Kidney Disease in Cats: Signs, Stages, Fluids and Care at Home

Which cats get kidney disease

• It's one of the most common diseases in older cats.
• Cornell reports it in up to 40% of cats over 10 and up to 80% of cats over 15.
• It becomes more common from about age 5 to 6.
• Age is the only known risk factor, so senior cats should be checked for it regularly.
• Many things can damage the kidneys: high blood pressure, infections, cancer, inherited problems, and toxins such as lilies and antifreeze. Often the cause can't be found.

Sources: 1, 2, 3

Signs to watch for

Most cats show no signs in the early stages, because the body makes up for the lost function. Signs often appear only after about two thirds of kidney function is gone.

• Drinks more water than usual
• Urinates more, so the litter box is wetter
• Eats less
• Loses weight, or looks thin
• Less energy than usual
• A coat that looks unkempt
• Later: vomiting, diarrhea, mouth sores, and dehydration

These signs can come from other diseases too. If you notice them, book a visit with your vet. Annual or twice-yearly checkups, with blood and urine tests, help find kidney disease early.

Sources: 1, 2, 3

How vets find it and stage it

The tests

• Blood tests measure waste products the kidneys normally filter. One of them, SDMA, rises when about 40% of kidney function is lost. Creatinine usually rises only after about 75% is lost.
• Urine tests show how concentrated the urine is, whether protein is being lost, and whether there's an infection.
• Blood pressure is checked too. Cornell says about 60% of cats with CKD develop high blood pressure; Merck puts it at about 20%.
• Your vet may also suggest an ultrasound or X-rays.
• Vets ideally compare at least two sets of blood and urine tests, taken within two weeks, from a calm, well-hydrated cat.

The stages

Vets group CKD into four stages, using the International Renal Interest Society (IRIS) system:

• Staging should happen when your cat is hydrated and stable. Dehydration or another illness can make the disease look more advanced than it is.
• Vets also note whether your cat loses protein in the urine and has high blood pressure. These "substages" help guide treatment.

Sources: 1, 2

How vets usually treat it

Your vet chooses the treatment. The goal is to slow the disease and keep your cat feeling well. Here's what to expect:

• A kidney diet, usually the first change. See Food below.
• Hydration: wet food, fresh water, and sometimes fluids under the skin at home.
• Medication for related problems, such as high blood pressure, protein loss in the urine, anemia, low potassium, nausea or a poor appetite. Not every option suits every cat, and some haven't been fully proven.
• Treating infections. Urinary tract infections are common in cats with CKD and can make kidney damage worse.
• In later stages, your vet may recommend fluids in a vein at the clinic or a feeding tube.
• Dialysis and kidney transplants exist, but they're not practical for most cats and are explored with a veterinary specialist.

Regular rechecks track how the disease is changing. Your vet checks weight, hydration, blood pressure, blood and urine:

Sources: 1, 2, 3

Sub-Q fluids at home

Dehydration can speed up kidney damage and make signs worse. Fluids given under the skin (subcutaneous or "sub-Q" fluids) help keep some cats hydrated, especially in later stages. They can help extend the length and quality of a cat's life.

What it involves

• Your vet teaches you how to do it.
• Fluids go in through a small needle, just under the skin between the shoulder blades.
• A soft bump, like a camel's hump, is normal. It is absorbed over a few hours.
• Sub-Q fluids aren't for a cat that is severely dehydrated or in shock. Those cats need fluids in a vein at the clinic.

How much and how often

• Your vet sets the amount and the schedule. Many owners learn to give fluids every 1–3 days.
• The best schedule hasn't been studied directly. In a survey of 399 owners giving fluids, schedules ranged from once or twice a week to twice a day. Once a day was the most common (39%).
• Cats with kidney or heart disease can get too much fluid more easily, so vets may choose smaller amounts. Never change the amount without talking to your vet.
• Ask your vet before adding any medication to the fluids. Some may work less well that way.

Keep a record. Write down each time you give fluids, the amount your vet prescribed, and how your cat seemed. Weight gain can be an early sign of too much fluid. The free sub-Q fluids log below keeps it on one page.

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Caring for a cat with kidney disease at home

• Water everywhere. Keep clean bowls of fresh water in several places. Many cats like a water fountain.
• Wet food adds water to the diet.
• Make sure your cat eats, especially while switching foods.
• Give medications as your veterinarian prescribed, and bring a list to every visit.
• Watch the basics: appetite, water, urination and weight. Your vet asks about these at checkups.
• Keep lilies out of the house, and store antifreeze safely.

Sources: 1, 2, 3

Food

Your vet will recommend a diet for your cat. Here's what the published sources say:

• Kidney diets are lower in protein, phosphorus and sodium, and higher in water-soluble vitamins, fiber and antioxidants.
• In some studies, cats with CKD on a prescription kidney diet lived 2–3 times longer than cats on standard food.
• Switch gradually. Many cats are slow to accept a new food. Food temperature, texture and flavor can help.
• Wet and dry versions come in many flavors. Your vet can help you find one your cat will eat.
• When to start a kidney diet, and which one, is still debated. You and your vet decide together.
• Eating comes first. A cat with CKD who goes without food even for a short time can become seriously ill.

Ask your vet whether a prescription diet fits your cat, and talk to them before changing food.

Sources: 1, 3

What to expect over time

• CKD can't be cured, and the damage usually can't be reversed. But many cats live well for years.
• The stage at diagnosis matters. In many studies, cats diagnosed at Stage 2 lived two to three years on average. Cats diagnosed at Stage 4 lived less than six months on average.
• These are averages. Regular rechecks show how fast your own cat's disease is changing.
• With treatment, even cats with as little as 5% of normal kidney function can live a long time.
• Finding it early and starting treatment early is linked with a longer, better life.
• More protein in the urine, higher phosphorus in the blood, and anemia can mean a less favorable outlook.
• If treatment no longer helps, euthanasia may need to be considered. Your vet can help you think through your cat's quality of life.

Sources: 1, 2, 3

Find a vet or specialist

• Your own veterinarian is your first call for anything about your cat's kidney disease.
• Board-certified specialists in small animal internal medicine and in veterinary nutrition can help with complex cases or diet plans. Search by ZIP code on VetSpecialists.com, the American College of Veterinary Internal Medicine's directory.
• In an emergency, go to the nearest emergency animal hospital.

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