Kidney Disease
Kidney disease in pets, also known as renal disease, is a common condition that affects both cats and dogs, particularly as they age.
It involves a gradual decline in kidney function, impacting their ability to filter waste products and regulate fluids and minerals.
While there is no cure for chronic kidney disease, early detection and management can significantly improve a pet's quality of life and prolong their survival.
Cats and Kidney Disease
Chronic kidney disease (CKD) is one of the most common conditions we diagnose in older cats.
The kidneys gradually lose their ability to filter waste products from the blood, regulate fluid balance, and support overall health.
While CKD cannot be cured, early detection and good management can make a huge difference to quality of life.
Why cats are prone to kidney disease
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Cats are particularly vulnerable as they age.
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Their kidneys can slowly lose function over time, often without obvious signs until the disease is well advanced.
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Regular health checks and blood tests are the best way to catch problems early.
Signs of kidney disease in cats
Cats are masters at hiding illness. Some of the most common clues include:
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Drinking more water than usual
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Urinating more often, sometimes with larger volumes
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Weight loss despite a normal or even increased appetite
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Vomiting, nausea, or reduced appetite
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Sleeping more or seeming less active
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A dull or unkempt coat
If you notice any of these changes, a blood and urine test is the first step.
Blood tests for kidney function
We look at several key values:
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SDMA (Symmetric Dimethylarginine): detects kidney changes earlier than other markers.
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Creatinine: rises as kidney function declines.
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Urea (BUN): another waste product that increases with kidney disease.
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Electrolytes (sodium, potassium, calcium, phosphate): imbalances are common and need to be managed.
We also always look at a urine sample, and recommend an ultrasound of the kidneys to assess size, internal changes, and blood flow. All this information allows us to build a picture of what's actually happening, and to tailor medication and diet changes to try and lengthen and improve your cats life.
Staging kidney disease (IRIS system)
Once results are back, we grade the condition using the IRIS staging system, which guides treatment and monitoring:
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Stage 1: Early disease – bloodwork may look almost normal but SDMA can be raised.
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Stage 2: Mild disease – creatinine begins to rise. Cats may drink and urinate more but still feel well.
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Stage 3: Moderate disease – blood values show clear kidney damage, and signs like weight loss or lethargy are common.
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Stage 4: Severe disease – advanced kidney failure, often with nausea, poor appetite, and marked weight loss.
Managing kidney disease in cats
Treatment depends on the stage. Options include:
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Special prescription diets designed to support kidney health
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Medications to manage blood pressure and protein loss
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Supplements to balance electrolytes or support appetite
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Regular monitoring to adjust care as your cat’s needs change
How this helps your cat
With the right support, many cats with CKD live for years after diagnosis, enjoying good quality of life. Blood tests give us the information we need to intervene early, slow progression, and keep your cat comfortable.
Dogs and Kidney Disease
Chronic kidney disease (CKD) is less common in dogs than in cats, but when it does occur it can have a big impact on their health. The kidneys filter waste products from the blood, balance fluids and electrolytes, and help regulate blood pressure. When they start to fail, waste builds up in the body and dogs can begin to feel very unwell.
Signs of kidney disease in dogs
Kidney problems can develop gradually, but sometimes they appear suddenly. Common signs include:
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Drinking and urinating more than usual
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Reduced appetite or fussiness with food
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Weight loss and muscle wastage
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Vomiting or nausea
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Lethargy or reduced stamina
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Bad breath or mouth ulcers in advanced cases
If your dog is showing any of these changes, a blood and urine test is the best first step.
Blood tests for kidney function
We measure several key values to assess the kidneys:
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Creatinine: rises when kidney function declines.
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SDMA (Symmetric Dimethylarginine): a sensitive marker that can pick up changes earlier than creatinine.
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Urea (BUN): another waste product that increases when kidneys are not filtering properly.
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Electrolytes (sodium, potassium, calcium, phosphate): imbalances are common and may need correction.
A urine sample is tested alongside the blood to give us the full picture, along with ultrasound of the kidneys to assess their size, appearance and blood flow.
Staging kidney disease (IRIS system)
We use the IRIS staging system to grade kidney disease and guide treatment:
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Stage 1: Early – SDMA may be raised before creatinine changes. Many dogs show no obvious signs.
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Stage 2: Mild – creatinine is slightly raised. Dogs may still feel well, but subtle signs can appear.
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Stage 3: Moderate – clear changes in blood values with noticeable signs such as weight loss, appetite changes, or vomiting.
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Stage 4: Severe – advanced kidney failure, often with significant illness.
Managing kidney disease in dogs
Treatment depends on the stage, but can include:
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Prescription diets designed to slow disease progression
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Medication to manage high blood pressure or protein loss
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Fluids (sometimes given under the skin at home) to prevent dehydration
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Supplements to support appetite or correct electrolyte imbalances
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Regular monitoring to adjust treatment as the condition changes
How this helps your dog
Although kidney disease is progressive, early diagnosis and good management can give many dogs a much better quality of life for months or even years after diagnosis.
Blood and urine testing gives us the information we need to make the right treatment plan for your dog.