after diagnosis. Keep a record of when they happen and what had changed at home: a pattern often emerges. Talk to your vet about a plan for episodes (what pain relief to keep to hand, when to come back) and review the environment calmly, perhaps with help from a feline behaviourist if there is conflict between cats. For males with repeated blockages there is an operation, perineal urethrostomy, that widens the urinary outlet; it is not the first option, but it can save a cat that blocks again and again.
Blood in the urine of a young cat is usually idiopathic cystitis, linked to stress and drinking too little. But the first thing is to check that it is urinating: a male passing no urine is an emergency measured in hours. Water, weight, clean litter trays and less stress are the best prevention.
Educational content from Michipedia, translated from the Spanish original. It does not replace the advice of a vet or a feline behaviour specialist. Every cat is an individual.