Kidney disease is one of the health conditions that cats owners should know about, because it affects quality of life, and it is easier to manage when it is caught early. This guide explains what kidney disease is, the signs to watch for, what causes it, how it is diagnosed, how it is treated, whether it can be prevented, and how to live with a cat that has it. Every suggestion here is general guidance, not a prescription for an individual cat.
The signs are the focus of this guide. kidney disease in a kitten is often harder to spot than in an adult, because a kitten is growing fast, and its signs are easily mistaken for growing pains or a quiet personality. This guide lists every sign to watch for, explains what each one means, and covers when a sign means a vet visit, not waiting. A kitten that is not growing, not gaining weight, or not moving well needs a vet check, not just more food or more rest.
What is kidney disease in cats?
Kidney disease — chronic kidney disease, or CKD — is a condition where the kidneys slowly lose their ability to filter waste from the blood, balance water and minerals, and make the hormones that control red blood cells and blood pressure. It is one of the most common conditions in older cats, especially older cats, and it develops slowly over months or years. The kidneys have a lot of spare capacity, so a cat can lose two-thirds of its kidney function before it shows any signs — which is why kidney disease is often found late, and why early checks matter.
The rest of this guide covers the signs, the causes, how kidney disease is diagnosed, how it is treated, whether it can be prevented, and how to live with a cat that has it. A cat with kidney disease should be checked by a vet, because the right treatment depends on the individual cat, its age, and how advanced the condition is — and because some of the signs of kidney disease can also be signs of other conditions, which need a vet to tell apart. The cat ideal weight calculator works out a target weight range, and the when is a cat considered a senior guide gives the senior thresholds by size.
Signs of kidney disease in cats
The signs of kidney disease in cats are listed below. Not every cat with kidney disease will show every sign, and some cats will show only one or two — but any one of these signs, especially if it lasts more than a few days or gets worse, is worth mentioning to a vet. A cat that is bright, eating, drinking, and otherwise well between episodes is less likely to be seriously ill than a cat that is lethargic, off its food, or losing weight — but the only way to know is to check.
- Drinking much more water than usual, and urinating much more.
- Weight loss, even though the cat is eating normally at first.
- A poor appetite, or a cat that goes off its food.
- Vomiting, or nausea that makes the cat lick its lips and turn away from food.
- Bad breath, with a smell like ammonia.
- A dull coat, lethargy, and a cat that seems generally unwell.
- Mouth ulcers, and a cat that drools or paws at its mouth.
If two or more of those signs apply, or if one sign is severe — a cat that cannot urinate, cannot breathe, cannot stand, or has had a seizure lasting more than five minutes — see a vet the same day. Those are signs that need a vet, not waiting. Bring a note of when the signs started, how often they happen, and what the cat eats and drinks — that information helps the vet far more than a guess about the cause. The how to tell if your cat is overweight guide gives the hands-on check for weight, which matters for many of these conditions.
Causes and risk factors for kidney disease
Kidney disease has many causes, and in older cats it is often simply wear and tear with age: the kidneys filter blood for a lifetime, and they wear out. In some breeds it is inherited — Persian cats, for example, are prone to polycystic kidney disease, where cysts grow in the kidneys. Infections, toxins, some medicines, and blockages can all damage the kidneys, and some other conditions, such as high blood pressure and dental disease, are linked to it. In many cases the exact cause is never found, and the vet treats the disease rather than the cause.
Some cats are more prone to kidney disease than others, because of their genes, their breed, their size, or their age — but breed and age are not destiny, and a cat of any breed can develop kidney disease. What an owner can control is weight, food, exercise, and vet checks: a cat at a healthy weight, with measured food and daily exercise, is less likely to develop kidney disease and will cope better with it if it does. A cat that is overweight, that eats a poor diet, or that never sees a vet is more likely to develop kidney disease and to have it found late, when it is harder to treat.
How kidney disease is diagnosed
A vet diagnoses kidney disease with a blood test and a urine test: the blood shows waste products that the kidneys should have filtered out, and the urine shows whether the kidneys can concentrate urine properly. The vet may also check blood pressure, and may use an ultrasound to look at the kidneys. Kidney disease is staged from 1 to 4, from early to advanced, using the IRIS staging system — stage 1 is early, with few or no signs, and stage 4 is advanced, with clear signs and a need for intensive care. Early diagnosis matters, because treatment works best when it starts early.
If you are worried about your cat, see a vet and mention kidney disease by name, with the signs you have seen and when they started. Bring a note of what the cat eats, how much, and any medicines it takes, and whether it has had kidney disease or a related condition before. A video of the signs, if it is safe to take one, helps the vet far more than a description — especially for seizures, limping, or breathing problems. Do not try to diagnose kidney disease yourself, and do not buy medicines or special diets for it without veterinary advice, because the wrong treatment can make it worse.
Treatment and management of kidney disease
Treatment depends on the stage, but the core is the same: a diet with controlled protein and phosphorus, plenty of fresh water, and medicines as the vet advises. The diet matters most: a kidney diet is lower in protein and phosphorus than a normal food, which makes the kidneys' job easier and slows the disease. Fresh water should always be available, in several places, and some cats need extra fluids under the skin at home, which the vet teaches the owner to give. Medicines may be needed for high blood pressure, nausea, or anaemia. There is no cure for chronic kidney disease, but treatment can slow it down and keep the cat comfortable for months or years.
