Health & Medical

Your dog has asked to go out four times in an hour, squatted for ages in the wet grass, produced barely a teaspoon, and there is a pink tinge to it. So which is it? A bladder infection that a week of antibiotics will sort out, or a stone sitting in there that no amount of medication will touch? From the outside, honestly, you cannot tell. Straining, frequency, blood and accidents indoors look identical whether the bladder wall is inflamed or there is a lump of mineral rolling around inside it. That is the whole reason imaging exists.

Bladder stones, called uroliths, form when minerals dissolved in urine come out of solution and clump together. It happens over weeks to months, in dogs and cats alike. Sometimes there is one stone the size of a marble, sometimes a hundred grains like coarse sand, and plenty of animals carry them quietly for months before anything obvious goes wrong. A stone irritates the bladder lining constantly, which is why so many of these patients have been treated for recurrent cystitis two or three times before anyone takes a picture.

Struvite and oxalate are not interchangeable

The two common types behave so differently that lumping them together causes real harm. Struvite stones in dogs are usually driven by a urinary tract infection with bacteria that split urea and push the urine alkaline. Treat the infection, feed a therapeutic dissolution diet, and a good proportion of these genuinely shrink away over some weeks with recheck imaging along the way. In cats struvite is more often sterile, forming without any infection, and it also frequently responds to the right diet.

Calcium oxalate is the awkward one. It does not dissolve. There is no diet, no supplement and no medication that will make an oxalate stone disappear, and anything sold on that promise is not telling you the truth. Oxalate stones come out, or they stay. They turn up more often in miniature schnauzers, bichon frises, shih tzus and Yorkshire terriers, and in Burmese, Persian and Himalayan cats, and they have a stubborn habit of recurring. Less common types exist too, including urate stones linked to Dalmatians and liver shunts, and cystine stones seen mostly in intact male dogs.

The only way to be certain which type you are dealing with is to have a retrieved stone analysed at a laboratory, which is cheap and routinely done. Before that, urine pH, the crystals seen under the microscope, the breed and the appearance on imaging give a reasonable working guess. This is precisely why buying a prescription urinary diet online without a diagnosis is a bad idea. A diet designed to dissolve struvite can encourage oxalate formation in the wrong patient.

The night a male cat stops peeing

Everything above assumes urine is still coming out. When it stops, the situation changes completely. Male cats have a long narrow urethra that a small stone or a plug of crystals and mucus can seal shut. Male dogs have a bone in the penis with a narrowing where stones lodge. In both cases the bladder fills and cannot empty, pressure backs up to the kidneys, and potassium climbs in the bloodstream until it affects the heart rhythm. This can kill within a day or two, and the animal is in serious pain long before that.

The signs get misread with tragic regularity. A blocked cat goes in and out of the tray, strains, produces nothing or a drop, cries, and is very often assumed to be constipated. He may vomit, hide, and then become weak and collapsed. If you see a cat straining repeatedly with nothing coming out, treat it as an emergency that night, not a problem for the morning surgery. The same applies to a male dog straining unproductively.

At the clinic the team will feel a tight, painful bladder, run bloods for kidney values and potassium, pass a urinary catheter under sedation to relieve the obstruction, and give fluids and pain relief. Most blocked animals stay in for a few days. A minority who block repeatedly are offered surgery to widen the urethral opening, a bigger conversation best had once the crisis has passed.

Getting them out, and keeping the next ones away

Radiographs pick up most struvite and calcium oxalate stones, since both show well on X-ray. Urate and cystine stones can be effectively invisible, so ultrasound is often added, and it also catches small stones hiding behind the pelvis. Urinalysis and a culture round out the picture.

Removal options depend on size, type, species and what your practice or a nearby referral centre offers. A cystotomy, opening the bladder surgically, remains the standard and is well tolerated. Very small stones in female patients can sometimes be flushed out with a technique called voiding urohydropropulsion, and some referral hospitals offer laser lithotripsy or cystoscopic basket retrieval instead. Prices vary widely, so ask for an estimate that includes follow-up imaging.

That follow-up radiograph after surgery matters more than people realise. Small stones are genuinely easy to leave behind, and confirming an empty bladder before the animal goes home saves a repeat operation later.

Prevention is unglamorous and works. Water is the strongest tool you have, because dilute urine simply cannot hold as much dissolved mineral. Wet food does far more than a fountain ever will, though fountains help some cats. Add water to meals and give cats more bowls than seems necessary. Feed the diet matched to the analysed stone type and nothing else on the side, since treats and table scraps quietly undo it. Do not let a dog hold urine all day. And keep the recheck appointments, because urine testing and periodic imaging catch a returning stone while it is still small.

All of this is general information rather than advice about your particular animal. If your pet is straining, bleeding or uncomfortable, the useful next step is a urine sample and a picture of the bladder, and if nothing at all is coming out, that step happens tonight.