Protect the kidneys: feeding cats with CKD

Chronic kidney disease is a common condition in senior cats. In fact, it is the number one cause of death in cats over the age of 7. The condition can’t be cured, but the progression of this disease can be slowed, symptoms reduced and quality (and length) of life improved – with nutrition.

The primary treatment for chronic kidney disease is a change in diet. Renal diets are designed to have moderate amounts of high quality protein, reduced phosphorus and magnesium, moderate sodium and an enhanced profile of omega 3 and 6 fatty acids. These nutritional factors are help reduce damage and workload on the kidneys, maintain body condition and appetite and reduce inflammation and free radical damage. It’s important to remember that a kidney diet is not just a low protein diet; especially in cats, there is no need to reduce protein levels until later stages.

Speaking of stages, the IRIS guidelines help veterinarians categorise the severity of the cat’s renal disease. This staging helps us determine what type of food may be most suitable for your pet and when we should consider introducing it for the best outcome. You can read more about IRIS stages here.

Infographic on the IRIS stages of Chronic Kidney Disease and associated symptoms.

The first two IRIS stages are often considered silent, as we may not see any symptoms at all. Often cats will not start to show signs until 70% of kidney function is lost, by which time the progression is rapid. This is why we recommend blood testing for all pets over the age of 7, where we move into the senior lifestage and kidney disease can begin to silently kick in. This is also, when we can have the greatest impact on slowing the progression of the disease. Chronic Kidney Disease can’t be reversed, but it can be slowed down.

Many people are nervous about introducing a renal diet too early, however a diet change can be started as early as IRIS Stage 1; recent research showed that cats not only accepted the diet better (before the nausea of later stages kicked in) and their kidney parameters showed NO CHANGE while on the diet! Food has literally stopped kidney disease in its tracks. Waiting until later, when the disease has set in and ureamia is present is not advised, as not only will the cat no longer accept the food and potentially develop a food aversion as a result of their discomfort, but they will not get the same benefit that they would have if it was started earlier on.

So what is it about renal diets that protects the kidneys?

Key Nutritional Factors for Chronic Kidney Disease

Controlled protein: protein is metabolised and broken down by the kidneys, so controlling the amount in the diet and including a highly digestible, high quality protein source, you are reducing the workload on the kidneys and allowing them to rest and recover. Most renal diets also include amino acids to further reduce the kidneys needing to break down protein to fulfill their amino acid requirement. The protein levels are not reduced until IRIS Stage 3 or 4 as cats still have a high protein requirement that needs to be balanced with their kidney’s reduced capacity to break it down.

Moderate sodium: some sodium helps encourage drinking, which allows the waste products built up in the kidneys to be flushed out. Too low sodium and the cat won’t drink, too high sodium and the cat will be further dehydrated, therefore a balance is important.

Low phosphorus and potassium: low phosphorus diets have shown to delay the development of kidney disease and also reduce the formation of waste products that can crystallise and damage the kidney tissue.

Omega 3 Fatty Acids: have an anti-inflammatory effect on the body, reducing the chronic pain and discomfort associated with kidney disease and other age-related conditions.

Vitamin E & C: these vitamins are powerful antioxidants which combat free radical damage that can further damage the kidney, and support the immune system for overall health.

What about water?

Cats with chronic kidney disease will drink more as their kidneys begin to lose the ability to concentrate urine. As a result, cats often become dehydrated as they lose majority of the water they are drinking through excretion. To combat this, drinking is still encouraged to continually replace fluid loss, and wet renal food is a fantastic way of adding moisture into the diet; feeding a wet diet can reduce a pet’s water requirements by up to 75%! Wet renal diets are also easier to digest, slightly fattier and have a more appealing flavour profile to some cats. In advanced stages, your vet may recommend having intravenous or subcutaneous fluids to replace the fluids your pet has lost. You can also, if your pet won’t eat or drink, syringe feed your pet a slurry of renal wet food and/or rehydration solutions. Some cats may require a feeding tube if they refuse to eat due to the associated nausea, mouth ulcers, changes in taste perception or pain.

Top tips for feeding renal patients:

Offer a variety of flavours and textures of food: your cat’s sense of taste will change slightly as a result of the condition, and they may like different flavours or textures they previously have turned down. They also rapidly develop food aversions as a result of the nausea associated with kidney disease, so having a few renal foods to cycle through can help avoid this.

Transition slowly onto the new diet: Never rapidly change your cat’s food, but especially for pets with kidney disease. A transition of up to three weeks has been shown to be ideal for renal patients. It is also important never to try and introduce a therapeutic diet while the pet is in hospital, it’s always better to begin the transition in the cat’s own environment where they are not stressed or unwell.

Have rehydration solutions on hand: Veterinary hydration solutions such as Lectade or Oralade can be kept on hand and used at home if the cat stops eating and drinking, or becomes dehydrated (clients can be taught to check skin tenting) to help ensure cats are getting enough fluids, especially if vomiting or diarrhea is present. It may also be a good idea to have oral syringes to help syringe feed the cat some water if they won’t drink on their own.

Have you ever cared for a cat with kidney disease? What challenges did you encounter in nutritionally managing their condition?


Forrester SD, Adams LG & Allen TA., (2019) Small Animal Clinical Nutrition. Chapter 37: Chronic Kidney Disease. Table 37-9, pp781

Fritsch, D. A., Jewell, D. E., Leventhal, P. S., Brejda, J., Ahle, N. W., Schiefelbein, H. M., & Forrester, S. D. (2015). Acceptance and effects of a therapeutic renal food in pet cats with chronic kidney disease. Veterinary record open, 2(2), e000128.

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