Chronic kidney disease (CKD) is associated with an irreversible loss of kidney function that occurs gradually over months or years and eventually leads to kidney failure.  It is a common disease in older cats.  The kidneys are organs that maintain the body’s balance of fluid and electrolytes (potassium, sodium and chloride) and filter out waste material in the form of urine.  The kidneys also regulate the metabolism of calcium and phosphorus, help maintain normal blood pressure and produce a hormone (erythropoietin) that stimulates red blood cell production.

Signs of kidney disease (increased thirst, urination, vomiting, and weight loss) may not become evident until more than 65% to 75% of the total kidney function has been lost.  As more of the kidney becomes non-functional, the body decompensates in many areas and requires more intervention to maintain normal function. CKD is classified into four stages based on results of lab work and clinical signs. For more information on CKD, FelineCRF.com is a good source.

Many lab tests are needed to evaluate CKD and follow-up testing is critical in helping us keep up with the many changes that occur as the disease progresses.  We commonly measure several parameters of kidney function via blood and urine:  BUN (waste by-product of protein metabolism), Creatinine (waste by-product of muscle metabolism), Specific gravity of urine (ability of kidney to concentrate urine), urine sediment and culture (bladder infections), Packed Cell Volume (PCV)-red blood cell level (anemia), Total protein (dehydration), Phosphorus/Calcium. Potassium, and Blood pressure.  In addition, we assess body condition, weight and overall physical status at regular exams. 

Treatment for CKD depends on stage of disease at presentation and the signs that are present. In the early stages, a diet change may be all that is needed to keep the cat stable. Patients with advanced disease will require numerous medications, treatments and frequent veterinary evaluations. 

Home Management: An important key to long-term management of CKD is the care that your cat receives at home.  You may take several steps to help slow the progression of the disease.  Always ensure that your cat has access to fresh, cool water.  Some owners have reported that their cats prefer to drink from a running water source.  There are “kitty fountains” available in many pet stores.  Another way to encourage your cat to eat and drink is to maintain a stress-free daily routine.  Stressed cats will often stop eating and drinking, which will further compromise their kidney function.  Cats who have CKD will urinate more.  Be sure litter boxes are cleaned daily and placed in easily accessed areas.  Medications that can potentially damage kidneys should be avoided whenever possible.

Kidney friendly diets:  Dietary management is an important factor in slowing the progression of renal failure.  Prescription renal (kidney) diets are usually restricted in the amount of protein, sodium and phosphorus they contain, but provide daily requirements of non-protein calories, vitamins and minerals.  Reduced protein diets will generate fewer nitrogen-based waste products and help reduce the level of wastes in the blood.  Prescription diets k/d, l/p, NF, Iams Renal and others are specially formulated diets that we have available to treat CKD.  These are long-term diets and any transition to them should be done gradually. Cats can be very picky and it may take up to 3 weeks to make a switch.  Try several different diets and be patient.  Canned diets are generally preferred over dry, but both are acceptable for most cats.  If your cat absolutely, positively will not eat a kidney friendly diet, a good quality senior type diet may be used

Fluids:  Patients with CKD tend to produce large amounts of urine (polyuria) due to the kidneys’ impaired ability to reabsorb water back into the blood stream.  If the cat is unable to drink enough to compensate for the loss of water from the kidneys, dehydration will occur.  Adequate hydration is an important component in the treatment of CKD.  In many cats, supplemental fluid may have to be administered at home.  Injecting fluids under the skin is an easy and effective way of providing extra fluid needs to the damaged kidneys.  Most owners are very capable of performing this valuable treatment.  

Anti-nausea medication/Appetite stimulants: Other organs are ultimately affected by a decrease in kidney function.  The increased level of wastes in the blood may cause irritation to the lining of the stomach resulting in nausea, vomiting and anorexia.  To help control these symptoms, patients are often treated with drugs known as H2 blockers and/or drugs to control vomiting.  Pepcid AC (1/4 of a 10 mg tablet) is commonly given once daily. We often use Mirtazipine every 3 days to stimulate appetite.

Phosphate binders: The level of phosphorus in the body may be abnormally high in patients with renal failure and can lead to significant problems with calcium and bone density.  Phosphorus is absorbed from food in the intestinal tract.  Dietary management with a kidney friendly diet is often all that is needed for control of phosphorus.  If the cat will not eat a special diet or if the diet alone is not effective, powdered aluminum hydroxide is added to the food to bind up phosphorus and minimize its absorption from intestines. 

Potassium:  As kidneys lose function, the potassium level may also decrease causing hypokalemia.  This can lead to muscle problems and weakness.  Potassium supplementation, if needed, is given twice daily.  It is available as a tablet or powder.   

Anti-hypertensive medication: Hypertension (high blood pressure) may also be associated with renal failure.  Increased blood pressure may result in further damage to the kidneys along with damage to other organs (examples: detached retinas causing sudden blindness).  Dietary sodium (salt) restriction (via kidney friendly diets) is one step in treating this condition, but anti-hypertensive drugs are often needed to reduce blood pressure.  We commonly use amlodipine once to twice daily to control high blood pressure.

Erythropoietin:  In a healthy animal, the kidneys synthesize the hormone erythropoietin, which stimulates cells in the bone marrow to make red blood cells.   When the kidneys’ ability to synthesize erythropoietin is reduced a complication called anemia results.  There is a synthetic version of this hormone, Epogen® that is produced for use in humans.  Epogen® may be used in cats, and is administered at home as an injection similar to insulin therapy for diabetics.  Because Epogen® is a human product, cats may develop immunity or tolerance to this therapy with time.  Thus, treatment is usually reserved for later in the course of this disease.  Anemic cats tend to be tired due to decreased oxygen and nutrient carrying ability.  

Severe renal failure may require more aggressive treatment.  Often, cats need to be hospitalized and receive IV fluids and closer monitoring.  Kidney dialysis is sometimes available when kidney function has deteriorated dramatically.  Kidney transplants are done in some areas of the country.   

Please monitor your cat carefully for changes in eating, drinking, elimination or behavior and contact us if these should occur.  Early detection and management of kidney disease can often provide years of quality life for our kidney patients.