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A closer look at urinary blockage in cats
A urinary blockage (vets say urethral obstruction) happens when the tube that carries urine from the bladder out of the body, the urethra, becomes plugged. Urine keeps being made but cannot leave. The bladder swells and becomes painful, and within hours the kidneys can no longer clear waste from the blood.
The most dangerous change is a rise in potassium. High potassium disturbs the heart’s rhythm, and it is the main reason blocked cats can die quickly. That is why a blockage is always an emergency, at any hour.
Blockages are one part of a wider group of problems called feline lower urinary tract disease (FLUTD). Most cats with FLUTD are not blocked: they strain, urinate small amounts often, or pee outside the box because their bladder is inflamed. Those cats still need a vet, but a cat that cannot pass urine at all needs one now.
Risk factors
- Being male. Male cats have a long, narrow urethra that narrows further at the tip. The large majority of blocked cats are male.
- Age. Most blocked cats are young to middle-aged adults, often between about one and ten years old.
- Weight and lifestyle. Overweight, indoor, less active cats are at higher risk.
- Low water intake. Cats eating only dry food, or that drink little, produce concentrated urine.
- Stress. Changes at home (a move, a new pet or baby, conflict with another cat, building work, a change of litter) are strongly linked to bladder inflammation in cats.
- A previous blockage or bout of FLUTD. Cats that have had urinary problems before are more likely to have them again.
Causes
- Urethral plugs. The most common cause in male cats: a soft, toothpaste-like plug of protein, inflammatory cells and crystals that lodges in the urethra.
- Urinary stones (uroliths), most often struvite or calcium oxalate, that move from the bladder into the urethra.
- Spasm and swelling of the urethra caused by bladder inflammation, which can narrow it enough to stop urine flow even without a plug.
- Feline idiopathic cystitis (FIC): bladder inflammation with no single identifiable cause, closely linked to stress. It is the most common underlying problem in cats with lower urinary signs.
- Less common causes: scar tissue from previous blockages, injuries and, rarely, tumours.
Signs to watch for
- Straining or crouching in the litter box for a long time with little or no urine
- Repeated trips to the litter box, or going in and out without producing much
- Crying or howling while trying to urinate
- Licking the genital area a lot
- Small, dry or absent urine clumps in the litter
- Blood in the urine (pink or red urine, or spots) in cats that are not yet fully blocked
- As it progresses: hiding, not eating, vomiting, lethargy, weakness and collapse
Owners often think a straining cat is constipated. If you are not sure which it is, treat it as a blockage and get your cat to a vet.
How vets diagnose a blockage
A blocked bladder is usually easy for a vet to feel: it is large, firm and painful. To understand how sick the cat is, your vet will normally:
- Check heart rate and rhythm (sometimes with an ECG), temperature and hydration
- Run blood tests for kidney values and potassium
- Test the urine once a sample can be collected, looking for crystals, blood, infection and concentration
- Take X-rays or an ultrasound to look for stones in the bladder or urethra
Treatment
Treatment is urgent and almost always means a stay in hospital.
- Stabilise. Intravenous fluids, pain relief, and medicines to protect the heart if potassium is dangerously high.
- Relieve the blockage. Under sedation or anaesthesia, the vet gently flushes the urethra and passes a soft urinary catheter into the bladder. Sometimes the bladder is first drained with a needle through the belly wall to relieve pressure.
- Keep urine flowing. The catheter usually stays in for one to three days while fluids flush the kidneys and the urethra heals. Cats often produce very large amounts of urine at this stage, and blood values are checked repeatedly.
- Remove the catheter and watch. The vet confirms the cat can urinate on its own before sending it home, often with pain relief and medication to relax the urethra.
If stones are found, treatment depends on their type: some struvite stones dissolve on a prescription diet, while others need surgery. Cats that block repeatedly despite good home care may be offered a perineal urethrostomy, an operation that widens the end of the urethra.
Recovery and outlook
Most cats treated promptly recover well. The highest-risk time for re-blocking is the first few weeks at home, so watch the litter box closely and go back to the vet immediately if straining returns. Kidney values usually return to normal once urine flows again, though very prolonged blockages can cause lasting harm.
The outlook is much worse if treatment is delayed. Acting at the first signs gives your cat the best chance and usually means a shorter, simpler hospital stay.
Prevention
You cannot prevent every case, but these steps make a real difference for cats that have had urinary problems, and are good for any cat:
- More water. Feed wet food, or add water to food. Offer several water bowls around the home, and try a pet water fountain: many cats drink more from moving water.
- Feed the diet your vet prescribes. Urinary diets help dissolve some stones and reduce crystals. Do not switch to an over-the-counter “urinary” food without asking, as the right diet depends on what your cat’s urine showed.
- Reduce stress. Keep routines predictable, give each cat its own food, water, resting places and litter box, and add hiding and climbing spots. Pheromone diffusers help some cats.
- Get the litter boxes right. The usual rule is one more box than the number of cats, in quiet places, scooped at least daily, with a litter your cat likes.
- Keep your cat at a healthy weight and encourage play and activity.
- Know your cat’s normal. Learn what normal urine clumps look like, so you notice quickly if they get smaller or disappear.
What happens at the emergency hospital
Knowing what to expect can make a stressful night a little easier.
- Triage. A blocked cat is treated as a priority. Staff check the bladder, heart rate and temperature as soon as you arrive.
- An estimate. You will usually be given a treatment plan and cost estimate before the main treatment starts. Ask questions: there is time to talk while your cat is being stabilised.
- Stabilising. An intravenous catheter, fluids, pain relief and blood tests come first.
- Unblocking. Your cat is sedated or anaesthetised while the urethra is flushed and a urinary catheter placed.
- Hospital stay. Usually one to three days with the catheter in, then time to make sure your cat can urinate on its own.
If you are in Houston, the 24-hour emergency hospitals in our listings are on the 24-hour emergency vets page.
Caring for your cat at home afterwards
- Watch the litter box closely for the first two weeks. Use a litter that shows urine clumps clearly, and check several times a day.
- Give every dose of medication, including pain relief and any medicine to relax the urethra. Discomfort itself can trigger spasm.
- Feed the diet your vet prescribed, and add water or switch to the wet version if your vet agrees.
- Keep the home calm. Delay visitors, moves or new pets if you can.
- Go back immediately if straining returns, if your cat is passing only drops, or if it stops eating or starts vomiting.
Bladder inflammation without a blockage
Many cats, male and female, have bouts of bladder inflammation (cystitis) without being blocked. Signs include going to the litter box often, passing small amounts, blood in the urine, and peeing outside the box. These cats are uncomfortable and need a vet visit, usually within a day, but they are not in the same immediate danger as a blocked cat. The difference is whether urine is coming out: if you are not certain, treat it as an emergency.
In young and middle-aged cats, the most common cause of cystitis is feline idiopathic cystitis, which is closely linked to stress. In older cats, bacterial infections, bladder stones, kidney disease and diabetes become more likely, which is why your vet may recommend urine and blood tests.
Questions to ask your vet
- What caused the blockage: a plug, a stone, or spasm?
- What did the urine test show, and which diet do you recommend?
- How long should my cat stay on the prescription diet?
- What signs should bring us straight back?
- What can we change at home to lower stress?
- If it happens again, what are the options, including surgery?