Blood in cat urine: causes, symptoms and prevention

• male cats, with a narrower urethra;
• older animals, in which tumours and chronic diseases are more common;
• overweight and inactive cats;
• pets eating dry food and drinking little water.

The male cat's risk particularly concerns urethral obstruction; bloody urine in a female also needs investigation. Dry food alone does not establish the cause. Total water intake, urine composition, any stone type and the cat's environment affect the situation, and the same dietary change does not suit every cat. Weight or food type cannot distinguish cystitis, infection and a tumour.

To find the cause, investigations include:

• a urine sample to assess red blood cells, protein and bacteria;
• blood biochemistry to assess kidney function;
• bladder and kidney ultrasound;
• X-rays to identify stones;
• cytology or biopsy if a tumour is suspected;
• clotting tests to rule out clotting disorders.

The first assessment establishes whether urine flow is obstructed and whether the cat is stable. The vet examines the abdomen and bladder by touch and asks about urine output, symptom duration, medicines, injuries and previous urinary problems. Mention possible toxin exposure or bleeding noticed elsewhere too.

Urine specific gravity reflects concentration, while microscopy examines red blood cells, inflammatory cells, crystals and possible bacteria. A dipstick alone does not replace this examination. Urinary protein is also interpreted alongside bleeding and other findings, as protein does not automatically indicate damage to kidney filtration in this situation.

A sample can be collected directly from the bladder with a sterile needle, for example. This reduces contamination with external bacteria and helps interpret culture results. However, sampling or catheterisation may introduce small amounts of blood. This is considered particularly when red blood cells are only a laboratory finding and bloody urine has not been seen at home.

If infection is suspected, bacterial culture and susceptibility testing help select a medicine. Bacteria without symptoms are not the same as a urinary tract infection needing treatment. Imaging looks for stones, bladder wall changes and upper urinary tract problems, among other things. Recurring symptoms are reinvestigated where necessary because the cause is not always the same as before.

If the vet requests a home sample, follow the collection and transport instructions and state when it was taken. Do not delay emergency care while waiting for a sample. Never squeeze the bladder yourself to obtain urine: this causes pain and can damage it.

Treatment addresses the cause and pain. Urethral obstruction requires restoration of urine flow, often with a catheter under sedation or anaesthesia, and correction of fluid and electrolyte balance. Some patients need other procedures. An obstruction cannot safely be relieved at home by giving water or old medicines.

If needed, an antibiotic for infection is selected according to investigations. It is not started solely because there is blood or the word cystitis is used. If the cat's condition allows, a culture sample is taken before treatment. Pain relief and changes to the cat's environment and routine are central to FIC management. Looking for stressors does not mean the pain is imagined.

Urinary stone treatment depends on location and composition. Some struvite stones can be dissolved with a diet chosen by the vet, but calcium oxalate stones do not dissolve in the same way. Do not choose acidifying supplements or urinary products yourself. A tumour or clotting disorder needs its own treatment plan.

After discharge, monitor urine output, the number of attempts, pain, eating and general health. Record whether visible blood decreases or increases too. If urine is not passing normally, your cat vomits or their condition worsens, contact the treating practice immediately. Monitoring is often needed after an obstruction even once urine flow has been restored.

Normal-looking urine can still contain microscopic red blood cells, so watching colour alone cannot replace agreed follow-up samples. Use the sampling method agreed for the follow-up visit.