For the past ten years, everything written about feline kidneys rested on a single document from 2016. On the third of September 2026 that document stopped being current — it was replaced by new guidelines written by a panel of feline nephrologists. I read them in full and set them against the old version, to see which sentences repeated online have just lost their validity.

The document in question is “2026 iCatCare consensus guidelines on the diagnosis and management of chronic kidney disease in cats”, published in the journal “Journal of Feline Medicine and Surgery”. It replaces the ISFM guidelines from 2016.

Let me start with a caveat, because it organises this whole text. These are guidelines for veterinary surgeons, not for owners. They contain doses, thresholds and decision trees that only make sense in the hands of someone who has examined a particular cat. What I am doing is translating into plain language what has changed and what is worth asking about at the clinic. My text does not replace a veterinary visit or a professional treatment plan.

Why this document matters so much

Chronic kidney disease (CKD) is one of the most common causes of death in cats. Its prevalence rises dramatically with age: among older cats it is estimated at anywhere from 28 to as much as 81 percent. That enormous spread is real, and it comes mostly from how the age brackets are drawn. The lower figure (around 28 percent) describes a broad group of all cats over twelve, while rates of 81 percent describe a narrow group of markedly geriatric patients aged 15 to 20.

Where the 81 percent comes from

The upper figure comes from the 2014 study by Marino and colleagues, in which 17 out of 21 cats aged 15–20 were affected. That is twenty-one animals from a single clinic, and the count included the earliest, mildest stage of the disease — the authors themselves note that their result is clearly higher than previously reported ones. The 28–81 percent spread therefore reflects not only the age of the cats but also how each study chose to count the disease.

The problem is that for a long time there is nothing at all to see. The cat looks normal, eats normally, and the disease is already destroying the organ. That is why the first chapter of the new guidelines is devoted entirely to screening. The recommendation is unambiguous: from the age of seven, a cat is checked preventively even when nothing appears to be wrong. The required minimum is body weight, blood work and urinalysis. Between 7 and 10 years of age we do this once a year, and after ten — preferably every six months.

In a screening programme run at Ghent University, 259 apparently healthy cats over seven years of age were examined, and those that turned out to be genuinely healthy at the first visit — 201 animals — were followed for another two years. Asymptomatic kidney disease at stage two or higher was found right at the outset in 7.7 percent of those examined. What is more, among senior cats, meaning those over ten, who were fully healthy at the start, kidney disease developed within the next two years in 23.5 percent — that is, in nearly one in four.

Recommendations that did not change

Before I move on to what is new, it is worth mentioning the things that stayed the same. This is not medicine being turned upside down, but a sensible shift of emphasis.

The renal diet is still the foundation. The evidence is strong and the new guidelines leave no room for debate here: a specialist food significantly extends survival and reduces the risk of a drastic deterioration in the cat's condition (a so-called uraemic crisis).

Phosphorus remains enemy number one. A high blood phosphorus concentration is directly associated with shorter survival.

The IRIS staging system stays. The four stages of the disease are set on the basis of creatinine — or creatinine and SDMA. Only then are substages added, according to the degree of proteinuria and blood pressure. That division still applies in every consulting room.

Hydration is crucial. Wet food, cat fountains, adding water to meals, and in advanced cases subcutaneous fluid therapy at home — this is still the gold standard.

Phosphate binders. They come into play when, after 4 to 6 weeks of diet alone, blood phosphorus is still too high. The guidelines repeat an important rule: binders must be mixed thoroughly into every meal, because they bind phosphorus in the digestive tract and have to arrive there together with the food.

What changed — the key new points

Protein is no longer the main culprit

Online, it has become settled wisdom that a renal diet is above all a brutal cut to the protein in the bowl. The new guidelines correct this clearly: the ingredient the fight for the cat's life is really about is restricted phosphorus, not protein as such.

The numbers are concrete. Veterinary renal diets usually contain 80–130 mg of phosphorus per 100 kcal, while ordinary maintenance foods contain as much as 400–600 mg. That is three to seven times less.

At the same time, there is a warning against cutting protein too hard — especially in cats that are losing weight — because it leads to dangerous loss of muscle mass. The new document says it plainly: if a cat is eating too few calories, a diet somewhat higher in protein may be the better and safer choice, as long as it prevents malnutrition.

