Chronic kidney disease is a common condition in older cats. It is caused by damage to the kidneys that gradually occurs throughout the cat’s life. In essence, the kidneys “wear out.” As this happens, the kidneys lose their ability to function. In the early stages, cats appear normal.
Kidney disease can be found on routine blood and urine screening tests.
Our Video on Feline Kidney Disease
There are a lot of things that normal kidneys do. A normal kidney's functions include:
Fluid balance regulation
Blood toxin removal
Blood pressure regulation
Red blood cell production
Healthy kidneys help keep a cat's metabolism in balance.
Because the kidneys have a lot of reserve, we generally do not see any signs and can not detect the disease until about 65% of the kidney function is lost.
The first important function of the kidneys that is usually diminished is their ability to conserve water. They gradually lose the ability to concentrate urine. Because of this, the first sign usually seen with chronic renal disease is increased drinking and urinating. The urine becomes noticeably dilute - more and more like water. This can be detected with a urinalysis.
As kidney disease progresses, more functions are diminished. As this happens, the cat starts to show signs associated with loss of these functions, such as lethargy and weight loss.
Cats start to lose their ability to conserve water when about 65% of their kidney function is lost.
They start to lose the ability to excrete toxins when about 75% of their kidney function is lost.
With Kidney Disease
Cats with kidney disease commonly get:
Kidneys lose their ability to maintain metabolic balance.
Treatment of kidney disease is aimed at:
Reducing progression of the disease
Treating secondary conditions (e.g., toxin accumulation, anemia)
Maintaining quality of life
Ultimately, the primary goal of treatment is to increase the quality and length of the cat’s life.
The success of treatment varies but many cats live for years with this disease.
It is important to remember that a main goal of treatment is to increase or maintain quality of life. If a given treatment diminishes this quality of life significantly, then it should be discontinued.
It is also important to remember that it is our job to advise you of the best possible medical care and that this level of care can be expensive. Obviously, it is up to you to decide what tests and treatments are appropriate for your cat.
The primary goal of treating cats with kidney disease is to increase the quality and length of the cat’s life.
With Kidney Disease
Weighing the patient is a critical means of assessing effect of treatment and progression of disease. Regardless of the results of the other tests, if the patient is not on a calorie restricted diet but is losing weight, something is wrong.
We recommend a complete exam every 6 months to assess the overall condition of the patient. It is to look for problems related to the kidney disease and to look for new disease.
The kidneys produce urine so it makes sense that testing urine can tell us a lot about the status of the kidneys. A urinalysis can tell us whether the kidneys are currently concentrating the urine (this usually does not improve with treatment). It can also give an indication of something else occurring within the kidneys – e.g., infection, protein loss.
One of the important tests for cats with kidney disease is to monitor their weight.
Blood Chemistry Panel.
The blood tests that are included in the panel look for changes that occur as the kidney disease progresses:
BUN / Creatinine / Phosphorus – waste products that increase with disease.
Potassium (K+) – decreases with kidney disease. Low potassium can also cause/contribute to reduced kidney function.
CO2 – is an indirect measure of total body acid – CO2 decreases as acid levels increase.
Calcium (Ca+) – increases with kidney disease.
A complete blood count (CBC). measures the number and types of cells in the blood. It is used to diagnose anemia (low red blood cell count). It can also give an indication of infection and other
Measuring blood pressure.
Blood Pressure Measurement.
The kidneys help regulate blood pressure, and as their function diminishes, cats often develop high blood pressure. This high blood pressure can damage internal organs – including the kidneys themselves.
Urine Culture and Sensitivity.
As the urine becomes more dilute and as the kidneys become more “sick”, they are more susceptible to infection. This infection can further damage the kidneys and is best treated with long-term antibiotics. Since infection is often hidden (i.e., the urinalysis can be normal even with infection present) it is best to culture the urine occasionally to check for infection.
It is worthwhile to radiograph the abdomen to look at kidney size and shape and to check for stones.
Radiograph of a cat with a kidney stone.
We consider water to be the most important treatment for kidney disease. It is imperative that your cat always has plenty of fresh water available. Most cats prefer bottled or filtered water to tap water and it is worth the small expense to provide this. If your cat prefers to drink running water, we recommend a fountain made for cats (Petwell Pet Fountains have worked well, in our experience).
Low Phosphorus Foods.
Cats with kidney disease lose some of their ability to eliminate phosphorus into the urine. Diets that are low in phosphorus can help prevent the cats' blood phosphorus from getting too high.
This is a list of cat foods that are relatively low in phosphorus while still being high in protein and relatively low in fat and carbohydrates:
This is an oral drug that can help decrease the production of a hormone called PTH. PTH is a substance that is increased with kidney disease and contributes to the negative clinical signs seen with the disease. Some of the blood tests should be repeated a month after this medication is started to assess for negative effects.
With kidney disease, stomach acids are sometimes increased, causing a loss of appetite. This human over-the-counter drug can decrease the amount of acid. We usually recommend trying Pepcid AC at ¼ to ½ tablet every day or every other day. If it seems helpful in improving appetite, then the Pepcid should be continued. Pepcid AC, or its generic equivalent, famotidine, can be found at most stores. Do Not use Pepcid Complete.
Omega-3 (n-3) Fatty Acids.
There is some evidence that omega-3 fatty acids may decrease the progression of renal disease. It may be helpful to supplement your cat’s diet with omega-3’s – i.e., fish oils (not flaxseed oil).
There are several other treatments for cats with renal disease that may be recommended based on the results of the tests.
Available water is critical to cats with kidney diease.
with Kidney Disease
There are a few prescription diets that are made for cats with kidney disease.
None of these have been shown to be better for cats with kidney disease than over-the-counter high protein, low phosphorus, canned foods. It is our opinion that in the long run, these diets are more harmful than helpful for most cats.
Cats with kidney disease can not conserve water. If for any reason they are not able to drink (e.g. no access to water or vomiting), they will become dehydrated quickly. For this reason, they must always have water available and should be treated promptly for any other sickness that they develop.
Sometimes we recommend a different diet for cats with kidney disease. It is more important that these cats eat than that they eat the correct food. It is usually best to introduce the diets gradually and if your cat will not eat the recommended food, feed them something else.
Commercial diets made “to promote urinary health” are not made for cats with kidney disease. They are made for cats with urinary bladder disease. As such, they are high in acid and are potentially detrimental to cats with kidney disease. These may be the worst food to feed cats who have kidney disease.
The blood parameters fluctuate normally throughout the day. For this reason, one abnormal reading may not be significant. So we often do not start treating based on one blood or urine test.