Kidney problems in cats: early warning signs and the role of diet

September 20 2026, by Michael van Wassem, 6 min reading time

Drinking more, losing weight, a dull coat: these are early signs of chronic kidney disease in cats. Here's how to spot them in time, and how diet can help.

Have you noticed your cat suddenly drinking and urinating much more, losing weight despite eating normally, or occasionally vomiting for no clear reason? These can be early signs of chronic kidney disease (CKD), one of the most common health problems in older cats. Kidney disease can't be cured, but it's often caught late — while early detection and the right diet can make the difference between a cat that stays well for years and one that declines quickly. In this article, you'll learn what to watch for, what causes it, and how diet and home care can help.

What is chronic kidney disease in cats?

A cat's kidneys filter waste products from the blood, regulate fluid balance, and help produce red blood cells. In chronic kidney disease (CKD), kidney tissue deteriorates gradually and irreversibly. Because cats naturally have a large reserve of kidney function, owners often don't notice anything until roughly 70% of the kidney tissue is already affected. That's exactly why kidney disease in cats is so easy to miss: the first, subtle signs are easily overlooked.

CKD mainly affects cats aged 7 and older, though it can develop at any age. According to veterinary sources such as the International Renal Interest Society (IRIS), an estimated 1 in 3 cats over the age of 10 has some degree of reduced kidney function.

Early signs you shouldn't miss

Because the kidneys have so much reserve capacity, the first signs are often subtle. Watch closely for:

• Drinking and urinating more (polyuria/polydipsia) — often the first noticeable sign
• Gradual weight loss, even if your cat is eating normally
• Reduced appetite or becoming fussier about food
• A dull coat and less grooming than usual
• Occasional vomiting, especially in the morning
• Bad breath with a slightly ammonia-like or "uraemic" smell
• Lethargy or less interest in play

Any single one of these signs may not mean much on its own, but a combination — especially in a cat aged 7 or older — is a good reason for a check-up at the vet.

⚠️ See a vet immediately if your cat stops eating or drinking altogether, vomits repeatedly, lies listlessly in a corner, or is clearly in pain. These can be signs of an acute kidney problem that needs urgent care.

Causes and risk factors

Chronic kidney disease usually doesn't have a single clear cause, but develops from a combination of factors that damage kidney tissue over time:

• Age — the biggest risk factor; kidney function naturally declines over the years
• Genetic predisposition — breeds such as the Persian, Abyssinian and Birman have a higher risk of (hereditary) kidney cysts
• Gum disease and tartar — chronic inflammation in the mouth can put strain on the kidneys over time
• High blood pressure, often linked with kidney problems
• Previous bladder or kidney infections, dehydration, or poisoning (for example from lilies, which are highly toxic to cats even in small amounts)
• Untreated diabetes or thyroid problems, which put extra strain on the kidneys

How does a vet diagnose kidney disease?

Kidney disease is diagnosed through blood and urine tests. The vet looks at kidney values such as urea and creatinine, and nowadays also SDMA — a marker that can show abnormalities earlier than the classic values. A urine test shows how concentrated the urine still is and whether protein is being lost. Based on the results, kidney disease is classified into an IRIS stage (1 to 4), which helps tailor treatment and dietary advice to the severity of the condition. The earlier the diagnosis is made, the more time there is to slow the progression with diet and treatment.

The role of diet in kidney problems

Diet is one of the most important pillars in managing chronic kidney disease. Specially formulated renal diets for cats are adjusted in several ways:

• Limited phosphorus levels — high phosphorus speeds up the decline of kidney function
• Adjusted, high-quality protein — less protein, but of excellent quality, so fewer waste products are created for the kidneys to process
• Extra omega-3 fatty acids, which have an anti-inflammatory effect on the kidneys
• Increased potassium levels, since cats with kidney disease often lose potassium through their urine

This type of diet is usually prescription-only and should always be used in consultation with your vet — don't adjust your cat's diet on your own once a diagnosis is confirmed. Your vet can point you towards a suitable renal diet food for your cat's specific stage of kidney disease.

Practical tips for home

Besides the right food, there's a lot you can do yourself to take some of the strain off your cat's kidneys:

• Encourage water intake. Cats with kidney problems often drink too little for their increased needs. A cat water fountain keeps water moving and fresh, which many cats find more appealing than still water from a bowl.
• Choose wet food more often. Wet food naturally contains far more moisture than dry kibble and helps support fluid balance.
• Put out several water bowls around the house, ideally away from the litter tray and food bowl.
• Keep things calm and low-stress. Stress can raise blood pressure, which puts extra strain on the kidneys. A cosy, quiet resting spot such as the Gor Pets Camden Pyramid Bed can help an unwell or senior cat feel safe and settled.
• Schedule six-monthly check-ups from around age 7, so any kidney problems are picked up early.

Frequently asked questions

Can chronic kidney disease in cats be cured?
No, damaged kidney tissue doesn't repair itself. With the right diet, medication and follow-up care, the disease's progression can often be slowed, allowing many cats to enjoy a good quality of life for years.

Can I prevent kidney disease in my cat?
It can't always be fully prevented, but adequate water intake, a healthy weight, good dental care and prompt treatment of infections significantly lower the risk.

From what age should I be extra alert?
The risk increases noticeably from around age 7. For breeds with a genetic predisposition, earlier screening is a good idea.

Can I adjust my cat's diet myself if I suspect kidney problems?
No, wait for the results of blood and urine tests first. Renal diet food is specifically formulated and isn't suitable for every cat — always speak to your vet first.

Summary and conclusion

Chronic kidney disease is one of the most common, yet most underestimated, health problems in older cats. Watch for signs such as increased drinking and urination, weight loss and reduced appetite, and have your cat checked regularly from around age 7. If a diagnosis is confirmed, an adjusted diet — in consultation with your vet — is one of the most effective ways to ease the strain on the kidneys and help your cat enjoy a comfortable life.

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Gezondheid & Preventie Katten Kennisbank Senior-verzorging Voeding

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