Health guide · Dog · Renal / Urinary

Kidney disease

in dogs

The kidneys filter blood silently, and that silence is exactly what makes kidney disease so insidious: symptoms often only appear once two-thirds of kidney function has been lost. Early diagnosis, an appropriate diet, and rigorous monitoring can significantly slow progression and preserve quality of life.

Definition

What is kidney disease?

The kidneys work continuously: filtering waste from the blood, regulating blood pressure, and producing hormones. When their function progressively deteriorates, waste accumulates in the blood and the whole body feels the effects. Kidney disease can be acute (sudden onset, sometimes reversible) or chronic (slow progression, generally irreversible).

What the kidneys do

Waste filtration

Elimination of urea, creatinine, and other metabolic toxins through the urine.

Blood pressure regulation

Control of blood pressure through fluid management and certain hormones.

Hormone production

Stimulation of red blood cell production via erythropoietin.

Mineral balance

Regulation of phosphorus, potassium, calcium, and other essential electrolytes.

Acute vs chronic: an important distinction

Acute kidney injury (AKI)

Sudden onset, often caused by poisoning (antifreeze, medications), a severe infection (such as leptospirosis, which is transmissible to humans and preventable by vaccination), or circulatory shock. Potentially reversible if treated quickly and aggressively.

Chronic kidney disease (CKD)

Progressive and irreversible deterioration of kidney function over months to years. Most common in older dogs. Long-term management aims to slow progression.

65–75 %

Silent loss of function

65 to 75% of kidney function must be lost before standard blood tests detect the problem. SDMA (symmetric dimethylarginine), a more sensitive biomarker, allows earlier detection. This is why annual check-ups in older dogs are so important.

Possible causes

Congenital abnormalities or hereditary nephropathies (certain predisposed breeds)
Leptospirosis: a zoonotic bacterial infection, preventable by vaccination (a common cause of acute kidney injury)
Other bacterial or viral infections, Lyme disease
Autoimmune diseases attacking kidney tissue
Kidney stones (nephrolithiasis)
Exposure to toxins: antifreeze (ethylene glycol), grapes or raisins, certain medications
Complications from acute kidney injury
Unknown cause (very common, especially in older dogs)

Reducing the risk

Leptospirosis vaccination for at-risk dogs, to discuss with your veterinarian based on lifestyle and exposure
Keep antifreeze, grapes (fresh or dried), and human medications out of reach
Never give NSAIDs or human painkillers without veterinary advice
Treat infections and dehydration promptly

IRIS Staging

Stages of chronic kidney disease

The IRIS (International Renal Interest Society) system classifies CKD into 4 stages based on serum creatinine and SDMA. Azotemia is the build-up of waste (urea, creatinine) in the blood when filtration is insufficient. This classification guides treatment decisions and provides a realistic picture of prognosis.

Stage 1

Non-azotemic

Creatinine: < 125 µmol/L

SDMA ≈ < 18 µg/dL

No azotemia. Detected only via SDMA, urinalysis, or imaging. No symptoms.

Stage 2

Mild azotemia

Creatinine: 125–250 µmol/L

SDMA ≈ 18–35 µg/dL

Mild azotemia. Subtle symptoms may appear. Most dogs feel relatively normal.

Stage 3

Moderate azotemia

Creatinine: 250–440 µmol/L

SDMA ≈ 36–54 µg/dL

Moderate azotemia. Symptoms are more pronounced. Treatment significantly impacts quality of life.

Stage 4

Severe azotemia

Creatinine: > 440 µmol/L

SDMA ≈ > 54 µg/dL

Severe azotemia. Uremic crisis possible. The priority becomes comfort: supportive home care to keep your dog at ease. If quality of life declines despite care, euthanasia may be considered gently, and our team supports you.

