The kidneys perform very important life functions that are classified into three categories. First, they excrete wastes, which are by-products of protein breakdown. Secondly, the kidney regulate the body's water balance as well as the balance of sodium and chloride in the bloodstream. Thirdly, the kidneys produce hormones that affect the production of red blood cells and control calcium and phosphorus balance in the body. They also regulate hormones that control blood pressure. Because of these functions, it is easy to understand why disease of the kidneys can cause significant illness. The kidneys must lose 2/3 to 3/4 of their functions before toxins build up in the blood stream and we are able to diagnose kidney failure. Before this 2/3 to 3/4 loss of normal kidney tissue, the animal will act normal, making early diagnoses of kidney disease difficult.

Chronic renal failure (CRF) is the most common form of kidney disease. CRF most often affects middle aged to elderly animals and can lead to a progressive loss of kidney function. In most cases, the cause of kidney failure is due to the replacement of normal kidney tissue with non-functioning scar tissue. Specifically why this happens is usually unknown. Sometimes however, we can blame the kidney failure on viral or bacterial infections, kidney stones, cancer, or deposit of protein (amyloid) in the kidney's filtering system. In most cases it is not possible to cure the disease and CRF gradually worsens over a period of weeks, months, or even years. It is difficult or impossible to determine whether an individual's disease will progress slowly or rapidly.

A diagnosis of CRF is made on the basis of clinical signs, physical exam findings, and laboratory evaluation. Clinical features of CRF include drinking and urinating excessively, weight loss, vomiting, bad breath, poor appetite and weakness. Diagnosis requires blood work and an analysis of the urine. Changes in blood work include elevated toxins (BUN and creatinine), elevated phosphorus and anemia (low red blood cell count). Urine abnormalities include poor concentration and an excess amount of protein. As kidney disease progresses, animals may stop drinking and eating altogether and become more depressed. On-going weight loss and increased vomiting may also occur as kidney disease worsens.

Treatment of kidney failure involves correcting dehydration and blood chemistry imbalances. One of the most important measures of therapy is to keep the patient well hydrated. This may involve a period of hospitalization to treat with intravenous (IV) fluids. Fluid therapy improves clearance of toxins, corrects dehydration and also treats electrolyte and acid/base imbalances.

When the patient is stable and at home, some owners are willing to administer subcutaneous (under the skin) fluids. This can be of great benefit since maintaining hydration and assisting the removal of toxins is paramount in minimizing the signs and progression of kidney disease.
In addition to fluid therapy, long term treatment of kidney disease with a protein restricted diet has been a cornerstone of therapy and remains an important measure for managing CRF. This helps decrease blood toxins which are by-products of excess dietary protein. To accomplish this goal, it is ideal to utilize a prescription food made especially for kidney disease, such as Purina NF and Hill's K/D diets. Specially prepared homemade diets are an acceptable alternative to prescription food.

Elevated blood phosphorus often accompanies kidney disease due to a complex process that involves increased parathyroid hormone. Treatment of increased phosphorus involves reducing the phosphorus intake by lowering phosphorus content in the diet. This is another important feature of prescription kidney diets. If dietary phosphorus restriction alone is not effective, then medicine that binds phosphorus is given with meals to prevent phosphorus absorption.

Since high blood pressure is common with kidney disease, a salt restricted diet is beneficial. Ailing kidneys also allow vitamins to be lost more readily; therefore, increased vitamin supplementation is also a feature of commercial prescription diets. Restricting protein, salt and phosphorus, as well as adding more vitamins should all be taken into account for maximum patient benefits.

Elevated toxins cause nausea, an increase in stomach acidity, and can even lead to ulcers in the mouth and stomach. These problems are treated with antacids and anti-nausea medication. Dialysis and kidney transplants have limited availability. We are fortunate, however, that there is a feline renal transplant program at North Carolina State University. The patient and his/her owner must meet narrow enrollment guidelines for acceptance. The cost of transplant therapy is several thousand dollars and owners must also adopt the donor cat. Even if limited, it is reassuring to know this form of therapy is available.

The specific treatment method is tailored to each individual patient and their owner's desires. Even though CRF cannot be cured, many of our kidney disease patients live with extended quality of life and continue to bring happiness to their homes.