The Tao of Dilution

The Tao Te Ching says nothing under heaven is softer than water, and nothing better at overcoming the hard. Its author wasn’t thinking about cats. Most of what an owner can do about urinary disease is the same patient, unheroic business: more water through the animal.

Much of what’s sold for urinary cats is a proxy for that. Dilute urine is the nearest thing to a lever an owner controls.

§ 1Why dilution

Cats descend from desert animals and keep the desert in their kidneys: brilliant at concentrating urine, weak on thirst. They’re built to drink their prey. Feed them food under ten percent moisture and you get small volumes of strong urine.

Strong urine helps crystals form, irritates an inflamed bladder, and sits longer between visits. Dilute it and several problems ease at once.

Vets measure this as urine specific gravity (USG). For cats with urinary disease the working goal is usually below somewhere around 1.030 to 1.040. Your vet reads it with a refractometer. It’s the one number that says whether anything here is working.

USG: the only number in this guide that isn’t an opinion.

§ 2Wet food

Canned food is roughly 70 to 80 percent moisture. Dry is 6 to 10. Switching moves daily water intake more than any fountain, and the cat doesn’t have to decide anything. If you make one change, make this one.

• Go gradually. Mix in more wet over a week or two. Hard switches fail, sometimes theatrically.
• Add water. A tablespoon at a time. A surprising number of cats accept soup.
• If wet won’t work, make dry wetter: soak kibble in warm water for ten minutes.

Nigel eats wet food. It was not optional.

§ 3Getting a cat to drink

Marginal next to wet food. Marginal gains stack, and they’re cheap.

• More bowls, more places. Cats drink opportunistically.
• Away from food. Many cats visibly prefer it.
• Wide and shallow. Ceramic or glass; whiskers clear of the sides.
• Fountains — maybe. Some cats drink more from moving water; others ignore it with the contempt reserved for things you paid for. Only buy one you’ll actually clean.
• Flavor. Water from tuna packed in water, or plain unsalted broth. Check labels for onion and garlic, which are toxic to cats.
• Fresh daily. Cats notice stale water.

Art history’s most famous fountain was a urinal in a gallery, and the question was whether it counted. Here the question is simpler. It counts if he drinks from it.

§ 4Prescription diets

They do something real, and what they do depends on the diagnosis, not on the word urinary on the bag.

• Struvite stones can often be dissolved by a diet that adjusts urine pH and minerals, over weeks, monitored with imaging. The water wears the stone away.
• Calcium oxalate stones can’t be dissolved by any diet. They come out; diet then aims to prevent new ones. A diet built for one stone can work against the other, so don’t pick one off a shelf.
• Idiopathic cystitis — most cases, no stones — is different again. Some diets add stress- or bladder-targeted ingredients; evidence for those additions is mixed. The wet version of any of them delivers more water. Use the cans.

§ 5Supplements

The evidence is thin, and this is where the money goes.

• Glucosamine-type products, sold to restore the bladder lining: weak controlled evidence in cats. A 2025 systematic review found the evidence for most commonly recommended recurrent-FIC strategies shakier than their popularity suggests.
• Cranberry targets bacteria sticking to the bladder wall — usually not the problem.
• Urine acidifiers have real effects and real risks. Push pH without knowing the stone type and you can create the opposite problem.

Honest framing: a cheap experiment with weak evidence, not a treatment. Spend first on cans, bowls and the environment.

A supplement is hope in capsule form. Sometimes hope is cheap enough.

§ 6Is it working?

1. USG at the vet. Ask for the number at every recheck. Write it down next to the last one.
2. Clump size. Bigger, more numerous clumps usually mean more, more dilute urine — the goal. Free and daily. How to read them.
3. Visit frequency. More urine, more visits. A camera or smart scale makes it precise; a notebook will do.

Give each change three or four weeks. Change one thing at a time if you can bear it. You’ll likely do this for the rest of his life; know which parts earn their place.

§ 7Coda

There’s something absurd about meeting a life-threatening disease with extra bowls and a spoon of broth. Serious illness, we assume, needs machines and long drug names. The long-term management of most feline urinary disease is small, soft, daily things, without drama and without end.

If the old book is right, that’s the strongest kind of care. The water doesn’t argue with the stone. It just keeps arriving.

Works cited

1. Cornell Feline Health Center. Feline Lower Urinary Tract Disease. Cornell University College of Veterinary Medicine.
2. He C., et al. “Prevalence, Risk Factors, Pathophysiology, Potential Biomarkers and Management of Feline Idiopathic Cystitis: An Update Review.” Frontiers in Veterinary Science, 2022.
3. “Understanding the current evidence base for the commonly recommended management strategies for recurrent feline idiopathic cystitis: a systematic review.” New Zealand Veterinary Journal, 2025.
4. Today’s Veterinary Practice. “Diagnosing and Managing Feline Lower Urinary Tract Disease.”
5. Grauer G.F., Pohlman L.M. “Urinalysis Interpretation in Canine & Feline Patients.” Clinician’s Brief, 2016.