Kidney Disease In Cats And Dogs

Written by Shula Berg BVSc CertAVP(GSAS) GPAdvCert(SASTS) MRCVS
Clinically reviewed by Elizabeth McLennan-Green BVM&S CertAVP(SAM) MRCVS

Table of Contents

 - Overview
 - Symptoms
 - Diagnosis
 - Treatment
 - Outlook

What is Kidney Disease?

Kidney disease, also known as renal failure, is a common condition in middle-aged to older cats and dogs. Occasionally, there is an underlying cause such as cysts in the kidneys or ingestion of a toxin (such as lilies in cats, or raisins in dogs), however, in the majority of cases, no cause is found. Renal failure is a progressive condition. Many animals can survive for several years as treatment slows down deterioration, but eventually affected pets will need to be put to sleep (euthanasia). 

What are the symptoms of Kidney Disease?

The kidneys filter waste products out of the blood into urine; when they are not working properly, these waste products start to build-up in the blood, making the animal feel unwell. Common symptoms of renal disease include: 

  • Increased thirst and urination 
  • Decreased appetite
  • Weight loss
  • Dehydration
  • Lethargy
  • Bad breath
  • Vomiting 

Which tests are used to diagnose Kidney Disease?

Renal failure can be identified on a general blood test, either because the pet is unwell or on a routine test such as a pre-anaesthetic screen. Renal disease is characterised by elevation of urea, creatinine and phosphorous. Additional tests are needed to confirm the diagnosis, and can screen for underlying causes and assess disease progression: 


A specific blood test. SDMA levels rise in early renal disease, and can help confirm and stage diagnosis. 


Animals with renal disease have very dilute urine - elevation of urea/creatinine with concentrated urine is usually caused by dehydration not kidney disease. Measuring the protein:creatinine ratio in urine gives us a measure of how "leaky" the kidneys are - too much protein in the urine suggests more advanced disease. 

Blood pressure 

Animals with renal disease often have or develop high blood pressure (hypertension), this should be checked at diagnosis and monitored regularly if possible.


Ultrasound can be used to assess the structure of the kidneys, and looks for cysts and tumours. X-ray may be used if kidney stones are suspected, though these are less common in animals than in people. 

How is Kidney Disease treated?

Management of kidney disease is focused on slowing deterioration and maintaining quality of life, and includes: 


A prescription renal diet contains high calories with low protein, controlled Phosphorus, reduced Sodium and increased Potassium, vitamins and antioxidants. It should be introduced over 1-3 weeks, and ideally be the sole food if this is tolerated. 


Avoiding dehydration is extremely important. Water intake can be encouraged with wet food, more frequent meals, and the use of water fountains. Some patients who are very dehydrated may need administration of fluids via a drip for 24-72 hours, requiring a hospital stay. 


There is no medication for kidney function, however, both high blood pressure and excessive protein in the urine can be managed medically; sometimes one drug will treat both problems. 

Animals with renal disease often feel sick, so medication to reduce stomach acid or prevent nausea may be prescribed. In some cases, it may be appropriate to use appetite stimulants, though these are not usually a long-term solution. 

What is the outlook for cats and dogs with Kidney Disease?

Renal failure is a terminal condition and, ultimately, affected animals will deteriorate. For pets who are diagnosed on a routine blood test, or who are still quite well, the condition can often be managed successfully for months or even years. Pets who present very unwell have a much more guarded prognosis, as there is often progressed damage to the kidneys and it can be hard to get significant improvement, even with aggressive treatment.


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Page last reviewed: 21st February 2024

Next review due: 21st February 2026