Kidney Failure in Older Dogs: Early Signs and Management

Here's the heartbreaking reality of chronic kidney disease (CKD): by the time you notice symptoms, your dog has already lost approximately 75% of their kidney function.

That's because kidneys are remarkably resilient. They compensate silently, day after day, until they simply can't anymore. Then symptoms appear rapidly—seemingly out of nowhere.

But there's good news: if caught early through proactive screening, CKD can be managed for months or even years. Dogs can maintain good quality of life long after diagnosis.

Here's what you need to know about this common senior dog disease.

Understanding Chronic Kidney Disease

What the Kidneys Do

Healthy kidneys perform critical functions:

• Filter waste: Remove toxins and metabolic waste from blood
• Concentrate urine: Conserve water by making concentrated urine
• Balance electrolytes: Regulate sodium, potassium, phosphorus
• Produce hormones: Including erythropoietin (for red blood cell production) and renin (for blood pressure)
• Activate vitamin D: Essential for calcium regulation

When kidneys fail, all of these functions are compromised.

Acute vs. Chronic Kidney Disease

Acute kidney injury (AKI): Sudden damage from toxins (antifreeze, grapes, lilies), infection, or blockage. May be reversible if treated immediately.

Chronic kidney disease (CKD): Gradual, irreversible loss of kidney function over months to years. This is what we're discussing here.

How Common Is It?

CKD affects an estimated 10% of dogs over 10 years old, making it one of the most common senior dog conditions. Some breeds are predisposed, including:

• Cocker Spaniel
• German Shepherd
• Samoyed
• English Cocker Spaniel
• Bull Terrier
• Shih Tzu

But any senior dog can develop CKD.

The Silent Progression

Why You Don't Notice Early Stages

The kidneys have enormous reserve capacity. Dogs (and humans) can function normally with only 25-30% of kidney function. This is why people can donate a kidney and live normally.

But it means 70-75% of function can be lost before any clinical signs appear. By the time you're Googling "why is my dog drinking so much water," significant damage has already occurred.

IRIS Staging System

Veterinarians use the IRIS (International Renal Interest Society) staging system:

The goal: Catch it at Stage 1 or 2, when intervention makes the biggest difference.

Early Warning Signs

The Classic Symptoms

Increased thirst (polydipsia):

• Draining the water bowl
• Seeking water from unusual sources
• Drinking from toilets, puddles

Increased urination (polyuria):

• Needing to go out more frequently
• Accidents in the house (new behavior)
• Large volume of very pale, dilute urine

These happen because failing kidneys can't concentrate urine. To flush out toxins that should be concentrated, the body produces more urine—and the dog drinks more to compensate.

Other Signs

Bad breath (uremia):

• Ammonia or urine-like smell to breath
• Caused by toxin buildup in blood

Weight loss:

• Even while eating normally
• Muscle wasting

Decreased appetite:

• Nausea from toxin buildup
• May be intermittent at first

Vomiting:

• Occasional to frequent
• Sometimes first thing in the morning (empty stomach)

Lethargy:

• Less energy
• Sleeping more
• Reluctance to exercise

Poor coat condition:

• Dull, dry fur
• May lose sheen

Weakness:

• Especially in rear legs
• May have trouble rising

Advanced Symptoms

In later stages:

• Mouth ulcers
• Severe vomiting and diarrhea
• Pale gums (anemia)
• Seizures
• Complete appetite loss
• Dehydration despite drinking

How Kidney Disease Is Diagnosed

Routine Bloodwork

Blood urea nitrogen (BUN): Waste product filtered by kidneys. Elevated in kidney disease—but also in dehydration, high-protein diets, and other conditions.

Creatinine: More specific to kidney function. Doesn't elevate until about 75% of function is gone.

SDMA (symmetric dimethylarginine): A newer, more sensitive marker. Can detect kidney disease when only 40% of function is lost—much earlier than creatinine.

This is why annual bloodwork for senior dogs is essential. SDMA can catch what creatinine misses.

Urinalysis

Urine specific gravity (USG): Measures concentration. Healthy kidneys produce concentrated urine (high USG). Failing kidneys produce dilute urine (low USG) even when the dog is dehydrated.

Protein in urine: Some kidney diseases cause protein loss in urine.

Signs of infection: Urinary tract infections are common with kidney disease.

Blood Pressure

Kidney disease often causes high blood pressure, which can further damage the kidneys. Blood pressure monitoring is part of complete assessment.

Additional Testing

Urine protein:creatinine ratio (UPC): Quantifies protein loss

Ultrasound: Evaluates kidney structure for tumors, stones, or anatomical issues

Blood pressure monitoring: Essential for complete staging

Managing Chronic Kidney Disease

CKD cannot be cured or reversed. But with proper management, many dogs maintain good quality of life for extended periods.

