Purpose of the Diets

Dietary management is one of the most effective methods of slowing

the progression of chronic kidney disease (CKD). Kidney diets

double the survival time of many animals with CKD and dramatically

decrease the need for hospitalization.

Description of Dietary Components

• Protein: Kidney diets have less protein than standard adult

maintenance diets. The protein that is present must be easily

used by the body. The best protein is from animal sources such

as egg, milk, beef, or chicken, and not from vegetable sources

such as tofu. The minimum protein contents shown on labels of

pet food containers cannot be directly compared, because those

values are affected by the amount of moisture in the diet and

by the caloric content, which vary widely. Labels also do not

indicate the biologic value of the protein, which is a measure of

how fully the protein can be used by the body. Animal proteins

have higher biologic value than vegetable proteins, and egg

whites have the highest biologic value.

• Phosphate: Phosphate restriction is an important part of formulating

a kidney diet. Protein contains phosphate, so protein

restriction also reduces phosphate.

• Fatty acids: Most commercial kidney diets are supplemented

with omega-3 fatty acids, which may have a beneficial effect

on kidney function.

• Sodium: Although sodium restriction is commonly recommended

for people with CKD, the role of salt (sodium chloride)

in CKD of dogs and cats is not completely understood.

Excessive salt supplementation or restriction may be detrimental;

moderate salt restriction is common in most kidney diets.

• Potassium: Because the kidneys are unable to conserve potassium,

low blood levels of potassium may develop in dogs

and cats with CKD. Kidney diets, especially for cats, are frequently

supplemented with potassium to account for the extra

urinary losses. In some patients, particularly those on chronic

dialysis and those receiving medications that may increase

blood potassium, high blood levels of potassium (hyperkalemia)

may develop while the animal is on a kidney diet.

• Vitamins: The B vitamins are water soluble, so they can be lost

in urine. Kidney diets typically contain increased levels of

B vitamins compared to maintenance diets.

Indications for Dietary Therapy

Kidney diets are generally recommended if the blood creatinine

concentration is greater than 2.0 mg/dL (milligrams per deciliter)

in dogs or 2.8 mg/dL in cats. Dogs and cats with acute kidney failure

may need more protein than most kidney diets provide.

Follow-up Care

Changing Diets

Animals with CKD frequently have decreased appetite, and rapid

diet changes are rarely well accepted. It may take weeks for your

pet to accept the new diet, so patience is necessary. A simple way to

change the diet is to offer the new food in the cat’s usual container

(bowl) next to the usual offering, while using a different container

for the old product. If you can put both products in similar containers,

the diet change may be easier. If the cat does not eat a new

canned food within 1 hour, take it up until the next feeding time.

Once the cat has been exposed to the food for a day or two,

offer the new food first, when the cat is the hungriest. After the

cat has eaten some of the new food or has initially refused it, offer

the old diet. Repeat this process until the cat is eating the new diet.

Once the cat is eagerly eating the new diet, you can start decreasing

the old diet until you are no longer feeding the old food. You

may decrease the old food in increments of ¼ cup until the change

is complete. This same process can be used for dogs.

Appetite stimulants may be helpful for cats while changing the

diet, on a continual basis, or as needed. If a cat with CKD will not

eat the kidney diet or does not eat enough to sustain normal body

weight, a feeding tube may be inserted so that an adequate amount

of the right kind of food can be fed easily. In addition, medications

and fluids can be given through the feeding tube, decreasing the

stress on both patient and caretaker.