When a Dog Cannot Pee: A Blocked Bladder Is an Emergency

A dog straining with nothing coming out is not constipated. It is one of the fastest-killing emergencies there is, and the two look identical.

Your dog keeps going out to the garden. It squats, strains, holds the position, and comes back in. Twenty minutes later it does it again. It is uncomfortable, restless, and cannot settle.

Almost everyone reads this as constipation. It is the most dangerous misreading in this entire guide, because a blocked bladder can rupture, or poison the blood, within 24 to 48 hours, and sometimes faster in a small dog.

How to tell the difference

Straining to pee and straining to poo look exactly the same from across a room. There is only one reliable distinction and it is worth learning:

Look at what comes out. If your dog is repeatedly posturing and producing no urine at all, or a few blood-tinged drops, that is a urinary blockage. It is not about how hard the dog is straining. It is about the empty patch of grass.

If there has been no urine passed in twelve hours despite obvious straining, treat it as an emergency regardless of what else you think might be going on.

What to do

1. Watch your dog squat once, properly, to confirm there is nothing coming out.
2. Stop all food and water from that moment. The vet will almost certainly need to sedate your dog to pass a catheter, and an empty stomach is safer. Withholding water from a dog that clearly wants it is the hardest instruction on this page, and it matters.
3. Ring on the way and use the exact words "my dog cannot pee". That phrase gets a catheterisation kit and sedation prepared before you arrive, and can save twenty to forty minutes.
4. Carry your dog gently, with your hands under the chest and body, not under the belly. The bladder is stretched close to its limit and pressure on the abdomen can rupture it.
5. Watch it on the way in. If breathing slows or the gums go pale or grey, say so the moment you arrive.

Why it moves so fast

When urine cannot leave, waste products build up in the blood and pressure builds in the bladder. Potassium rises, and high potassium interferes with the heart. Dogs with a complete blockage can go into shock or cardiac arrest, which is why this is treated with the urgency of a road accident rather than a plumbing problem.

What not to do

Do not press, squeeze or massage the belly to try to help things along. The bladder is already at bursting point.

Do not give diuretics, cranberry juice, herbal teas, apple cider vinegar or anything else recommended online. None of them can push urine past a physical blockage. They delay you and some worsen the kidney damage that is already starting.

Do not wait until morning, or until Monday. From complete blockage to rupture or fatal poisoning of the blood is a day or two, sometimes less. The out-of-hours fee is a fraction of the surgery you will be paying for if you wait, and vastly less than the alternative.

What you might see

• Repeated squatting with nothing, or a few blood-tinged drops
• Crying, whining or yelping while trying
• A hard, swollen, painful belly low down
• Restlessness and an inability to lie comfortably
• Excessive licking at the genitals
• Vomiting, which means toxins are already building
• Lethargy, weakness or collapse, which is late and serious

Who it happens to

Male dogs are considerably more prone, because their urethra is longer and narrows towards the end, so a stone or a plug of crystals that a female would pass gets stuck.

If your dog has had bladder stones, crystals or urinary infections before, this page applies to you more than most. Know the signs now, and never let straining with an empty result be filed as constipation.

Sources

This article was written using guidance from PDSA, the UK's largest veterinary charity, whose Pet Health Hub is written by its own vets and nurses; Merck Veterinary Manual, a peer-reviewed reference used by veterinary professionals worldwide; and RECOVER Initiative, the body that sets the international, evidence-based guidelines for pet CPR. This guidance is for general information and does not replace a consultation with your own veterinarian. In an emergency, always contact a vet. Read [how we write our health guidance](https://rochsociety.com/how-we-write-our-health-guidance/). Last reviewed July 2026.