Chronic Kidney Disease in Cats

Laurie Anne Walden, DVM

Chronic kidney disease is common in cats. It can affect cats at any age but is most common in older cats.[1] The disease has no cure. The goals of treatment are to slow the progression of the disease and maintain a good quality of life for the cat.
 
Functions of the Kidneys
The kidneys filter the blood and excrete waste products into the urine. When the kidneys don’t work properly, these waste products accumulate in the body. The kidneys balance the body’s water level by adjusting the urine concentration. Kidney disease impairs the ability to concentrate the urine and retain water in the body, so animals with kidney disease become dehydrated. The kidneys also help regulate blood pressure, red blood cell production, and acid-base balance.
 
Signs of Kidney Disease
Kidney disease is already advanced (at least two-thirds of kidney function lost) by the time signs of illness appear. Cats typically have the following signs:

• Increased thirst
• Increased urine volume
• Decreased appetite
• Decreased activity
• Weight loss
• Vomiting
• Unkempt coat

 
Keep an eye on the size of the urine clumps in your cat’s litter box. Enlarging urine clumps can mean that urine volume is increasing, which is one of the earliest signs of kidney disease. Other disorders (like diabetes) can also increase the urine volume, so larger-than-usual urine clumps warrant a visit to the veterinarian.
 
As chronic kidney disease progresses, the loss of kidney function leads to further problems:

• Hypertension (high blood pressure)
• Dehydration
• Muscle wasting
• Mouth ulcers
• Anemia (lack of red blood cells)
• Electrolyte and mineral imbalances

 
Causes of Kidney Disease
Acute kidney injury is a rapid loss of kidney function over hours to days. Some of the many possible causes are toxins, infections, and shock. Depending on the cause and severity, acute kidney damage can sometimes be reversed with treatment.
 
Chronic kidney disease is more common than acute kidney injury in cats. In chronic kidney disease, kidney function gradually decreases over time. The cause is usually not known. The same entities that cause acute kidney injury can lead to chronic kidney failure. Other possible causes are high blood pressure, abnormal kidney development, infection or inflammation of the kidneys, disorders that alter blood flow to the kidneys, and cancer.[2]
 
Diagnostic Tests
Tests are used to diagnose kidney disease, assess the stage of the disease, identify metabolic problems caused by the disease, diagnose other disorders (like thyroid disease) that cats with kidney disease sometimes also have, and possibly reveal the cause of the kidney problem.
 
Blood tests and urinalysis (analysis of urine) are typically the first diagnostic tests for cats with suspected kidney disease. Blood pressure measurement, urine culture to test for bacterial infection, and ultrasound or x-ray imaging of the urinary tract are also commonly performed for cats with kidney disorders.
 
Cats with chronic kidney disease benefit from regular testing to monitor disease progression and adjust treatment. In general, these cats should see a veterinarian for blood tests, urinalysis, and blood pressure measurement every 3 to 6 months.[2]
 
The stage and substage of chronic kidney disease are evaluated with specific tests[3]:

• Blood creatinine level
• In some cases, blood symmetric dimethylarginine (SDMA) level
• Urine protein level
• Blood pressure

 
Treatment
Chronic kidney disease can’t be cured, but it can be managed. The prognosis is variable; some cats can live with the disease for years. If your cat has kidney disease, work with your veterinarian to craft a treatment plan that will give your cat a good quality of life.
 
Treatment strategies are based on the stage of disease and the individual cat’s needs and may include the following[1,4]:

• Diet change to a clinical kidney diet (best done gradually so the cat will accept the new food)
  
• Fluid therapy, often done at home by injecting fluid under the cat’s skin
• Medications and supplements to treat hypertension, loss of appetite, high blood phosphate level, low blood potassium level, protein loss, and anemia

 
References
1. Sparkes AH, Caney S, Chalhoub S, et al. ISFM consensus guidelines on the diagnosis and management of feline chronic kidney disease. J Feline Med Surg. 2016;18(3):219-239.
2. Brown SA. Renal dysfunction in small animals. Merck Veterinary Manual website. https://www.merckvetmanual.com/urinary-system/noninfectious-diseases-of-the-urinary-system-in-small-animals/renal-dysfunction-in-small-animals. Accessed February 26, 2019.
3. International Renal Interest Society. IRIS staging of CKD. http://www.iris-kidney.com/pdf/IRIS_2017_Staging_of_CKD_09May18.pdf. Updated 2017. Accessed February 26, 2019.
4. International Renal Interest Society. Treatment recommendations for CKD in cats. http://www.iris-kidney.com/pdf/IRIS_2017_CAT_Treatment_Recommendations_09May18.pdf. Updated 2017. Accessed February 26, 2019.
 
Photo by Nicolas Picard on Unsplash

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