top of page

Renal Diets For Cats – What We Need To Know

A grey and white tabby cat sitting over a clear bowl full of water. It is drinking from the bowl and its pink tongue is visible through the clear bowl.

We often receive enquiries from customers about what to feed cats with chronic kidney disease (also known as CKD). CKD is sadly a common diagnosis for cats, and is a progressive disease that slowly disables kidney function over time. Although it cannot be cured, veterinary treatment and lifestyle changes can slow down the progression and allow cats to have a good quality of life!

Which Renal Diets Are Right For Our Cats?

Feedings cats with CKD can be difficult as there is often conflicting advice available. Vets will most often recommend feeding cats a renal diet limited in protein and phosphorus, and some brands of commercial cat food even offer specialist diets that claim to fulfil the specific needs of cats diagnosed with CKD.

Although these diets have proven to be beneficial, many contain ingredients that are known allergens (e.g. cereals, chicken) and are not always particularly digestible or palatable for cats. We believe it is incredibly important to assess your cat's willingness to eat their food, as cats with CKD can easily lose weight and become malnourished. Keeping your cat eating should remain the highest priority, and we always recommend working closely with your vet to ensure you are doing what is right for your cat.

How Important Is Protein?

Cats with CKD may benefit from lower levels of protein compared to healthy cats. However, the lower protein content is not as important as the need to ensure any food fed as part of renal diet is low in phosphorus.

When protein is metabolised, uraemic toxins are created in the body. Healthy kidneys will filter toxins out of the blood and excrete them from the body. However, when the kidneys are damaged and unable to work efficiently, these toxins can build up in the body and cause a condition called azotaemia. This results in weight and appetite loss, vomiting, and lethargy.

Regardless of the level of protein in our cats' food, it is best to ensure that the protein source is highly digestible and free of derivatives, by-products and meat meal. High quality protein is easier to digest and puts less stress on the kidneys.

The Importance Of Low Phosphorus

Cats fed a high phosphorus diet have been observed having more severe levels of kidney inflammation and deterioration. The kidneys filter phosphorus from the blood, so when the they become damaged, the levels of phosphorus in the blood can rise to dangerous levels and eventually fuse with calcium in the blood. These elements combining can damage the kidneys even further by forming mineral deposits in the soft tissue surrounding the organs.

This process is known as mineralisation.

Certain ingredients found in cat food are naturally high in phosphorus so are best avoided. Organ meats such as chicken liver, sardines, lentils, brewer’s yeast, and cereals are all high in phosphorus, so pet foods containing these ingredients should not be a part of a cat's renal diet.

Don't Forget About Hydration!

It is absolutely vital that cats diagnosed with CKD are well hydrated. Due to the excess urine produced as a result of the lack of kidney function, cats with CKD require higher levels of hydration.

Dehydration in cats with CKD can lead to acute kidney failure, so feeding a high-quality wet food diet is recommended due to its high moisture content. Wet foods containing jelly, gravy, or sauces are best avoided, as these foods may have a higher salt or sugar content. Wet foods where the meats are cooked in their juices are likely to be a healthier alternative.

Although not all cats will drink water from a bowl, fresh drinking water should be available at all times. Nowadays, there are lots of different water bowls available to encourage our cats' drinking habits, including fountains, and filtered water bowls.

The Potential Of Fish Oils

The use of omega oils as a supplement for cats with CKD has promising results! Eicosapentaenoic Acid (EPA) is a beneficial omega oil found in marine sources such as fish and is a proven anti-inflammatory. This anti-inflammatory response is believed to aid kidney health and may be beneficial to cats diagnosed with CKD.

Liquid fish oil supplements may also be used to add palatability to food, especially if your cat is not accepting a new renal diet. Plant-based omega oils should not be used, as the omega oil Alpha-Linoleic Acid (ALA) can cause an inflammatory response that could be detrimental to cats with existing inflammatory conditions such as CKD. This is especially important if their kidneys are already inflamed. If you wish to learn more about the effects of different omega oils, we wrote a blog post about it here!


Providing a suitable renal diet for a cat diagnosed with CKD can be difficult. A veterinary or prescription diet may not necessarily be suitable for your cat, however there are alternatives available. Being aware of the nutritional content of your cat's food is important, as well as taking into account the quality of the protein and any other important information that is listed on the pet food label.

If you suspect your cat may have CKD, always consult your vet before changing your cat’s diet. Your vet will be aware of the specific results relevant to your cat’s kidneys and any other complicating factors, which might influence what foods should be fed to your cat.

If your cat is already diagnosed with CKD and you would like to discuss further options in regards to nutrition and diet, contact our team at The Thoughtful Pet Food Store and we will be happy to assist!

1,251 views0 comments


bottom of page