Treatment is a decision made with the vet, weighing the cat's age, health, and quality of life against the treatment and its side effects. Some owners choose not to treat, and to keep the cat comfortable instead — and that is a valid choice, made with the vet, not on the basis of a web page. Whatever is decided, the treatment must be followed every day, at the same times, and the cat must be checked regularly, because kidney disease changes over time, and the treatment needs to change with it. Do not stop a medicine suddenly, and do not change the dose without veterinary advice.
Living with a cat with kidney disease
A cat with kidney disease can live a comfortable life for months or years with the right care, but it needs a routine: a kidney diet, fresh water in several places, medicines as the vet advises, and regular vet checks with blood and urine tests. The owner must watch appetite, drinking, and weight, and mention any change to the vet promptly — a cat with kidney disease that stops eating or drinking needs a vet the same day. As the disease advances, the cat will need more care, and the vet will help the owner decide what is best for the cat at each stage, including when the kindest choice is to let it go.
Keep a routine: the same times for food, medicines, walks, and play, the same places for furniture, food, and water, and a calm, predictable home. Keep a note of appetite, drinking, weight, and behaviour, and mention any change to the vet promptly — a change that lasts more than a few days, or that gets worse, is worth a vet visit. Keep the cat at a healthy weight, with measured food and daily exercise at a level that suits its body, and keep vet checks regular: once a year as an adult, and twice a year as a senior. The senior cat diet guide covers feeding older cats, and the cat calorie calculator works out daily calories for any weight.
Signs of kidney disease in kittens
A kitten with kidney disease may show the signs differently from an adult: it may be quieter than its littermates, slower to play, reluctant to jump or climb, or not gaining weight as it should. Those signs are easy to miss, because a kitten is expected to sleep a lot and to be clumsy — but a kitten that is consistently quieter, slower, or lighter than its littermates should be checked by a vet. Early help works better than late help.
Can kidney disease be prevented?
Kidney disease cannot always be prevented, because much of it is about age and genes — but the risk can be reduced. Keep the cat at a healthy weight, keep its teeth clean, because dental disease is linked to kidney damage, and keep fresh water available at all times, because good hydration supports kidney health. Do not give medicines without veterinary advice, because some medicines damage the kidneys. Have the cat checked regularly as it gets older, with blood and urine tests, so kidney disease is found early, when treatment works best — stage 1 and 2 are far easier to manage than stage 4.
Early checks matter most: have the cat checked regularly, so kidney disease is found early, when treatment works best. Keep the cat at a healthy weight, with measured food and daily exercise, and mention any change in drinking, eating, weight, or behaviour to your vet early, because a change caught early is easier to treat than one left for weeks.
For related reading, see the cat ideal weight calculator, the cat body condition score chart, the how to tell if your cat is overweight guide, the senior cat diet guide, the cat calorie calculator, the when is a cat considered a senior guide.
Frequently asked questions
What is kidney disease in cats?
Kidney disease — chronic kidney disease, or CKD — is a condition where the kidneys slowly lose their ability to filter waste from the blood, balance water and minerals, and make the hormones that control red blood cells and blood pressure. It is one of the most common conditions in older cats, especially older cats, and it develops slowly over months or years. The kidneys have a lot of spare capacity, so a cat can lose two-thirds of its kidney function before it shows any signs — which is why kidney disease is often found late, and why early checks matter.
What are the signs of kidney disease in cats?
The most common signs are: Drinking much more water than usual, and urinating much more. Weight loss, even though the cat is eating normally at first. A poor appetite, or a cat that goes off its food. See the full list above for every sign to watch for, and see a vet promptly if two or more apply, or if one sign is severe.
What causes kidney disease in cats?
Kidney disease has many causes, and in older cats it is often simply wear and tear with age: the kidneys filter blood for a lifetime, and they wear out. In some breeds it is inherited — Persian cats, for example, are prone to polycystic kidney disease, where cysts grow in the kidneys. Infections, toxins, some medicines, and blockages can all damage the kidneys, and some other conditions, such as high blood pressure and dental disease, are linked to it. In many cases the exact cause is never found, and the vet treats the disease rather than the cause.
How is kidney disease diagnosed?
A vet diagnoses kidney disease with a blood test and a urine test: the blood shows waste products that the kidneys should have filtered out, and the urine shows whether the kidneys can concentrate urine properly. The vet may also check blood pressure, and may use an ultrasound to look at the kidneys. Kidney disease is staged from 1 to 4, from early to advanced, using the IRIS staging system — stage 1 is early, with few or no signs, and stage 4 is advanced, with clear signs and a need for intensive care. Early diagnosis matters, because treatment works best when it starts early.
How is kidney disease treated?
Treatment depends on the stage, but the core is the same: a diet with controlled protein and phosphorus, plenty of fresh water, and medicines as the vet advises. The diet matters most: a kidney diet is lower in protein and phosphorus than a normal food, which makes the kidneys' job easier and slows the disease. Fresh water should always be available, in several places, and some cats need extra fluids under the skin at home, which the vet teaches the owner to give. Medicines may be needed for high blood pressure, nausea, or anaemia. There is no cure for chronic kidney disease, but treatment can slow it down and keep the cat comfortable for months or years.
When should a cat with kidney disease see a vet?
See a vet promptly if the cat shows any of the signs above, especially if they last more than a few days or get worse — and the same day if the cat cannot urinate, cannot breathe, cannot stand, has had a seizure lasting more than five minutes, or is lethargic or off its food. Bring a note of when the signs started and what the cat eats and drinks. A cat with kidney disease should be checked by a vet, because the right treatment depends on the individual cat, its age, and how advanced the condition is.
Results on this page are estimates for general information only and are not veterinary advice. If your pet is ill, underweight, overweight, pregnant, or has a health condition, consult your veterinarian before changing diet or care.