Chronic Renal Disease

What is “Chronic Renal Disease”?

Chronic renal disease is the most common form of kidney disease in cats.  In CRD, your cat’s kidneys have begun to fail, and are no longer able to perform their normal function of removing waste products from the blood.  Chronic Renal Insufficiency is chronic renal disease in its early stage.  This gradually progresses to Chronic Renal Failure.  The term failure does not mean the kidneys have quit working, just that they are functioning very poorly.

There is no cure for chronic renal disease; the kidneys get progressively worse.  With medical treatment, though, most cats can live for several more months to years.

What causes Chronic Renal Disease?

There are many causes of CRD. The most common cause in cats is aging. Other causes are infection, stones, cancer and congenital disease. Most of the time the initiating disease process is difficult or impossible to determine.

What signs occur in my cat?

Chronic renal disease usually occurs in older cats.  Signs of kidney disease are listed below.

Weight loss

Cats with kidney disease lose large amounts of protein in their urine. This protein loss, along with a poor appetite, can lead to weight loss.  Weight loss is often the first and only sign seen in cats with chronic renal disease.

Increased thirst and urination

The kidney is an organ of water conservation. When kidneys begin to fail they lose their ability to concentrate urine. This causes your cat to urinate more, which in turn causes him to drink more.

Lethargy

Another function of the kidneys is to remove by-products of protein metabolism (called BUN and creatinine) and certain minerals (phosphorus) from the blood. These by-products build up in the blood if the cat has kidney failure and can cause lethargy.  Many CRD cats are also anemic, which contributes to lethargy and weakness.

Inappetance or vomiting

Again, as the kidneys fail, toxins build up in the bloodstream that can cause your cat to feel nauseous.  He or she may just have a poor appetite, or may start vomiting.

How is Chronic Renal Disease diagnosed?

Blood Test

Evaluation of BUN and creatinine is performed by a blood test. The blood test also gives information about electrolytes and minerals that will help us further evaluate the cat and prescribe treatment.  Unfortunately, up to 75% of the kidneys must be malfunctioning before the blood tests can detect kidney disease.

Urinalysis

The inability to concentrate urine is diagnosed through urinalysis. The urinalysis can also detect infection, blood and loss of protein.

Additional tests

Some cats with CRD have high blood pressure.  Your cat will be tested for hypertension and medication will be prescribed if he or she has elevated blood pressure.

Ultrasound can be used to evaluate the kidneys. This is a non-invasive procedure that may help in determining a prognosis. Ultrasound can also be used to biopsy the kidneys.

What is the treatment for Chronic Renal Disease?

If your cat has renal failure, he or she needs to be hospitalized for treatment for 3-5 days.  This treatment consists of giving large quantities of intravenous fluids to “flush out” the kidneys. Fluid therapy includes replacement of various electrolytes, especially potassium. Other important aspects of initial treatment include proper nutrition, antibiotics, and drugs to control vomiting and diarrhea.

There are three possible outcomes to this treatment: 1) the kidneys will resume functioning and continue to function for a few months to years.  2) The kidneys will resume functioning during treatment but fail again as soon as treatment stops. 3) Kidney function will not return. Unfortunately, there are no reliable tests that will predict the outcome.

What if my cat does not need to be hospitalized?

If your cat is not critically ill from CRD, or if she recovers from the hospitalized treatment, home treatment can be started.  The goal of home treatment is to keep your cat feeling well and to keep the kidneys functioning as long as possible. This is accomplished with one or more of the following, depending on the individual patient.

1. Abundant supply of fresh water
   Your cat must have an abundant supply of fresh water available at all times. Do not restrict your cat’s water in an attempt to decrease their urination. This may because your cat to become extremely ill.
2. A prescription diet for kidney disease
   Prescription diets for kidney disease have been shown to improve the quality of life in affected cats.  These diets are restricted in protein, in phosphorus, and are non-acidifying.  They also have anti-oxidants and are usually higher in calories than maintenance diets.  We carry several brands of dry and canned kidney diets.
3. Vitamins
   CRD cats lose lots of vitamins in their high volume of urine.  Supplementing vitamins helps replenish these.
4. Potassium supplement
   Many CRD cats lose potassium in their urine.  Low potassium levels leads to weakness and a poor appetite.
5. Fluids given at home
   Some cats will need fluids given under the skin (subcutaneously, or “SubQ”).  Extra fluids support the kidneys as their function deteriorates. This is done once daily to once weekly, depending on the degree of kidney disease.
6. A stomach acid controller
   Increase stomach acid is a common side effect of chronic renal disease. This causes stomach ulcers, which lead to inappetance, nausea, and vomiting. The excess stomach acid can be controlled by an oral medication.
7. Lactulose
   Since CRD leads to dehydration, many cats become constipated.  A cat laxative helps relieve this painful condition.
8. Epogen
   Many CRD cats are anemic.  Epogen stimulates red blood cell production, which alleviates the anemia. This treatment is in the form of injections given at the hospital or at home, and is usually reserved for severe cases.
9. Other medications include phosphate binder, hypertension medicine, and antibiotics.

What follow-up treatments are required?

Periodic blood tests and a urinalysis are run to measure your cat’s response to treatment and the progression of the kidney disease.  These are run every 1 – 6 months, depending on the severity of the disease.

Most importantly, you need to monitor your cat at home.  Things to watch for are: appetite, water intake, weight, and signs of illness, such as lethargy, vomiting, or diarrhea.

What is the prognosis for my cat?

The prognosis is quite variable depending on the stage of the disease when it is first diagnosed, the response to the initial stage of treatment, and your cat’s tolerance of the at-home care. Cats handle chronic renal disease fairly well. If they respond to the initial treatment, they typically remain stable for years, with periodic exacerbations that may require fluid therapy either at home or in the hospital.