Kidney (renal) problems in cats

Written by Liz Palika Reviewed by Kristin Westafer, DVM

Overview

The kidneys are very important organs. They have multiple functions in the body including filtering and eliminating waste from the blood, producing urine, and regulating blood pressure. The kidneys also produce a hormone, erythropoietin, that is responsible for stimulating the bone marrow to produce red blood cells. Vitamin D is also activated by the kidneys and is very important for proper calcium absorption from the gastrointestinal tract.

Renal (kidney) insufficiency or failure can be caused by several different things. Now that our feline friends are living longer because of better health care, their kidneys often become worn out and their function diminishes over time. However, if the kidneys are damaged because of reduced blood flow to the kidneys from conditions like shock, heart failure, or even dehydration, then renal disease can result. Kidney problems can also occur secondary to some medications, ingestion of household plants, like lilies, or after the ingestion of anti-freeze. If there is a blockage in the urethra serious kidney problems can result.

Most kidney disease in the cat is slow in onset and occurs as the cat ages. The decline of the kidneys develops over time, and often progresses despite treatment. Kidney disease is called renal insufficiency in the early stages of disease and progresses to renal failure once certain blood values are elevated on routine bloodwork. Although more common in older cats, renal insufficiency and failure can sometimes be inherited and show up in cats under one year of age, especially in the Persian cat.

Clinical signs are often missed during the early stages of kidney disease because the changes are very subtle. When a cat has renal insufficiency, 66% of their kidney function is lost and they produce very dilute urine. As renal insufficiency progresses to kidney failure, greater than 75% of their kidney function is lost. Cats with renal failure often feel poorly and decline because of the increased amount of waste products in their blood.

Cats with kidney disease may also have protein in their urine and develop high blood pressure. The increased loss of protein is thought to ultimately worsen kidney function over time and measures are usually taken to decrease the amount of protein in the urine. High blood pressure can cause secondary heart problems, vision loss, as well as worsening of kidney function.

Symptoms

The symptoms will sometimes vary, depending upon the underlying cause, however the most common ones include:

Occasional vomiting
Excessive thirst and urination – cats often make frequent trips to the litter box and produce large quantities of urine. You may notice that you are having to clean the litter box more often.
Vomiting becoming more frequent as the disease progresses
Weight loss and lack of appetite
Diarrhea
Poor grooming habits
Complete lack of urine production
Decreased appetite
Inappropriate elimination or urinating outside the litter box
Elevated blood pressure
Weakness, especially in the neck
Anemia

Treatment

Kidney values are often increased because of reduced blood flow to the kidneys, as from shock, blood loss, heart failure, or dehydration, these elevations may resolve completely with appropriate treatment. This treatment will vary depending upon the individual situation, but usually requires intravenous fluid administration and hospitalization. However, if these values do not resolve after treatment, your cat may have true kidney disease and will require more appropriate treatment.

If the kidney disease has been caused by problems with the urinary system (such as an urethral obstruction), this kidney disease may be resolved partially or completely when the blockage is corrected. A urinary blockage is an emergency condition and cats will need treatment immediately. If your cat is making frequent trips to the litter box and is not producing urine, is straining, acting painful, or becomes laterally recumbent, they need to be evaluated by a veterinarian immediately.

Treatment options for renal disease vary according to the severity of the disease. Cats with early kidney disease should be placed on an appropriate died that is mildy protein restricted and made with high quality protein. Early kidney disease appropriate diets are also mildy phosphorus restricted and only mildly sodium restricted. Commercial diets are available and some veterinarians recommend appropriate home cooked diets that are balanced for cats. Taurine and multiple vitamin formulations are important (especially B complex vitamins) and must be added if you are attempting a home cooked diet. Cats with renal failure may need to be placed on a diet that is moderately protein restricted and made with good quality protein, as well as a diet that is moderately phosphorus restricted and low in sodium. Cats with any stage of kidney disease may need phosphorus binders in their diet and potassium supplementation. Medications to decrease the amount of protein lost in the urine and to improve blood pressure, such as ACE inhibitors like benazapril, may also be needed. Veterinary medical treatment may also be required for a period of time for severe cases. Additionally, if your cat has a high blood phosphorus level, a drug known as calcitriol may be added to their treatment.

Cats that develop anemia as a result of their kidney disease may require blood transfusions or injections of human origin erythropoietin. Unlike dogs, cats must be blood typed and cross matched before they are given blood products; otherwise, they can develop severely life threatening transfusion reactions. Erythropoietin injections have shown to be beneficial for some cats, however, they are costly. Cats also develop antibodies to the foreign erythropoietin over time and the injections lose their effectiveness.

As your cat’s kidney function decreases over time, they will eventually be unable to drink enough water to keep up with the amount of fluid they are losing through their urine. When this occurs, these cats become dehydrated and will require periodic or daily administration of fluids under their skin. Your veterinarian will show you how to do this. Most cats tolerate this very well and enjoy the attention they get from the treatment.

The costs for diagnosing and treating kidney disease will vary. The examination, which can include palpating the kidneys, may run from $30 to $50. Blood and urine tests, as well as x-rays, can add $200 to $400 to the bill. Hospitalization, IV fluids, and other treatments usually run $200 to $300 per day. However, this will vary greatly by your area of the country and on a case-by-case basis.

What to expect after kidney problems

Acute kidney failure can be fatal if treatment is delayed. However, cats with chronic kidney disease can survive for a long time despite having lost more than 66% of their renal function, if they are provided adequate treatment. The specific care depends upon your cat’s individual situation.

Increase their water intake. Fresh water should always be available. Water intake should be encouraged. Some cats prefer to drink water from different locations, such as kitty fountains, coffee cups, or bowls in differing locations around the house. Some cats also have a preference for bottled or tap water. Switching to wet food or adding a small amount of water to their dry diet will also increase the amount of water they are consuming.
A special diet appropriate for your cat’s stage of kidney disease
Make sure the cat is getting adequate supplements of taurine, multi vitamins, and B complex vitamins if you are feeding a homemade diet
Regular veterinary check-ups
Medications to treat your cat’s specific problems as related to their kidney disease