Chronic kidney disease (CKD) is a very common problem in older cats and sadly by the time it is detected, it is often quite advanced. It is irreversible so once diagnosed, our aim is to slow down the progression of the disease and reduce the symptoms to ensure a comfortable life for as long as possible. So why can’t we pick it up earlier and what can we do about it?
What is Chronic Kidney Disease?
The normal kidneys have many important functions but primarily they remove waste products from the bloodstream, which are then excreted as urine. Think of the kidneys like sieves: normally they trap waste products and let the filtered blood through to go back into circulation. However in CKD the sieve has holes punched through it and so waste products pass through into the ‘clean’ blood. CKD, or renal insufficiency, is any chronic disease process that stops this system from working efficiently and is the end stage of many different diseases affecting the kidneys. This is distinct from acute renal failure where the kidneys are damaged suddenly and can be reversible. Unfortunately, in most cases it is not possible to determine the specific cause of the kidney disease in cats without getting a biopsy of the kidneys, which is invasive and has considerable risk of complications. For these reasons CKD is usually managed as a single syndrome regardless of the underlying cause, with some notable exceptions e.g. chronic kidney infection or cancer.
Specific breeds can be predisposed to specific causes of CKD such as polycystic kidney disease in oriental breeds and amyloidosis in Abyssinians. Also cats can be born with kidney problems and therefore CKD is not exclusively a disease of older cats at all. In fact very young animals can be affected. So you can see that this is getting complicated – there are no easy answers with this disease unfortunately.
Signs of Kidney Disease in Cats
Outward signs a cat might have CKD include:
- increased urination – basically the kidneys lose the ability to concentrate the urine so more water is excreted in the urine, leading to increased thirst. If fresh water is not available, this can very quickly lead to severe dehydration. The dilute urine can encourage bacterial growth leading to urinary tract infections.
- even with fresh water available, there is generally ongoing mild dehydration which can lead to constipation.
- inappetance – as the toxins build up in the bloodstream (since they are not filtered out by the damaged kidneys) they make the cat feel lousy, like an ongoing hangover. Understandably many cats don’t feel like eating much. Blood electrolyte levels are also affected.
- this leads to weight loss, lethargy, general poor condition and weakness
- high enough levels of toxins can lead to vomiting, mouth and stomach ulcers and bad breath
- acute blindness can occur due to high blood pressure as the body tries to compensate
- the kidneys help stimulate red blood cell production and so with damaged kidneys, anaemia can develop, contributing to the weakness and lethargy
These signs develop slowly over months to years and progress over time, although we can slow it down.
Kidney disease in cats is often diagnosed and subsequently staged based on clinical signs and lab tests. The stage of disease can guide prognosis and treatment. Therefore the earlier kidney disease is suspected/detected, the better the outcome is for quality and quantity of life. Lab tests can detect disease before the onset of clinical signs and CKD is one of the main reasons many vets recommend annual or biannual urine and blood tests, especially in older animals or those at higher risk of developing CKD. I don’t think we do a good enough job of explaining to clients why regular checkups and tests are so important, since many don’t see the value, but early detection can make such a huge difference in prognosis and quality of life I can’t overemphasise how critical I think these are!
If a specific cause of CKD is suspected, further tests such as ultrasound, xrays or even biopsy may be recommended.
Management of Chronic Kidney Disease
CKD is irreversible but early detection and appropriate management can slow down progression of kidney disease in cats considerably. Basically we want to slow down further damage to the kidneys and treat the signs that have already occurred.
Although kidney transplants are available for cats in some countries, this is not a standard treatment option and would need to be discussed with your veterinarian. Usually this is only suitable for cats with very early disease before the onset of outward signs.
A Prescription Diet
The core of CKD management is a special diet. One of the key factors that causes progression of kidney disease in cats is the amount of protein in the diet since protein “supplies” the major toxins of CKD, creatinine and urea. Thus we want to restrict the amount of protein to minimise further kidney damage while also supplying enough high-quality protein for normal bodily functions and to minimise weight loss since cats are carnivores and need protein in their diet. We want to maximise the calories through non-protein sources and restrict other nutrients that can damage the kidneys or cause electrolyte disturbances. The easiest and most effective way to do all this is to feed your cat a specially formulated prescription diet for kidney disease. The downside is because these diets are controlled in protein levels, they aren’t particularly tasty and so our feline patients tend to turn their noses up. As much as is possible it is worth persisting to try to get them to eat one of these diets since this is the main thing you can do to slow down kidney disease in cats.
What About Other Foods?
People often ask can I feed other foods as well or can I feed fish or steak or another favourite food? The prescription diets are designed to be complete and balanced and are most effective when fed alone. It’s not that you can’t feed other foods but every excess bit of protein your cat is getting is damaging the kidneys just a little bit more and making the disease just that little bit worse so you need to decide whether the happiness your cat gets from a bit of their favourite food is worth it. Despite diet being the best therapy, if your cat just won’t eat it at all then it is more important for it to be eating something rather than the right thing. This is especially true in the later stages of the disease when weight loss and dehydration are a constant battle so at that point I feel any calories are good calories.
The Importance of Hydration
It is also really important to provide a continuous supply of fresh water since dehydration can occur so quickly and lead to kidney failure. The more they drink, the more the toxins are flushed out and the better they feel. Sometimes this can be assisted by giving fluids under the skin at home every few days. If dehydration is worsening, then this may require a couple of days in hospital on a drip. However it is also best to avoid stress whenever possible.
Depending on what specific signs your cat is showing both outwardly and on lab tests, other treatments may be required. If there is a urinary tract infection your cat will need antibiotics. If it is constipated it may need to have an enema or be given laxatives. If there are electrolyte disturbances then medications may be prescribed to fix these. If there is vomiting, then this is controlled and stomach protectants/antacids may be given for ulcers. Medications may also be prescribed if there is high blood pressure or anaemia.
Cats with CKD need ongoing management and regular checkups to make sure that treatment is optimal for each specific case at each stage of the disease. The length of time that cats with CKD can be managed with good quality of life is extremely variable and difficult to predict, but depends a lot on the stage at diagnosis.
This is a highly complex disease but I hope this clears up some of the confusion about chronic kidney disease in cats should you ever have to deal with it. Please don’t hesitate to post further questions or points of clarification and if requested. I sincerely hope that as medical technologies continue to improve, we find better ways to manage and hopefully one day cure the diseases leading to CKD (in people as well as in animals!).
Image: Teresa Boardman via Flickr
Dr Robyn Hall is a Sydney based veterinarian with a strong interest in feline medicine and well-being. She shares her life with two beautiful tabby domestic shorthairs, Elara and Callista, who she adopted from a vet clinic whilst living in Perth.