Therapeutic Diet: The Foundation

Prescription kidney diets (Hill's k/d, Royal Canin Renal, Purina NF) are the cornerstone of management. They feature:

Reduced phosphorus: Critical—phosphorus retention accelerates kidney damage. Studies show phosphorus restriction extends survival.

Moderate, high-quality protein: Enough to maintain muscle mass, but not excessive (high protein creates more waste to filter).

Increased omega-3 fatty acids: Reduce inflammation and may slow progression.

Reduced sodium: Helps manage blood pressure.

Added potassium and B vitamins: Often depleted in CKD.

The evidence: Dogs on kidney diets live significantly longer than those on regular food. Diet is often the single most effective intervention.

Hydration

Hydration is crucial because:

• Kidneys can't concentrate urine (they waste water)
• Dehydration accelerates kidney damage
• Flushing toxins requires adequate fluid intake

Strategies:

• Water available in multiple locations
• Add water or low-sodium broth to food
• Wet food instead of or in addition to dry
• Subcutaneous fluids

Subcutaneous fluids: Many owners learn to give fluids under the skin at home. It sounds scary but becomes routine. A bag of balanced fluids is infused under the skin, where it's absorbed over hours. This dramatically helps hydration.

Managing Phosphorus

Even on a low-phosphorus diet, phosphorus levels may remain elevated. Options include:

Phosphate binders: Given with food, they bind dietary phosphorus in the gut so it's excreted rather than absorbed. Aluminum hydroxide or newer options like Epakitin.

Managing Nausea and Appetite

CKD causes nausea, which reduces appetite, which causes weight loss, which worsens overall condition.

Anti-nausea medications:

• Cerenia (maropitant)
• Ondansetron
• Famotidine or omeprazole for stomach acid

Appetite stimulants:

• Mirtazapine (also helps with nausea)
• Entyce (capromorelin)

Managing Anemia

Advanced CKD causes anemia because failing kidneys don't produce enough erythropoietin. Signs include pale gums, weakness, and rapid heart rate.

Treatment options:

• Erythropoietin injections
• Iron supplementation
• In severe cases, blood transfusion

Managing Blood Pressure

Hypertension is common and damaging. If present:

• ACE inhibitors (enalapril, benazepril)
• Amlodipine
• Low-sodium diet

Blood pressure should be monitored regularly and medications adjusted as needed.

Monitoring and Follow-Up

CKD management requires regular monitoring:

Frequency: Every 3-4 months for stable patients; more often if unstable

Tests:

• Bloodwork (BUN, creatinine, phosphorus, potassium)
• Urinalysis
• Blood pressure
• Body weight and condition

Treatment is adjusted based on results.

Proactive Screening: The Key to Early Detection

Because symptoms don't appear until late stages, proactive screening is the best way to catch CKD early.

When to Start Screening

All dogs over age 7: Annual bloodwork including SDMA

High-risk breeds: Start at age 5

Dogs with known risk factors: Start early and screen more frequently

What to Request

Ask your vet specifically for:

• SDMA (more sensitive than creatinine alone)
• Complete urinalysis (includes specific gravity)
• Creatinine and BUN

This combination catches kidney disease earlier than creatinine alone.

Living with CKD: What to Expect

Timeline

With good management:

• Stage 2: Often managed for years
• Stage 3: Typically months to a year or more
• Stage 4: Weeks to months

These are general guidelines—individual dogs vary enormously.

Quality of Life

A dog with well-managed CKD can have excellent quality of life:

• Comfortable and pain-free
• Eating well (with appropriate diet and anti-nausea support)
• Engaged with family
• Enjoying walks and play (adjusted for energy level)

When It's Time

Eventually, CKD progresses despite treatment. Signs that quality of life is declining:

• Refusing to eat despite all interventions
• Constant nausea or vomiting
• No interest in normal activities
• Incontinence causing distress
• Owner's assessment: "more bad days than good"

Your vet can help you assess quality of life and make compassionate decisions when the time comes.

The Bottom Line

Chronic kidney disease is common in senior dogs and usually silent until advanced. By the time classic symptoms appear, 75% of kidney function is already gone.

Key takeaways:

1. Screen proactively: Annual bloodwork with SDMA for dogs over 7
2. Know the signs: Increased thirst and urination are red flags
3. Diet is crucial: Prescription kidney diets extend survival
4. Hydration matters: Subcutaneous fluids can make a big difference
5. Regular monitoring: Allows treatment adjustment as disease progresses
6. Quality of life is achievable: Many dogs live comfortably for months to years after diagnosis

If you have a senior dog, consider scheduling wellness bloodwork. Finding CKD at Stage 2 instead of Stage 4 can mean years more quality time with your companion.

Related: Senior Dog Diet Guide Related: When Is It Time to Say Goodbye?