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What to do when our pets' kidneys fail
Second of a two-part series.
My first article focused on a brief description of how a dog or cat's kidneys fail, as well as how to diagnose kidney disease/failure. This article will focus on how to slow the process once a pet is diagnosed with kidney disease/failure.
Adequate hydration is key in slowing the progression of disease. Ensuring a constant supply of fresh water at home is a must. Some patients will need to be admitted to the hospital for IV fluid diuresis, whereas some patients can receive subcutaneous fluids (IV fluids injected under the skin) at home.
Diuresis is different from dialysis in veterinary medicine in two ways. First, diuresis refers to giving IV fluids at a rate higher than is needed for hydration, forcing what is left of the functioning kidney to work harder to clear toxins from the system as compared to a machine actually filtering the toxins from the blood. Second, dialysis is very expensive and there are not many facilities that can provide it.
We, as veterinarians, used to think that we needed to restrict protein in order to minimize unwanted breakdown products of digestion to "take the load" off of kidneys.
After many years we understand that restricting protein does not really help as much as we thought and may cause other problems. Today's kidney diets are what are called modified protein diets. These diets are usually egg or dairy based because we know that proteins derived from these two classes of proteins are highly digestible and have less breakdown products than other types of protein. These diets are fully fortified but are also supplemented with extra potassium (patients with kidney failure lose potassium) and omega fatty acids.
Medications to ameliorate indigestion and increase appetite are also used to keep our patients eating when they are not feeling so well from an increase in toxic substances not cleared by failing kidneys.
Although the exact cause is unknown, we do know that pets with kidney dysfunction will have hypertension, or high blood pressure [what is called a renal (kidney) secondary hypertension]. This increased blood pressure will unfortunately lead to more kidney damage and speed up failure — kind of a vicious cycle.
Your veterinarian may suggest monitoring blood pressure on your pet and intervene with medications to control blood pressure when necessary to break this cycle.
High blood phosphorus
Failing kidneys do not regulate phosphorus levels correctly which leads to elevated blood phosphorus levels. When this happens, phosphorus chelates, or binds, with calcium in the bloodstream to form compounds that actually deposit in tissue (particularly the kidneys). This accelerates kidney failure. Phosphorus binders literally bind to phosphorus in the stomach and intestines before it is absorbed into the bloodstream so it stays in the gut and passes with the feces.
There is a hormone specifically produced by the kidneys called erythropoietin. Erythropoietin's job is to tell new red blood cells to come out of the bone marrow when old red blood cells die. When the kidneys decrease or fail to produce this hormone, our patients develop anemia (low red blood cell count). Injections of synthetic erythropoietin help to maintain adequate red blood cell counts when the kidneys can no longer do the job.
Quality of life
There comes a time when our patient's kidneys are so damaged that they no longer respond to fluid therapy, special diets or medications. This is the time to speak to your veterinarian about quality of life. For better or worse, there is an option in veterinary medicine that is not available in human medicine in the United States. That option is to end suffering. End-stage kidney failure is not a pleasant way to pass and I know that as much as I love my pets, I do not want them suffering at the end of their lives after all the joy they have given me.
Dr. Kearns has been in practice for 14 years.