IRIS substaging: whatever the stage, each dog is also classified by proteinuria (urine protein-to-creatinine ratio, UPC: non-proteinuric < 0.2; borderline 0.2 to 0.5; proteinuric > 0.5) and by systolic blood pressure. Proteinuria and hypertension worsen the outlook at any given stage and guide treatment; their interpretation is for your veterinarian. The SDMA values shown are approximate guides (IRIS formally stages by creatinine).

Clinical signs

Signs and symptoms

Kidney disease symptoms develop gradually, often confused with normal aging. The accumulation of toxins (uremia) affects appetite, energy, the digestive tract, and ultimately the nervous system.

Early stage

Often attributed to normal aging

Tires quickly, sleeps more
Mild to moderate weight loss
Poor appetite, mild nausea

Intermediate stage

See your veterinarian

Increased thirst and urination (polyuria/polydipsia), often the first change owners notice at home
Ammonia-smelling breath (uremic halitosis)
Vomiting, diarrhea
Panting
Dull coat, reclusive behavior

Advanced stage

Specialized care needed

Sunken eyes, visible dehydration
Mouth ulcers
Excessive drooling and oral discomfort (uremic mouth ulcers)
Unsteady gait, confusion
Abnormal vocalizations
Marked muscle wasting

Emergency

When to seek immediate help?

These signs indicate acute decompensation. Bring your dog to an emergency clinic without delay:

Severe respiratory distress or uncontrollable panting
Inability to walk, sudden collapse
Seizures
Sudden blindness, wide fixed pupils, or dog bumping into objects (hypertensive emergency: prompt blood-pressure treatment can preserve vision)
Sudden drop or absence of urine output, or repeated straining to urinate with no result
Bluish gums or tongue (cyanosis)
Uncontrollable vomiting or diarrhea
Crying or whimpering in pain
Extreme agitation or coma

If poisoning is suspected (antifreeze, grapes or raisins), do not wait for symptoms to appear: seek care immediately. The sooner treatment begins, the better the chances of preventing permanent kidney damage.

Diagnosis

How is the diagnosis made?

Diagnosing kidney disease requires a combination of tests: symptoms alone are not sufficient, as they often appear late. Regular screening in older dogs is the best way to catch the problem early.

Blood tests

Creatinine, urea, and SDMA reflect the kidneys' filtration capacity. SDMA changes as soon as 25% of function is lost, well before creatinine. The panel also includes electrolytes (phosphorus, potassium, calcium) and a complete blood count (for anemia).

Urinalysis

Urine specific gravity (concentration) is the first value to deteriorate. Overly dilute urine signals that the kidneys are no longer concentrating properly. The presence of protein (proteinuria) and sediment helps characterize the type and severity of damage.

Imaging

Abdominal ultrasound visualizes the size, shape, and texture of the kidneys. Small, irregular kidneys are typical of advanced CKD. X-rays and ultrasound also detect kidney stones, cysts, or tumors.

Additional tests

Urine culture to screen for a urinary tract infection or occult pyelonephritis (a treatable cause, often missed on sediment). Blood pressure measurement, part of IRIS substaging: hypertension is common, treatable, and accelerates progression.

IRIS staging

Once the values are known, the veterinarian classifies the disease into stage 1 through 4 using the IRIS system. This stage guides treatment, monitoring frequency, and allows for an honest conversation about prognosis.

An important fact: a dog can appear completely normal at CKD stages 1 and 2. Incidental discovery during a routine blood panel is common. This is one of the strongest arguments for annual blood screening in any dog over 7 years old.

Treatment

Treatment and management

There is no cure for CKD. The goal is to slow progression, control complications, and maintain quality of life for as long as possible. A multimodal approach is essential.

Renal diet

Specially formulated foods with reduced protein and phosphorus to decrease the kidneys' workload
Wet or moistened food to increase fluid intake
Omega-3 fatty acids (EPA/DHA): already built into most renal foods; an anti-inflammatory effect that may help slow progression. Do not add a supplement without veterinary advice
Gradual transition over 2 to 4 weeks to improve acceptance
Strictly avoid salty treats, table food, and phosphorus-rich foods

The renal diet has the strongest impact on CKD progression, even beyond many medications.

