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Chronic Kidney Disease in Cats: Signs, Diagnosis and Care

Good to know: general information, not veterinary advice. Read our disclaimer.
Older tabby cat drinking water from a bowl in a sunny kitchen

Short answer: chronic kidney disease (CKD) is a gradual, usually age-related loss of kidney function that is common in older cats. It cannot be cured, but early diagnosis, the right diet, good hydration and treatment of complications such as high blood pressure can help many cats keep a good quality of life for months or years. Drinking and urinating more, losing weight and eating less are the main signs to act on.

What CKD is and how common

The kidneys filter waste from the blood and help control hydration and blood pressure. In CKD, they slowly lose that ability. International Cat Care (iCatCare) says it is more common in mid-aged to older cats, typically those over seven, and that cats can lose roughly two-thirds to three-quarters of functional kidney tissue before signs appear. Estimates of how many cats are affected vary by source and age group: iCatCare cites 20 to 50% of cats over 15, while Cornell Feline Health Center gives up to 40% of cats over 10 and 80% of cats over 15. The common message is that it becomes more likely with age and is often missed early.

Causes

iCatCare says the cause is unknown in most cats. Recognised causes include polycystic kidney disease (inherited in Persians and related breeds), kidney tumours including lymphoma, bacterial kidney infection, toxins and some drugs, and damage to the kidneys' filtering units. If a treatable underlying cause is found, treating it can halt progression. Cornell says age is the only known risk factor.

Signs to watch for

  • drinking more and urinating more;
  • weight loss and poor appetite;
  • lethargy and a poor, unkempt coat;
  • vomiting and bad breath;
  • high blood pressure, which can cause sudden vision changes, and anaemia, which can cause weakness and pale gums (Cornell).

Early CKD often causes no obvious signs, which is why regular checks matter. If you notice more trips to the litter box, bigger clumps or a cat spending more time at the water bowl, tell your vet. See also our article on litter box problems, where changes in urination are a common first clue.

How it is diagnosed

  • Blood tests: urea, creatinine and, in many practices, SDMA. Cornell says SDMA rises earlier, when about 40% of kidney function has been lost, compared with about 75% for creatinine.
  • Urine tests: to see how concentrated the urine is, plus protein and infection checks.
  • Blood pressure: both sources stress measuring it; Cornell says roughly 60% of cats with CKD develop high blood pressure.
  • Imaging: X-rays or ultrasound in some cases.

The vet may also assign a stage using the IRIS staging system, which guides treatment and prognosis (Cornell). Routine screening of older cats, including urine, blood pressure and weight, is recommended by iCatCare. Our guide to the yearly vet check-up explains what these visits include.

Treatment and management

  • Diet: wet food is preferred for the extra fluid. iCatCare recommends reduced phosphate and moderately reduced protein, usually through a veterinary kidney diet. Cornell reports that some studies found cats on these diets lived two to three times longer than cats on standard food. Switch gradually, and make sure the cat keeps eating.
  • Hydration: fresh water in several places, a fountain, water added to food, and, if the vet advises, fluids under the skin at home or in clinic. Cornell says some owners give them every one to three days.
  • Medication: depending on the cat, vets may use blood pressure medication, drugs to reduce protein loss in urine, phosphate binders, anti-sickness medication, appetite support or treatment for anaemia.
  • Specialist options: iCatCare says transplants are available at some centres but are not guaranteed to extend life beyond medical management.

Food choices matter, so see how much to feed your cat and, for breed-specific nutrition ideas, essential nutrients for Ragdoll cats. Do not change to a kidney diet without veterinary advice.

Outlook

iCatCare says many cats live a good quality of life for months or years with treatment and monitoring, though the disease generally progresses. Cornell reports average survival of about two to three years for IRIS stage 2 and under six months for stage 4, and notes that more protein loss in the urine, higher blood phosphorus and lower red blood cell counts are linked to a poorer outlook. These are averages: individual cats vary a lot.

Helping your cat at home

  • Weigh your cat every month or two and write the number down; our senior cat guide explains why.
  • Watch appetite, thirst and litter box use, and tell the vet about changes.
  • Offer water in several quiet spots and keep the bowls clean.
  • Keep up regular vet checks and any repeat blood or urine tests.
  • If your cat vomits more often, read when vomiting is normal and when it is not.

Keep reading

Sources

Further reading

Reminder: Kittyslovers (The Best Kitty Corner) is an independent blog. Our authors are not veterinarians and this article has not been reviewed by a veterinary professional. Always consult a licensed veterinarian about your cat's health, diet, supplements and medication. Found an error? Let us know.