If you think your cat may be blocked, call an emergency vet now. Do not wait for morning. Do not wait to finish this page.
A urinary blockage is one of the few true emergencies in cat ownership. A completely obstructed cat can go into kidney failure and cardiac arrest within 24 to 48 hours. Treated quickly, most cats recover well. That gap is the entire reason this page exists.
The signs
Any of these warrant a same-day call. Several together warrant an immediate one.
- Straining in the litter box with little or nothing coming out. This is the classic sign, and it is very often mistaken for constipation.
- Going in and out of the box repeatedly, or crouching for long periods.
- Crying, howling or yowling while trying to urinate.
- Blood in the urine, or pink-tinged spots outside the box.
- Urinating outside the box, when that is not normal for your cat.
- Excessive licking at the genital area.
- A hard, tense abdomen, or an obvious flinch when it is touched.
- Vomiting, lethargy, hiding, or refusing food alongside any of the above. These suggest it has already been going on a while.
Who it happens to
Male cats are at far higher risk than females, because their urethra is longer and much narrower and obstructs more easily. Neutered males are the most commonly affected group. It is more likely in cats on entirely dry diets, in overweight and indoor cats, and in cats under stress.
Female cats can develop urinary disease too. Full obstruction is much less common in them.
Why straining is so easily missed
A cat straining in the litter box looks exactly like a constipated cat. Owners reasonably wait a day to see if it passes. With a blockage, that day is most of the window.
If you are not certain which you are looking at, treat it as urinary and call. A vet would far rather see a constipated cat than a blocked one twelve hours too late.
What to do right now
- Call an emergency vet. Say the words "I think my cat may have a urinary blockage" and they will triage you immediately.
- Go in. This cannot be assessed over the phone.
- Do not give human painkillers. Paracetamol is lethal to cats and ibuprofen is dangerous.
- Do not wait to see if it resolves. It does not resolve.
Afterwards
Cats that have blocked once are at higher risk of blocking again, and your vet will usually discuss diet, water intake and stress. Raising water intake is a standard part of that conversation, because dilute urine is less likely to form the crystals and plugs that obstruct.
That is a discussion to have with your vet about your specific cat, after the emergency is over. It is not something to act on from a web page.
This article is not veterinary advice and cannot diagnose anything. It exists so that the signs are recognisable. If in any doubt at all, call a vet.