Kidney Disease in Cats: Catching It Early

Chronic kidney disease is one of the most common serious illnesses in older cats, and one of the most commonly caught late. That is not because owners are inattentive. It is because cats are remarkably good at concealing it and because the early signs are genuinely easy to live alongside.

The kidneys have a great deal of spare capacity. A cat can lose roughly two thirds of its kidney function before anything looks wrong at all, and what is lost does not come back. What can be changed is the speed of everything that follows, and that is where the difference between an early and a late diagnosis shows up.

The early signs

There are two that matter, and they arrive quietly.

• Drinking more, and urinating more. Failing kidneys cannot concentrate urine, so the cat loses water and drinks to keep up. In practice this looks like a water bowl needing filling more often, larger clumps in the litter tray, or a cat that has started drinking from taps and puddles when it never used to
• Gradual weight loss, often while still eating reasonably. This is the one owners tend to notice only in a photograph from a year ago

Later signs are more obvious and less useful, because by then a good deal of time has passed: reduced appetite, vomiting, bad breath with a chemical edge to it, lethargy, a dull unkempt coat, weakness in the hind legs, and constipation from ongoing dehydration.

If you take one practical thing from this page, let it be that a cat over about eight which has started drinking noticeably more deserves a blood and urine test, even if it seems perfectly well otherwise.

Why weight loss in an older cat is never just age

It is worth saying plainly. An older cat losing weight nearly always has a specific, nameable reason, and there are four common ones: kidney disease, an overactive thyroid, diabetes, and a painful mouth. Every one of those is either treatable or manageable, and several are very manageable indeed.

Putting it down to age is the single most expensive assumption in feline medicine, because the treatable window closes while nothing is being done.

What the tests show

Diagnosis needs blood and urine together, and the urine matters as much as the blood.

• Urea and creatinine, waste products the kidneys clear. These rise, but only once about three quarters of function is lost, which is why they are late markers
• SDMA, a newer marker that rises earlier and can flag disease before creatinine moves
• Urine specific gravity, which measures how well the kidney is concentrating urine. This often changes before the blood does, and it is why a vet asks for a urine sample rather than only taking blood
• Urine protein, since protein loss both signals and accelerates damage
• Blood pressure, which is frequently high in these cats and does further kidney damage if left alone
• Phosphate and potassium, which drive much of how ill the cat actually feels

Cases are then staged, which sounds bureaucratic and is genuinely useful: it sets what treatment is appropriate now and how often the cat should be rechecked.

What actually helps

There is no cure, and there is a great deal of effective management. Cats diagnosed early and managed properly often live comfortably for years.

• A prescription renal diet. This is the single most effective intervention there is, with better evidence behind it than anything else on the list. It works by reducing phosphate and adjusting protein, and it only works when fed exclusively, which is the part that trips households up
• Water, in every way you can manage it. Wet food as the base of the diet, water added to it, several bowls in different rooms, wide shallow dishes, a fountain if the cat likes moving water. Dehydration makes every part of this worse
• Phosphate binders where diet alone is not controlling phosphate
• Blood pressure medication where indicated, which protects both the kidneys and the eyes
• Medication for protein loss, which slows progression measurably
• Anti-nausea medication and appetite support, which are not cosmetic. A cat that feels sick and stops eating deteriorates fast, and treating the nausea often restores the appetite entirely
• Potassium supplementation where levels are low, which frequently accounts for weakness
• Fluids under the skin in advanced cases, sometimes given at home once an owner has been shown how

The renal diet problem

Two things go wrong with it. The first is that the cat will not eat it, which is common and usually solvable by transitioning slowly over two or three weeks rather than switching abruptly, and by trying more than one brand and texture before concluding it is hopeless.

The second is that a cat eating the renal diet is also being given other food by somebody in the household, out of sympathy. That is entirely understandable and it undoes the benefit, because the diet works through what the cat is not eating. If the cat genuinely refuses it, say so at the recheck rather than quietly abandoning it, because a cat eating something is better than a cat eating nothing.

Monitoring, and why it is not padding

Rechecks every three to six months, more often in advanced cases, with blood, urine and blood pressure. It can feel like being asked back for the sake of it. It is not. This is a condition where the treatment changes as the disease progresses, and where problems like low potassium, high phosphate and rising blood pressure are invisible at home and easy to correct once seen.

What to watch for between visits

• Water intake climbing further, or dropping suddenly
• Appetite falling away, or vomiting starting
• Weight, which is worth recording monthly at home
• New weakness, wobbliness or hind leg weakness
• Sudden blindness or dilated pupils, which is a blood pressure emergency
• Any acute deterioration, since a cat with chronic disease can have an acute crisis on top of it

Our free senior pet care guide gives you somewhere to keep those monthly weights and recheck dates.

The reason this is caught late is not ignorance, it is arithmetic. Testing an apparently well cat costs money for what will probably be reassurance, and once diagnosed the costs are permanent: the prescription diet every month, medication, and bloodwork several times a year for the rest of the cat's life. That is a difficult thing to sustain, and what usually happens is that rechecks get stretched and the diet slips.

Consultations, diagnostics and the ongoing monitoring this needs are covered on Skeepy Pet HMO plans at any vet clinic in Nigeria, which makes testing an older cat that is only drinking a bit more an easy decision rather than a gamble.