What Is Chronic Kidney Disease (CKD)?
Chronic kidney disease (CKD) is one of the most common conditions in middle-aged and senior cats, affecting approximately 30 to 40% of cats over 10 years old. The kidneys play a vital role in the body: they filter waste products from the blood, regulate electrolyte balance, control blood pressure, and produce essential hormones. When this function progressively declines, the body begins to accumulate toxins that should be eliminated through urine.
Unlike acute kidney injury — which appears suddenly and may have reversible causes — CKD develops slowly and silently over months or years. This is why early diagnosis is essential to slow the progression of the disease and maintain the animal's quality of life.
What Are the Warning Signs?
CKD symptoms in cats can be subtle at first, making them difficult for owners to detect. Watch out for the following signs:
- Increased thirst and urinary frequency — the cat drinks more water and urinates more frequently or in larger volumes
- Progressive weight loss, even with apparently normal appetite
- Lethargy and lack of energy — the cat sleeps more and plays less
- Frequent vomiting, especially in the morning or after eating
- Ammonia-smelling breath (elevated blood urea)
- Dull, poorly maintained coat
- Decreased appetite in more advanced stages
- High blood pressure, which can cause vision problems
It is important to note that cats are experts at hiding discomfort. Many owners only notice the signs when the disease is already at an intermediate or advanced stage — reinforcing the importance of regular check-ups.
How Is It Diagnosed?
The veterinarian diagnoses CKD through a combination of tests:
Blood Tests
- Creatinine and BUN (blood urea nitrogen): classic markers of kidney function, elevated when there is significant loss of function
- SDMA (symmetric dimethylarginine): a more sensitive biomarker, capable of detecting CKD up to 17 months before creatinine levels change — excellent for early diagnosis
- Phosphorus, potassium, and other electrolytes
Urinalysis
Reduced urine specific gravity (very dilute urine) is one of the first signs that the kidneys are unable to properly concentrate the filtrate.
Blood Pressure
Hypertension is common in cats with CKD and must be monitored and treated, as it worsens kidney damage and can compromise vision.
Abdominal Ultrasound
Allows evaluation of the size, shape, and structure of the kidneys, as well as identification of cysts, stones, or other changes.
CKD Staging: The IRIS System
The International Renal Interest Society (IRIS) developed a widely used staging system to classify CKD into four stages, based primarily on creatinine and SDMA levels:
| Stage | Creatinine (mg/dL) | Description |
|---|---|---|
| 1 | < 1.6 | Non-azotemic; changes detected by other means |
| 2 | 1.6 – 2.8 | Mild azotemia |
| 3 | 2.9 – 5.0 | Moderate azotemia |
| 4 | > 5.0 | Severe azotemia |
The earlier the diagnosis, the greater the window of time for effective intervention.
Treatment and Management Options
CKD has no cure, but it is fully manageable. The goal of treatment is to slow progression, control symptoms, and maintain the cat's quality of life for as long as possible.
Renal Diet
Diet is the foundation of CKD management. Therapeutic renal diets are formulated with:
- Phosphorus restriction — reduces kidney workload and slows progression
- High-quality protein in controlled amounts — minimizes urea accumulation
- Higher moisture content — wet food is strongly recommended to increase water intake
Never change your cat's diet without veterinary guidance.
Hydration
Keeping the cat well hydrated is essential. In addition to wet food, running water sources (circulating fountains) encourage consumption. In more advanced stages, the veterinarian may recommend subcutaneous home fluid therapy.
Medications and Supplements
Depending on the stage and test results, the following may be indicated:
- Antihypertensives (amlodipine) to control blood pressure
- Phosphate binders to reduce intestinal absorption
- Potassium supplementation if hypokalemia is present
- Appetite stimulants and antiemetics in more advanced stages
- Erythropoietin if severe anemia is present
Regular Monitoring
Cats diagnosed with CKD should have regular veterinary follow-up — generally every 3 to 6 months at Stage 2, and more frequently at Stages 3 and 4. Routine tests allow quick adjustments to treatment before the situation worsens.
Prevention and Early Detection
Although it is not always possible to prevent CKD — especially when there is a genetic predisposition — some measures help with early detection:
- Annual check-up from age 7, including complete blood count, serum biochemistry, and urinalysis
- Adequate hydration throughout life
- Avoid nephrotoxic medications without veterinary supervision (such as some anti-inflammatories)
- Up-to-date vaccination to prevent infections that can compromise the kidneys
A Note About the Veterinary Consultation
Close monitoring between owner and veterinarian is essential in CKD management. Bringing a detailed history — how much the cat drank, ate, whether it vomited, what the urine was like — makes an enormous difference in the quality of the consultation and clinical decisions.
Tools that help veterinarians efficiently record and organize this information contribute directly to more precise and personalized care for each patient. Modern veterinary medicine is increasingly moving toward this model of continuous, data-driven monitoring.
If you suspect your cat may have CKD, or if it is over 7 years old and has not yet had a kidney check-up, consult your veterinarian. Early diagnosis can make all the difference.
