Tanya's Comprehensive Guide to Feline Chronic Kidney Disease (2024)

Many people fear the worst because their vet has said their cat has lost a massive amount of kidney function so they think there is little hope. How Bad Is It? explains why it is actually normal not to be able to diagnose CKD until up to two thirds of kidney function has gone.

Even if your cat has lost over 90% of function, there may still be hope: Renal dysfunction in small animals (2016) Brown SA Merck Veterinary Manual says "With appropriate therapy, animals can survive for long periods with only a small fraction of functional renal tissue, perhaps 5%-8% in dogs and cats."

So Is There Any Hope?

In most cases, I would say yes. Whilst I cannot promise that your cat will pull through a crisis or survive for years, I can tell you firstly, the numbers do not tell the whole story; and secondly, that not being proactive is definitely going to reduce his or her chances.

Just as I cannot promise your cat will be a success story, so your vet cannot know for sure that s/he will not be. None of us has a crystal ball, so by all means listen to your vet's opinion but do not assume that your vet's opinion is fact.

Factors Affecting the Prognosis

Vets have some idea of the prognosis based on your cat's test results and their previous experience, but there are so many factors other than your cat's blood test results which affect the prognosis, including:

how sick your cat is at diagnosis
your cat's attitude and tolerance levels (my Thomas ate like a horse with creatinine over 7 mg/dl (650 µmol/l international)
how much your cat wants to fight
how well your cat copes with being handled
how good the veterinary care is which your cat receives, including how proactive your vet is
whether any other illnesses are present
which treatments are used
the caregiver's efforts
how much you can afford to spend (though many treatments probably cost less than you think, see Obtaining Supplies Cheaply).

The only ones of these which we can control are the latter two (and possibly which vet you use, though that also depends upon where you live), so I recommend focusing on these and then, whatever happens, you know you've done your best.

Renal Disease (2006) Polzin DJ Delaware Valley Academy of Veterinary Medicine says "A host of factors influence prognosis of CKD, both favorably and unfavorably. Included among these factors are the quality of medical care provided to the patient, the degree of interaction between the veterinarian and pet owner, and the level of owner commitment."

You will notice I don't include age. Old age is not a disease, so try not to let your cat's age work against him or her.

What Do the Numbers Mean?

How Bad Is It? provides information on what the various test results mean and discusses the commonly used IRIS staging system. Let's talk briefly here about what the numbers seen in bloodwork tend to indicate in terms of the prognosis.

Some vets consider levels in Stage 3 (creatinine between 2.9-5.0 mg/dl or 250-440 µmol/L) to indicate high numbers and therefore to carry a very poor prognosis; but on Tanya's CKD Support Group, these are actually considered to be "medium numbers", and in fact many cats on the group have lived three or four years or longer with levels around 3-4 mg/dl (260-400 µmol/L).

Dr Katherine James has mentioned that most people seem to opt for euthanasia when creatinine remains consistently in the 660-900 µmol/l (US: 7.5-10 mg/dl) range, and the cat is doing badly. I generally consider the prognosis to be more guarded if a cat's creatinine level is over 7 mg/dl (627 µmol/L) when stable (I don't worry as much if the creatinine is at this level in a cat who is recently diagnosed and on intravenous fluids at the vet's because of dehydration, or if the cat has an infection).

However, this is just a rough guide; some cats in Stage 4, with very high numbers despite IV therapy and rehydration, may respond very well to treatment and enjoy several months of quality life, particularly if their numbers have worsened gradually over time, giving their bodies time to adjust to the reduced levels of kidney function.

If Your Vet Recommends Euthanasia

Some vets seem to recommend euthanasia almost immediately. This may be the appropriate approach in some cases, but not in all, though if your vet is negative, this may lead you to think there is no hope when in fact there might be. For example, I have heard of some vets who recommend immediate euthanasia for cats whose numbers are barely out of the normal range and who are acting completely normally! I also hear quite often about vets who, no matter how bad or otherwise the cat's bloodwork is, impose arbitrary deadlines along the lines of "if s/he's not better by tomorrow/within three days/whatever period the vet mentions, you have to put to sleep." In our house vets like this are known as Dr Doom and Gloom. Yes, they may be correct in that your cat might be one of the unlucky ones; but I prefer a vet who says something like "I cannot make any promises, but I'd like to try x, y and z and see if that helps your cat. If it doesn't, at least we know we've tried our best."

Your vet's approach does make a difference. Renal Disease (2006) Polzin DJ Delaware Valley Academy of Veterinary Medicine says "The estimate of prognosis often influences the owner's decisions about treatment options in complying with recommendations for management of the patient. A comprehensive evaluation of the patient is the best way to establish a reasonably accurate prognosis."

