Nutritional Management of Chronic Kidney Disease in Cats
What is chronic kidney disease?
Chronic kidney disease is an irreversible loss of kidney function. Chronic kidney disease is diagnosed in approximately 1 in 3 cats over 10 years of age. Although there are acquired causes, in most cases the cause for this condition is unknown.
Based on clinical exams and laboratory tests performed by your veterinarian, chronic kidney disease in cats can be staged (from stage 1 to stage 4) and managed with a combination of medical treatments and therapeutic diets. Although there is no cure for this disease, there is evidence that it can be successfully managed, and diet is an important part of that.
When do I need to start feeding a therapeutic diet to my cat?
Based on clinical evidence, the IRIS suggests therapeutic diets be considered for cats with stage 2 and recommends feeding therapeutic renal diets to cats with stages 3 and 4. There are therapeutic “early renal” diets that may be beneficial for some cats.
Cats that receive a therapeutic renal diet in the hospital often reject the diet at home after discharge, so veterinarians recommend starting a therapeutic renal diet in a comfortable home setting.
What are the goals of the nutritional management of chronic kidney disease?
There are four main goals:
a) to provide enough energy and nutrients.
b) minimize electrolyte and acid-based imbalances.
c) improve quality of life by reducing the severity of clinical signs, which helps the cat feel better.
d) slow down the progression of the disease and help prolong lifespan.
To achieve these goals, there are therapeutic diets supported by clinical evidence, that are formulated for cats with CKD.
Cats with chronic kidney disease typically show a waning and waxing appetite. Ensuring adequate food intake is essential. If energy needs are not met, the consumption of body tissues occurs, which leads to the loss of lean body mass and increases the risk of mortality. Therapeutic diets are high in calorie density and tend to be palatable.
If the patient will not eat any of the commercial therapeutic diets for chronic kidney disease, consulting with a veterinary nutritionist is recommended to consider formulating a therapeutic home-cooked diet. However, in some cases, assisted feeding may be necessary. The use of feeding tubes aids in feeding the correct amount of the appropriate diet. A feeding tube is also an easy route to provide water and medications.
Because the kidneys eliminate less phosphorus through the urine with progressive chronic kidney disease, dietary intake of phosphorus must be reduced. This is addressed in therapeutic renal diets. Dietary modification may take several weeks to have an effect on the phosphorus status in the body. Thus, phosphorus should be monitored and if diet alone fails to achieve the phosphorus target, adding an intestinal binding agent may be recommended by your veterinarian.
Protein should be reduced to minimize the breakdown products that may cause clinical signs such as vomiting, lethargy, decreased appetite, and diarrhea, especially in later stages of chronic kidney disease. Excessive reduction can result in muscle wasting. For this reason, high quality protein sources are used in therapeutic diets for chronic kidney disease. Different therapeutic renal diets have different degrees of protein reduction, and the choice of diet should be made for the individual patient.
It is not uncommon to see low potassium in cats with chronic kidney disease due to increased losses in the urine. This may result in decreased food intake and/or muscle weakness. Therapeutic renal diets are supplemented with potassium. Your cat’s potassium status should be assessed regularly, and in some cases, additional supplementation will be recommended by your veterinarian.
Although dietary sodium restriction is recommended for humans with chronic kidney disease, there is no evidence suggesting this is necessary in cats. In fact, there is evidence that excessive restriction can be harmful. Therapeutic renal diets have lower amounts of sodium compared to maintenance diets formulated for healthy adult cats but still meet nutritional requirements for this essential mineral.
Animals with chronic kidney disease have an increase in their urine volume, and therefore increase losses of water-soluble vitamins. Deficiencies of these vitamins may contribute to decreased appetite. Therapeutic diets are supplemented with increased amounts of water-soluble vitamins (such as B vitamins) and further vitamin supplementation is rarely necessary.
Omega-3 Fatty Acids
Therapeutic diets are supplemented in polyunsaturated omega-3 fatty acids (EPA and DHA) for kidney protective effects. Further omega-3 fatty acid supplementation is rarely needed if the patient is fed a therapeutic renal diet.
How do I transition my cat from their original diet to a therapeutic diet?
Transition to a therapeutic diet is recommended over 3 weeks. A typical transition protocol is:
- week 1: 25% therapeutic diet, 75% original diet
- week 2: 50% therapeutic diet, 50% original diet
- week 3: 75% therapeutic diet, 25% original diet
- week 4: 100% therapeutic diet
Provide small, frequent meals. Canned diets should be warmed to slightly above room temperature prior to serving. When warming, ensure there are no areas that are too hot, as microwaves can often heat food unevenly. All meals should be offered in a secure, familiar environment with minimal distractions. Positive reinforcement (petting and praise) should accompany meals to help encourage food intake. It is not recommended that medications be mixed with a therapeutic renal diet. Many medications have an unpleasant taste and will decrease food intake and/or result in food aversion.
What is the outcome of cats with chronic kidney disease?
Evidence shows that nutritional modification can slow down progression of chronic kidney disease and help manage clinical signs. It has also been shown that when food intake is adequate, therapeutic renal diets can maintain body weight and body condition for up to two years. However, nutritional therapy like any other kind of therapy needs to be tailored to the individual cat and the outcome may vary significantly. Consulting with a Board Certified Veterinary Nutritionist can help your cat receive a customized nutritional plan.