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The truth about renal diets for cats

If your cat has recently been diagnosed with renal (kidney) disease, you will be anxious to know what steps you can take to improve or maintain your cat's quality of life. Providing an appropriate diet designed specifically for renal disease sufferers is arguably the simplest way for you, as an owner, to positively impact on your cat’s quality of life.

It is important to consult your vet before changing your cat’s diet – this is especially true of patients with other diseases as well. In some cases the other condition also requires a special diet, and should take precedence over dietary modification specific to the kidney problem. Most vets will also have some preference for a specific brand or brands.

Although the inconvenience and expense of purchasing these ‘prescription diet’ foods is often greater than the regular canned food or dry kibble you are used to feeding your cat, vets argue they are genuinely effective  in the fight against kidney disease.

The advent of these foods in recent years has had a significant and positive impact on the lives of vast numbers of cats suffering from renal disease, and vets almost universally advise their use as an essential part of the treatment regime. For these reasons it is important for owners to understand how kidney foods work to support their beloved cat.

How do these foods help?

There are two primary mechanisms by which these foods work.

  1. Low quantity, high quality protein content

    Dietary protein is broken down in the gut to make the building blocks that make up the body and help it to function. During this process, toxic by-products are produced that normally leave the body via the urinary system. When the kidneys aren't working properly, they cannot do this job efficiently anymore so the uremic toxins build up in the blood and cause the cat in renal failure to feel very poorly. The predominant effect of the low protein diet is to minimize production of uraemic toxins so that the cat feels better.

    Cats are obligate carnivores, meaning that their natural diet would consist almost entirely of protein and fat. Protein therefore tastes good to cats and stimulates their appetites - this is one of the reasons cats with kidney disease must continue to have some protein in their diet. Special kidney foods contain less protein than regular foods, however, although present in lesser amounts, the protein that is used in them is of a higher quality than that in a normal diet. Therefore there is less protein to cause the toxic waste effect in the blood, but the protein that is within the diet is able to be used to greater effect by the cat. 
  2.  Restricted phosphate content

    High phosphorus accelerates renal failure, and restricted phosphorus slows it down. Therefore, reduced phosphate content will help to protect the kidneys from further damage, thereby slowing the progression of kidney disease. In cats restricted phosphate content helps to reduce the incidence of a secondary syndrome called Renal Secondary Hyperparathyroidism. Restricting the dietary phosphate content also helps to reduce the incidence of calcification of various body tissues, including the kidneys.

Whilst understanding each of these aspects of renal diets, the most important point is that research has shown that foods meeting these criteria can provide significant benefits to your cat in terms of improving their clinical condition and decreasing the levels of the toxins in the bloodstream that your vet uses to monitor the progression of renal disease.


Choosing the right food

 Cats with renal failure are often elderly and commonly have oral pain and a reduced appetite; therefore, highly palatable food is essential. It is easy to be overwhelmed by the choice in renal diets, but remember the most important criteria for a renal diet is that your cat will eat it!

If a special kidney diet is recommended for your cat it is important to note that some animals will demonstrate a preference for one brand over another. If the first kidney food you offer your cat is not met with enthusiasm do not despair, talk to your vet about which other brands might be suitable. These foods are designed with palatability in mind; it is probable that your cat will like one of the other options available.

Another point to remember is that if your cat has had to stay in hospital to become stabilised, they may have developed an aversion to the food used within the veterinary clinic. If this is the case, trying another brand once the cat is feeling better should help.

The list below outlines the diets available (most come in wet and dry varieties):

  • Hills Prescription Diet Feline K/D

    • Reduced levels of high-quality protein

    • Extra omega-3 fatty acids to improve blood flow to kidneys

    • High levels of anti-oxidants

    • Highly palatable

  • Royal Canin Veterinary Diet Feline Renal (wet)

    • EPA, DHA, Antioxidants and low phosphorus for chronic kidney disease management

    • Reduced levels of high quality protein

    • Alkalinising agents for metabolic equilibrium

    • Designed aroma profile for cat's specific prefernce

    • Wet food helps increase fluid intake

Correcting dehydration is an essential objective in management of patients with renal failure. In order to encourage as much fluid consumption as possible it is worth considering that use of a wet diet, as a dry food has a negligible water content. If your cat enjoys drinking from a dripping tap you may want to consider a water fountain to increase water intake.


 There are some supplements available that can also help with some of the functions that the renal diets provide, such as the phosphate binder Ipakitine (this works by "binding" to dietary phosphate and allowing it to be excreted in the faeces rather than the urine). Also if your vet has determined any other renal-failure related deficiencies such as low potassium, supplements are available - please discuss with your vet as it is not advisable to supplement with these types of minerals unless the cat is deficient.

This article is intended as a guide only. Always consult your veterinarian prior to changing your cats diet as they will be able to advise the most suitable food for your cats specific problems.

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