In fairness to vets, it can be difficult for them to strike the right balance between giving you encouragement and raising your hopes, only for them to be dashed. However, in the vast majority of cases, you need to treat your cat properly for at least two weeks before you can make an informed decision. Deciding on euthanasia should always be your decision, not the vet's, because you have to live with the feelings of guilt and loss which often follow.

CKD is not generally considered to be a painful disease (dehydration feels a bit like a hangover, uncomfortable but not agonising), so in most cases there is no need to rush into an irrevocable decision. Cats who are severely dehydrated or severely anaemic can look really ill; but treatment may help. Dr SP DiBartola has stated "Don't pass judgement on a lethargic dehydrated cat with markedly abnormal laboratory results. 2 to 3 days of conscientious intravenous fluid therapy can produce remarkable results." The laboratory diagnosis of feline kidney disease (2008) Heine R Veterinary Focus 18(2) pp16-22 states "cats can sometimes, especially in cases of acute kidney injury secondary to obstructive FLUTD, develop creatinine values of 1600-1800 •mol/L (20.98-23.6 mg/dL) and yet recover."

Therefore I would suggest that in most cases it is better not to be talked into euthanasia on the day of diagnosis or if your cat's numbers do not improve after a day or two on IV fluids, because in many cases there is room for hope; the cat just needs some time to stabilise with proper treatments tailored to his or her particular needs.

Scenarios You May Be Facing

Let's take a look at the various scenarios you may be facing when your cat has CKD. Some of these may occur at initial diagnosis, whilst others may arise further down the line.

Cat who is not in crisis
Cat who is in crisis: very high numbers and/or receiving intravenous fluids (IV or a drip)
If bloodwork worsens suddenly after a period of stability
If a cat with low bloodwork values acts sick

Cat Not in Crisis

If your cat has been diagnosed early and is stable, you are fortunate in many ways because with careful monitoring and a proactive approach, your cat may stay relatively well for months or years. Feline chronic kidney disease (2015) Grauer GF Today's Veterinary Practice 5(2) pp36-41 says "Diagnosis of early CKD, followed by appropriate treatment, may result in improved survival. There is solid evidence that dietary treatments, and increasing evidence that antiproteinuric treatments, can slow the progression of CKD."

For cats who are stable but who have relatively high bloodwork values, perhaps at the top end of Stage 3 or even higher (creatinine over 5 mg/dl or 440 µmol/L), there is still hope: the values may fall with treatment, but even if they do not, there is a possibility your cat may remain at this level for some time (see below). Also, If your cat is stable despite having such numbers, your cat clearly copes well with CKD, which is usually a good sign, although treatments should still be begun as soon as possible, including possibly a session on intravenous fluids.

Cat in Crisis: Very High Numbers and/or Receiving Intravenous Fluids (IV)

Since it is so hard to diagnose CKD early (see What Happens in CKD? to understand why), your cat may be in crisis at diagnosis. Please do not be too despondent if this is the case, particularly if your cat has crashed and is on intravenous fluids (a drip) at the vet's, as happened to Thomas. Many cats have horrendous bloodwork at diagnosis, or may experience a sudden crisis after having CKD for a while, which is often a reflection of severe dehydration. The true bloodwork values will not be apparent until your cat is rehydrated and stabilised, either via sub-Qs for less critical cases or via IV for more severe ones.

For cats who are in crisis, there is usually a trigger of some kind, such as:

infections, such as urinary tract or kidney infection or occasionally dental problems
kidney stones

hypertension

dehydration

All of these can make your cat and the bloodwork look terrible, but once you get the situation under control, you may well find that your cat's condition greatly improves and the bloodwork may also improve, sometimes quickly, or sometimes over a period of several weeks.

Some cats with very high numbers will actually be suffering from acute kidney injury (AKI) rather than CKD, or possibly acute on chronic kidney disease. Whilst AKI is difficult to treat, if treatment is successful the cat may actually make a complete recovery.

Cats with severe anaemia (PCV or HCT below 20%) often appear extremely ill, but usually feel and look dramatically better once the anaemia is under control.

There are a variety of possible outcomes for a cat who has crashed and is on IV with extremely high bloodwork values:

The cat's numbers improve on IV and the cat looks and acts better, and continues to do well at home.

The cat's numbers do not improve on IV, but the cat nevertheless acts better, and the numbers gradually reduce at home (usually with sub-Q therapy).

The cat's numbers do not improve on IV or with sub-Qs, but the cat acts better and continues to do well at home despite the high numbers.

The cat's numbers do not improve on IV, and the cat continues to act ill once s/he is home, and is put to sleep.

