Chronic kidney failure (also called chronic renal failure) is a degenerative disease of the kidneys that is most common in middle aged to senior cats, but is also seen occasionally in dogs of the same age category. In chronic kidney failure, the functional tissue of the kidneys deteriorates due to age and genetic factors. The result is that the kidneys become small and irregular, and become less able to perform their chief function, which is to rid the body of toxic waste products that accumulate regularly as a result of everyday metabolism. The kidneys also lack the ability to effectively perform their other chief functions, which is to concentrate the urine, stimulate the bone marrow to produce blood cells, and regulate blood pressure.
One of the first clinical signs appreciated by the owner of a dog or cat in kidney failure is that the patient begins to drink and urinate excessively. This can go on for some time before the patient starts to show signs of illness. As the kidney failure progresses, in addition to increased drinking and urination, the patient experiences weight loss, loss of appetite, and vomiting Kidney failure also predisposes the patient to chronic lower urinary tract infections, and anemia. Infections occur because the first line of defense against ascending infection, high concentration of the urine, is no longer possible. Since chronically failing kidneys cannot adequately concentrate urine, it remains very dilute, eliminating that initial barrier of protection against infection. Anemia occurs because the failing kidneys cannot produce enough of the hormone erythropoietin, a hormone normal kidneys would secrete to stimulate the bone marrow to synthesize red blood cells as numbers get lower.
Short of kidney transplant (which are being done at great expense but with questionable results at select veterinary colleges), kidney failure cannot be cured. Therefore, treatment is geared toward diluting out the toxic metabolic compounds that accumulate in the body as the result of the kidneys’ inability to filtrate them out of the blood stream. This is done through a process known as intravenous diuresis, which is aggressive intravenous fluid therapy administered for typically 2-3 days.
Another consequence of chronic kidney failure, is ulceration of the mucus membranes of the body. Mucus membranes include the gums and lining of the gastrointestinal tract. The high levels of toxins that can occur in kidney failure, compromise these sensitive tissues, therefore, healing them is an integral component in treating the kidney failure patient. A such, gastrointestinal protectants and antibiotics are also incorporated to combat nausea, secondary infection, and any secondary gastrointestinal ulcers.
If the patient is anemic, bone marrow stimulating therapy may be instituted with the synthetic hormone Epogen, an analogue of erythropoietin. Prognosis depends on the severity of disease at the time of diagnosis. Finally, if the patient is found to have secondary hypertension as the result of chronic kidney failure (far more commonly a problem seen in cats), blood pressure reducing medication such as amlodipine will be necessary for maintenance therapy.
When/if stabilization is achieved, the patient is maintained on a protein, sodium, and phosphorus restricted diet. This serves to minimize the work load of the kidneys thereby slowing the degeneration process, as well as keeping the patient more comfortable by minimizing toxins produced as metabolic waste. Minimizing the sodium intake helps to control secondary hypertension that often develops with kidney failure, while minimizing phosphorus decreases weakening of bone that occurs secondary to retention of phosphorus that often occurs as the result of kidney failure. A number of canine and feline kidney sparing prescription diets are available from your veterinarian, such as Hills K/D and Eukanuba Multistage Renal. While many patients will readily eat prescription renal diets, as there are engineered to be palatable, in cases where a kidney failure patient utterly refuses prescription diets, there are home cooked diet recipes that may be fed as well. Your vet can provide you with such recipes.
In dogs and cats afflicted with kidney failure that are cooperative patients, the owner can be taught to administer subcutaneous fluids at home. This is when fluids are administered by placing a needle just under the skin over the back between the shoulder blades. A bubble of fluid forms that gets absorbed over the course of a few hours. Subcutaneous fluids serve to hydrate the patient, increasing quality of life, while also helping the body to dilute out and excrete toxic waste products. In early stage kidney failure, I usually start with the owner doing this weekly, then gradually increase up to daily as the condition worsens over time.
Roger L. Welton, DVM
Founder and Chief Editor, Web-DVM.net
President, Maybeck Animal Hospital
Article updated 11/12/2012