Kidney Disease in Dogs: Common Causes, and How to Manage Chronic Kidney Disease

Your dog’s kidneys are filters that remove the body’s waste products. They reduce and eliminate the waste through urine and then return water and salts to the body to maintain regular hydration and electrolyte balance. These powerful filtration systems also manage blood pressure and red blood cell production. 

Like humans, dogs are usually born with two fully healthy kidneys, which is more than what is needed to do the kidneys’ job. But kidneys can wear out as your dog ages.

Chronic kidney disease (CKD) occurs when the kidneys can no longer effectively filter waste products out of the blood. 

Let’s take a closer look at what to expect if your dog is diagnosed with kidney disease.

What causes kidney disease in dogs?

Several things can cause kidney disease in dogs. Here are some of the common causes of acute (sudden) and chronic (ongoing) kidney disease.

Acute kidney disease

Acute kidney disease is a sudden decline in your dog’s kidney function. It can be caused by things such as:

• Exposure to poisons and toxic substances, such as antifreeze

• Ingestion of foods or plants that are harmful to dogs 

• Injury or sudden trauma

• Heatstroke

• Kidney stones

Chronic kidney disease

Chronic kidney disease is a progressive, degenerative loss of kidney function. For a dog to  be diagnosed with CKD, their reduced kidney function has existed for months or years. 

In dogs, the most common cause of chronic kidney disease is aging. Simply put, the kidney tissues eventually wear out as the dog ages.

Unfortunately, it’s difficult to diagnose chronic kidney disease in its earliest stages with the tests we have available. When a dog shows signs of kidney disease, they have already lost at least 75% of their kidney function.

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What are the symptoms of kidney disease in dogs?

The first symptoms of chronic kidney disease in dogs are often increased thirst and urination. When kidney function decreases, fewer toxins are removed from your dog's body. Your dog urinates more frequently to remove the waste to compensate for this. To balance the fluid loss, dogs drink more water to prevent dehydration.

The most common signs of kidney disease include:

• Lack of appetite

• Lack of energy

• Vomiting

• Diarrhea

Symptoms of advanced kidney failure may include:

• Loss of appetite

• Lack of energy

• Terrible-smelling breath

• Weakness

• Blood in urine

• Mouth ulcers

• Noticeable weight loss

• High amounts of protein in urine

How is dog kidney disease diagnosed?

Kidney disease is diagnosed in dogs through lab tests. Urinalysis (urine testing) and blood chemistry analysis are the primary tests to determine kidney function. 

A urinalysis can give your veterinarian insight into how well your dog’s kidneys may be functioning. On the urinalysis, they will also look at your dog’s urine specific gravity (USG). USG measures how much water is in your dog’s urine. High amounts of water may indicate that your dog’s kidneys aren’t working well.

Blood work to measure the levels of waste products in the blood can also help determine how well your dog’s kidneys are functioning. Your vet will likely look at the following levels:

1. Blood urea nitrogen (BUN)

2. Creatinine (an increase in creatinine levels indicates decreased kidney function)

3. SDMA (symmetric dimethylarginine)

In some cases, your veterinarian may recommend taking images of your dog’s kidneys. An ultrasound can look for damage and other indicators of kidney disease.

What are the stages of kidney disease in dogs?

Veterinarians use the International Renal Interest Society (IRIS) guidelines for staging chronic kidney disease in dogs. The IRIS scale divides kidney disease into four stages, based on a dog’s symptoms and laboratory results. Your dog’s disease stage guides your vet in determining the most appropriate, effective treatment.

As the stages go up, the kidney function worsens, and the kidneys must work harder to filter toxins from the blood.

Stage 1

The kidneys can still filter waste from the blood, and your dog shows no signs of illness. Their blood work may be normal. Your veterinarian only knows about the disease because of your dog’s abnormal ultrasound results or slightly elevated SDMA.

On your dog’s blood test results, their creatinine levels are normal (less than 1.4). Their SDMA blood test results are also normal (less than 18).