The cat's numbers do or do not improve on IV, but the cat crashes again once at home.

Obviously I cannot predict to which category your cat might belong, but it is usually worth trying treatments. Yes, not every CKD cat can be saved; but euthanasia is an irrevocable decision so you need to be very sure, and for most people that means giving their cat every chance. Dr SP DiBartola has stated "Don't pass judgement on a lethargic dehydrated cat with markedly abnormal laboratory results. 2 to 3 days of conscientious intravenous fluid therapy can produce remarkable results."

For a severely ill cat, one or two days on IV are simply not going to be long enough. Thomas was on IV for four solid days and nights, and only began to eat a little on day 3. Also, Thomas's numbers did not improve at all on IV fluids. He had urea of 89 mmol/l (BUN: 241 mg/dl) at diagnosis, and it was the same after four days and nights of IV. Some cats will actually have numbers which worsen while on IV fluids. Try not to panic! Your cat did not get this sick overnight, and s/he won't necessarily get better in only 2-3 days. In Thomas's case, my vet suspected he would fall into category 4 of my possible scenarios above, but in fact he was in the second category. He was acting a little better by the end of the four days on IV fluids, and with home treatments over a few weeks we eventually reduced his numbers tourea 27 mmol/l (BUN: 76 mg/dl) and creatinine 316 µmol/l (US: 3.57 mg/dl), where they stabilised for some months.

So even if you are dealing with category 4, I would recommend that you make sure that your cat is given a reasonable stint on IV, and is given a reasonable chance of success at home, especially if anaemia is present. Being at the vet's is very stressful for most cats, and they often need a few days at home convalescing before they begin to act better.

Prolonging the life of the renal failure patient (2000) Elliott J Waltham Focus 10(3) pp10-14 states that "in a retrospective study, the correlation between plasma creatinine and survival in cats who presented with signs of stable CKD was very poor, with only 5% of the variation in survival time being predicted by the initial plasma creatinine concentration."

The laboratory diagnosis of feline kidney disease (2008) Heiene R Veterinary Focus 18(2) pp16-22 states "cats can sometimes, especially in cases of acute kidney injury secondary to obstructive FLUTD, develop creatinine values of 1600-1800 μmol/L (20.98-23.6 mg/dL) and yet recover."

Vet Info mentions a cat they treated who lived for eight years with CKD despite initially presenting in crisis (click on Kidney Failure - Daily Fluid Treatment).

If Bloodwork Worsens Suddenly, Especially After a Period of Stability

Please do not panic if your cat's bloodwork worsens suddenly. Firstly, you need to ensure that any possible causes of the problem are addressed. Common triggers include:

infections, such as urinary tract or kidney infection or occasionally dental problems
kidney stones
hypertension
high phosphorus levels
dehydration

An ultrasound can help determine if urinary tract infections or kidney stones are present. Once you have addressed the problem, you may find your cat's bloodwork improves once again.

If you cannot find a cause, it may be that your cat's CKD is progressing. If we take the analogy of a CKD cat falling over a precipice, what seems to happen to quite a few CKD cats is that the cat's bloodwork deteriorates in stages, like moving one step closer to the edge of the precipice; but the cat may remain stable at each step for some time. Thomas, for example, was in IRIS Stage 2 with a creatinine level of 318 µmol/l (US: 3.57 mg/dl), nearly double what it should be, for six months; and he then moved a step closer, but still managed a couple of months with creatinine of 627 µmol/l (USA: over 7 mg/dl) and had a very good quality of life during this period. Other cats may not show such extreme changes, with gradual falls that may be a year or more apart. Reassessment of "normal" values in dogs and cats with chronic kidney disease Grauer GF International Renal Interest Society says "Cats may have stable renal for months to years and be relatively unaffected by the CKD or they may have slowly progressive disease over several years. Animals may be stable for a long period of time but then experience an abrupt, unpredictable decline in renal function."

If your cat already has high numbers, and these worsen, try not to be too discouraged. Creatinine is not a linear measurement, so a worsening of creatinine that is already relatively high is not as sinister as it might first appear. The Diagnosis page explains more about this.

If your cat's bloodwork has suddenly worsened, don't give up hope. If you review your treatment programme and add new treatments as necessary (including a period on intravenous fluids if the bloodwork values are high and your vet considers it appropriate) and work closely with your vet, you may well find your cat stabilises once again, albeit at the higher bloodwork values.

If your cat's phosphorus levels are high, it is particularly important to get these under control, because they may make the CKD progress faster and also make many cats feel bad.

