Chronic renal (kidney) failure in cats is a common problem as pets age, especially those who have been fed a diet of primarily dry cat food. Switching to homemade cat food may offer the best chance of recovery.
Cat food specifically tailored for the needs of cats with renal failure should contain high-quality protein to minimize strain on kidneys. At first it might even be important to feed a low-protein diet, depending on the animal's illness and the vet's recommendations. A low-phosphorus diet can reduce mineral deposits in the kidneys. The food should also be low-sodium and contain omega-3 fatty acids and vitamin E to slow disease progression. Cats need supplemental taurine. A B-vitamin complex will increase appetite and energy.
Low-protein foods may use cooked brown rice as a base, with addition of high-quality omega-3-rich fish oils, vitamin E, and a bit of brewer's yeast for flavor and nutrients. Reduce the amount of oils if the cat has loose stools. Mixing in tuna canned in water may help tempt pets to eat.
Once the cat will take the base food, gradually add chopped vegetables for fiber and nutrients. Steamed mashed carrots, potato peelings, frozen peas, and fresh spinach or kale may be acceptable. Do not use cooked spinach, and never give a cat onions.
Spirulina is a nutritious blue-green algae that some cats love. Others will take tiny amounts mixed in with food. Baby food, while not formulated with nutrients cats need, is sodium-free and may be used to improve calorie intake.
If kidney failure is not far advanced or is improving, high-quality protein is a better option than low-protein, which may make wasting and malnutrition worse over time. Try to mimic a cat's natural diet to find the best ingredients.
Normally a cat would eat fish, birds and small rodents that have partially digested greens, seeds and other vegetable matter in their crops, stomachs and intestines. They would ingest organ meats and bones. None of the meat or vegetable matter would be cooked.
Try chicken hearts and gizzards, egg and ground turkey mixed with wheatgrass juice or spirulina, non-dairy probiotic and enzyme supplements, and alfalfa sprouts. Experiment with what the cat will accept, especially if she is used to dry kibble. To lower phosphorus, avoid milk and beef. Offer fresh filtered or distilled water to drink.
Cats prefer food that is body temperature and fresh (just killed). To tempt cats with a piece of raw chicken gizzard, wave it around as though it were alive and moving before tossing it to the cat. Bits of catnip can be added to food to make it more interesting. Be sure to practice safe handling methods when using raw meats.