Health guide · Cat · Renal / Chronic

CKD / CRF

Chronic Kidney Disease in cats

Chronic kidney disease (CKD) is one of the most common conditions in senior cats. It progresses slowly and silently, but proper management can offer years of good quality of life.

Definition

What is chronic kidney disease?

CKD is a progressive and irreversible deterioration of the kidneys. When more than 65 to 75% of nephrons (filtering units) are damaged, the body can no longer effectively eliminate waste: this is called azotemia. The disease primarily affects middle-aged to senior cats and progresses silently, often detected late without regular checkups.

50%

of cats over 15 years old are affected

3rd

most common condition in senior cats

+17 months

earlier detection with the SDMA marker

Years

of survival possible with proper management

The 4 key kidney functions

Waste filtration

Removal of blood urea nitrogen (BUN), creatinine, and other metabolic waste products from the bloodstream.

Blood pressure regulation

Control of blood volume and arterial pressure via the renin-angiotensin system.

Erythropoietin production

Secretion of the EPO hormone that stimulates red blood cell formation in the bone marrow.

Fluid and electrolyte balance

Regulation of water, potassium, sodium, and phosphates throughout the body.

CKD is distinct from acute kidney disease (AKD), which occurs suddenly following trauma, poisoning, or severe infection. Both forms can coexist in the same animal.

Clinical signs

Signs and symptoms

CKD often progresses silently. Early signs are subtle and frequently attributed to normal aging. Learning to recognize them early can change the course of the disease.

Early stage

Often mistaken for normal aging

•Fatigue, prolonged sleep
•Progressive muscle loss, stiff gait
•Mild to moderate weight loss
•Bad breath (halitosis)
•Loss of appetite, mild nausea
•Occasional vomiting or diarrhea

Intermediate stage

Consult your veterinarian

•Increased urination (polyuria)
•Noticeably increased thirst (polydipsia)
•Withdrawal, quieter behavior
•Mild breathing difficulty or panting
•Excessive drooling, oral discomfort
•Unkempt coat, reduced self-grooming

Advanced stage

Urgent consultation recommended

•Sunken eyes, severe dehydration
•Oral ulcers (gums, tongue)
•Unsteady gait (ataxia), marked weakness
•Nighttime vocalizations, disorientation
•Seizures (if uremia is very severe)

Emergencies

When to seek immediate care?

These signs indicate acute renal decompensation or a serious complication requiring immediate veterinary care.

Respiratory distress, intense panting
Inability to move, sudden collapse
Seizures or tremors
Complete refusal to eat for several consecutive days
Uncontrollable vomiting or diarrhea
Prostration, unresponsive to stimuli
Vocalizations of intense pain

In an emergency, contact your veterinarian or an emergency clinic immediately.

Diagnosis

How is the diagnosis made?

Many cats with CKD show no clinical signs in the early phase. Regular checkups starting at age 7 to 9 is the best way to detect the disease before symptoms appear.

SDMAThe SDMA (symmetric dimethylarginine) marker can detect kidney failure up to 17 months before creatinine rises, when only 25 to 40% of kidney function has been lost. It is now the reference marker for early feline CKD screening.

Blood tests

BUN (blood urea nitrogen) and creatinine levels to assess azotemia. SDMA is a more sensitive marker detecting kidney function loss much earlier. Complete panel including electrolytes, phosphorus, potassium, and blood count (anemia).

Urinalysis

Urine specific gravity measurement: dilute urine (isosthenuria) is an important early sign. Assessment for protein (urine protein-to-creatinine ratio), abnormal cells, crystals, and bacteria.

Imaging

Abdominal X-rays to evaluate kidney size and shape. Ultrasound to examine kidney structure, detect cysts (polycystic disease), kidney stones, or focal lesions.

Additional tests

Urine culture to rule out underlying infection. Blood pressure measurement (hypertension is frequent). Active screening for comorbidities: hyperthyroidism, dental disease, heart disease, whose management can slow kidney progression.

Treatment

Treatment and management

CKD is not curable, but it is manageable. The goal is to slow progression, support remaining kidney function, and ensure the best possible quality of life. A personalized plan, regularly adjusted, is essential.

Renal diet

Wet food (cans): promotes natural hydration and reduces kidney workload.
Low phosphorus: reduces hyperphosphatemia, which accelerates kidney damage.
High-quality protein, controlled amount: limits nitrogenous waste production without causing malnutrition.
Veterinary prescription: renal foods (Hills k/d, Royal Canin Renal, etc.) meet strict criteria; do not substitute without advice.

Hydration

Water fountains: encourage voluntary drinking and reduce urine concentration.
Exclusive wet food: provides 70 to 80% of required water directly through food.
Subcutaneous fluids at home: technique taught by the veterinarian for advanced stages; prevents dehydration crises.
Periodic hospitalizations: intravenous fluid therapy during acute decompensations.

Medications and supplements

Antihypertensives: amlodipine, telmisartan, benazepril to control blood pressure and reduce proteinuria.
Phosphate binders: calcium carbonate, chitosan: reduce intestinal phosphorus absorption.
Anti-nausea / appetite stimulants: maropitant, mirtazapine, ondansetron to maintain adequate food intake.
Anemia treatment: recombinant erythropoietin, darbepoetin, iron supplements based on severity.

Comorbidities and follow-up

Hyperthyroidism: must be managed carefully (risk of unmasking underlying CKD); close kidney monitoring after treatment.
Urinary tract infections: culture and targeted antibiotherapy; untreated infections accelerate deterioration.
Dental disease: source of chronic inflammation that can worsen kidney progression.
Regular monitoring: blood and urine panels every 3 to 6 months to continuously adjust treatment.

