Kidney Disease and Kidney Failure in Cats: Signs and Care

Chronic kidney disease versus acute kidney failure

The kidneys filter waste out of the blood, balance water and salts, and help control blood pressure and red blood cell production. In chronic kidney disease (CKD) they lose that ability slowly, usually over months or years. Cornell Feline Health Center reports that CKD affects up to 40 percent of cats over 10 and 80 percent of cats over 15, and VCA Animal Hospitals notes that only about 10 percent of cases occur in cats under three. Most cases are the end result of age-related wear, though inherited cysts, infections, stones, tumors and viruses can also be behind it.

Acute kidney injury is a sudden loss of kidney function over hours or days. VCA lists urinary blockage, antifreeze, lilies and other toxic plants, rodent poisons, certain medicines including some human painkillers, heatstroke, trauma, shock and infection among the causes. Unlike CKD, acute injury is potentially reversible if it is caught early and treated aggressively, which is why its warning signs need same-day action.

Signs of kidney disease in cats

Because the kidneys have so much spare capacity, VCA explains that roughly two-thirds of their function is usually gone before a cat shows any sign of CKD. The early signs are increased thirst, larger or more frequent clumps in the litter box, gradual weight loss, a variable appetite and a dull or unkempt coat. Owners often notice a water bowl that empties faster or a cat that has started drinking from taps and glasses.

As the disease advances, cats may eat poorly, become lethargic, vomit, have bad breath or mouth ulcers, and develop anemia, which shows as pale gums and weakness. High blood pressure is common: Cornell reports it develops in about 60 percent of cats with CKD and can cause sudden vision changes. Acute kidney failure looks more dramatic, with sudden appetite loss, vomiting, weakness and either a lot of urine or very little.

When to call your vet today

Book a visit soon if your cat is drinking or peeing more than usual, losing weight, or eating less, especially if it is over seven. These signs have several possible causes, including diabetes and an overactive thyroid, so testing is the only way to know. Call the same day if your cat has stopped eating, is vomiting more than once, seems unusually weak or has pale gums.

If your cat already has CKD, call your vet whenever it goes off its food for more than a day, vomits repeatedly, or seems suddenly worse. Kidney cats can dehydrate quickly, and a timely adjustment in treatment often helps them bounce back.

When it's an emergency

Go to your vet or the nearest emergency vet immediately if your cat may have chewed or licked any part of a lily, drunk or walked through antifreeze, eaten rodent poison or been given a human painkiller. VCA notes that toxic lilies can cause kidney failure within 6 to 48 hours, and early treatment is what makes recovery possible. Call ASPCA Animal Poison Control at (888) 426-4435 or Pet Poison Helpline at (855) 764-7661 on the way; a fee may apply.

A cat that is straining in the litter box and producing little or no urine also needs emergency care, as a blocked bladder can quickly cause kidney failure. So does a cat that has collapsed, has a seizure, or has stopped eating and drinking and is vomiting.

What you can safely do at home

Never give a cat human pain relievers or any medicine that has not been prescribed for it; several common drugs damage cat kidneys. Keep lilies out of the house entirely and store antifreeze and rodent poisons where cats cannot reach them. Make fresh water easy to find, with several bowls or a fountain around the house.

If your cat has been diagnosed, follow the plan your vet gives you closely. Switch to a prescribed kidney diet gradually, as directed, and keep notes on appetite, weight, thirst and vomiting between visits. Some owners learn to give fluids under the skin at home, but only with training and instructions from their vet.

What the vet will likely check

Diagnosis rests on blood tests for waste products, such as creatinine, BUN and SDMA, together with a urine test showing how well the kidneys concentrate urine and whether protein is leaking into it. Cornell notes that SDMA tends to rise earlier than creatinine, which helps catch the disease sooner. Your vet will also check blood pressure and red blood cell levels, and may use ultrasound or X-rays to look at the kidneys' size and shape or for stones.

Vets grade CKD using the IRIS staging system, which guides treatment and outlook. Most cats are managed with a therapeutic diet lower in phosphorus and protein, which Cornell says may help them live considerably longer, plus treatments matched to their test results, such as medicines for blood pressure, nausea, appetite or anemia, phosphate binders, potassium, and extra fluids. Acute kidney failure is treated in the hospital, mainly with intravenous fluids over one to several days, and the outlook depends on how much damage was done.

Prevention and long-term outlook

Most CKD cannot be prevented because age is the main risk factor, but it can be caught early. Regular checkups with blood and urine tests for cats over seven, and sooner for breeds prone to inherited kidney cysts, give your vet the best chance to start treatment while your cat still feels well. Preventing acute injury is simpler: no lilies, no access to antifreeze or rodent poison, and no human medicines.

Kidney damage is generally not reversible, but VCA notes that with good management most cases progress slowly and many cats enjoy several years of good quality life. Cornell reports that cats diagnosed at an earlier stage tend to live considerably longer than those diagnosed late.

This page is general information, not veterinary advice, and it cannot replace an examination by the vet who knows your pet.