Hydration

At-home subcutaneous fluids: most owners learn the technique after a quick training session
Multiple water stations, water fountain, filtered water
Intravenous fluid therapy during crises or hospitalizations
Monitor daily water intake

At-home subcutaneous fluids noticeably improve comfort and appetite. The technique is straightforward to learn.

Supportive medications

Phosphate binders (with or just before meals) to reduce intestinal phosphorus absorption; away from food they are largely ineffective
RAAS blockers (ACE inhibitors such as benazepril or enalapril, or the ARB telmisartan): they reduce proteinuria and blood pressure, with monitoring of kidney values and potassium
Amlodipine: added when high blood pressure is not controlled by RAAS blockade
Erythropoietin or erythropoiesis-stimulating agents if severe anemia
Anti-nausea medications (maropitant), appetite stimulants
Correction of electrolyte and acid-base imbalances based on bloodwork: a potassium supplement (gluconate or citrate) only if hypokalemia is documented; an alkalinizing agent (sodium bicarbonate) for the metabolic acidosis of advanced stages

The medication list varies based on which complications are present. The vet adjusts at each follow-up.

Regular monitoring

Blood and urine tests every 3 to 6 months depending on stage
Blood pressure measurement at each visit (hypertension accelerates CKD)
Urine protein-to-creatinine ratio (UPC) to monitor proteinuria
Monitoring of potassium and acid-base status (potassium can be low, or high in advanced stages)
Regular home weigh-ins to catch early weight loss

Close monitoring allows treatment adjustments before a complication becomes an emergency.

Comorbidities to manage

Urinary tract infections or pyelonephritis: urine culture and targeted antibiotics; untreated, they accelerate kidney damage
Dental disease: a source of chronic inflammation that may worsen kidney progression
Concurrent conditions (Cushing's disease, heart disease): managing them helps slow kidney decline

Screening for and treating associated diseases is an integral part of kidney management.

Prognosis

What to expect long-term?

Prognosis depends on the stage at diagnosis, the underlying cause (if treatable), and the response to treatment. CKD is incurable, but many dogs live comfortably for months to years after diagnosis.

Stages 1 and 2, caught early and managed with a strict renal diet, can remain stable for years.

Appropriate supportive care (hydration, complication management) noticeably improves daily comfort.

Some AKI causes (poisoning, infection) are treatable: partial or full recovery is possible with rapid intervention.

Stages 3 and 4 carry a more guarded prognosis, generally a few months with symptom management.

Uncontrolled hypertension and proteinuria accelerate progression: treating them is a priority.

CKD is not curable and progresses over time, but comfort care and good follow-up preserve quality of life.

Treatment decisions and prognosis discussions are based on the IRIS stage. Ask your veterinarian which stage your dog is in and what that means practically for their daily life and long-term care.

Home care

Home management

Comfort adjustments

Elevated bowls and multiple water stations throughout the home

Filtered water to encourage drinking (reduces unwanted minerals)

Warm, quiet resting area away from noise

Ramps or steps to access furniture if the dog is weakened

Non-slip surfaces to prevent falls

At-home subcutaneous fluids after training by the veterinary team

Essential actions

Follow the prescribed renal diet strictly, without exception
Daily monitoring: appetite, water intake, urination, vomiting, weight
Administer all medications on schedule
Weigh the dog weekly (early weight loss is a warning sign)
Keep all blood monitoring appointments
Encourage gentle physical activity according to the dog's energy level
Consult promptly if repeated vomiting, sudden appetite loss, or marked lethargy
Avoid all NSAIDs (anti-inflammatories) without explicit veterinary guidance

Never do

Give any human or over-the-counter medication without veterinary advice: NSAIDs (aspirin, ibuprofen, meloxicam) worsen CKD and can trigger acute kidney injury; acetaminophen (Tylenol) can cause liver damage and methemoglobinemia
Restrict access to water: a dog with kidney disease urinates heavily and dehydrates quickly, so water must stay available at all times
Change the diet without consulting (some seemingly healthy foods are harmful)
Dismiss weight loss as normal aging in an older dog
Skip follow-up appointments when the dog seems to be doing well

Tracking quality of life day to day

A simple tool: keep a good-days-versus-bad-days journal. Each day, note whether your dog ate on its own, moved comfortably, sought your company, and still enjoyed its usual routines. When bad days start to outnumber good ones, tell us: together we will assess quality of life using a validated scale.

