Early warning signs of kidney disease in cats

Articles · Kidney Disease

Chronic kidney disease (CKD) is one of the most common conditions in older cats, yet its earliest signs are easy to miss because they are so subtle. Cats are masters at hiding illness, and the kidneys can lose a great deal of function before obvious symptoms appear. This guide covers the early warning signals worth watching — increased drinking, changes in urination, and gradual weight loss — and why noticing and logging them early can make a real difference.

What are the earliest signs of kidney disease in cats?

The earliest and most common signs are increased thirst (drinking more) and increased urination — together called polyuria and polydipsia, or “PU/PD.” A cat may also slowly lose weight, eat a little less, or seem subtly less themselves. Early on, many cats show no obvious signs at all.

These signs are easy to overlook because they develop gradually and can be mistaken for normal aging. According to veterinary sources, polyuria is usually the primary change, with increased drinking happening to compensate for the extra water lost in urine. Practically, this might look like a water bowl that empties faster than it used to, more or larger clumps in the litter box, or having to change the litter more often. Because these shifts are gradual, they are exactly the kind of thing a simple home log can surface before they become obvious. We built our tools for CKD cats around catching these patterns early.

Why is kidney disease so hard to catch early?

Kidney disease is hard to catch early because cats compensate remarkably well, and the kidneys have significant reserve capacity. A cat can look and act completely normal while a large portion of kidney function is already gone, which is why early CKD is often described as a “silent” disease.

The numbers behind this are striking. According to the Cornell Feline Health Center, blood creatinine — a standard kidney marker — generally does not rise until a cat has lost almost 75% of kidney function. A newer marker, SDMA, can flag trouble earlier, when about 40% of function is lost, which is why many vets now include it in senior screening. The takeaway is not to panic but to monitor: because the disease hides, regular senior bloodwork and attention to subtle home changes are the best ways to find it sooner. Our SDMA explainer covers why that earlier marker matters.

How common is kidney disease in older cats?

Kidney disease becomes increasingly common with age, making it a concern for nearly every senior cat owner. According to the Cornell Feline Health Center (2022), CKD affects up to 40% of cats over 10 years of age and up to 80% of cats over 15 years of age.

Those figures explain why vets emphasize routine screening for senior cats. Age is, in fact, the main known risk factor — the Cornell center notes it is the only well-established one — which is why regular monitoring of older cats is so valuable regardless of breed or lifestyle. This is not a reason to fear your cat getting older; it is a reason to lean into preventive checkups and home awareness so that if CKD does develop, you and your vet catch it at an earlier, more manageable stage. The earlier kidney disease is identified, the more options exist to support your cat.

What specific changes should I watch and log at home?

The most useful things to watch are water intake, litter box habits, weight, and appetite. Because these change gradually, writing them down turns vague impressions into a clear trend you and your vet can actually evaluate. A note that the water bowl now needs refilling twice as often is far more useful than “I think she’s drinking more.”

Here are concrete signals worth logging:

• Water intake: refilling the bowl more often, lingering at the water dish or fountain, or drinking from unusual places.
• Urination: larger or more frequent clumps, more trips to the litter box, or accidents outside it.
• Weight: gradual loss, which owners often miss because they see the cat every day. Even a small percentage of body weight matters in a cat.
• Appetite and energy: eating slightly less, increased pickiness, or being a bit more withdrawn.
• Coat and grooming: a duller or unkempt coat can accompany not feeling well.

None of these alone diagnoses anything — many have other causes — but a cluster of them, or a clear trend, is a reason to call your vet. Tracking weight and water is something we make quick in our daily care features.

Can my cat have kidney disease with no symptoms at all?

Yes — and this is one of the most important things to understand. Many cats with early CKD show no outward signs whatsoever, because their bodies compensate well for declining kidney function. A cat in IRIS stage 1 or even stage 2 can look, eat, and play completely normally while kidney changes are already underway.

This is precisely why bloodwork matters even for a seemingly healthy senior cat. Two lab markers do the heavy lifting in early detection. Creatinine is the long-standing standard but rises late, while SDMA, a newer marker, tends to rise earlier. According to IDEXX research, in one analysis SDMA was elevated an average of 26.9 months before creatinine rose in cats and dogs that developed CKD, giving vets a meaningful head start. Because early signals live in the bloodwork rather than in behavior, “my cat seems fine” is not a reason to skip senior screening — it is a reason to value it.

When should I call the vet?

You should call your vet if you notice a persistent change in drinking, urination, weight, or appetite — especially if more than one of these is happening together. You do not need to wait for dramatic symptoms; the whole point of watching early signs is to act before a cat feels seriously unwell.

It is also wise to keep up with routine senior wellness exams and bloodwork even if your cat seems fine, since early CKD often has no visible signs. If you have been logging changes at home, bring that record — your vet can spot a trend in water intake or weight far more easily from your notes than from memory. Early conversations let your vet decide whether screening tests are warranted and, if CKD is found, start support sooner. Our FAQ covers what to expect at a kidney-focused checkup.

To recap: the earliest signs of feline CKD are increased drinking and urination, often with gradual weight loss, and many cats show nothing at all early on. The disease hides because creatinine rises late, so routine senior screening plus attentive home tracking are your best tools. When in doubt, a clear log and a vet visit beat waiting.

Pawtient AI’s anomaly alerts and water and weight tracking help you notice gradual changes — like a creeping rise in water intake — before they become obvious; see how Pawtient AI helps. Pawtient AI is an AI assistant and second opinion, never a diagnosis — always consult your veterinarian.

Sources

• Cornell Feline Health Center. “Chronic Kidney Disease.” Cornell University College of Veterinary Medicine, 2022. https://www.vet.cornell.edu/departments-centers-and-institutes/cornell-feline-health-center/health-information/feline-health-topics/chronic-kidney-disease
• Today’s Veterinary Practice. “Feline Chronic Kidney Disease.” https://todaysveterinarypractice.com/urology-renal-medicine/feline-chronic-kidney-disease/
• International Renal Interest Society (IRIS). “IRIS Staging of CKD.” 2023. https://www.iris-kidney.com/iris-staging-system

By Pawtient AI Editorial Team. Educational content reviewed against published veterinary guidelines (IRIS, AAHA, WSAVA, ACVIM, AAFP). Not a substitute for veterinary care.