Why this is not an invitation to feed as before

The fact that protein is not the main culprit does not mean diet stops mattering. It means something else: that we have been looking at the wrong number on the label. Manufacturers usually do not give phosphorus per 100 kcal, so comparing foods on your own is genuinely difficult — this is exactly the moment at which an animal nutritionist earns their fee.

Half is better than nothing (the fussiness problem)

Cats are perfectly capable of refusing renal food outright. The guidelines take a very practical view: a specialist diet making up even 50 percent or more of everything the cat eats has been shown to have a beneficial effect on extending its life.

They also recommend introducing the new food very slowly (over 1–2 weeks), placing it in a separate bowl right next to the old one — rather than mixing the two in one bowl, which cats hate. And there is a warning never to introduce a new therapeutic food while the cat is hospitalised and feeling very unwell. It will develop a lasting aversion to the taste of the food that is meant to save its life.

SDMA firmly cooled down

SDMA (a sensitive blood marker of kidney function) was initially marketed as an outright revolution, detecting disease many months before creatinine rises. The new document cools that enthusiasm considerably, treating SDMA as a useful marker but ultimately comparable to creatinine. It has a clear advantage in thin, wasted cats, because unlike creatinine it does not depend on muscle mass, but it also hides traps — its results can be distorted by hyperthyroidism, among other things.

Importantly, for older cats a higher diagnostic threshold has been proposed: 18 instead of 14 micrograms per decilitre. That is a proposal written into the guidelines, not a change laboratories have already adopted — worth asking about if your cat's result falls between those two numbers.

Pain and anaesthesia — no more excuses

This is probably the most groundbreaking chapter, supported by new evidence. The position is clear: neither procedures under anaesthesia nor pain relief should be withheld solely because of kidney disease. Suffering (severely painful teeth, say, or joint degeneration) hugely lowers a cat's quality of life and appetite. And with diseased kidneys, appetite is literally the currency that buys extra time.

Procedures such as extracting painful teeth must not be postponed — they simply need to be planned far more carefully and safely. The mere existence of a CKD diagnosis does not force a cat to live in pain.

This is not an instruction for medicating on your own

I am not giving doses or product names to buy on your own initiative, because treating a cat's pain at home ends, at best, in failure. Human painkillers are toxic to cats. This is an argument for a conversation with your vet, not a trip to the pharmacy.

Active treatment of poor appetite and nausea

A renal cat that has stopped eating is a cat at high risk. The guidelines clearly move away from routinely loading cats up with drugs for heartburn and excess stomach acid — it turns out that gastric ulceration in cats with CKD is far less common than previously believed. The emphasis now falls on modern drugs that block nausea centrally, and on pharmacological appetite stimulation. Waiting idly for the cat to start eating by itself is not acceptable.

The owner moved into the centre of attention

This is a remarkable novelty. An official medical document for clinicians places strong emphasis on the physical and psychological burden carried by the person looking after a chronically ill animal. The guidelines suggest how to optimise the home environment for the cat's welfare, while calling for the owner to be brought into the joint creation of a gentle treatment plan.

Here, at last, is a loud acknowledgement that a plan of treatment and tablet-giving has to fit the mental resources of the person who will be carrying it out at home, every single day.

A smaller volume of subcutaneous fluids

The recommended volume of fluids given subcutaneously at home by the owner (to improve the cat's hydration) has been brought down to a realistic 75–100 millilitres per cat every 1 to 3 days. The earlier guidelines gave 75–150 millilitres. Exactly how much and how often is set by the attending vet, because the volume is matched to the individual cat.

One number worth taking home from the appointment

Hearing the words “chronic kidney disease” is not yet a sentence with an expiry date. The new document stresses strongly that creatinine should be repeated 2 to 4 weeks after the first diagnosis. That interval lets the vet tell stable disease apart from the rapidly progressive kind.

In the studies cited, median survival of cats with progressive disease was just 287 days, while in cats with stabilised disease it was an impressive 894. The same diagnosis on the chart, and two radically different futures.

A diagnosis of “chronic kidney disease” does not yet say how much time is left. That is told by the second creatinine, a month later.