Stage 2

In early stage 2 kidney disease, your dog’s kidneys can still filter waste from the blood. Their behavior may be normal. And their blood test results may also be normal. But your dog’s creatinine levels may be slightly elevated (1.4 to 2.8), as well as their SDMA levels (18 to 35).

Stage 3

Kidney values in your dog’s blood work will show up as elevated. Their creatinine levels will typically be between 2.9 and 5.0, and their SDMA results will typically be between 36 and 54.

You might notice your dog drinking and urinating more than usual. And you may see other changes in your pup, such as a lack of appetite or less energy.

Stage 4

Your dog’s kidney values will be significantly elevated. You can expect their creatinine levels to be over 5.0 and their SDMA values to be greater than 54.

At stage 4, it may be challenging to encourage your dog to eat. In the late stages of kidney disease, daily fluid support at home is often recommended to help the kidneys.

How fast does kidney disease progress?

Disease progression depends on each individual dog. Other factors — such as how advanced the disease is at diagnosis and your dog’s response to treatment — can also affect how fast CKD progresses. However, many dogs respond very well to treatment.

Measuring disease progression, or substaging, is done by measuring urine protein loss and blood pressure. The earlier the disease is detected, the better chance that your dog can live a normal life for longer.

How do you treat kidney disease in dogs?

Treatment for kidney disease depends on the results of your dog’s blood and urine tests. In general, a combination of the following treatments will be recommended.

Fluids

At any stage of kidney disease, make sure that your dog has plenty of fresh water available. Depending on the severity of your dog’s kidney disease, they may also need additional fluids to support their kidneys.

Your vet may recommend fluids to flush out your dog’s kidneys. Flushing can remove toxins from mildly damaged kidneys, helping them function again. If enough healthy kidney cells remain, this procedure may help the kidneys heal and regain some function.

If your dog responds well to the IV flushing, your veterinarian might recommend following up with home fluid therapy. This involves giving your dog maintenance fluids under the skin (subcutaneously), sometimes as often as every day.

Medications

Most medications prescribed for dogs with CKD aim to improve your dog’s comfort and quality of life.

Your vet may also prescribe medication to control your dog’s vomiting and diarrhea. Common medication options for this purpose include maropitant (Cerenia) and ondansetron (Zofran).

If your dog loses their appetite or starts losing weight, your vet can prescribe medications to help. Common options include capromorelin or mirtazapine. 

Sometimes dogs with kidney disease develop other complications, such as high blood pressure. Your veterinarian may need to prescribe additional medications to help manage these conditions.

Nutritional management

Nutritional management is one of the most common ways to manage canine kidney disease. This often starts with feeding your dog a specific renal diet. Your veterinarian will recommend the best option for your dog. Some renal diets are only available with a prescription from your vet. 

Your veterinarian may also recommend food that reduces the amount of protein or phosphates in your dog’s diet. 

And your dog might need supplements to manage electrolyte imbalances. Supplements may include oral sodium bicarbonate or potassium citrate. Check with your veterinarian before giving your dog one of these supplements. Certain options may be safer for your dog to take, depending on their health.

Dialysis 

Sometimes dialysis, a medical procedure commonly used in humans with late-stage kidney disease, is used in veterinary medicine.

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Written by:

Lauren Lee, BA, MA

Lauren Lee, BA, MA, is a writer specializing in animal care and pet health content. Since she was a young child, her passions have been writing and anything to do with animals.

Edited by:

Renée Fabian, MA

Renée Fabian is the senior pet health editor at GoodRx. She’s worked for nearly 10 years as a journalist and editor across a wide range of health and well-being topics.

Reviewed by:

Ghanasyam Bey, DVM

Ghanasyam Bey, DVM, is from Cleveland, Ohio, and attended Princeton University for undergraduate studies. After a year of biology research at Duke University, he attended Ohio State College of Veterinary Medicine.

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