Prognosis

IRIS stages and prognosis

The IRIS (International Renal Interest Society) system classifies CKD into 4 stages based on plasma creatinine and SDMA. The stage guides therapeutic decisions and provides an indication of long-term prognosis.

Stage 1

Asymptomatic

Créatinine: < 1.6 mg/dLSDMA: < 18 µg/dL

No measurable azotemia. Detected only via SDMA or urinalysis. Excellent prognosis with early management: several years of good quality of life are achievable.

Stage 2

Mildly azotemic

Créatinine: 1.6 to 2.8 mg/dLSDMA: 18 to 25 µg/dL

Clinical signs often absent or subtle. The vast majority of cats respond well to treatment and maintain good quality of life for 2 to 5 years or more.

Stage 3

Moderately azotemic

Créatinine: 2.9 to 5.0 mg/dLSDMA: 26 to 38 µg/dL

Clinical signs present and often significant. Intensified treatment. Median survival of 1 to 3 years with good management. Quality of life can be preserved with rigorous follow-up.

Stage 4

Severely azotemic

Créatinine: > 5.0 mg/dLSDMA: > 38 µg/dL

Severe uremia, risk of crises. Survival of weeks to a few months. Palliative care for comfort. Euthanasia should be considered when quality of life becomes unacceptable.

Prognosis is also influenced by comorbidities (hypertension, anemia, proteinuria), response to treatment, and speed of care implementation. A Stage 2 cat with severe hypertension or proteinuria may progress faster than a well-controlled Stage 3 cat.

Home care

Improving daily comfort

Raised, easily accessible food and water bowls

Filtered or fresh water, changed daily

Water fountain to encourage drinking

Prescription renal wet food

Quiet, warm, secure resting places

Multiple clean litter boxes, easily accessible (no stairs if possible)

Subcutaneous fluids at home

For cats in Stage 3 or 4, administering subcutaneous fluids at home (100 to 150 ml, 2 to 3 times per week) can significantly improve their comfort and reduce hospitalizations. Your veterinarian will train you on the technique: it is simpler than it looks, and most cats tolerate it very well.

Active disease management

Strictly follow all prescribed medications (antihypertensives, phosphate binders, etc.)

Monitor appetite, water intake, and urine volume every day

Weigh your cat weekly: sudden weight loss is a warning sign

Control stress: avoid sudden changes, loud noises, unsupervised new animals

Regular veterinary visits (every 3 to 6 months minimum) to continuously adjust treatment

Adapted enrichment: gentle toys, perches, calm interaction; avoid intense exercise when the cat is weak

Maintain a stable routine and accessible quiet spaces at all times

Monitor every day

Appetite and food intake

Urine volume and appearance

Weight and energy level

FAQ

Frequently asked questions

How can CKD be detected before symptoms appear?

The SDMA marker can detect kidney function loss when only 25 to 40% of renal capacity is gone, approximately 17 months before creatinine levels rise. Annual blood panels including SDMA starting at age 7 is the best early screening strategy. Urine specific gravity is another early indicator: dilute urine can signal CKD even before blood markers rise.

My cat has both hyperthyroidism and CKD: which to treat first?

This is a delicate question. Hyperthyroidism increases renal blood flow and can mask CKD: creatinine may appear normal despite underlying kidney failure. Treating hyperthyroidism without closely monitoring the kidneys can reveal CKD that seemed absent. Current recommendation: start hyperthyroidism treatment gradually, with close kidney monitoring at 1, 3, and 6 weeks after starting treatment.

Do I really need to give subcutaneous injections at home?

Not necessarily, but for cats in advanced stages, home subcutaneous fluids often significantly improve comfort, reduce hospitalizations, and can extend survival. The technique is taught by the veterinarian and tolerated well by most cats. Most owners, even without medical experience, manage it very well after a demonstration. If your cat is in Stage 3 or 4, discuss this option with your veterinarian.

My CKD cat has a poor appetite; how do I help maintain weight?

Loss of appetite is one of the most challenging complications to manage. Effective strategies: gently warm food (releases aromas), offer several small meals instead of two large ones, try different renal food textures and flavors. Appetite stimulants such as mirtazapine (tablet or transdermal gel) or capromorelin can be prescribed. The anti-nausea drug maropitant helps when nausea is present. Never switch back to non-renal food without veterinary advice.

Is CKD hereditary? Could my other cat develop it?

Certain breeds have a genetic predisposition: Persians and Himalayans are predisposed to polycystic kidney disease (PKD), a hereditary form of CKD detectable by ultrasound or DNA test. Siamese and Abyssinians also show a slight predisposition. That said, the vast majority of feline CKD cases are idiopathic (unknown cause) or age-related. Regular screening of all cats over age 7 remains recommended regardless of breed.

When does euthanasia become the most humane decision?

Terminal CKD manifests as complete anorexia, extreme weakness, seizures, disorientation, and inability to enjoy anything. When your cat no longer eats, cannot move comfortably, and appears to be in constant suffering despite care, euthanasia is the most compassionate act. Your veterinarian can help objectively assess quality of life (QoL scales) and support you through this decision.

This guide is provided for informational and educational purposes only. It does not constitute veterinary medical advice and is not a substitute for a consultation with a qualified veterinarian. Every animal is unique; their health must be evaluated individually. If you have concerns about your cat's health, contact our clinic or consult a veterinarian promptly.

Your senior cat deserves regular kidney screening.

Early detection can make all the difference. Our team is here to support you at every stage of your cat's kidney disease.

Book an appointment 514 223-1197