Kidney disease in dogs

Types of kidney disease in dogs

The kidneys are vital organs and have a critical role in urine production, filtration and excretion of toxins, maintaining fluid balance, hydration, blood pressure, pH, balance of calcium and phosphorus, and red blood cell production. 

Like us, dogs have two kidneys, distinctive bean-shaped organs that are located on either side of the spine. Each kidney contains around a million microscopic filtering units called nephrons. As filtrate travels through these units, essential substances like water, glucose, and electrolytes are reabsorbed into the bloodstream, while waste products and excess substances are concentrated in urine. The urine is then carried through the ureters to the bladder for storage and eventual elimination through the urethra. 

We are born with many more nephrons than we need – over time or due to a certain disease process, nephrons are damaged and die off. When only ⅓ of nephrons are left, a patient may present with signs and indicators of kidney disease. There are two types of kidney disease that can develop in dogs. 

Chronic kidney disease (CKD)

CKD involves the gradual and irreversible loss of functional kidney units (nephrons). Signs of kidney disease may not be evident until ⅔ of the nephrons have been damaged. While there is no treatment for CKD, early detection and treatments can help slow the progression of disease and maintain good quality of life. 

CKD is common most in senior dogs, associated with aging and “wearing out” of the kidneys. There are several possible causes: 

• Age-related degeneration
• Secondary to a kidney injury (such as that caused by an infection or toxin discussed below)
• Inherited conditions – such as glomerulonephritis or amyloidosis 
• Neoplasia – cancers, such as lymphoma
• Immune-mediated disease 
• Idiopathic (unknown cause)

     
Certain breeds may be prone to CKD, including Basenji, Bernese Mountain Dog, Boxer, Bull Terrier, Cairn Terrier, Cavalier King Charles Spaniel, Cocker Spaniel, English Cocker Spaniel, Shar-Pei, and West Highland White Terrier. 

Acute kidney injury (AKI)

AKI is characterized by a rapid and severe decline in kidney function, often triggered by a toxin or infection. With prompt and appropriate treatment, recovery of kidney function may be possible. Triggers of acute kidney injury in dogs include: 

• Toxins – such as ingestion of antifreeze, grape/raisins, rodenticide, or medications like NSAIDs (ibuprofen) or certain antibiotics
• Infections – such as pyelonephritis (kidney infection), leptospirosis, and tick-borne disease 
• Urinary obstruction – inability to urinate 
• Major events such as ischemia, shock, trauma, heat stroke, insect or snake envenomation, low blood pressure, or organ failure

     
Dogs with chronic kidney disease are also susceptible to illness leading to a sudden worsening of their renal function, known as acute-on-chronic disease. 

Symptoms of kidney disease 

The early signs of kidney disease can be subtle and generally include: 

• Increased thirst (polydipsia) – You might notice your dog emptying their water bowl more frequently or begging for water more often. Pets with kidney disease drink more water because they are trying to keep up with fluid loss through large amounts of dilute urine. They also need more water in an attempt to help flush out toxins. 
• Increased urination (polyuria) – Your dog may need to go outside more frequently or have accidents in the house. 

      
As kidney disease progresses, more severe symptoms can develop:

• Loss of appetite – Your dog may become pickier about food or refuse meals altogether.
• Weight loss
• Lethargy – Your dog may seem less energetic or playful.
• Vomiting
• Diarrhea
• Oral ulcers and bad breath – due to sores developing in the mouth.
• Urinary accidents, incontinence, inability to urinate, or bloody urine (hematuria) 
• Weakness
• Unkempt fur coat 
• Muscle wasting 
• Vision disturbances as a result of high blood pressure 
• Potential for seizures or other severe complications

        
Chronic kidney disease tends to have a gradual onset. The kidneys may feel small and irregular on abdominal palpation by your vet. Acute kidney injury can cause a sudden onset of severe clinical signs and may result in anuria (lack of urine production) and enlarged kidneys. 

How veterinarians diagnose kidney disease 

In addition to a medical history and thorough physical exam, kidney disease is diagnosed on routine bloodwork and urine testing.  

Bloodwork

Bloodwork provides insights into kidney function by measuring creatinine and BUN (blood urea nitrogen). These waste products increase in the blood when kidney function declines. They are also responsible for making your pet feel ill. Electrolyte imbalances (potassium, phosphorus, calcium) are also common in kidney disease. 

It’s important to examine the numbers of red and white blood cells, as anemia (decreased red blood cells) is common in dogs with CKD, while high numbers of white blood cells may indicate infection or inflammation. 

SDMA (symmetric dimethylarginine) is a newer and more sensitive biomarker that can detect kidney dysfunction earlier than traditional bloodwork values. Ask your vet if this test is recommended for your dog. 

