Cat Urinary Problems: Blockages, Cystitis and Crystals

Quick answer

A cat that strains in the litter tray and passes little or no urine may be blocked, and that is an emergency. A blocked cat can die within a day or two without treatment, and males are at the highest risk. Other urinary problems, such as stress-related cystitis, crystals and stones, cause similar signs: frequent trips to the tray, small amounts of urine, blood in the urine or peeing outside the tray. They all need a vet, and most can be managed well once the cause is known.

The emergency first: urethral blockage

The urethra carries urine from the bladder out of the body. In male cats it is long and narrow, so a plug of crystals, mucus and inflammatory debris, a small stone, or spasm of the urethra can block it completely. Females can be affected but rarely are.

When urine can't get out, the bladder swells and waste products and potassium build up in the blood. High potassium affects the heart, and that is what makes a blockage so dangerous. Owners often mistake straining for constipation and wait. Please don't.

Signs of a blockage:

• Repeated visits to the tray, squatting and straining, with only drops or nothing coming out
• Crying in the tray or when picked up
• Licking at the genitals
• Restlessness, hiding, then vomiting, refusing food and lethargy as it gets worse
• Collapse in late stages

If you're not sure whether your cat has peed, put down a clean, empty tray (or one with a little non-absorbent litter or shredded plastic bag) and check it. No urine in several hours alongside straining means go now.

What causes urinary signs in cats

Vets group these problems as feline lower urinary tract disease (FLUTD). It's a description of symptoms rather than one disease. The main causes are below.

Feline idiopathic cystitis (FIC)

"Idiopathic" means no single cause can be found, and FIC accounts for around half to two-thirds of cats with lower urinary signs. It's a painful inflammation of the bladder closely tied to how a cat's body responds to stress. Flare-ups often follow a house move, building work, a new pet or baby, or tension with another cat, even one the owner thinks they get along fine. Signs can come and go, and many episodes settle within days, but the pain is real and the inflammation can lead to a urethral plug in males.

FIC is a diagnosis of exclusion: your vet will rule out stones, infection and other problems first.

Crystals and stones

Minerals in urine can form crystals (tiny grains seen under a microscope) and stones (larger, often visible on X-ray). The two most common types are struvite and calcium oxalate. Crystals don't always cause trouble on their own, but they can clump into plugs, and stones irritate the bladder wall.

Struvite stones can often be dissolved with a prescription urinary diet. Calcium oxalate stones cannot, so they may need to be removed surgically. This is why your vet needs to test the urine and often take an X-ray before choosing a diet.

Urinary tract infection

Bacterial infections are less common in young cats than people expect. They turn up more in older cats, particularly those with kidney disease, diabetes or an overactive thyroid. A urine culture shows whether there's an infection and which antibiotic will work.

Less common causes

Tumours, injuries and anatomical problems are rarer but are more likely in older cats or cats with signs that keep coming back.

Risk factors

Urinary problems are most common in young to middle-aged adult cats. Cats are more likely to be affected if they:

• Are overweight or inactive
• Drink little, especially on a dry-food-only diet
• Live indoors with limited activity, or in multi-cat homes with tension
• Have had a previous episode

Neutered males are often mentioned, but any cat can be affected.

What the vet may do

Expect a physical exam, including feeling the bladder. A large, hard bladder in a straining male points to a blockage. Tests may include a urine sample, blood tests (especially for kidney values and potassium), X-rays or ultrasound.

A blocked cat is usually stabilised with a drip and medication, then sedated or anaesthetised so a catheter can be passed to clear the urethra. Most stay in hospital for a few days. Cats that block repeatedly may be offered surgery to widen the urethra.

For cystitis without a blockage, treatment usually involves pain relief, increasing water intake and reducing stress. Antibiotics are only used when an infection is confirmed. Follow your vet's dosing and keep up any prescribed diet until they say otherwise.

Preventing flare-ups at home

Get more water into your cat. This is the single most useful change. Dilute urine is less likely to form crystals and is gentler on an inflamed bladder.

• Feed wet food for some or all of the diet, unless your vet advises otherwise.
• Add a little water to wet food.
• Offer several water bowls around the house, away from food and litter trays. Many cats prefer wide, shallow bowls or a water fountain.

Reduce stress. Give each cat its own resources: food, water, beds, scratching posts and litter trays (one per cat plus one) in separate places so no cat has to pass a rival to use them. High perches and hiding places help a cat feel safe. Keep routines predictable. Our guide on keeping an indoor cat happy has more ideas.

Make the tray inviting. Clean, quiet, easy to reach, with unscented litter. A cat that holds urine because it dislikes the tray is more prone to problems. The basics are in how to litter train a kitten, and they apply to adult cats too.

Keep your cat at a healthy weight and encourage play every day.

Stick to the prescribed diet if your cat has had crystals or stones, and don't mix in other foods without asking your vet.

When to see a vet

Go to a vet immediately if your cat:

• Is straining in the tray and passing little or no urine (especially a male)
• Cries in pain when trying to pee or when its belly is touched
• Is vomiting, very lethargic or collapsing alongside urinary signs

Book a same-day appointment if your cat:

• Is going to the tray much more often, passing small amounts
• Has blood in its urine
• Is peeing outside the tray, especially on cool, smooth surfaces like baths, sinks or tiles
• Is licking its genitals a lot

Mention it at a check-up if your cat:

• Is drinking or peeing noticeably more than usual. That's a different pattern, often linked to kidney disease, diabetes or thyroid problems, and still worth testing.