Chronic Renal Failure
The term “chronic renal failure” (CRF) means the kidneys have sustained irreversible damage. By
definition, renal failure is the inability of the kidneys to remove waste products from the blood as well
as to conserve water. Kidney failure is NOT the inability to make urine. In fact, most animals in kidney
failure are actually producing large quantities of urine, but the body’s wastes are not being effectively
eliminated and the body’s water is not being appropriately conserved.
How it Affects a Pet
The kidneys are essentially filters through which the blood flows for cleansing. When aging and kidney
damage cause the filtration process to become inefficient and ineffective, the kidneys are no longer
able to conserve water, resulting in the production of more urine. To keep a pet from becoming
dehydrated due to increased fluid loss in the urine, thirst is increased; this results in increased water
consumption. Thus, early clinical signs of kidney failure are increased water consumption and
increased urine production. The clinical signs of more advanced kidney failure include loss of appetite,
depression, vomiting, diarrhea, and very bad breath. Occasionally, ulcers will be found in the mouth.
Diagnosis
Bloodwork, including a complete blood count and biochemical profile, is essential for the appropriate
diagnosis of chronic renal failure. Specifically, determining the level of metabolic waste products,
including blood urea nitrogen (BUN) and blood creatinine, helps make a diagnosis of kidney failure. A
sterile urine sample collected by your veterinarian is also needed to complete the study of kidney
function.
Treatment
The goal of treatment is to maintain the efficiency of the remaining amount of functional kidney tissue.
Perhaps most importantly, treatment is aimed to make your pet feel clinically well! We must recognize
your pet’s kidneys have reached this point due to long-standing disease or aging. Therefore, they will
never be normal again. However, many animals still have enough functional kidney tissue so
treatment will be very rewarding.
First Phase Treatment
The first phase of treatment is performed in the hospital, and is not required for every patient living
with chronic renal failure. In-hospital therapy includes aggressively addressing your pet’s hydration
status with intravenous fluid therapy, as well as treating any underlying disease process potentially
complicating your pet’s ability to cope with his/her limited kidney function. Once your pet is feeling
better and is able to be discharged from our care, second phase treatment may begin.
Second Phase Treatment
The second phase of treatment is performed at home. The goal is to help prevent further
deterioration of kidney function as long as possible. This is accomplished with one or more of the
following, depending upon the situation.
1. Kidney Failure Diet: Diets are formulated with several characteristics beneficial to pets with a
history of kidney disease. These diets are typically restricted in protein to prevent a buildup of
protein waste products in the blood. They are also lower in phosphorus to help control the
phosphorus level in the blood.
2. Potassium Supplementation: Potassium is lost in the urine when urine production becomes
excessive. A potassium supplement will replace this loss. Low potassium levels have been shown
to further reduce kidney function. For this reason, a potassium supplement is recommended when
serum potassium levels are consistently low.
3. Fluids Administered at Home: Once your pet is stabilized, fluids may be given under the skin
(subcutaneously). This serves to help maintain your pet’s hydration and clinical wellness. This is
done once daily to once weekly, depending upon the degree of kidney failure and how your pet
feels. Although this might not sound like something you can do, you will be surprised at how easily
the technique may be learned, and how well most pets will tolerate it.
4. Drugs for Excess Stomach Acid: Evidence indicates excess stomach acid may cause nausea, and
may reduce your pet’s appetite. Drugs with this action are usually given only if appetite is
improved while they are administered.
5. Phosphate Binder: Phosphorus levels are often elevated in animals living with chronic renal failure.
This contributes to lethargy and poor appetite. Certain drugs will bind excess phosphates in the
intestinal tract so they are not absorbed, resulting in lower blood levels of phosphorus. If the lowprotein diet is not successful in maintaining normal phosphorus levels in the blood, a phosphate
binder may be necessary.
6. Drugs for High Blood Pressure: Many animals with kidney failure have high blood pressure. It will
become normal in many pets following hospital treatment, but remains elevated in others. These
drugs are used only if needed.
7. Drugs to Regulate the Parathyroid Gland and Calcium Levels: An elevated phosphorus level may
stimulate the body to remove calcium from bone through series of complicated hormonal
reactions. Should an imbalance between phosphorus and calcium develop, your pet’s veterinarian
may prescribed various medications to address these biochemical changes.
8. Drugs to Stimulate Bone Marrow Production of New Red Blood Cells: The kidneys produce
erythropoietin, hormone that stimulates the bone marrow to make red blood cells. Therefore,
many pets with renal failure have low red blood cell counts, a condition commonly referred to as
anemia. Epogen™ and Procrit™ are synthetic forms of erythropoietin, and may be used to help
correct the anemia in some pets. Unfortunately, complications may occur, and these drugs are
only used if necessary. These drugs may not be used long term, as the immune system recognizes
them as “foreign”, making antibodies (immune proteins) against it.
Life Expectancy
Although BUN and creatinine levels reflect kidney failure, they do not predict what will happen
tomorrow or next week. A pet with marginal kidney failure may have normal blood tests. If an animal
is stressed with major illness or surgery, the kidneys may fail, sending the blood test values up quickly.
The prognosis is quite variable depending on response to the initial stage of treatment, as well as your
ability to perform the follow-up care. However, we encourage treatment in most situations because
many pets will respond and lead a good, quality life for up to 4 years.