Urinalysis 

An evaluation of the urine is essential for assessing kidney health. Dogs with kidney disease often produce dilute urine (low urine specific gravity). Proteinuria (protein in the urine) is another indicator of kidney damage.

Additional diagnostics

Additional tests may be recommended to help determine the extent of kidney damage and look for an underlying cause.

• Testing for specific disease processes – Your vet may recommend testing your dog for leptospirosis or tick-borne disease. 
• Blood pressure measurement is important because hypertension is a common complication of kidney disease. 
• Imaging can also provide valuable information. Radiographs (X-rays) help assess kidney size and shape, and can potentially reveal stones or other abnormalities. Ultrasound provides a detailed evaluation of the kidney’s internal structure and architecture. 
• A urine culture can help detect and grow bacteria causing an infection. 
• Urine protein creatinine ratio (UPCR) can help determine the significance of protein in the urine. 
• In certain cases, a renal biopsy might be recommended to obtain a tissue sample and definitively diagnose the underlying cause of the kidney disease.

Staging of kidney disease 

If your dog has been diagnosed with chronic kidney disease, your vet will determine the stage of the disease using guidelines from the International Renal Interest Society (IRIS) based on creatinine and SDMA levels. Here’s a very simplified summary of the IRIS CKD Stages (separate staging criteria exist for AKI):

• Stage 1: Early kidney disease without apparent clinical signs – creatinine may be within the normal range and SDMA may be normal or slightly increased.
• Stage 2: Mild kidney disease – clinical signs may be mild or absent, and creatinine and SDMA levels are often mildly elevated.
• Stage 3: Moderate kidney disease – clinical signs are present and creatinine and SDMA levels are elevated. 
• Stage 4: Severe kidney disease – creatinine and SDMA levels are high, and the dog is likely to be showing clinical signs of severe disease.
        

Substaging can provide further information and is based on the presence of protein in the urine and the measurement of blood pressure. Understanding the stage of kidney disease allows your vet to provide tailored treatment plans and discuss the long-term outlook with pet parents.

Treatment of kidney disease in dogs  

Treatment for kidney disease in dogs depends on whether it’s acute or chronic and the underlying cause. In cases of AKI, addressing the primary problem, such as removing an obstruction or treating an infection, is essential. 

For CKD, while there is no cure, the focus is on slowing the disease’s progression and managing symptoms. Your vet will tailor a specific treatment plan to your pet, depending on the stage of kidney disease, individual needs, and response to therapies. Dogs who are severely ill often require hospitalization for several days on IV fluids. Regular checkups and monitoring are also essential for optimal management and adjustment of the treatment plan over time. 

Here’s what treatment might involve:

• Dietary Modification – Switching to a specialized prescription kidney diet is one of the most important aspects of managing CKD. Kidney diets contain restricted amounts of protein, phosphorus, and sodium to help reduce the workload on the kidneys. Your veterinarian will recommend the most appropriate diet (like Hill’s Prescription Diet K/D, Purina Veterinary Diet NF, or Royal Canin Renal Support) based on your dog’s needs.

   

• Managing Symptoms and Complications – Several medications can help address complications of kidney disease and improve your dog’s quality of life, such as:
  • Medications to manage nausea and vomiting.
  • Medications to control blood pressure (hypertension is common in CKD).
  • Phosphate binders to reduce phosphorus absorption from food (if dietary restriction alone is insufficient).
  • Supplements for potassium or B-vitamins, which can be depleted in kidney disease.
  • Medications to address anemia (low red blood cell count).
  • Medications for protein loss in the urine (proteinuria).
  • A drug to regulate the parathyroid gland and calcium levels.

     

• Fluid Support:  Encouraging your dog to drink is essential. In some cases, your vet may recommend giving subcutaneous fluids (administered under the skin) at home to maintain hydration. This helps prevent dehydration and flush toxins from the kidneys. Your veterinary team will teach you how to administer fluids safely and effectively.

   

• Advanced Therapies: In rare cases with severe kidney failure, advanced options such as dialysis or kidney transplant might be considered, though availability is limited.

Prognosis and prevention

Kidney disease is a serious but often manageable condition in dogs. While there’s no cure for CKD, early detection and appropriate intervention are vital for improving quality of life and potentially slowing disease progression. The prognosis for AKI can be more variable. While the initial prognosis may be guarded, some dogs can experience full recovery with prompt and appropriate treatment.

Prevention is another key aspect to protecting your dog’s kidney health. This includes annual wellness exams and bloodwork (especially for senior dogs), providing plenty of fresh water at all times, avoiding known nephrotoxins (grapes/raisins, certain medications, antifreeze, etc.), and managing underlying health conditions that may increase risk to the kidneys.