What to ask at the clinic (an owner's crib sheet)

If your cat has just been diagnosed with CKD, write these questions down and take them to the appointment:

  1. Which stage (IRIS scale) is my cat in, and was that assessed when he was already stable and hydrated?
  2. What is his phosphorus concentration, and does it fall within the safe range for this stage?
  3. Have we measured blood pressure and the crucial urine protein-to-creatinine ratio? Those determine the substage and any additional treatment.
  4. When exactly do we repeat creatinine, to check whether the disease is progressing or holding still?
  5. Which diet specifically are we starting, why, and what is our plan B if the cat refuses to eat it?
  6. Is my cat currently in physical pain anywhere (teeth, joints), and how can we address that while protecting the kidneys?

Guidelines and tables describe a statistical patient, and what you have at home is your own, beloved, particular cat. Remember that this document is the most important signpost veterinary medicine has, but the final decision and the fine-tuning of therapy always belong to you and a trusted attending vet, with respect for the cat's character and for the realities of your life.

References

  1. Taylor, S., Finch, N., Caney, S., Elliott, J., Geddes, R., Mortier, F., Parker, V., Quimby, J., Segev, G. & White, J. (2026). 2026 iCatCare consensus guidelines on the diagnosis and management of chronic kidney disease in cats, Journal of Feline Medicine and Surgery, 28(9)doi:10.1177/1098612X261466553
  2. Sparkes, A.H., Caney, S., Chalhoub, S., Elliott, J., Finch, N., Gajanayake, I., Langston, C., Lefebvre, H.P., White, J. & Quimby, J. (2016). ISFM consensus guidelines on the diagnosis and management of feline chronic kidney disease, Journal of Feline Medicine and Surgery, 18(3), 219–239doi:10.1177/1098612X16631234
  3. Mortier, F., Daminet, S., Marynissen, S., Smets, P. & Paepe, D. (2024). Value of repeated health screening in 259 apparently healthy mature adult and senior cats followed for 2 years, Journal of Veterinary Internal Medicine, 38(4), 2089–2098doi:10.1111/jvim.17138
  4. Marino, C.L., Lascelles, B.D.X., Vaden, S.L., Gruen, M.E. & Marks, S.L. (2014). Prevalence and classification of chronic kidney disease in cats randomly selected from four age groups and in cats recruited for degenerative joint disease studies, Journal of Feline Medicine and Surgery, 16(6), 465–472doi:10.1177/1098612X13511446
  5. International Renal Interest Society (2026). IRIS Treatment Recommendations for CKD in Cats, IRIS Kidney↗

Frequently asked

Does a cat with kidney disease have to be put on a low-protein diet?

The new guidelines frame this differently from most advice articles. The ingredient that genuinely slows the disease and extends life is restricted phosphorus, not the reduction of protein in itself. Renal diets do contain less protein than maintenance foods, but the guidelines explicitly warn against cutting too far: if the cat is eating too few calories, a diet higher in protein may be the better choice. Maintaining healthy body weight and muscle is listed among the treatment priorities, and progressive weight loss is one of the signals used to identify rapidly progressive disease. The specific diet is chosen by the attending vet or a nutritionist, after assessing body condition and test results.

What should I do if my cat refuses to eat renal food?

First: do not treat it as a defeat. According to the guidelines, the survival benefit already shows when the renal diet makes up half or more of what the cat eats. Second: change the food gradually, over at least one to two weeks, offering the new food in a separate bowl next to the current one rather than mixing the two together. Third: never introduce a new food while the cat is ill or hospitalised — it will associate the food with feeling terrible and may reject it permanently.

At what age should a cat be screened for kidney disease?

The guidelines recommend screening cats from the age of seven, even with no visible symptoms: body weight, blood work and urinalysis. Once a year between 7 and 10 years of age, and preferably every six months after ten. The reason is concrete: in a screening study at Ghent University, asymptomatic kidney disease was found at the very first visit in 7.7% of apparently healthy cats over seven years old, and among senior cats that were healthy at the start, 23.5% developed the disease within two years.

Can a cat with kidney disease be given painkillers?

This is one of the biggest changes in the new document. The guidelines state plainly that neither anaesthesia nor pain relief should be withheld because of kidney disease — they should be planned so that the kidneys are not burdened. For non-steroidal anti-inflammatory drugs this applies to cats with stable disease, meaning cats whose body weight and creatinine have changed only minimally for at least two months. These drugs are ruled out in dehydrated and unstable cats and in stage four. The decision belongs to the vet, but an owner should know that a kidney diagnosis alone does not sentence a cat to a life with pain.