Monitor every day

Appetite and amount eaten

Water intake

Urination (volume and frequency)

Weight and energy level

FAQ

Frequently asked questions

My dog has elevated creatinine but seems normal. Is this serious?

Not immediately urgent, but worth taking seriously. Elevated creatinine means a significant portion of kidney function is already lost. Many dogs compensate well for a period of time. The important thing is to act now: start a renal diet, look for complications (hypertension, proteinuria), and set up regular monitoring. The earlier you act, the more slowly the disease will progress.

My dog refuses the renal diet. What can I do?

This is one of the most common challenges. The transition must be very gradual (introduce the new food over 2 to 4 weeks, roughly 10% more each day, slower if your dog hesitates). Try several brands and formats (wet, dry, different flavors). Warming the food slightly can increase palatability. If refusal persists, talk to your vet: options include home-cooked diets formulated by a veterinary nutritionist.

At-home subcutaneous fluids: is this really manageable?

Absolutely. The vast majority of owners who learn the technique adapt quickly and describe it as less difficult than they feared. Your clinic will provide hands-on training. Most dogs tolerate subcutaneous fluids very well, and their comfort and appetite noticeably improve after each session.

What is the difference between acute kidney injury and chronic kidney disease?

Acute kidney injury (AKI) occurs suddenly, often after poisoning, a severe infection (such as leptospirosis), or circulatory shock. It is potentially reversible if treated very quickly and aggressively. Chronic kidney disease (CKD) develops gradually over months to years and is not reversible: the goal is to slow it, not cure it. A dog that already has CKD can also decompensate suddenly (dehydration, infection, a toxin): treated quickly, that flare can return the dog to its previous baseline.

Is kidney disease hereditary in dogs?

Most cases are age-related or of unknown cause, but some breeds have familial nephropathies or renal dysplasia (for example the English Cocker Spaniel, Bull Terrier, Shar-Pei, or Boxer). These forms often appear in young dogs. If your dog belongs to a predisposed breed, earlier and more frequent kidney screening is recommended: talk to your veterinarian.

My dog has been drinking a lot for a few weeks. Could it be kidney disease?

Polydipsia and polyuria (drinking and urinating a lot) can indicate kidney disease, but also diabetes, Cushing's disease, a urinary infection, or other problems. A veterinary consultation with blood and urine tests is essential to tell them apart. Do not assume: the correct diagnosis guides all treatment decisions.

How long can my dog live with chronic kidney disease?

There is no universal answer. Some dogs at stage 2 live another 2 to 4 years with good management. At stage 3 or 4, we are typically looking at months to about a year. Quality of life matters as much as duration: the goal is for your dog to eat well, stay comfortable, and enjoy their days. Have an open conversation about these expectations with your veterinarian.

When does euthanasia become the most humane decision?

It is normal to dread this moment and to grieve, sometimes well before it comes: these feelings are valid. As long as your dog eats, moves comfortably, and enjoys its days, comfort care has its place. When it no longer eats, cannot move without pain, and appears to be suffering despite care, euthanasia can be the kindest choice, the one that ends the suffering. It is a deeply personal decision: a good-days-versus-bad-days journal (see Home management) helps make it objective, and together we will assess quality of life using a validated scale. When the time comes, we ensure a gentle, respectful process, and you can stay with your dog.

Is your dog showing these symptoms?

Increased thirst, weight loss, recurring vomiting? A blood panel can make all the difference for early detection.

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