If A Cat with Low Bloodwork Values Acts Sick

I would expect a cat with low bloodwork values (creatinine below 3.5 mg/dl or 300 µmol/l), Stages 1, 2 and the lower part of Stage 3 of the IRIS classification system) not to appear too sick. These cats may have the occasional bout of vomiting, and may sometimes not want to eat, but overall they should be doing quite well as long as they are not dehydrated and are eating enough.

Therefore if your low numbers cat is consistently off colour (lethargic and exhibiting general malaise) even after treatment for obvious problems, I would ask your vet about other possible causes:

High phosphorus levels make cats feel poorly.
Many cats with hypertension feel off colour, but improve greatly once their blood pressure is back to normal.
Cats with anaemia can look and act very sick. Cats with anaemia caused by the CKD would normally have more advanced CKD, but anaemia may also be caused by infection or inflammation.

My Ollie had low kidney values (creatinine of 2.8 mg/dl) but had fairly regular diarrhoea. It turned out this was caused by hyperthyroidism and it disappeared once the hyperthyroidism was under control.

Some CKD cats who persistently exhibit general malaise despite treatment for obvious problems may have some kind of gastro-intestinal problem. Pancreatitis is a common cause in CKD cats; other possible causes include inflammatory bowel disease (IBD) or cancer (lymphoma). It would probably be worth considering an abdominal ultrasound in order to rule out such problems.

Treat the Cat, Not the Numbers

Test results matter, but they are not the whole story. This is why we have a mantra on Tanya's CKD Support Group: "treat the cat, not the numbers."

Of course, it is still important to do what you can to improve the bloodwork and to treat whatever issues arise, because this will both make your cat more comfortable and increase his/her chances of survival. This mantra is simply a way of pointing out that many cats do astonishingly well despite their bloodwork results being poor. There are no guarantees and it is a fine line to tread, but it is usually worth trying treatments, although you must also consider your cat's temperament when deciding how much to fight the CKD.

TheSuccess Stories page tells the stories of some CKD cats who have managed to lead happy and in many cases, lengthy, lives at various stages of the disease, including one cat, Paris, who survived for over sixteen years.

Survival Times

The longest surviving CKD cat I know of lived for sixteen years after diagnosis, having been diagnosed at six months of age. The next longest surviving lived for twelve years, having been diagnosed at three years old. A number of cats on Tanya's CKD Support Group have lived for 5-8 years after diagnosis, including cats who were diagnosed aged 12-14 who lived to be 19-21 years old. So yes! In many cases there is hope.

Survival in cats with naturally occurring chronic kidney disease (2000-2002) (2008) Boyd LM, Langston C, Thompson K, Zivin K & Imanishi M Journal of Veterinary Internal Medicine 22(5) pp1111-7 discusses survival times of cats who were in the following stages at diagnosis:

Creatinine Level mg/dl	Creatinine Level µmol/L	Median Survival Time	Range (in Days)	No of Cats
2.3 - 2.8	2.3 - 249	1151	2 - 3107	82 (39.4%)
2.9 - 5.0	250 - 440	778	22 - 2100	84: (40.4%)
Over 5.0	Over 440	103	1 - 1920	42: (20.2%)

The median is a halfway point, i.e. 50% of cats lived less than the median, and 50% lived longer than the median. So sadly 50% of the cats in Stage 4 at diagnosis lived less than four months, but that means that 50% of Stage 4 cats lived for longer than four months. What I find interesting is that at least one cat in Stage 4 lived for 1920 days after diagnosis, or more than five years! It should also be noted that this study looked at cats some fifteen years ago, and treatments have improved since then.

I would say (and the above study seems to support this view) that cats who are diagnosed early with low numbers have the best chance — many of them live for years. Although it is less common, some cats with high numbers also live for years, as the Success Stories page shows.

Finding the right balance: medical management of renal patients (2014) Vaden SL Eukanuba Veterinary Diets Clinical Symposium, Norway says "Although most cases of chronic kidney disease (CKD) are progressive and irreversible, survival can be relatively long. With appropriate medical management, many affected animals will die of other causes."

What pet owners should know about kidney function and the diagnosis and management of chronic kidney disease in dogs and cats (2019) DiBartola SP International Renal Interest Society says "Some dogs and cats with chronic kidney disease can live several years with conscientious management of their disease by the veterinarian and pet owner."

Renal Disease (2006) Polzin DJ Delaware Valley Academy of Veterinary Medicine says "With appropriate therapy, cats with stages 2 and 3 CKD commonly survive 1 to 3 years. However, many survive much longer"

Dr D Chew said in a webinar that I attended that it is not unusual for CKD cats to live for 3-5 years after diagnosis, and his own CKD cats have survived longer than that.

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This page last updated: 25 June 2020

Links on this page last checked: 25 June 2020